Lincoln Electric Welder SVM141 A User Manual
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SVM141-A  
November, 1998  
Square Wave TIG 275  
For use with machine code numbers: 10523 & 10525  
Safety Depends on You  
Lincoln arc welding and cutting  
equipment is designed and built  
with safety in mind. However,  
your overall safety can be in-  
creased by proper installation . . .  
and thoughtful operation on  
your part. DO NOT INSTALL,  
OPERATE OR REPAIR THIS  
EQUIPMENT WITHOUT  
READING THIS MANUAL AND  
THE SAFETY PRECAUTIONS  
CONTAINED THROUGHOUT.  
And, most importantly, think  
before you act and be careful.  
SERVICE MANUAL  
World's Leader in Welding and Cutting Products  
Premier Manufacturer of Industrial Motors  
• Sales and Service through Subsidiaries and Distributors Worldwide •  
Cleveland, Ohio 44117-1199 U.S.A. TEL: 216.481.8100 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com  
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ii  
ii  
SAFETY  
ARC RAYS can burn.  
ELECTRIC SHOCK can kill.  
3.a. The electrode and work (or ground) circuits  
are electrically “hot” when the welder is on.  
Do not touch these “hot” parts with your bare  
skin or wet clothing. Wear dry, hole-free  
gloves to insulate hands.  
4.a. Use a shield with the proper filter and cover  
plates to protect your eyes from sparks and  
the rays of the arc when welding or observing  
open arc welding. Headshield and filter lens  
should conform to ANSI Z87. I standards.  
4.b. Use suitable clothing made from durable flame-resistant  
material to protect your skin and that of your helpers from  
the arc rays.  
3.b. Insulate yourself from work and ground using dry insulation.  
Make certain the insulation is large enough to cover your full  
area of physical contact with work and ground.  
4.c. Protect other nearby personnel with suitable, non-flammable  
screening and/or warn them not to watch the arc nor expose  
themselves to the arc rays or to hot spatter or metal.  
In addition to the normal safety precautions, if welding  
must be performed under electrically hazardous  
conditions (in damp locations or while wearing wet  
clothing; on metal structures such as floors, gratings or  
scaffolds; when in cramped positions such as sitting,  
kneeling or lying, if there is a high risk of unavoidable or  
accidental contact with the workpiece or ground) use  
the following equipment:  
FUMES AND GASES  
can be dangerous.  
5.a. Welding may produce fumes and gases  
hazardous to health. Avoid breathing these  
• Semiautomatic DC Constant Voltage (Wire) Welder.  
• DC Manual (Stick) Welder.  
• AC Welder with Reduced Voltage Control.  
fumes and gases.When welding, keep  
your head out of the fume. Use enough  
ventilation and/or exhaust at the arc to keep  
3.c. In semiautomatic or automatic wire welding, the electrode,  
electrode reel, welding head, nozzle or semiautomatic  
welding gun are also electrically “hot”.  
fumes and gases away from the breathing zone. When  
welding with electrodes which require special  
ventilation such as stainless or hard facing (see  
instructions on container or MSDS) or on lead or  
cadmium plated steel and other metals or coatings  
which produce highly toxic fumes, keep exposure as  
low as possible and below Threshold Limit Values (TLV)  
using local exhaust or mechanical ventilation. In  
confined spaces or in some circumstances, outdoors, a  
respirator may be required. Additional precautions are  
also required when welding on galvanized steel.  
3.d. Always be sure the work cable makes a good electrical  
connection with the metal being welded. The connection  
should be as close as possible to the area being welded.  
3.e. Ground the work or metal to be welded to a good electrical  
(earth) ground.  
3.f. Maintain the electrode holder, work clamp, welding cable and  
welding machine in good, safe operating condition. Replace  
damaged insulation.  
5.b. Do not weld in locations near chlorinated hydrocarbon vapors  
coming from degreasing, cleaning or spraying operations.  
The heat and rays of the arc can react with solvent vapors to  
form phosgene, a highly toxic gas, and other irritating  
products.  
3.g. Never dip the electrode in water for cooling.  
3.h. Never simultaneously touch electrically “hot” parts of  
electrode holders connected to two welders because voltage  
between the two can be the total of the open circuit voltage  
of both welders.  
5.c. Shielding gases used for arc welding can displace air and  
cause injury or death. Always use enough ventilation,  
especially in confined areas, to insure breathing air is safe.  
3.i. When working above floor level, use a safety belt to protect  
yourself from a fall should you get a shock.  
5.d. Read and understand the manufacturer’s instructions for this  
equipment and the consumables to be used, including the  
material safety data sheet (MSDS) and follow your  
employer’s safety practices. MSDS forms are available from  
your welding distributor or from the manufacturer.  
3.j. Also see Items 6.c. and 8.  
5.e. Also see item 1.b.  
Mar ‘95  
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iii  
iii  
SAFETY  
WELDING SPARKS can  
cause fire or explosion.  
CYLINDER may explode  
if damaged.  
6.a. Remove fire hazards from the welding area.  
If this is not possible, cover them to prevent  
7.a. Use only compressed gas cylinders  
containing the correct shielding gas for the  
the welding sparks from starting a fire.  
Remember that welding sparks and hot  
materials from welding can easily go through small cracks  
and openings to adjacent areas. Avoid welding near  
hydraulic lines. Have a fire extinguisher readily available.  
process used and properly operating  
regulators designed for the gas and  
pressure used. All hoses, fittings, etc. should be suitable for  
the application and maintained in good condition.  
7.b. Always keep cylinders in an upright position securely  
chained to an undercarriage or fixed support.  
6.b. Where compressed gases are to be used at the job site,  
special precautions should be used to prevent hazardous  
situations. Refer to “Safety in Welding and Cutting” (ANSI  
Standard Z49.1) and the operating information for the  
equipment being used.  
7.c. Cylinders should be located:  
•Away from areas where they may be struck or subjected to  
physical damage.  
6.c. When not welding, make certain no part of the electrode  
circuit is touching the work or ground. Accidental contact can  
cause overheating and create a fire hazard.  
•A safe distance from arc welding or cutting operations and  
any other source of heat, sparks, or flame.  
7.d. Never allow the electrode, electrode holder or any other  
electrically “hot” parts to touch a cylinder.  
6.d. Do not heat, cut or weld tanks, drums or containers until the  
proper steps have been taken to insure that such procedures  
will not cause flammable or toxic vapors from substances  
inside. They can cause an explosion even though they have  
been “cleaned”. For information, purchase “Recommended  
Safe Practices for the Preparation for Welding and Cutting of  
Containers and Piping That Have Held Hazardous  
Substances”, AWS F4.1 from the American Welding Society  
(see address above).  
7.e. Keep your head and face away from the cylinder valve outlet  
when opening the cylinder valve.  
7.f. Valve protection caps should always be in place and hand  
tight except when the cylinder is in use or connected for  
use.  
7.g. Read and follow the instructions on compressed gas  
cylinders, associated equipment, and CGA publication P-l,  
“Precautions for Safe Handling of Compressed Gases in  
Cylinders,” available from the Compressed Gas Association  
1235 Jefferson Davis Highway, Arlington, VA 22202.  
6.e. Vent hollow castings or containers before heating, cutting or  
welding. They may explode.  
6.f. Sparks and spatter are thrown from the welding arc. Wear oil  
free protective garments such as leather gloves, heavy shirt,  
cuffless trousers, high shoes and a cap over your hair. Wear  
ear plugs when welding out of position or in confined places.  
Always wear safety glasses with side shields when in a  
welding area.  
FOR ELECTRICALLY  
powered equipment.  
6.g. Connect the work cable to the work as close to the welding  
area as practical. Work cables connected to the building  
framework or other locations away from the welding area  
increase the possibility of the welding current passing  
through lifting chains, crane cables or other alternate circuits.  
This can create fire hazards or overheat lifting chains or  
cables until they fail.  
8.a. Turn off input power using the disconnect  
switch at the fuse box before working on  
the equipment.  
8.b. Install equipment in accordance with the U.S. National  
Electrical Code, all local codes and the manufacturer’s  
recommendations.  
6.h. Also see item 1.c.  
8.c. Ground the equipment in accordance with the U.S. National  
Electrical Code and the manufacturer’s recommendations.  
Mar ‘95  
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iv  
iv  
SAFETY  
PRÉCAUTIONS DE SÛRETÉ  
6. Eloigner les matériaux inflammables ou les recouvrir afin de  
prévenir tout risque d’incendie dû aux étincelles.  
Pour votre propre protection lire et observer toutes les instructions  
et les précautions de sûreté specifiques qui parraissent dans ce  
manuel aussi bien que les précautions de sûreté générales suiv-  
antes:  
7. Quand on ne soude pas, poser la pince à une endroit isolé de  
la masse. Un court-circuit accidental peut provoquer un  
échauffement et un risque d’incendie.  
Sûreté Pour Soudage A L’Arc  
8. S’assurer que la masse est connectée le plus prés possible de  
la zone de travail qu’il est pratique de le faire. Si on place la  
masse sur la charpente de la construction ou d’autres endroits  
éloignés de la zone de travail, on augmente le risque de voir  
passer le courant de soudage par les chaines de levage,  
câbles de grue, ou autres circuits. Cela peut provoquer des  
risques d’incendie ou d’echauffement des chaines et des  
câbles jusqu’à ce qu’ils se rompent.  
1. Protegez-vous contre la secousse électrique:  
a. Les circuits à l’électrode et à la piéce sont sous tension  
quand la machine à souder est en marche. Eviter toujours  
tout contact entre les parties sous tension et la peau nue  
ou les vétements mouillés. Porter des gants secs et sans  
trous pour isoler les mains.  
b. Faire trés attention de bien s’isoler de la masse quand on  
soude dans des endroits humides, ou sur un plancher met-  
allique ou des grilles metalliques, principalement dans  
les positions assis ou couché pour lesquelles une grande  
partie du corps peut être en contact avec la masse.  
c. Maintenir le porte-électrode, la pince de masse, le câble de  
soudage et la machine à souder en bon et sûr état defonc-  
tionnement.  
9. Assurer une ventilation suffisante dans la zone de soudage.  
Ceci est particuliérement important pour le soudage de tôles  
galvanisées plombées, ou cadmiées ou tout autre métal qui  
produit des fumeés toxiques.  
10. Ne pas souder en présence de vapeurs de chlore provenant  
d’opérations de dégraissage, nettoyage ou pistolage. La  
chaleur ou les rayons de l’arc peuvent réagir avec les vapeurs  
du solvant pour produire du phosgéne (gas fortement toxique)  
ou autres produits irritants.  
d.Ne jamais plonger le porte-électrode dans l’eau pour le  
refroidir.  
e. Ne jamais toucher simultanément les parties sous tension  
des porte-électrodes connectés à deux machines à soud-  
er parce que la tension entre les deux pinces peut être le  
total de la tension à vide des deux machines.  
11. Pour obtenir de plus amples renseignements sur la sûreté, voir  
le code “Code for safety in welding and cutting” CSA Standard  
W 117.2-1974.  
f. Si on utilise la machine à souder comme une source de  
courant pour soudage semi-automatique, ces precautions  
pour le porte-électrode s’applicuent aussi au pistolet de  
soudage.  
2. Dans le cas de travail au dessus du niveau du sol, se protéger  
contre les chutes dans le cas ou on recoit un choc. Ne jamais  
enrouler le câble-électrode autour de n’importe quelle partie  
du corps.  
PRÉCAUTIONS DE SÛRETÉ POUR  
LES MACHINES À SOUDER À  
TRANSFORMATEUR ET À  
REDRESSEUR  
3. Un coup d’arc peut être plus sévère qu’un coup de soliel,  
donc:  
a. Utiliser un bon masque avec un verre filtrant approprié  
ainsi qu’un verre blanc afin de se protéger les yeux du ray-  
onnement de l’arc et des projections quand on soude ou  
quand on regarde l’arc.  
1. Relier à la terre le chassis du poste conformement au code de  
l’électricité et aux recommendations du fabricant. Le dispositif  
de montage ou la piece à souder doit être branché à une  
bonne mise à la terre.  
b. Porter des vêtements convenables afin de protéger la  
peau de soudeur et des aides contre le rayonnement de  
l‘arc.  
2. Autant que possible, I’installation et l’entretien du poste seront  
effectués par un électricien qualifié.  
c. Protéger l’autre personnel travaillant à proximité au  
soudage à l’aide d’écrans appropriés et non-inflammables.  
3. Avant de faires des travaux à l’interieur de poste, la debranch-  
er à l’interrupteur à la boite de fusibles.  
4. Des gouttes de laitier en fusion sont émises de l’arc de  
soudage. Se protéger avec des vêtements de protection libres  
de l’huile, tels que les gants en cuir, chemise épaisse, pan-  
talons sans revers, et chaussures montantes.  
4. Garder tous les couvercles et dispositifs de sûreté à leur  
place.  
5. Toujours porter des lunettes de sécurité dans la zone de  
soudage. Utiliser des lunettes avec écrans lateraux dans les  
zones où l’on pique le laitier.  
Mar. ‘93  
SQUARE WAVE TIG 275  
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v
v
MASTER TABLE OF CONTENTS FOR ALL SECTIONS  
RETURN TO MAIN INDEX  
Page  
Safety...................................................................................................................................................................i-iv  
Installation...............................................................................................................................................Section A  
Technical Specifications ...............................................................................................................................A-2  
Safety Precautions .......................................................................................................................................A-3  
Input Supply Connections ............................................................................................................................A-4  
Input Reconnect Procedure .........................................................................................................................A-5  
User Supplied Connectors ...........................................................................................................................A-6  
Output Connections......................................................................................................................................A-6  
Work Cable Connection ...............................................................................................................................A-6  
TIG Torch Connection ..................................................................................................................................A-7  
Twist-Mate Adapter for LA-9 and LA-17 TIG Torch......................................................................................A-8  
Twist-Mate Adapter for LW-18 and LW-20 TIG Torch...................................................................................A-8  
Stick Electrode Cable Connection................................................................................................................A-9  
Operation.................................................................................................................................................Section B  
Safety Precautions .......................................................................................................................................B-2  
General Description......................................................................................................................................B-3  
Recommended Processes and Equipment..................................................................................................B-3  
Design Features and Advantages................................................................................................................B-3  
Welding Capability........................................................................................................................................B-4  
Limitations ....................................................................................................................................................B-4  
Controls and Settings...................................................................................................................................B-5  
Welding Operation........................................................................................................................................B-6  
Stick Welding................................................................................................................................................B-9  
Auxiliary Power.............................................................................................................................................B-9  
Accessories ............................................................................................................................................Section C  
Maintenance............................................................................................................................................Section D  
Safety Precautions.......................................................................................................................................D-2  
Routine and Periodic Maintenance..............................................................................................................D-2  
Overload Protection .....................................................................................................................................D-2  
Fan As Needed (F.A.N.)...............................................................................................................................D-2  
Service Procedures......................................................................................................................................D-2  
Component Location and Access ................................................................................................................D-3  
Spark Gap Adjustment.................................................................................................................................D-3  
Theory of Operation ...............................................................................................................................Section E  
General Description......................................................................................................................................E-2  
Input Power Circuit.......................................................................................................................................E-2  
Output Rectification, Control Board and Feedback......................................................................................E-3  
High Voltage / High Frequency Circuit.........................................................................................................E-4  
DC Welding Output ......................................................................................................................................E-5  
AC Welding Output.......................................................................................................................................E-6  
SCR Operation.............................................................................................................................................E-7  
Protective Circuits ........................................................................................................................................E-8  
Troubleshooting and Repair..................................................................................................................Section F  
How to Use Troubleshooting Guide .............................................................................................................F-2  
PC Board Troubleshooting Procedures........................................................................................................F-3  
Troubleshooting Guide .................................................................................................................................F-4  
Test Procedures..........................................................................................................................................F-18  
Oscilloscope Waveforms ............................................................................................................................F-33  
Replacement Procedures...........................................................................................................................F-42  
Retest After Repair.....................................................................................................................................F-59  
Electrical Diagrams................................................................................................................................Section G  
Parts Manual .......................................................................................................................................P316 Series  
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Section A-1  
Section A-1  
TABLE OF CONTENTS  
- INSTALLATION SECTION -  
Installation.............................................................................................................................Section A  
Technical Specifications, Square Wave TIG 275 (K1617-1) .......................................................A-2  
Safety Precautions......................................................................................................................A-3  
Select Suitable Location .....................................................................................................A-3  
Stacking...............................................................................................................................A-3  
Lifting and Moving...............................................................................................................A-3  
Tilting...................................................................................................................................A-3  
Environmental Rating ..........................................................................................................A-3  
Machine Grounding and High Frequency Interference Protection .....................................A-3  
Input Supply Connections ..........................................................................................................A-4  
Input Reconnect Procedure........................................................................................................A-5  
User Supplied Connectors .........................................................................................................A-6  
Output Connections....................................................................................................................A-6  
Work Cable Connection..............................................................................................................A-6  
TIG Torch Connection.................................................................................................................A-7  
Twist-Mate Adapter for LA-9 and LA-17 TIG Torch....................................................................A-8  
Twist-Mate Adapter for LW-18 and LW-20 TIG Torch................................................................A-8  
Stick Electrode Cable Connection..............................................................................................A-9  
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A-2  
A-2  
INSTALLATION  
TECHNICAL SPECIFICATIONS - Square Wave TIG 275  
INPUT - SINGLE PHASE ONLY  
Input Current at  
40% Duty Cycle  
Input Current at  
60% Duty Cycle  
Input Current at  
100% Duty Cycle  
Idle Current  
Idle Power  
Standard  
Voltage  
Code  
Number  
DC  
95/86/43 130/120/61  
43/35 61/49  
AC  
DC  
76/69/34 106/97/50 57/52/26 82/75/38  
34/28 50/41 26/21 38/31  
AC  
DC  
AC  
5/4/2  
2/1.5  
900 W Max.  
900 W Max.  
208/230/460/1/60 (K1617-1)  
460/575/1/60 (K1617-2)  
10523  
10525  
RATED OUTPUT & ADDITIONAL OUTPUT CAPACITY  
Duty Cycle  
Amps  
Volts at Rated Amperes  
Current Range  
Auxiliary Power  
40% Duty Cycle  
DC TIG & AC/DC Stick  
275 A  
255 A  
31.0 V  
16.1 V  
5-315 Amps  
115 Volts AC, 10 Amps  
NEMA Class II (40)  
AC TIG  
Grounded NEMA-5-15R  
Receptacle and  
60% Duty Cycle  
DC TIG & AC/DC Stick  
AC TIG  
225 A  
200 A  
29.0 V  
15.4 V  
MAX O.C.V.  
AC & DC 80V  
10 Amp Circuit Breaker  
100% Duty Cycle DC TIG & AC/DC Stick  
AC TIG  
175 A  
150 A  
27.0 V  
14.8 V  
Normal O.C.V.  
72 V (AC) 59 V (DC)  
RECOMMENDED INPUT WIRE AND FUSE SIZES  
For all Stick, DC TIG and Balanced AC TIG  
For Unbalanced AC TIG Welding above 180A,  
255A 40% Duty Cycle, Maximum Penetration  
w/o Optional K1620-1 Power Factor Capacitors  
Based on the 1996 U.S. National Electrical Code  
Welding at 275A 40% Duty Cycle  
w/o Optional K1620-1 Power Factor Capacitors  
Based on the 1996 U.S. National Electrical Code  
Type 75°C  
Type 75°C  
Copper  
Type 75°C  
Type 75°C  
Copper  
Input  
Fuse  
Input  
Copper Wire in  
Fuse  
Input  
Copper Wire in  
Voltage / (Super Lag) Amperes  
Conduit AWG Ground Wire in (Super Lag) Amperes  
Conduit AWG Ground Wire in  
phase/  
or Breaker  
Size(1)  
(IEC) Sizes  
Conduit AWG or Breaker  
(IEC) Sizes  
Conduit AWG  
(IEC) Sizes  
Frequency  
40°C (104°F) Ambient  
(IEC) Sizes  
Size(1)  
150  
150  
70  
40°C (104°F) Ambient  
2
2
2
2
208/1/60  
230/1/60  
460/1/60  
575/1/60  
125  
125  
60  
111  
100  
50  
4 (21.2 mm )  
6 (13.3 mm )  
130  
120  
61  
3 (25.0 mm )  
6 (13.3 mm )  
2
2
2
2
4 (21.2 mm )  
6 (13.3 mm )  
3 (25.0 mm )  
6 (13.3 mm )  
2
2
2
2
8 (8.4 mm )  
10 (5.3 mm )  
8 (8.4 mm )  
8 (8.4 mm )  
2
2
2
2
50  
40  
10 (5.3 mm )  
10 (5.3 mm )  
60  
49  
8 (8.4 mm )  
10 (5.3 mm )  
(1)  
Also called “inverse time” or “thermal/magnetic” circuit breakers; circuit breakers which have a delay in tripping action that decreases as the magnitude of cur-  
rent increases.  
PHYSICAL DIMENSIONS  
Height  
Width  
Depth  
Weight  
Power  
Source  
24.06 in.  
611 mm  
Lift Hook add 3.57” (91 mm)  
19.15 in.  
486 mm  
28.00 in.  
711 mm  
Approx. 330 lbs.  
150 kg.  
Power Source  
on  
33.40 in.  
848 mm  
27.65 in.  
702 mm  
40.65 in.  
1033 mm  
Approx. 375 lbs.  
170 kg.  
Undercarriage  
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A-3  
A-3  
INSTALLATION  
Read this entire installation section before you  
start installation.  
TILTING  
Each machine must be placed on a secure, level sur-  
face, either directly or on a recommended undercar-  
riage. The machine may topple over if this procedure is  
not followed.  
SAFETY PRECAUTIONS  
WARNING  
ENVIRONMENTAL RATING  
ELECTRIC SHOCK can kill.  
The Square Wave TIG 275 power source carries an  
IP21S environmental rating. It may be used in normal  
industrial and commercial environments. It is rated for  
use in damp, dirty rain-sheltered environments.  
• Only qualified personnel should per-  
form this installation.  
• Turn the input power OFF at the dis-  
connect switch or fuse box before  
working on this equipment.  
MACHINE GROUNDING AND HIGH FRE-  
QUENCY INTERFERENCE PROTECTION  
• Do not touch electrically hot parts.  
• Always connect the Square Wave TIG 275 grounding  
screw (located on the right rear corner of the base) to  
a good electrical earth ground.  
The frame of the welder must be grounded.  
ground screw marked with the symbol is located  
A
at the right rear corner of the base for this purpose.  
See your local and national electrical codes for proper  
grounding methods.  
• Always connect the Square Wave TIG 275 to a power  
supply grounded per the National Electrical Code and  
any local codes.  
The spark gap oscillator in the high frequency genera-  
tor, being similar to a radio transmitter, can be blamed  
for many radio, TV and electronic equipment interfer-  
ence problems. These problems may be the result of  
radiated interference. Proper grounding methods can  
reduce or eliminate radiated interference.  
SELECT SUITABLE LOCATION  
Place the welder where clean cooling air can freely cir-  
culate in through the rear louvers and out through the  
side louvers. Dirt, dust or any foreign material that can  
be drawn into the welder should be kept at a minimum.  
Failure to observe these precautions can result in  
excessive operating temperatures and nuisance trips.  
The Square Wave TIG 275 has been field tested under  
recommended installation conditions and has been  
found to comply with F.C.C. allowable radiation limits.  
A certificate (S14929) is being sent with each welder  
for customer convenience. If he desires or is required  
to obtain certification of compliance with F.C.C. RF  
Energy Radiation Limits, this certificate can be used. It  
is the customer's responsibility to obtain this certifica-  
tion. This welder has also been found to comply with  
NEMA standards for high frequency stabilized power  
sources.  
STACKING  
Square Wave TIG 275’s cannot be stacked.  
LIFTING AND MOVING  
Radiated interference can develop in the following four  
ways:  
The Square Wave TIG 275 should be lifted with a hoist.  
(It weighs approximately 330 lbs./150 kg.) An optional  
undercarriage is available to easily move the unit.  
Refer to the Accessories section of this manual. The  
Square Wave TIG 275 is designed to be used with a  
K932-1 Undercarriage. Complete installation instruc-  
tions are included with the K932-1 Undercarriage.  
When the undercarriage is properly installed, the  
Square Wave TIG 275 lift bale is nonfunctional. Do not  
attempt to lift the power source with the undercar-  
riage attached. The undercarriage is designed for  
hand moving only; mechanized towing can lead to per-  
sonal injury and/or damage to the Square Wave TIG  
275.  
1. Direct interference radiated from the welder.  
2. Direct interference radiated from the welding leads.  
3. Direct interference radiated from feedback into the  
power lines.  
4. Interference from re-radiation of “pickup” by  
ungrounded metallic objects.  
Keeping these contributing factors in mind, installing  
equipment per the following instructions should mini-  
mize problems.  
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A-4  
A-4  
INSTALLATION  
1. Keep the welder power supply lines as short as  
possible and enclose as much of them as possible  
in rigid metallic conduit or equivalent shielding for  
a distance of 50 feet (15.2m). There should be  
good electrical contact between this conduit and  
the welder case ground. Both ends of the conduit  
should be connected to a driven ground and the  
entire length should be continuous.  
INPUT SUPPLY CONNECTIONS  
Be sure the voltage, phase, and frequency of the input  
power is as specified on the rating plate, located on the  
rear of the machine.  
See Figure A.1 for the location of the rating plate, the  
entry hole, and the reconnect panel.  
2. Keep the work and electrode leads as short as  
possible and as close together as possible.  
Lengths should not exceed 25 ft (7.6m). Tape the  
leads together when practical.  
FIGURE A.1  
3. Be sure the torch and work cable rubber coverings  
are free of cuts and cracks that allow high frequen-  
cy leakage. Cables with high natural rubber con-  
tent, such as Lincoln Stable-Arc® better resist high  
frequency leakage than neoprene and other syn-  
thetic rubber insulated cables.  
5
4. Keep the torch in good repair and all connections  
tight to reduce high frequency leakage.  
5. The work piece must be connected to an earth  
ground close to the work clamp, using one of the  
following methods:  
1
a) A metal underground water pipe in direct con-  
tact with the earth for ten feet or more.  
b) A 3/4” (19mm) galvanized pipe or a 5/8”  
(16mm) solid galvanized iron, steel or copper  
rod driven at least eight feet into the ground.  
4
2
3
1. Input Entry  
2. Rating Plate  
3. 115V Receptacle & Breaker  
(60 HZ. Machines only)  
4. 220V Receptacle & Breaker  
(50/60 HZ. Machines Only.)  
5. Gas Input Fitting  
The ground should be securely made and the ground-  
ing cable should be as short as possible using cable of  
the same size as the work cable, or larger. Grounding  
to the building frame electrical conduit or a long pipe  
system can result in re-radiation, effectively making  
these members radiating antennas. (This is not recom-  
mended).  
Remove the right case side to reveal the reconnect  
panel. Welder supply line entry provision is in the case  
rear panel. Entry is through a 1.4 inch (36 mm) diam-  
eter hole in the case back.  
6. Keep all access panels and covers securely in  
place.  
All connections should be made in accordance with all  
local codes and national electrical codes. Installation  
by a qualified electrician is recommended.  
7. All electrical conductors within 50 ft (15.2m) of the  
welder should be enclosed in grounded rigid metal-  
lic conduit or equivalent shielding. Flexible helical-  
ly-wrapped metallic conduit is generally not suit-  
able.  
1. Connect the terminal marked  
(at the base of the  
welder below the reconnect panel) to an earth  
ground.  
8. When the welder is enclosed in a metal building,  
the metal building should be connected to several  
good earth driven electrical grounds (as in 5 (b)  
above) around the periphery of the building.  
2. Connect the imput leads to terminals marked L1 (U)  
and L2 (V) on the reconnect panel. Use a single  
phase line or one phase of a two or three phase line.  
Failure to observe these recommended installation  
procedures can cause radio or TV and electronic  
equipment interference problems and result in unsatis-  
factory welding performance resulting from lost high  
frequency power.  
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A-5  
A-5  
INSTALLATION  
Fuse the input circuit with the recommended super lag  
fuses or delay type1 circuit breakers. Choose an input  
and grounding wire size according to local or national  
codes or refer to the Technical Specifications page at  
the beginning of this section. Using fuses or circuit  
breakers smaller than recommended may result in  
“nuisance” tripping from welder inrush currents even if  
not welding at high currents.  
INPUT RECONNECT PROCEDURE  
On multiple input voltage welders, be sure the recon-  
nect panel is connected per the following instructions-  
for the voltage being supplied to the welder.  
Designations on the reconnect panel, LOW, MID, and  
HIGH correspond to the nameplated input voltages of  
a triple voltage welder. Dual voltage welders use only  
LOW and HIGH.  
Unbalanced AC TIG welding draws higher input cur-  
rents than those for Stick, DC TIG, or Balanced AC TIG  
welding. The welder is designed for these higher input  
currents. However, where unbalanced AC TIG welding  
above 180 amps is planned, the higher input currents  
require larger input wire sizes and fuses per the  
Technical Specifications page at the beginning of this  
section.  
EXAMPLE: On a 208/230/460 volt welder, LOW is  
208V, MID is 230V, and HIGH is 460V.  
Make sure all connections are tight. Replace the case  
side and all screws.  
1
Also called “inverse time” or “thermal/magnetic” circuit breakers, circuit  
breakers which have a delay in tripping action that decreases as the magni-  
tude of the current increases.  
FIGURE A.2  
RECONNECT PANEL INSTRUCTIONS FOR 208/230/460/Domestic model  
SINGLE PHASE INPUT POWER SUPPLY CONNECTION INSTRUCTIONS:  
Powered by high voltage which can kill. Turn off all input  
WARNING:  
power at the disconnect switch or fuse box before making any connections. Use  
input and grounding lead sizes as specified in the operating manual. Failure to follow  
instructions below can cause immediate failure of components within the welder.  
1. Connect the input power leads to the input terminals, L1 (U) and L2 (V), at the right  
below. Connect the input power leads with the hardware provided. Completely  
tighten all fasteners.  
2. Connect  
a
grounding lead to the ground stud located on the machine base near  
the input terminals.  
Welders are shipped connected for the highest rated single phase input voltage  
with the lead marked "A" connected to the stud marked "4 (HIGH)".  
3.  
4. For middle range input, reconnect the lead marked "A" to the stud marked "3 (MID)".  
For low range input, reconnect the lead marked "A" to the stud marked "2 (LOW)".  
5.  
4 (HIGH)  
SINGLE  
3 (MID)  
PHASE  
INPUT  
L1 (U)  
2 (LOW)  
L2 (V)  
LEADS FOR OPTIONAL  
POWER FACTOR CAPACITORS  
208/230/460 DOMESTIC MODEL  
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A-6  
A-6  
INSTALLATION  
Assemble the correct Twist-Mate-adapter plug to the  
work cable as follows:  
USER SUPPLIED CONNECTORS  
The Square Wave TIG 275 should be permanently  
wired into the power system. No plugs or connectors  
are necessary.  
1. Skin the cable jacket to 1.00 in (25.4 mm) for a #2  
thru 2/0 (35 thru 70 mm2) cable. Skin the cable  
jacket to 1.50 in (38.1 mm) for a 2/0 thru 3/0 (70 thru  
95 mm2) cable.  
OUTPUT CONNECTIONS  
WARNING  
2. If necessary, trim the cable end of the rubber boot to  
match the diameter of the cable.  
To avoid being startled by a high frequency shock, keep  
the TIG torch and cables in good condition.  
3. Slide the rubber boot onto the skinned cable end.  
Use soap for lubricant if required.  
ELECTRIC SHOCK can kill.  
BOOT  
• Turn the power switch of the power  
source “OFF” before installing  
adapters on cable or when connecting  
or disconnecting adapter plugs to  
power source.  
WELDING CABLE  
SEE  
ABOVE  
TRIM  
See Figure B.1 for the location of the work and elec-  
trode terminals, the gas and optional water solenoids,  
and the Remote Receptacle.The Square Wave TIG  
275 is equipped with Twist-Mate connectors for the  
electrode and work connection.  
4. Slide the copper tube into the brass plug. Insert  
skinned cable into the copper tube.  
SET SCREW  
(70-95 SIZE MAY  
HAVE 2 SET  
SCREWS)  
WORK CABLE CONNECTION  
The Twist-Mate connection allows fast and reliable  
work cable attachment to the work terminal of the  
Square Wave TIG 275 welding power supply.  
COPPER TUBE  
BRASS PLUG  
Assemble the work cable by attaching the correct  
Twist-Mate adapter and work clamp to an adequately-  
sized welding cable. The Twist-Mate cable plug includ-  
ed with the machine is designed to accept a welding  
cable size of of #2 to #1. See Table A.1 and A.2 for rec-  
ommended sizes and corresponding hardware.  
5. Tighten set screw(s) to collapse copper tube.  
Screw(s) must apply firm pressure against welding  
cable.  
6. Slide the rubber boot over the brass plug. The rub-  
ber boot must be positioned to completely cover all  
electrical surfaces after the plug is locked into the  
receptacle. For more details see S18737PRINT or  
instructions included with the adapter kit.  
TABLE A.1  
Cable Sizes for Combined Lengths of Copper  
Electrode and Work Cable  
Lengths up to  
Machine Size  
100 ft  
100 to 200 ft  
200 to 250 ft  
275 Amp  
40% Duty Cycle  
2
2
2
#1 (42.4mm )  
1/0 (53.5mm )  
2/0 (67.4mm )  
TABLE A.2  
Recommended Work and Stick Electrode  
Components  
Twist Mate  
Cable Plug  
for Work  
Lead  
Twist Mate  
Cable Plug  
for Work  
Lead  
Twist Mate  
Cable Plug  
for Work  
Lead  
Work  
Clamp  
Electrode  
Holder  
(#2 to #1)  
(1/0 to 2/0)  
(2/0 to 3/0)  
K852-50  
K852-70  
K852-95  
K910-1  
K909-4  
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A-7  
A-7  
INSTALLATION  
TIG TORCH CONNECTION  
WARNING  
The Twist-Mate connection allows fast and reliable TIG  
torch attachment to the electrode terminal of the  
Square Wave TIG 275 welding power supply. Twist-  
Mate TIG adapters are made of brass, combining high  
electrical conductivity with mechanical strength. They  
are available in several sizes and styles to accommo-  
date a wide selection of gas and water-cooled TIG  
torches.  
CYLINDER could explode if  
damaged.  
• Keep cylinder upright and chained to a  
support.  
• Keep cylinder away from areas where it could be  
damaged.  
• For Air-Cooled TIG Torch connections refer to TWIST-  
MATE ADAPTER for LA-9 and LA-17 TIG TORCH  
section.  
• Never allow the torch to touch the cylinder.  
• Keep cylinder away from live electrical circuits.  
• Maximum inlet pressure 150 psi.  
• For Water-Cooled TIG TORCH connections refer to  
TWIST-MATE ADAPTER for LW-18 and LW-20 TIG  
TORCH Section.  
The high-pressure cylinder of inert shielding gas must  
be equipped with a flow regulator that limits the gas  
pressure to 150 psi maximum at the machine’s gas  
inlet. This brass inlet fitting is located on the rear panel  
of the Square Wave TIG 275. Install a hose between  
the gas flow meter and the inlet fitting.  
Any torch having hoses and cables equipped with  
Compressed Gas Association (CGA) style fittings can  
be connected to an appropriate Twist-Mate adapter  
(see ACCESSORIES section). The power source  
must be switched off while making any of these  
connections.  
For other conditions, consult the manufacturer’s  
instructions for the water cooler or TIG torch being  
used.  
Do not operate a water-cooled torch without an ade-  
quate coolant supply. Set-ups using recirculated  
coolant require that the cooler be switched on and run-  
ning. If the water solenoid valve option is used with a  
cooler, the coolant does not flow until the solenoid is  
actuated.  
For set-ups using water as a single-pass through  
coolant, install a strainer into the system upstream of  
the Square Wave TIG 275 to reduce the concentration  
of particles that could contaminate the system.  
Otherwise, flow passages could become obstructed or  
clogged, causing torch overheating or failure. The  
optional water solenoid valve may also malfunction.  
When the water solenoid valve option is installed into  
the Square Wave TIG 275, connect the coolant supply  
line from either cooler outlet or single-pass supply to  
the “Water Inlet” fitting located on the machine’s case  
front. Connect the TIG torch’s smaller water fitting to  
the “Water Out” fitting also located on the case front. A  
non-metallic coolant line is required between the elec-  
trode connection and the drain or cooler inlet. This  
reduces the possibility of an electrical hazard.  
TIG welding torches are available with 12.5 and 25 foot  
cables (3.8m and 7.6m, respectively). Use the shorter  
length whenever possible to reduce radio interference  
problems.  
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A-8  
A-8  
INSTALLATION  
TWIST-MATE ADAPTER FOR LA-9  
and LA-17 TIG TORCH  
TWIST-MATE ADAPTER FOR LW-18  
and LW-20 TIG TORCH  
The Twist-Mate connection allows fast and reliable TIG  
torch connections to the electrode terminal of the  
Square Wave TIG 275. The Twist-Mate adapter, strain  
relief boot and retaining compound needed to connect  
an LA-9 or LA-17 torch (or any equivalent air-cooled  
TIG torch with a right-hand male 3/8-24 fitting) are  
included with the Square Wave TIG 275.  
The Twist-Mate connection allows fast and reliable TIG  
torch connections to the electrode terminal of the  
Square Wave TIG 275. The Twist-Mate adapter and  
strain relief boot needed to connect an LW-18 or LW-20  
torch (or any equivalent water-cooled TIG torch with  
the fittings shown in the diagrams under step 2 and 3)  
are included with the Square Wave TIG 275.  
Assemble the the LA-9 or LA-17 TIG torch to the Twist-  
Mate adapter as follows:  
Assemble the the LW-18 or LW-20 TIG torch to the  
Twist-Mate adapter as follows:  
1. Slide the strain relief boot over the TIG torch’s  
power cable with gas fitting.  
1. Slide the strain relief boot over the TIG torch’s  
power/water cable (large fitting) and gas hose  
(small fitting without notches on hex). Also slide a  
water hose into the strain relief boot as shown.  
STRAIN RELIEF BOOT  
TIG ADAPTER  
STRAIN RELIEF BOOT  
TIG ADAPTER  
POWER/WATER CABLE FROM TORCH  
GAS HOSE FROM TORCH  
WATER HOSE  
RETAINING COMPOUND  
TIG TORCH POWER CABLE WITH GAS FITING  
2. Apply a small amount of retaining compound to the  
fitting threads as shown. Thread the fitting to the  
TIG adapter and tighten to ensure a sealed gas  
connection and a good electrical connection. (35-45  
in-lbs)  
2. Thread the power/water cable (large fitting) from the  
torch to the large port on the TIG adapter and tight-  
en to ensure a water tight connection. Next, thread  
the gas hose (small fitting without notches on hex)  
to the port marked “G” on the TIG adapter and tight-  
en to ensure a sealed gas connection. Next, thread  
the water hose to cooler (or to water drain) to the  
port marked “W” on the TIG adapter.  
3. Hold the TIG adapter, with cable installed, firmly in  
place by securing it into the Twist-Mate receptacle  
on the power source or into a padded vise. Align  
the hex in the boot with the hex on the adapter.  
Firmly push the boot onto the adapter, rocking the  
boot to assist installation. Use soap for lubricant if  
required.  
POWER/WATER  
CONNECTION  
PORT (LH 7/8-14)  
WATER CONNECTION  
PORT (LH 5/8-18)  
W
COMPLETED ASSEMBLY  
G
GAS CONNECTION  
PORT (RH 5/8-18)  
3. Check all connections made in step 2 for gas and  
water leaks before proceeding.  
CONNECTION DIAGRAM  
MAGNUM  
WATER COOLER  
4. Examine the strain relief boot and TIG adapter for  
correct assembly. The boot should nest into the  
Twist-Mate receptacle on the power source. All  
electrical surfaces should be completely covered  
when in the Twist-Mate receptacle on the power  
source. For more details see M19115PRINT includ-  
ed with the machine.  
OPTIONAL  
WATER SOLENOID KIT  
COOLANT  
"IN"  
COOLANT  
"OUT"  
COOLANT  
"IN"  
COOLANT  
"OUT"  
OR  
WATER HOSE  
(SEPARATELY PROVIDED)  
WATER HOSE FROM TORCH  
(LH 5/8-18 MALE FITTING)  
LW-18 OR LW-20  
TIG TORCH  
(SEPARATELY PROVIDED)  
HOSE COUPLER  
(SEPARATELY PROVIDED)  
GAS HOSE FROM TORCH  
(RH 5/8-18 MALE FITTING)  
G
WATER HOSE  
(SEPARATELY PROVIDED)  
W
POWER/WATER CABLE FROM TORCH  
(LH 7/8-14 MALE FITTING)  
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A-9  
A-9  
INSTALLATION  
4. Hold the TIG adapter, with cables and hoses installed,  
firmly in place by securing it into the Twist-Mate recep-  
tacle on the power source or into a padded vise.  
Apply a thin film of lubricant to the boot’s lead in  
chamfer area. Also apply lubricant to the lead in  
chamfer and 2” diameter on the TIG adapter. Next  
align the strain relief boot keys with the TIG adapter  
slots. Now firmly push the boot onto the adapter,  
rocking the boot to assist installation.  
STICK ELECTRODE CABLE  
CONNECTION  
The Twist-Mate connection allows fast and reliable stick  
electrode attachment to the electrode terminal of the  
Square Wave TIG 275 welding power supply.  
Assemble the electrode cable by attaching the correct  
Twist-Mate adapter and electrode holder to an ade-  
quately-sized welding cable. See Table A.1 and A.2 for  
recommended sizes and corresponding hardware.  
COMPLETED ASSEMBLY  
Assemble the correct Twist-Mate adapter plug to the  
stick electrode cable as detailed in Work Cable  
Connection.  
WARNING  
DO NOT CONNECT A TIG TORCH AND STICK ELEC-  
TRODE CABLE AT THE SAME TIME. THEY WILL  
BOTH BE ELECTRICALLY HOT WHENEVER THE  
OUTPUT CONTACTOR IS ENERGIZED.  
5. Examine the strain relief boot and TIG adapter for  
correct assembly. The boot should nest into the  
Twist-Mate receptacle on the power source. The  
boot face will be 1/8 inch away from the machine  
front. All electrical surfaces should be completely  
covered when in the Twist-Mate receptacle on the  
power source. For more details see M19116PRINT  
included with the machine.  
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A-10  
A-10  
NOTES  
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Section B-1  
Section B-1  
TABLE OF CONTENTS  
- OPERATION SECTION -  
Operation...............................................................................................................................Section B  
Safety Precautions......................................................................................................................B-2  
General Description....................................................................................................................B-3  
Recommended Processes and Equipment................................................................................B-3  
Design Features and Advantages...............................................................................................B-3  
Welding Capability .....................................................................................................................B-4  
Limitations...................................................................................................................................B-4  
Controls and Settings.................................................................................................................B-5  
Welding Operation ......................................................................................................................B-6  
TIG Welding..........................................................................................................................B-6  
TIG Welding Guidelines........................................................................................................B-6  
TIG Welding Sequence of Operation (2-Step TIG Mode) ....................................................B-7  
TIG Welding Sequence of Operation (4-Step TIG Mode) ....................................................B-7  
Hand and Foot Amptrol Operation.......................................................................................B-8  
Advanced TIG Welding Features................................................................................................B-8  
AC Wave Balance and Auto Balance™......................................................................................B-8  
Stick Welding..............................................................................................................................B-9  
Auxiliary Power ...........................................................................................................................B-9  
60 Hertz Domestic Machines...............................................................................................B-9  
50/60 Hertz European Machines..........................................................................................B-9  
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B-2  
B-2  
OPERATION  
SAFETY PRECAUTIONS  
Read and understand this entire section before operat-  
ing the machine.  
WARNING  
ELECTRIC SHOCK  
can kill.  
• Do not touch electrically live parts or  
electrode with skin or wet clothing.  
•
Insulate yourself from work and ground.  
• Always wear dry insulating gloves.  
•
Read and follow “Electric Shock Warnings”  
in the Safety section if welding must be per-  
formed under electrically hazardous condi-  
tions such as welding in wet areas or on or  
in the workpiece.  
FUMES AND GASES  
can be dangerous.  
• Keep your head out of fumes.  
• Use ventilation or exhaust to  
remove fumes from breathing  
zone.  
WELDING SPARKS  
can cause fire or  
explosion  
• Keep flammable material away.  
• Do not weld on containers that  
have held combustibles.  
ARC RAYS  
can burn.  
• Wear eye, ear and body  
protection.  
Observe additional Safety Guidelines detailed in  
the beginning of this manual.  
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B-3  
B-3  
OPERATION  
machine. A build up of these materials can cause  
excessive operating temperatures and nuisance shut  
downs.  
GENERAL DESCRIPTION  
The Square Wave TIG 275 is a constant current, single  
range square wave AC/DC TIG (GTAW) arc welding  
power source with built-in high frequency stabilization.  
It also has stick (SMAW) capability. A TIG Pulser Kit,  
Power Factor Capacitor Kit, and a Water Solenoid Kit  
are available as field installed options.  
• 2-STEP/4-STEP TIG/STICK mode control switch. 4-  
STEP mode requires the use of an optional Arc Start  
Switch. This welding mode reduces fatigue by elimi-  
nating the need to manually control the weld current  
during the weld.  
The Square Wave TIG 275 includes advanced features  
such as Digital Voltage and Current Meters, Auto  
Balance™, 2-Step/4-Step operation, adjustable Down  
slope Time control and Fan as Needed. It also features  
Twist Mate connections for the electrode and work  
leads. In addition, fixed preflow and variable post flow  
timers are included to control the shielding gas, as well  
as the water flow when using the optional water sole-  
noid.  
• Down Slope Time control is active in 4-STEP TIG  
mode. It controls the amount of time (approximately  
1 to 10 seconds) it takes the weld current to ramp  
down from the Preset level to 25% ±10% of that level.  
• Post Flow Time control is active in the 2 and 4-STEP  
TIG modes. It controls the amount of time (approxi-  
mately 5 to 50 seconds) the shielding gas flows after  
the weld is completed.  
• Robotic Interface connection on the PC board can be  
connected to the machines Remote Receptacle for  
automated welding procedures. This interface allows  
remote control of the trigger and output current of the  
machine as well as providing a signal when the weld  
is established. (For details contact the Lincoln Automation Center)  
RECOMMENDED PROCESSES AND  
EQUIPMENT  
The Square Wave TIG 275 is recommended for the  
TIG (GTAW) and stick (SMAW) welding processes  
within its output capacity of 5 to 315 amps, on both AC  
and DC polarity. It is compatible with all Magnum TIG  
accessories, as well as many industry standard items,  
such as TIG torches, hoses, and water coolers.  
• Built in High Frequency Generator automatically per-  
forms in the correct mode. If the machine is in STICK  
mode, the HF stays ‘OFF’. IF the machine is in DC  
TIG mode, the HF comes ‘ON’ and stays on until the  
arc is established. IF the machine is in AC TIG mode,  
the HF comes ‘ON’ and stays on continuously to sta-  
bilize the arc.  
DESIGN FEATURES AND  
ADVANTAGES  
• Automatic Local/Remote current selection. The  
machine automatically senses if an Amptrol, Arc Start  
Switch or TIG Pulser is plugged in and transfers cur-  
rent control from local to remote.  
• Meets NEMA CLASS II (40) and IP21S environmen-  
tal certification. (Will be CSA NRTL/C certified in the  
future.) Domestic and Canadian Models Only.  
• Built in preflow time of 0.5 seconds. Preflow time is  
eliminated if welding restarts during the pervious  
weld’s post flow. This avoids unnecessary delays  
when making repeated welds.  
• Meets IEC-974-1 and IP21S environmental certifica-  
tion. (Will be CE certified in the future.) European  
Model Only.  
• Built in Digital Ammeter and Voltmeter for precise  
process control. This includes a persistence feature  
which captures and continues to display the peak  
welding current and it’s corresponding voltage for five  
seconds after the weld is completed.  
• Simple dial and switch design provides the customer  
with flexible control of the welding process without  
unnecessary complication. Controls which are not  
needed in the weld mode selected are automatically  
locked out.  
• AC Wave Balance control knob provides flexibility to  
the customer. Set it to the Auto Balance position and  
the circuitry automatically provides the proper amount  
of cleaning and penetration for normal AC TIG weld-  
ing. For special applications simply dial in the amount  
of cleaning and penetration needed.  
• Twist Mate connectors are provided for the electrode  
and work connections. This style connector makes  
the gas and current connections for the TIG torch at  
the same time. (Adaptor plugs are provided)  
• DC+/AC/DC- Polarity Switch allows the welder to  
change polarity without reconnecting leads.  
• Fan As Needed (FAN) circuit turns ‘ON’ the fan only  
when cooling is needed. FAN minimizes the amount  
of dust, dirt, and other foreign material drawn into the  
SQUARE WAVE TIG 275  
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B-4  
B-4  
OPERATION  
• Provides excellent arc starting and stability through-  
out the machines wide current range (5 to 315 Amps)  
to handle the vast majority of TIG welding applica-  
tions.  
WELDING CAPABILITY  
The Square Wave TIG 275 is rated at 275 amps, 31  
volts, at 40% duty cycle on a ten minute basis for DC  
TIG and AC/DC stick processes. It is capable of high-  
er duty cycles at lower output currents. If the duty  
cycle(s) are exceeded, the thermostatic protection will  
shut off the output until the machine cools to a normal  
operating temperature.  
• Simple output current dial allows the user to preset  
the peak current within the full output range of the  
machine.  
• Highly resistant to AC arc rectification.  
• Thermostatically protected to prevent equipment  
damage.  
LIMITATIONS  
• No tungsten spitting within current range of electrode.  
• Designed to make maintenance and servicing easy.  
The Square Wave TIG 275 is not recommended for AC  
TIG welding when high concentrations of helium gas  
are used for shielding. This causes starting and arc  
rectification problems. Also the Square Wave 275 is  
not recommended for arc gouging due to it's limited  
output capacity. The Square Wave TIG 275 is also not  
recommended for pipe thawing.  
• 115 Volt Receptacle with 10 Amp Circuit Breaker.  
Domestic and Canadian Models Only.  
• 220 Volt European (Schuko) type Receptacle with 2  
Amp Circuit Breaker. European Model Only.  
• Low Voltage Trigger Circuit (18 VAC) for maximum  
operator safety.  
• Remote Receptacle for Amptrol or Arc Start Switch  
connection.  
• Gas Valve Inlet fitting conforms to Compressed Gas  
Association (CGA) standards.  
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B-5  
B-5  
OPERATION  
CONTROLS AND SETTINGS  
All operator controls and adjustments are located on the case front of the Square Wave TIG 275. Refer to Figure  
B.1 and corresponding explanations following.  
FIGURE B.1 - CONTROL PANEL  
5
6
6
9
7
8
1. Output Control Knob  
2. AC Wave Balance Knob  
3. Post Flow Knob  
4. Down Slope Time Knob  
5. Mode Switch  
1
10  
6. Trimmer Potentiometer  
7. Digital Ammeter  
8. Digital Voltmeter  
9. Thermal Protection Light  
10. Power Switch  
2
3
11. Polarity Switch  
11  
12. Electrode Connection (Twist-Mate Connector)  
13. Work Connection (Twist-Mate Connector)  
14. Remote Control Amphenol  
15. Water Solenoid (Optional)  
4
12  
13  
14  
15  
1. Current Control - This knob is used to set the  
welding current from 5 to 315 amps. Read the  
complete Operating Instructions section for more  
information on Local and Remote setting of cur-  
rent.  
4. Down Slope Time Control - This knob is active in  
4-Step TIG mode only. It adjusts the time (from 0.5  
to 10 seconds) the welding output takes to ramp  
down from the preset level to 25% of that level.  
5. 2-Step/4-Step TIG/Stick Mode Control Switch -  
This switch selects the welding mode desired: TIG  
2-Step, TIG 4-Step, or Stick. Read the complete  
Operating Instructions section for more information  
on TIG 2-Step and TIG 4-Step.  
2. AC Wave Balance Control - This knob is active in  
the AC TIG mode only. It is used to set the amount  
of cleaning and/or penetration produced during an  
AC TIG weld. Auto Balance™ automatically sets  
the AC Wave balance according to the welding cur-  
rent. If manual adjustment is desired, the balance  
can be adjusted from +0 (maximum cleaning)  
6. Trimmer Potentiometers - Allows the meters to be  
calibrated in the field.  
to +10 (maximum penetration).  
Advanced Features section for a complete expla-  
nation of the AC Wave Balance.  
Read the  
7. Digital Ammeter - The ammeter displays actual  
welding current during a weld cycle and displays the  
peak current for approximately 5 seconds after  
welding is complete. Read the complete Operating  
Instructions section for more information on the  
Ammeter.  
3. Post Flow Time Control - This knob is active in  
the TIG mode only. It adjusts the post flow time  
from 5 to 50 seconds for shielding gas. It also  
adjusts cooling water flow when the optional  
K1621-1 Water Solenoid Kit is used.  
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B-6  
B-6  
OPERATION  
8. Digital Voltmeter - This meter displays welding  
WELDING OPERATION  
voltage, as measured on the output studs of the  
Square Wave TIG 275. After welding is complete,  
the meter displays the welding voltage corre-  
sponding to the peak welding current and displays  
this value for approximately 5 seconds.  
TIG WELDING  
Familiarize yourself with the Controls and Settings  
Section before attempting operation of the Square  
Wave TIG 275.  
9. Thermal Protection Light - A yellow light which  
only lights when an over temperature situation  
occurs. See the Maintenance Section for more  
information on thermostatic protection.  
TIG WELDING GUIDELINES  
TIG welding can be done in either the TIG 2-Step or  
the TIG 4-Step Weld Mode. TIG 2-Step is typically  
used with Hand or Foot Amptrols, with Remote Current  
control. TIG 4-Step typically uses an Arc Start switch  
and Local Current Control, because it provides a very  
brief current upslope, and a .5 to 10 second adjustable  
current downslope. TIG 4-Step also functions like a  
trigger interlock, making it unnecessary to hold down  
the Arc Start switch during a weld. This feature  
requires that the remote control device in use must  
have separate Arc Start and Output Control mecha-  
nisms. Read the TIG Welding Sequence of Operation  
sections for more details on 2-Step and 4-Step opera-  
tion.  
10. Power Switch - Controls the input power to the  
Square Wave TIG 275.  
11. Polarity Switch - Selects DC+, AC or DC- welding  
polarity without reconnecting leads. DO NOT  
SWITCH WHILE WELDING.  
12. Twist Mate Electrode and  
13. Work Connections - Easy to connect electrode  
and work connections. This style Electrode  
Connection makes the gas and current connec-  
tions for the TIG torch at the same time. (Adapter  
plugs are provided with the machine.)  
14. Remote Receptacle - For Amptrol, Arc Start  
Switch or Robotic Interface connection.  
Recommended tungsten electrode sizes, stickouts,  
currents, cup or nozzle sizes are shown in Table B.1.  
SINCE WELDING APPLICATIONS CAN VARY, THIS  
CHART IS INTENDED AS A GUIDE ONLY.  
15. Optional Water Solenoid Connections - Easy to  
install this optional feature which allows for water  
flow control for water cooled torches.  
(2)  
TABLE B.1 TYPICAL CURRENT RANGES FOR TUNGSTEN ELECTRODES  
AC  
Approximate Argon  
Gas Flow Rate  
C.F.H. (1/min.)  
+
-
DCEN (  
)
DCEP (  
)
Unbalanced Wave  
Balanced Wave  
1%, 2%  
1%, 2%  
Thoriated  
Tungsten  
Zirconiated  
Tungsten  
Electrode  
Diameter  
in. (mm)  
1%, 2%  
Thoriated  
Tungsten  
1%, 2%  
Thoriated  
Tungsten  
Thoriated  
Tungsten  
Zirconiated  
TIG Torch  
Nozzle  
Pure  
Tungsten  
Pure  
Tungsten  
Stainless  
Steel  
(5)  
Size(4),  
Aluminum  
(3)  
(3)  
(3)  
.010  
(.25)  
0.020 (.50)  
0.040 (1.0)  
2-15  
5-20  
15-80  
2-15  
5-15  
10-60  
2-15  
5-20  
15-80  
2-15  
10-20  
20-30  
---  
5-20  
20-60  
3-8 (2-4) 3-8  
5-10 (3-5) 5-10 (3-5)  
5-10 (3-5) 5-10 (3-5)  
(2-4)  
#4, #5, #6  
1/16  
(1.6)  
70-150  
10-20  
50-100  
70-150  
30-80  
60-120  
5-10 (3-5) 9-13 (4-6)  
13-17 (6-8) 11-15 (5-7)  
#5, #6  
3/32  
1/8  
(2.4)  
(3.2)  
150-250  
250-400  
15-30  
25-40  
100-160  
150-210  
140-235  
225-325  
60-130  
100-180  
100-180  
160-250  
#6, #7, #8  
15-23 (7-11)  
11-15 (5-7)  
5/32  
3/16  
1/4  
(4.0)  
(4.8)  
(6.4)  
400-500  
500-750  
750-1000  
40-55  
55-80  
80-125  
200-275  
250-350  
325-450  
300-400  
400-500  
500-630  
100-240  
190-300  
250-400  
200-320  
290-390  
340-525  
13-17 (6-8)  
18-22 (8-10)  
23-27(11-13)  
#8, #10  
21-25 (10-12)  
23-27 (11-13)  
28-32 (13-15)  
(1) When used with argon gas. The current ranges shown must be reduced when using argon/helium or  
pure helium shielding gasses.  
(2) Tungsten electrodes are classified as follows by the American Welding Society (AWS):  
Pure . . . . . . . . . . . . . . . EWP  
(4) TIG torch nozzle “sizes” are in multiples of 1/16ths of an inch:  
#4 = 1/4 in.  
#5 = 5/16 in.  
#6 = 3/8 in.  
#7 = 7/16 in.  
#8 = 1/2 in.  
#10 = 5/8 in.  
(6 mm)  
(8 mm)  
(10 mm)  
(11 mm)  
(12.5 mm)  
(16 mm)  
1% Thoriated . . . . . . . . EWTh-1  
2% Thoriated . . . . . . . . EWTh-2  
Though not yet recognized by the AWS, Ceriated Tungsten is now widely accepted as a substitute for  
2% Thoriated Tungsten in AC and DC applications.  
(5) TIG torch nozzles are typically made from alumina ceramic. Special applications may require lava nozzles,  
which are less prone to breakage, but cannot withstand high temperatures and high duty cycles.  
(3) DCEP is not commonly used in these sizes.  
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B-7  
B-7  
OPERATION  
TIG WELDING SEQUENCE OF OPERATION  
(2-Step TIG Mode)  
10. Hold the Arc Start Switch or Amptrol down until an  
arc is established. If using an Amptrol, read the  
Section on Hand and Foot Amptrol Operation.  
Release the Arc Start Switch or Amptrol to stop the  
arc and start the Post Flow timer. After the Post  
Flow time has expired, the gas and (optional water  
solenoid) valves will close. To make another weld,  
repeats steps 9 and 10.  
1. Connect an Arc Start Switch or an Amptrol to the  
Remote Amphenol.  
2. Turn the welder, gas supply and water supply (if  
equipped), on. The digital ammeter/voltmeter dis-  
plays will illuminate when the power is on.  
3. Select the 2-Step TIG Mode with the 2-Step/4-Step  
TIG/Stick switch.  
TIG WELDING SEQUENCE OF OPERATION  
(4-Step TIG Mode)  
4. Set the maximum output current using the output  
control knob.  
1. Connect an Arc Start Switch to the Remote  
Amphenol.  
5. Select AC or DC- electrode polarity. See Table B.2.  
2. Turn the welder, gas supply and water supply (if so  
equipped), on. The digital ammeter/voltmeter dis-  
play will illuminate when the power is on.  
TABLE B.2  
RECOMMENDED POLARITY  
SETTINGS FOR TIG WELDING  
3. Select the 4-Step TIG Mode with the 2-Step/4-Step  
TIG/Stick switch.  
4. Set the maximum output current using the output  
control knob.  
Electrode  
Polarity  
Type of Welding  
Stainless Steel  
DC-  
5. Select AC or DC- electrode polarity. See Table B.2.  
Aluminum & Magnesium  
Other Metals  
AC  
6. If welding with AC polarity, set the AC Wave  
Balance Knob to Auto Balance™. This gives the  
optimum ratio between cleaning and penetration,  
automatically adjusted for the output current. If  
manual adjustment of the AC Wave Balance is  
desired, adjust the wave balance to the desired  
settings. See the Advanced Features section for  
more information on setting and using the AC  
Wave Balance.  
DC-  
6. If welding with AC polarity, set the AC Wave  
Balance Knob to Auto Balance™. This gives the  
optimum ratio between cleaning and penetration,  
automatically adjusted of the AC Wave Balance is  
desired, adjust the wave balance to the desired  
settings. See the Advanced Features section for  
more information on setting and using the AC  
Wave Balance.  
7. Set the Post Flow time with the Post Flow knob.  
Post Flow time provides shielding gas flow (and  
cooling water, if used) after the weld. Use short  
Post Flow times with low currents and small tung-  
stens and long Post flow times at high output cur-  
rents and large tungstens.  
7. Set the post flow time with the post flow knob. Post  
flow control knob adjusts the time that the shielding  
gas flows (and cooling water flow, if the optional  
water solenoid is used) after the weld cycle. Use  
short post flow times with low currents and small  
tungstens, use long post flow times at high output  
currents with large tungstens.  
8. Set the Downslope Time with the Downslope Time  
Knob. This will adjust the time of the crater fill peri-  
od.  
8. Press and release the Arc Start Switch, and set the  
gas flow meter. The welder is now ready for weld-  
ing.  
9. Press and release the Arc Start Switch, to set the  
gas flow meter if necessary. The welder is now  
ready for welding.  
9. Position the tungsten electrode at the start of the  
weld at a 65° to 75° angle with the horizontal so  
that the electrode is approximately 1/8” (4 mm)  
above the work piece. Press the Arc Start Switch.  
This opens the gas (and optional water solenoid)  
valves to automatically purge air from the hose and  
torch. After a 0.5 second preflow time, the high fre-  
quency becomes available to strike the arc.  
10. Position the tungsten electrode at the start of the  
weld at a 65° to 75° angle with the horizontal so  
that the electrode is approximately 1/8” (4 mm)  
above the work piece. Press the Arc Start Switch.  
This opens the gas and water valves to automati-  
cally purge air from the hose and torch. After a 0.5  
second preflow time, the high frequency becomes  
available to strike the arc.  
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B-8  
B-8  
OPERATION  
11. Hold the Arc Start Switch down until an arc is  
established. The arc will start at a low current  
value that is equal to 25% of the preset current  
established in Step 4. It will remain at this current  
as long as the Arc Start Switch is closed. Release  
the Arc Start Switch. At this point, the Square  
Wave TIG 275 will quickly ramp up to the preset  
maximum welding current, (0.5 seconds upslope  
time) and the weld will continue indefinitely. Press  
the Arc Start Switch a second time to initiate the  
Downslope time. The current will go down to a  
crater fill current that is equal to 25% of the weld-  
ing current. Release the Arc Start Switch to stop  
the arc and start the Post flow timer. After the Post  
flow time has expired, the gas and optional water  
valves will close. To make another weld, repeat  
steps 10 and 11.  
ADVANCED TIG WELDING FEATURES  
AC WAVE BALANCE AND AUTO BALANCE™  
The AC Wave Balance feature is unique to the Square  
Wave TIG 275. It is active only in AC TIG mode. It con-  
trols the amount of positive and negative current in the  
AC output.  
The Square Wave TIG 275 allows the operator to  
select Auto Balance™. This selection provides auto-  
matic adjustment of the AC Wave Balance; it is suitable  
for most welding conditions. Auto Balance™ gives the  
ideal amount of cleaning and penetration, based on the  
welding current output.  
Manual adjustment of the AC Wave Balance is also  
possible. Manual Balance settings vary from 0 (maxi-  
mum cleaning) to 10 (maximum penetration). A setting  
of 3 yields a balanced output (equal amounts of clean-  
ing and penetration). Use the following as a guide  
when setting the Balance manually:  
HAND AND FOOT AMPTROL OPERATION  
Both the Hand and Foot Amptrol work in a similar man-  
ner. They are meant to be used for remote current con-  
trol. The TIG 2-Step mode must be selected when  
using an Amptrol for remote current control.  
BALANCED (3): The amounts of positive and negative  
are the same.  
CLEANING (0 to 2): Provides more positive current  
than negative current. Since the positive cur-  
rent produces the "cleaning" or oxide removal  
on aluminum, this setting is used for welding on  
heavily oxidized aluminum.  
For simplicity, the following explanation will refer only to  
"Amptrols", meaning both Foot and Hand models. The  
term "minimum" refers to a Foot pedal in the "up" posi-  
tion, as it would be with no foot pressure, or a Hand  
Amptrol in the relaxed position, with no thumb pres-  
sure. "Maximum" refers to a fully depressed Foot  
Amptrol, or a fully extended Hand Amptrol.  
PENETRATION (4 to 10): Provides more negative cur-  
rent than positive. The arc plasma will be more  
concentrated and more easily directed to where  
the heat is needed. Higher penetration settings  
allow a given size of tungsten to carry more cur-  
rent.  
The Amptrol is capable of controlling the output current  
from 5 amps to the preset current on the output control  
knob. For example, if the preset is at 200 amps, the  
Amptrol, when depressed just past its minimum posi-  
tion, will cause the Square Wave TIG 275 to weld at 5  
amps. At the Amptrol's maximum position, the output  
will be near 200 amps.  
CAUTION: Use only the amount of cleaning required  
because the greater amount of positive current will  
heat the tungsten more and possibly cause it to melt or  
"spit". Also, the arc is usually more flared and less sta-  
ble with more cleaning current.  
It is important to note that, for many applications, the  
tungsten will not start an arc at only 5 amps. (Refer to  
the TIG Welding Guidelines for recommended tungsten  
currents.) To start an arc reliably, it is important to  
depress the Amptrol far enough so that the machine  
output current is near the tungsten operating range. In  
the example above, a 3/32" tungsten may be used on  
DC- to weld near 200 amps. To start the weld, the  
operator may have to depress the Amptrol approxi-  
mately 1/4 of the way down, or to nearly 50 amps, in  
order to start the arc. Merely depressing the Amptrol to  
its 5 amp minimum position will not start the arc.  
In general, use just enough "cleaning" to remove  
oxides and to give good wetting of the puddle.  
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B-9  
B-9  
OPERATION  
STICK WELDING  
1. Turn the welder “on”. The digital ammeter/volt-  
meter will illuminate when the power is on.  
2. Set the Mode Switch to “STICK”. Set the output  
current using the Output Control Knob. No other  
functions or adjustments operate in the Stick  
Mode.  
3. Select the desired DC+/AC/DC- electrode polarity.  
4. Clamp the electrode in the electrode holder, start  
the weld by lightly touching the electrode to the  
work. Stop the weld by pulling the electrode away  
from the work piece.  
AUXILIARY POWER  
60 HERTZ DOMESTIC MACHINES  
The Square Wave TIG 275 machines rated for 60 Hz  
operation provides 10 amps of 115 volt AC power at a  
standard NEMA 5-15R receptacle, located on the lower  
case back of the machine. This circuit is protected  
from shorts and overloading by a 10 amp circuit break-  
er, located next to the receptacle. The auxiliary circuit  
is intended for running water coolers and small power  
tools, whose current draw is within the 10 amp rating.  
Note that some types of equipment, especially pumps  
and large motors, have starting currents which are sig-  
nificantly higher than their running current. These high-  
er starting currents may cause the circuit breaker to  
open. If this situation occurs, the user should refrain  
from using the Square Wave TIG 275 auxiliary for that  
equipment.  
50/60 HERTZ EUROPEAN MACHINES  
The Square Wave TIG 275 machines rated for 50/60Hz  
operation provides 2 amps of 220 volt AC power at a  
continental European (Schuko) type receptacle, locat-  
ed on the lower case back of the machine. This circuit  
is protected from shorts and overloading by a 2 amp  
circuit breaker, located above the receptacle. The aux-  
iliary circuit is intended for running water coolers whose  
current draw is within the 2 amp rating of the recepta-  
cle. Note that some types of equipment, especially  
pumps and motors, have starting currents which are  
significantly higher than their running currents. These  
higher starting currents may cause the circuit breaker  
to open. If this situation occurs, the user should refrain  
from using the Square Wave TIG 275 auxiliary for that  
equipment.  
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B-10  
B-10  
NOTES  
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Section C-1  
Section C-1  
TABLE OF CONTENTS  
- ACCESSORIES -  
Accessories...........................................................................................................................Section C  
Accessories Included with Machine............................................................................................C-2  
Optional Accessories ..................................................................................................................C-2  
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C-2  
C-2  
ACCESSORIES  
K932-1 Undercarriage. When the undercarriage is  
properly installed, the Square Wave TIG 275 lift bail is  
nonfunctional. Do not attempt to lift the power source  
with the undercarriage attached. THe undercarriage is  
desinged for hand moving only; mechanized towing  
can lead to personal injury and/or damage to the  
Square Wave TIG 275.  
ACCESSORIES INCLUDED WITH  
MACHINE  
K852-50 - Twist Mate Cable Plug for #2 to #1 Work  
Lead.  
K1622-1 - Twist Mate Adapter Kit for LA9 and LA17  
Torches.  
K1622-1 Twist-Mate Adapter Kit for LA9 & LA17  
Torches (Included with machine)  
K1622-2 - Twist Mate Adapter Kit for LW18 and LW20  
Torches.  
K1622-2 Twist Mate Adapter Kit for LW18 & LW20  
Torches (Included with machine)  
K852-50 Twist-Mate Cable Plug for #2 to #1 Work Lead  
(Included with machine)  
OPTIONAL ACCESSORIES  
Any necessary installation instructions are included for  
the following accessories:  
K963-1, -2 - Hand Amptrol  
K870 - Foot Amptrol  
K814 - Arc Start Switch  
K559-2 - Magnum® Cooler Mounting Bracket  
K932-1 - Undercarriage  
K1619-1 - TIG Pulser Kit  
K1620-1 - Power Factor Capacitor Kit  
K1621-1 - Water Solenoid Kit  
K1622-3 - Twist Mate Adapter Kit for LA26 Torch  
K852-70 - Twist Mate Cable Plug for 1/0 to 2/0 Work  
Lead  
K852-95 - Twist Mate Cable Plug for 2/0 to 3/0 Work  
Lead  
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Section D-1  
Section D-1  
TABLE OF CONTENTS  
- MAINTENANCE SECTION -  
Maintenance .........................................................................................................................Section D  
Safety Precautions......................................................................................................................D-2  
Routine and Periodic Maintenance.............................................................................................D-2  
Overload Protection ....................................................................................................................D-2  
Fan As Needed (F.A.N.)..............................................................................................................D-2  
Service Procedures.....................................................................................................................D-2  
Component Location and Access ...............................................................................................D-3  
Control PC Board .................................................................................................................D-3  
Display PC Board, Arc Starter/Bypass PC Board ................................................................D-3  
Spark Gap Assembly, High Voltage Transformer.................................................................D-3  
Main Rectifier........................................................................................................................D-3  
Spark Gap Adjustment................................................................................................................D-3  
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D-2  
D-2  
MAINTENANCE  
SAFETY PRECAUTIONS  
WARNING  
OVERLOAD PROTECTION  
This welder has thermostatic protection from excessive  
duty cycles, overloads, loss of cooling, and high ambi-  
ent temperatures. When the welder is subjected to an  
overload or loss of cooling, a thermostat will open.  
This condition will be indicated by the illumination of  
the yellow Thermostatic Protection Light on the case  
front . The fan will continue to run to cool the power  
source. No welding is possible until the machine is  
allowed to cool and the Thermostatic Protection Light  
goes out.  
ELECTRIC SHOCK can kill.  
• Only qualified personnel should per-  
form this maintenance.  
• Turn the input power OFF at the dis-  
connect switch or fuse box before  
working on this equipment.  
•
Do not touch electrically hot parts.  
FAN AS NEEDED (F.A.N.)  
The Square Wave TIG 275 has the F.A.N. circuit fea-  
ture, which means the cooling fan will operate only  
while welding, then for about 6 minutes after welding  
has stopped. The cooling fan will operate conintuous-  
ly if the yellow Thermstatic Protection Light in “ON.”  
WARNING  
To avoid receiving a high frequency shock, keep the  
TIG torch and cables in good condition.  
ROUTINE AND PERIODIC  
MAINTENANCE  
SERVICE PROCEDURES  
WARNING  
Very little routine maintenance is necessary to keep  
your Square Wave TIG 275 running in top condition.  
No specific schedule can be set for performing the fol-  
lowing items; factors such as hours of usage and  
machine environment should be considered when  
establishing a maintenance schedule.  
Use extreme caution when working with the secondary  
circuit of the high frequency transformer. Turn the input  
power off using the disconnect switch or fuse box  
before working inside the machine. This is particularly  
important when working on the secondary circuit of the  
high voltage transformer (T3) because the output volt-  
age is dangerously high.  
1. Periodically blow out dust and dirt which may accu-  
mulate within the welder using an air stream.  
2. Inspect welder output and control cables for fray-  
ing, cuts, and bare spots.  
DO NOT APPLY POWER TO THE SQUARE WAVE  
TIG 275 WITH THE SIDES AND ROOF REMOVED.  
The case front and case back assemblies tend to lean  
in towards the center assembly; there is a danger of a  
short circuit when this occurs. If you must troubleshoot  
the machine with power applied, do so with the roof in  
place, and check for shorts before applying power.  
3. Inspect the spark gap at regular intervals to main-  
tain the recommended spacing. See the Service  
Procedures Section for complete information on  
spark gap settings.  
4. The fan motor has sealed ball bearings which  
require no maintenance.  
Operation of the Square Wave TIG 275 should be trou-  
ble-free for the life of the machine. Should a malfunc-  
tion occur, however, the following procedures will be  
useful to trained service personnel with experience in  
repairing arc welding equipment.  
SQUARE WAVE TIG 275  
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D-3  
D-3  
MAINTENANCE  
COMPONENT LOCATION AND  
ACCESS  
SPARK GAP ADJUSTMENT  
The spark gap is set at the factory to a gap of 0.015  
inches (0.4 mm). This setting is adequate for most  
applications. Where less high frequency is desired, the  
setting can be reduced to 0.008 inches (0.2 mm).  
CONTROL PC BOARD  
Remove the left case side. Use a 3/8" Nut Driver or  
other suitable tool.  
To adjust the spark, first be sure that the input power to  
the machine is ‘OFF’ AT THE DISCONNECT SWITCH  
OR FUSE BOX. The high voltages developed in the  
high frequency circuit can be lethal. Next, remove the  
right case side. Use a 3/8" Nut Driver or other suitable  
tool. Check the spark gap spacing with a feeler gauge.  
If adjustment is required, pull off one of the two leads  
going to the aluminum spark gap blocks. Adjust the  
gap by loosening the Allen head screw, reset the gap  
and tightening the screw in the new position. Reattach  
the lead removed earlier, and reinstall the case side.  
NOTE: The Case side can be removed while roof is in  
place, as long as the three screws which secure the  
roof to the case side are removed. The PC Board is  
mounted on left divider assembly and can be removed  
with a phillips head screwdriver.  
DISPLAY PC BOARD, ARC  
STARTER/BYPASS PC BOARD  
Remove the roof and both case sides. Use a 3/8" Nut  
Driver or other suitable tool. These PC Boards are  
located on the inside case front of the machine.  
FIGURE D.1 SPARK GAP  
SPARK GAP ASSEMBLY, HIGH VOLTAGE  
TRANSFORMER  
Remove the right case side. Use a 3/8" Nut Driver or  
other suitable tool. The high voltage transformer is  
mounted to the base. The spark gap assembly is locat-  
ed on the inside case front.  
.015 Spark Gap  
MAIN RECTIFIER  
Remove the roof and both case sides. Next, remove  
the case back assembly. Use a 3/8" Nut Driver or other  
suitable tool. The main rectifier is mounted to the main  
transformer, in front of the cooling fan.  
RIGHT SIDE VIEW OF MACHINE  
SQUARE WAVE TIG 275  
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D-4  
D-4  
MAINTENANCE  
FIGURE D.2 - MAJOR COMPONENT LOCATIONS  
1. CASE FRONT (WITH DISPLAY BOARD)  
2. INTERNAL DIVIDER  
(WITH CONTROL BOARD)  
3. CASE SIDES  
4
4. CASE TOP  
5. CASE BACK  
6. FAN MOTOR ASSEMBLY  
7. RECONNECT PANEL  
8. BASE  
3
9. HIGH VOLTAGE TRANSFORMER  
10. MAIN TRANSFORMER  
11. CHOKE  
12. OUTPUT RECTIFIER BRIDGE  
13. HIGH FREQUENCY UNIT  
(SPARK GAP ASSEMBLY)  
5
12  
11  
2
6
10  
SQUARE  
W
A
VE  
TIG  
8
9
275  
7
13  
1
SQUARE WAVE TIG 275  
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Section E-1  
Section E-1  
TABLE OF CONTENTS  
- THEORY OF OPERATION SECTION -  
Theory of Operation .............................................................................................................Section E  
General Description ....................................................................................................................E-2  
Input Power Circuit......................................................................................................................E-2  
Output Rectification, Control Board and Feedback ....................................................................E-3  
High Voltage/High Frequency Circuit..........................................................................................E-4  
DC Welding Output .....................................................................................................................E-5  
AC Welding Output .....................................................................................................................E-6  
SCR Operation............................................................................................................................E-7  
Protective Circuits .......................................................................................................................E-8  
Thermal Protection ...............................................................................................................E-8  
Overload Protection..............................................................................................................E-8  
FIGURE E.1 - SQUARE WAVE TIG 275 BLOCK LOGIC DIAGRAM  
BY-PASS  
BOARD  
WORK  
POLARITY  
SWITCH  
ELECTRODE  
MAIN  
TRANSFORMER  
HI-FREQUENCY  
TRANSFORMER  
INPUT  
POWER  
SWITCH  
RECONNECT  
PANEL  
C
H
O
K
E
H1  
AC  
SCR  
BRIDGE  
DC+  
X1  
X2  
H2  
H3  
H4  
HIGH VOLTAGE  
TRANSFORMER  
CIRCUIT  
SHUNT  
DC-  
AC  
F
E
E
D
B
A
C
K
23VAC  
18VAC  
"A"  
115VAC  
MODE  
18VAC  
115VAC  
CONTROL  
BOARD  
SWITCH  
115VAC  
RECEPTACLE  
THERMAL  
LIGHT  
FAN  
THERMOSTATS  
REMOTE  
RECEPTACLE  
DOWNSLOPE GAS  
CONTROL VALVE CONTROL  
POSTFLOW  
OUTPUT  
CONTROL  
BALANCE  
CONTROL  
SQUARE WAVE TIG 275  
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E-2  
E-2  
THEORY OF OPERATION  
FIGURE E.2 – MAIN TRANSFORMER AND INPUT POWER  
BY-PASS  
BOARD  
WORK  
POLARITY  
SWITCH  
ELECTRODE  
MAIN  
TRANSFORMER  
HI-FREQUENCY  
TRANSFORMER  
INPUT  
POWER  
SWITCH  
RECONNECT  
PANEL  
C
H
H1  
O
K
E
AC  
SCR  
BRIDGE  
DC+  
X1  
X2  
H2  
H3  
H4  
HIGH VOLTAGE  
TRANSFORMER  
CIRCUIT  
SHUNT  
DC-  
AC  
F
E
E
D
B
A
C
K
23VAC  
18VAC  
"A"  
115VAC  
MODE  
18VAC  
115VAC  
CONTROL  
BOARD  
SWITCH  
115VAC  
RECEPTACLE  
THERMAL  
LIGHT  
FAN  
THERMOSTATS  
REMOTE  
RECEPTACLE  
DOWNSLOPE GAS  
CONTROL VALVE CONTROL  
POSTFLOW  
OUTPUT  
CONTROL  
BALANCE  
CONTROL  
the reconnect panel. When the input power switch is  
turned “on,” the input voltage is applied directly to the  
primary winding of the main transformer.  
GENERAL DESCRIPTION  
The Square Wave TIG 275 machine is a constant cur-  
rent, single range square wave AC/DC TIG (GTAW) arc  
welding power source with built-in high frequency sta-  
bilization. It also has stick welding (SMAW) capability.  
The machine includes advanced features such as  
Digital Voltage and Current Meters, Auto Balance, 2-  
Step/4-Step operation, adjustable Downslope Time  
Control and Fan as Needed. The Square Wave TIG  
275 is recommended for the TIG (GTAW) and stick  
(SMAW) welding processes within its output capacity of  
5 to 315 amps, on both AC and DC polarities.  
The main transformer changes the high voltage, low  
current input power to a low voltage, high current out-  
put available at the main secondary winding (X1 and  
X2). This 78 VAC winding supplies power to the weld-  
ing arc. In addition, four auxiliary windings are incor-  
porated in the main transformer. The 115 VAC winding  
supplies power to the 115 VAC receptacle. Through  
the control board, it also powers the gas solenoid, the  
high voltage transformer, and the cooling fan. The  
cooling fan is activated only when welding current is  
sensed. The 23 VAC winding provides power for the  
DC background current. This circuit is active in the DC  
welding mode. Two 18 VAC windings are included in  
the main transformer assembly. One 18 VAC winding  
is rectified on the control board and is used in the trig-  
ger circuitry. The other 18 VAC winding is used by the  
control board for phase detection. This voltage is also  
rectified and regulated to +15 VDC and +5 VDC power  
supplies that operate the circuitry on the control board.  
INPUT POWER CIRCUIT  
The desired single-phase input power is connected to  
the TIG 275 through the reconnect panel to the input  
power switch located in the front panel of the machine.  
The machine can be configured for any one of three  
input voltages (208 VAC, 230 VAC or 460 VAC) by con-  
necting the “A” lead to the appropriate terminal on  
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.  
SQUARE WAVE TIG 275  
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E-3  
E-3  
THEORY OF OPERATION  
FIGURE E.3 – OUTPUT RECTIFICATION, CONTROL BOARD AND FEEDBACK  
BY-PASS  
BOARD  
WORK  
POLARITY  
SWITCH  
ELECTRODE  
MAIN  
TRANSFORMER  
HI-FREQUENCY  
TRANSFORMER  
INPUT  
POWER  
SWITCH  
RECONNECT  
PANEL  
C
H
O
K
E
H1  
AC  
SCR  
BRIDGE  
DC+  
X1  
X2  
H2  
H3  
H4  
HIGH VOLTAGE  
TRANSFORMER  
CIRCUIT  
SHUNT  
DC-  
AC  
F
E
E
D
B
A
C
K
23VAC  
18VAC  
"A"  
115VAC  
MODE  
18VAC  
115VAC  
CONTROL  
BOARD  
SWITCH  
115VAC  
RECEPTACLE  
THERMAL  
LIGHT  
FAN  
THERMOSTATS  
REMOTE  
RECEPTACLE  
DOWNSLOPE GAS  
CONTROL VALVE CONTROL  
POSTFLOW  
OUTPUT  
CONTROL  
BALANCE  
CONTROL  
OUTPUT RECTIFICATION,  
CONTROL BOARD AND FEEDBACK  
The AC output from the main transformer secondary is  
rectified and controlled through the SCR bridge.  
Output current is sensed at the shunt as a low voltage  
signal and fed back to the control board. The control  
board senses the status and settings of the various  
operator controls such as the mode switch, the output  
control, the remote control receptacle, the downslope  
control, the balance control and the postflow control.  
Circuitry on the control board evaluates these com-  
mands, compares them to the feedback information  
received from the shunt and sends the appropriate gate  
firing signals to the output SCR bridge. The control  
board regulates the firings of the output SCRs, which  
control the output of the machine.  
See SCR  
Operation. The control board also monitors the ther-  
mostats and controls the gas solenoid, the thermal light  
and the cooling fan.  
SQUARE WAVE TIG 275  
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E-4  
E-4  
THEORY OF OPERATION  
FIGURE E.4 – HIGH VOLTAGE / HIGH FREQUENCY CIRCUIT  
BY-PASS  
BOARD  
WORK  
POLARITY  
SWITCH  
ELECTRODE  
MAIN  
TRANSFORMER  
HI-FREQUENCY  
TRANSFORMER  
INPUT  
POWER  
SWITCH  
RECONNECT  
PANEL  
C
H
O
K
E
H1  
AC  
SCR  
BRIDGE  
DC+  
X1  
X2  
H2  
H3  
H4  
HIGH VOLTAGE  
TRANSFORMER  
CIRCUIT  
SHUNT  
DC-  
AC  
F
E
E
D
B
A
C
K
23VAC  
18VAC  
"A"  
115VAC  
MODE  
18VAC  
115VAC  
CONTROL  
BOARD  
SWITCH  
115VAC  
RECEPTACLE  
THERMAL  
LIGHT  
FAN  
THERMOSTATS  
REMOTE  
RECEPTACLE  
DOWNSLOPE GAS  
CONTROL VALVE CONTROL  
POSTFLOW  
OUTPUT  
CONTROL  
BALANCE  
CONTROL  
HIGH VOLTAGE / HIGH FREQUENCY  
CIRCUIT  
The control board passes the 115 VAC voltage to the  
primary of the high voltage transformer. The secondary  
of the high voltage transformer is coupled to a spark  
gap generator and also to the high frequency trans-  
former. The high frequency transformer transfers the  
high frequency “spark” to the electrode terminal, which  
is coupled to the TIG torch.  
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.  
SQUARE WAVE TIG 275  
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E-5  
E-5  
THEORY OF OPERATION  
FIGURE E.5 – DC WELDING OUTPUT  
BY-PASS  
BOARD  
WORK  
POLARITY  
SWITCH  
ELECTRODE  
MAIN  
TRANSFORMER  
HI-FREQUENCY  
TRANSFORMER  
INPUT  
POWER  
SWITCH  
RECONNECT  
PANEL  
C
H
O
K
E
H1  
AC  
SCR  
BRIDGE  
DC+  
X1  
X2  
H2  
H3  
H4  
HIGH VOLTAGE  
TRANSFORMER  
CIRCUIT  
SHUNT  
DC-  
AC  
F
E
E
D
B
A
C
K
23VAC  
18VAC  
"A"  
115VAC  
MODE  
18VAC  
115VAC  
CONTROL  
BOARD  
SWITCH  
115VAC  
RECEPTACLE  
THERMAL  
LIGHT  
FAN  
THERMOSTATS  
REMOTE  
RECEPTACLE  
DOWNSLOPE GAS  
CONTROL VALVE CONTROL  
POSTFLOW  
OUTPUT  
CONTROL  
BALANCE  
CONTROL  
DC WELDING OUTPUT  
When the polarity switch is placed in either DC position,  
the AC voltage from the main transformer secondary is  
applied to the SCR bridge. The SCR bridge and choke  
circuits are connected in a conventional full wave  
bridge and filter configuration, resulting in a controlled  
DC output. Since the choke is in series with the nega-  
tive leg of the bridge and also in series with the weld-  
ing load, a filtered DC is applied to the output terminals.  
The bypass board protects the internal circuitry from  
interference.  
FIGURE E.6 – DC WELDING CURRENT GENERATION  
CHOKE  
ELECTRODE  
DC  
PRIMARY  
1Ø  
WORK  
SQUARE WAVE TIG 275  
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E-6  
E-6  
THEORY OF OPERATION  
FIGURE E.7 – AC WELDING OUTPUT  
BY-PASS  
BOARD  
WORK  
POLARITY  
SWITCH  
ELECTRODE  
MAIN  
TRANSFORMER  
HI-FREQUENCY  
TRANSFORMER  
INPUT  
POWER  
SWITCH  
RECONNECT  
PANEL  
C
H
O
K
E
H1  
AC  
SCR  
BRIDGE  
DC+  
X1  
X2  
H2  
H3  
H4  
HIGH VOLTAGE  
TRANSFORMER  
CIRCUIT  
SHUNT  
DC-  
AC  
F
E
E
D
B
A
C
K
23VAC  
18VAC  
"A"  
115VAC  
MODE  
18VAC  
115VAC  
CONTROL  
BOARD  
SWITCH  
115VAC  
RECEPTACLE  
THERMAL  
LIGHT  
FAN  
THERMOSTATS  
REMOTE  
RECEPTACLE  
DOWNSLOPE GAS  
CONTROL VALVE CONTROL  
POSTFLOW  
OUTPUT  
CONTROL  
BALANCE  
CONTROL  
AC WELDING OUTPUT  
Rotating the polarity switch to the AC position changes  
the welding power circuit. One lead (X1) of the main  
transformer secondary is connected to the machine’s  
output work terminal. The other secondary lead (X2) is  
connected to one of the AC connections of the SCR  
bridge. The electrode terminal is connected to the  
other AC side of the bridge. The choke is now electri-  
cally across the negative and positive SCR bridge con-  
nections. With the ability of the choke to store energy  
and the SCRs to turn on at the appropriate times, an  
AC square wave is developed and applied to the out-  
put terminals.  
FIGURE E.8 – AC SQUARE WAVE WELDING CURRENT GENERATION  
CHOKE  
ELECTRODE  
DC  
PRIMARY  
1Ø  
WORK  
SQUARE WAVE TIG 275  
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E-7  
E-7  
THEORY OF OPERATION  
FIGURE E.9 – SCR OPERATION  
INPUT  
CATHODE  
GATE  
OUTPUT  
NOTE: AS THE GATE  
PULSE IS APPLIED  
LATER IN THE CYCLE  
THE SCR OUTPUT  
IS DECREASED.  
ANODE  
GATE  
SCR OPERATION  
A silicon controlled rectifier (SCR) is a three-terminal  
device used to control rather large currents to a load.  
An SCR acts very much like a switch. When a gate sig-  
nal is applied to the SCR, it is turned ON and there is  
current flow from anode to cathode. In the ON state  
the SCR acts like a closed switch. When the SCR is  
turned OFF there is no current flow from anode to cath-  
ode. Thus, the device acts like an open switch. As the  
name suggests, the SCR is a rectifier, so it passes cur-  
rent only during positive half cycles of the AC supply.  
The positive half cycle is the portion of the sine wave in  
which the anode of the SCR is more positive than the  
cathode.  
An SCR is fired by a short burst of current into the gate.  
This gate pulse must be more positive than the cath-  
ode voltage. Since there is a standard PN junction  
between gate and cathode, the voltage between these  
terminals must be slightly greater than 0.6V. Once the  
SCR has fired, it is not necessary to continue the flow  
of gate current. As long as current continues to flow  
from anode to cathode, the SCR will remain on. When  
the anode to cathode current drops below a minimum  
value, called holding current, the SCR will shut off.  
This normally occurs as the AC supply voltage passes  
through zero into the negative portion of the sine wave.  
If the SCR is turned on early in the positive half cycle  
the conduction time is longer, resulting in greater SCR  
output. If the gate firing occurs later in the cycle the  
conduction time is less, resulting in lower SCR output.  
When an AC supply voltage is applied to the SCR, the  
device spends a certain portion of the AC cycle time in  
the on state and the remainder of the time in the off  
state. The amount of time spent in the ON state is con-  
trolled by the gate.  
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E-8  
E-8  
THEORY OF OPERATION  
PROTECTIVE CIRCUITS  
Protective circuits are designed into the Square Wave  
TIG 275 to sense trouble and shut down the machine  
before the trouble damages the internal machine com-  
ponents. Both thermal protection and current overload  
are included.  
THERMAL PROTECTION  
Thermostats protect the machine from excessive oper-  
ating temperatures. Excessive operating temperatures  
may be caused by a lack of cooling air or by operating  
the machine beyond the duty cycle and output rating.  
If excessive operating temperature should occur, caus-  
ing a thermostat to open, the Thermal Light will illumi-  
nate, the fan will continue to run and welding output will  
be disabled. Once the machine cools sufficiently, the  
thermostats are self-resetting. If the shutdown is  
caused by excessive output or duty cycle and the fan  
is operating normally, the power may be left on and the  
reset should occur within a 15 minute period. If the fan  
is not functioning properly or the air intake louvers are  
obstructed, the input power must be removed and the  
fan problem or air obstruction corrected.  
OVERLOAD PROTECTION  
The machine is electronically protected from producing  
excessively high output currents. The output is limited  
to 350 amps.  
SQUARE WAVE TIG 275  
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Section F-1  
Section F-1  
TABLE OF CONTENTS  
- TROUBLESHOOTING & REPAIR SECTION -  
Troubleshooting & Repair Section......................................................................................Section F  
How to Use Troubleshooting Guide ............................................................................................F-2  
PC Board Troubleshooting Procedures.......................................................................................F-3  
Troubleshooting Guide ................................................................................................................F-4  
Test Procedures  
High Frequency Circuit Disable Procedure ........................................................................F-18  
T1 Main Transformer Test...................................................................................................F-20  
Gas (Water) Solenoid Test..................................................................................................F-24  
Static SCR Test...................................................................................................................F-26  
Active SCR Test..................................................................................................................F-29  
Oscilloscope Waveforms  
Normal Open Circuit Voltage Waveform—AC TIG Mode...................................................F-33  
Normal Open Circuit Voltage Waveform—DC TIG Mode...................................................F-34  
Normal Open Circuit Voltage Waveform—AC Stick Mode .................................................F-35  
Normal Open Circuit Voltage Waveform—DC Stick Mode.................................................F-36  
Typical Output Voltage Waveform—Machine Loaded—AC TIG Mode ..............................F-37  
Typical Output Voltage Waveform—Machine Loaded—DC TIG Mode ..............................F-38  
Typical Output Voltage Waveform—Machine Loaded—AC Stick Mode.............................F-39  
Typical Output Voltage Waveform—Machine Loaded—DC Stick Mode ............................F-40  
Abnormal Open Circuit Voltage—DC TIG Mode—One Output SCR Not Functioning.......F-41  
Replacement Procedures  
High Voltage Transformer Removal and Replacement ......................................................F-42  
SCR Bridge Assembly Removal and Replacement............................................................F-45  
Polarity Switch Removal and Replacement........................................................................F-49  
Main Transformer and Output Choke Assembly Removal and Replacement....................F-54  
Retest After Repair....................................................................................................................F-59  
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F-2  
F-2  
TROUBLESHOOTING & REPAIR  
HOW TO USE TROUBLESHOOTING GUIDE  
WARNING  
Service and repair should be performed by only Lincoln Electric Factory Trained Personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician and machine  
operator and will invalidate your factory warranty. For your safety and to avoid Electrical Shock, please  
observe all safety notes and precautions detailed throughout this manual.  
This Troubleshooting Guide is provided to help  
you locate and repair possible machine malfunc-  
tions. Simply follow the three-step procedure list-  
ed below.  
Step 3. RECOMMENDED COURSE OF ACTION.  
The last column, labeled “Recommended Course  
of Action” lists the most likely components that may  
have failed in your machine. It also specifies the  
appropriate test procedure to verify that the subject  
component is either good or bad. If there are a  
number of possible components, check the com-  
ponents in the order listed to eliminate one possi-  
bility at a time until you locate the cause of your  
problem.  
Step 1. LOCATE PROBLEM (SYMPTOM). Look  
under the column labeled “PROBLEM” (SYMP-  
TOMS). This column describes possible symp-  
toms that the machine may exhibit. Find the list-  
ing that best describes the symptom that the  
machine is exhibiting. Symptoms are grouped  
into the following categories: Output Problems,  
TIG Welding Problems, Stick Welding Problems,  
and Function Problems.  
All of the referenced test procedures referred to in  
the Troubleshooting Guide are described in detail  
at the end of this section.  
Refer to the  
Troubleshooting and Repair Table of Contents to  
locate each specific Test Procedure. All of the  
referred to test points, components, terminal  
strips, etc., can be found on the referenced elec-  
trical wiring diagrams and schematics. Refer to  
the Electrical Diagrams Section Table of Contents  
to locate the appropriate diagram.  
Step 2. PERFORM EXTERNAL TESTS. The  
second column, labeled “POSSIBLE AREAS OF  
MISADJUSTMENT(S)”, lists the obvious external  
possibilities that may contribute to the machine  
symptom. Perform these tests/checks in the  
order listed. In general, these tests can be con-  
ducted without removing the case wrap-around  
cover.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs  
safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before  
you proceed. Call 216-383-2531 or 1-800-833-9353.  
WARNING  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and wave form checks with high frequency circuit OFF. Perform High Frequency  
Disable Procedure.  
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F-3  
F-3  
TROUBLESHOOTING & REPAIR  
PC BOARD TROUBLESHOOTING PROCEDURES  
WARNING  
• Remove the PC Board from the static-shielding bag  
and place it directly into the equipment. Don’t set the  
PC Board on or near paper, plastic or cloth which  
could have a static charge. If the PC Board can’t be  
installed immediately, put it back in the static-shielding  
bag.  
ELECTRIC SHOCK can kill.  
Have an electrician install and service  
this equipment. Turn the input power  
OFF at the fuse box before working on  
equipment. Do not touch electrically hot  
parts.  
• If the PC Board uses protective shorting jumpers,  
don’t remove them until installation is complete.  
CAUTION: Sometimes machine failures appear to be  
due to PC board failures. These problems can some-  
times be traced to poor electrical connections. To avoid  
problems when troubleshooting and replacing PC  
boards, please use the following procedure:  
• If you return a PC Board to The Lincoln Electric  
Company for credit, it must be in the static-shielding  
bag. This will prevent further damage and allow prop-  
er failure analysis.  
4. Test the machine to determine if the failure symp-  
tom has been corrected by the replacement PC  
board.  
1. Determine to the best of your technical ability that  
the PC board is the most likely component causing  
the failure symptom.  
NOTE: It is desirable to have a spare (known good) PC  
board available for PC board troubleshooting.  
2. Check for loose connections at the PC board to  
assure that the PC board is properly connected.  
NOTE: Allow the machine to heat up so that all electri-  
cal components can reach their operating temperature.  
3. If the problem persists, replace the suspect PC  
board using standard practices to avoid static elec-  
trical damage and electrical shock. Read the warn-  
ing inside the static resistant bag and perform the  
following procedures:  
5. Remove the replacement PC board and substitute  
it with the original PC board to recreate the original  
problem.  
PC Board can be damaged by static electricity.  
a. If the original problem does not reappear  
by substituting the original board, then the  
PC board was not the problem. Continue  
to look for bad connections in the control  
wiring harness, junction blocks, and termi-  
nal strips.  
• Remove your body’s static charge  
before opening the static-shield-  
ing bag. Wear an anti-static wrist  
strap. For safety, use a 1 Meg  
ohm resistive cord connected to a  
grounded part of the equipment  
b. If the original problem is recreated by the  
substitution of the original board, then the  
PC board was the problem. Reinstall the  
replacement PC board and test the  
machine.  
frame.  
ATTENTION  
Static-Sensitive  
Devices  
Handle only at  
Static-Safe  
• If you don’t have a wrist strap,  
touch an unpainted, grounded,  
part of the equipment frame.  
Keep touching the frame to pre-  
vent static build-up. Be sure not  
to touch any electrically live parts  
Workstations  
6. Always indicate that this procedure was followed  
when warranty reports are to be submitted.  
NOTE: Following this procedure and writing on the  
warranty report, “INSTALLED AND SWITCHED PC  
BOARDS TO VERIFY PROBLEM,” will help avoid  
denial of legitimate PC board warranty claims.  
at the same time.  
Reusable  
Container  
Do Not Destroy  
• Tools which come in contact with  
the PC Board must be either con-  
ductive, anti-static or static-dissi-  
pative.  
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F-4  
F-4  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
TROUBLESHOOTING GUIDE  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
OUTPUT PROBLEMS  
The machine is dead. No weld out- 1. Check the input voltage. The 1. Check the input power switch,  
put - no 115 VAC at the receptacle.  
(220 VAC receptacle on European  
models only).  
input voltage must match the  
rating plate and the voltage con-  
nection. Refer to Reconnect  
Procedure in the Installation  
section of this manual.  
reconnect panel and associated  
wires for loose or faulty connec-  
tions.  
2. The input power switch may be  
faulty.  
2. Make sure the input power  
switch is in the “ON” position.  
3. Perform the T1 Transformer  
Test.  
3. Check for blown or missing  
fuses in the input lines.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-5  
F-5  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
OUTPUT PROBLEMS  
No welding output. The 115 VAC is 1. Make sure the polarity switch is 1. Check for loose or faulty con-  
present at the receptacle. (220  
VAC receptacle on European mod-  
els only).  
in the proper position and func-  
tioning correctly.  
nections on the heavy current  
carrying leads. (Polarity switch,  
output choke, output terminals,  
etc.)  
2. One of the thermostats may be  
tripped. Allow the machine to  
cool. The thermal light will be 2. Check for faulty connections or  
on.  
a defective thermostat. Check  
leads #313, #314,.#315 and  
#316. See the Wiring Diagram.  
The thermal light will be on.  
3. Make sure the welding cables,  
torch and connections are in  
good operating condition.  
3. Perform the T1 Transformer  
Test.  
4. Perform the SCR Bridge Test.  
5. Check the current control R1 for  
proper operation. Normal resis-  
tance is 10,000 ohms. Also  
check associated leads for  
loose or faulty connections.  
6. The control board may be faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 216-  
383-2531 or 1-800-833-9353.  
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F-6  
F-6  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
TROUBLESHOOTING GUIDE  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
OUTPUT PROBLEMS  
No output from the machine in 1. The welding application may 1. One of the thermostats may be  
either Stick or TIG modes. The  
thermal light is on.  
have exceeded the recom-  
mended duty cycle. Allow the  
fan to cool the unit until the ther-  
mal light is off.  
faulty. Check or replace. See  
the Wiring Diagram.  
2. Check for loose or faulty wires  
on the thermostats and associ-  
ated circuitry. See the Wiring  
Diagram.  
2. The air louvers may be blocked.  
Remove the air obstruction and  
allow the unit to cool.  
3. The fan motor may be faulty or  
mechanically obstructed. The  
fan should run when welding or  
when a thermostat is open.  
4. The control board may be faulty.  
The machine does not respond (no 1. Make certain the machine is in 1. Check the continuity (zero  
gas flow, no high frequency and no  
open circuit voltage) when the arc  
start switch or Amptrol is activated.  
The thermal light is not lit.  
the TIG mode.  
ohms) of the leads between the  
remote receptacle and plug J7  
on the control board. See the  
Wiring Diagram.  
2. The Amptrol or arc start switch  
may be defective. Check for  
continuity (zero ohms) between  
pins “D” and “E” on the cable 2. Perform the T1 Transformer  
connector when the Amptrol or  
arc start switch is pressed.  
Test.  
3. The control board may be faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-7  
F-7  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
OUTPUT PROBLEMS  
The machine does not have weld- 1. Check the electrode cable and 1. Check the Stick/TIG switch (S3)  
ing output in the Stick mode. The  
machine operates correctly in the  
TIG mode.  
holder for loose or faulty con-  
nections.  
and associated leads. See the  
Wiring Diagram.  
2. Make sure the Stick/TIG switch 2. The control board may be faulty.  
(S3) is in the proper position  
and operating correctly.  
The machine welds at a very low 1. If welding in the TIG mode, the 1. Check the polarity switch and  
output regardless of the current  
control setting.  
remote control device may be  
defective.  
associated leads.  
2. Check the interior connections  
of the heavy current carrying  
leads.  
2. Make certain the input line volt-  
age is correct for the machine’s  
reconnect configuration.  
3. Perform the SCR Bridge Test.  
3. Check the welding cables  
and/or torch for loose or faulty  
connections.  
4. Perform the T1 Transformer  
Test.  
5. Check the current control for  
proper operation. Normal resis-  
tance is 10,000 ohms. See the  
Wiring Diagram.  
6. The control board may be faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 216-  
383-2531 or 1-800-833-9353.  
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F-8  
F-8  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
TROUBLESHOOTING GUIDE  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
OUTPUT PROBLEMS  
The machine welds at a very high 1. If welding in the TIG mode, the 1. Perform the SCR Bridge Test.  
output regardless of the current  
control setting.  
remote control device may be  
defective.  
2. Perform the T1 Transformer  
Test.  
3. Check the current control for  
proper operation. Normal resis-  
tance is 10,000 ohms. See the  
Wiring Diagram.  
4. Check leads #221 and #222  
between the output shunt and  
the control board. See the  
Wiring Diagram.  
5. The control board may be faulty.  
Accessories plugged into the 115 1. Make sure the accessory, plug 1. The circuit breaker (CB) may be  
volt receptacle do not work. (220  
VAC receptacle on European mod-  
els only).  
and associated leads are in  
good working condition.  
faulty.  
2. Check the receptacle and asso-  
ciated leads for loose or faulty  
connections.  
2. Make certain the correct input  
voltage is being applied to the  
machine. (The reconnect lead  
must be in the correct position.)  
3. Perform the T1 Transformer  
Test.  
3. The circuit breaker may be  
tripped. Reset if necessary.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-9  
F-9  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
OUTPUT PROBLEMS  
The machine makes a very loud 1. Inspect the output terminal insu- 1. Diode D1 may be shorted.  
buzzing noise in DC Stick or in DC  
TIG modes. There is no current  
draw from the machine’s output ter-  
minals. (The machine is not exter-  
nally loaded).  
lators for cracks or signs of  
overheating.  
Check and replace if necessary.  
2. Check the polarity switch (S2)  
for proper function and correct  
connections.  
3. Perform the SCR Bridge Test.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-10  
F-10  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
TROUBLESHOOTING GUIDE  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
TIG WELDING PROBLEMS  
The machine output is intermittent- 1. The problem may be caused by 1. Check for loose or faulty con-  
ly lost. Gas flow and high frequen-  
cy are also interrupted.  
high frequency interference.  
Make sure that the machine is  
grounded properly according to  
the installation instructions. If  
there are other high frequency  
sources in the area, make cer-  
tain that they are grounded  
properly.  
nections on the leads between  
the remote receptacle and plug  
J7 on the control board. See  
the Wiring Diagram.  
2. Check the plugs on the control  
board for loose connections.  
3. The control board may be faulty.  
2. Make sure the Amptrol is oper-  
ating properly.  
3. Check to make sure that the  
input voltage is correct for the  
machine to reconnect configura-  
tion.  
Refer to Reconnect  
Procedure in the Installation  
section of this manual.  
No gas or water flow (with optional 1. The gas (or water) supply is 1. Perform the Gas Solenoid  
water solenoid) when the arc start  
switch or Amptrol is activated in the  
TIG mode. All other machine func-  
tions are normal.  
either empty or not turned on.  
Test.  
2. The flow regulator may be set 2. The control board may be faulty.  
too low.  
3. Check the supply hoses for  
kinks or blockages.  
4. The filters may be blocked.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-11  
F-11  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
TIG WELDING PROBLEMS  
No high frequency. The machine is 1. If the machine is in a highly dirty 1. Check the high voltage trans-  
in the TIG mode and has normal  
output.  
environment with conductive  
contaminants, check and clean  
the spark gap with a low pres-  
sure air stream per the mainte-  
nance instructions.  
former (T2). The normal resis-  
tance of the secondary winding  
is 12.5k ohms.  
WARNING  
2. Check the spark gap operation  
and setting. Normal is (0.015”).  
Refer to the Maintenance  
Section of this manual.  
ELECTRIC SHOCK  
CAN KILL. When  
115 VAC is applied to  
the primary of T2, a  
very high voltage is  
developed on the secondary wind-  
ing.  
For assistance, call the  
Lincoln Electric Service Depart-  
ment. (216-383-2531 or 1-800-  
833-9353 (WELD).  
2. Check R5, C6, C5, L3 and L4.  
Replace if defective.  
3. The control board may be faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-12  
F-12  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
TIG WELDING PROBLEMS  
The high frequency “spark” is pre- 1. The spark gap may be too 1. The high voltage transformer  
sent but weak.  
large. Check and reset per  
instructions in the Maintenance  
Section of this manual.  
(T2) may be faulty.  
2. Capacitor C5 may be faulty.  
3. The high frequency transformer  
(T3) may be faulty.  
2. The work and/or torch cables  
may be in poor condition allow-  
ing the high frequency to “lead”  
to ground. Use good quality  
cables, preferably those with a  
high natural rubber content and  
as short as possible.  
3. If helium shielding gas is being  
used, reduce the percentage of  
helium.  
4. Make sure the tungsten elec-  
trode is the correct size for the  
process.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-13  
F-13  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
TIG WELDING PROBLEMS  
The high frequency “spark” is pre- 1. The torch may be faulty. Check 1. Check spark gap adjustment.  
sent at the tungsten electrode, but  
the operator is unable to establish  
a welding arc. The machine has  
normal open circuit voltage. Refer  
or replace.  
See the Maintenance section.  
2. The current control may be set 2. This may be a welding proce-  
too low.  
dure problem.  
to Technical Specifications in the 3. The tungsten electrode may be  
Contact the Lincoln Service  
Department (216) 383-2531 or  
1-800-833-9353 (WELD).  
Installation section.  
contaminated.  
sharpen.  
Replace or  
4. The electrode may be too large  
for the process.  
5. If a helium blend is being used  
as a shielding gas, reduce the  
percentage of helium.  
6. Check the welding cables for  
loose or faulty connections.  
When AC TIG welding, the arc is 1. The tungsten electrode may be 1. Check components R5 and C6  
erratic and there is a loss of “clean-  
ing” of the work piece.  
small for the process. Use a  
larger diameter tungsten or a  
pure tungsten.  
in the high voltage transformer  
primary circuit.  
2. Perform the SCR Bridge Test.  
2. If a helium blend is used as a  
shielding gas, reduce the per-  
centage of helium.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-14  
F-14  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
STICK WELDING PROBLEMS  
The stick electrode “blasts-off” 1. The welding current may be too 1. Perform the SCR Bridge Test.  
when touched to the work piece.  
high for the electrode size.  
Reduce current control setting  
or use a larger diameter elec-  
trode.  
2. The control board may be faulty.  
Variable or sluggish welding arc 1. Check the work and electrode 1. Check the polarity switch for  
when welding in the Stick mode.  
cables for loose or poor connec-  
tions.  
excessive wear or faulty con-  
nections.  
2. The welding cables may be too 2. Check the interior heavy current  
small or too long to permit the  
desired current to flow.  
carrying leads and connections.  
3. The welding current may be set  
too low.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-15  
F-15  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
FUNCTION PROBLEMS  
The control panel displays do not 1. The displays will read “000” until 1. Check the connections and  
function correctly.  
the torch trigger is activated  
and/or the welding arc is estab-  
lished. The voltmeter will nor-  
mally display open circuit volt-  
age in the Stick mode before  
the arc is established.  
associated leads between the  
display board and the control  
board. (Plugs P4, P20 and  
P21). See the Wiring Diagram.  
2. The display board may be  
faulty.  
3. The control board may be faulty.  
The voltmeter always reads “000” 1. None  
but the welding output is normal.  
1. Check the continuity (zero  
ohms) of leads #252 and #253  
between the polarity switch and  
plug J6 on the control board.  
See the Wiring Diagram.  
2. Check for open circuit voltage at  
leads #252 to #253 at plug J6  
on the control board. If open  
circuit voltage is present, also  
check for same voltage at plug  
J4 pin-8 to pin-5. If the same  
voltage is NOT present at plug  
J4, the control board may be  
faulty.  
3. If the correct voltages are pre-  
sent in Step #2, check the  
leads, plugs and connections  
between the control board and  
the display board.  
4. The display board may be  
faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-16  
F-16  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
FUNCTION PROBLEMS  
The ammeter display reads “000.” 1. None  
The machine has output but no  
control.  
1. Check leads #221 and #222  
between the output shunt and  
plug J2 on the control board.  
See the Wiring Diagram.  
2. The control board may be faulty.  
One of the display meters is blank. 1. None  
1. Check the leads and connec-  
tions between the display board  
and the control board. See the  
Wiring Diagram.  
2. The display board may be  
faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
SQUARE WAVE TIG 275  
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F-17  
F-17  
INSTALLATION  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
FUNCTION PROBLEMS  
The AC wave balance control does 1. The AC wave balance control is 1. Check the AC balance control  
not function properly.  
operational only in the TIG  
mode.  
(R2) and associated leads for  
loose or faulty connections.  
See the Wiring Diagram.  
2. The control board may be faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
216-383-2531 or 1-800-833-9353.  
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F-18  
F-18  
TROUBLESHOOTING & REPAIR  
HIGH FREQUENCY CIRCUIT DISABLE PROCEDURE  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician  
or machine operator and will invalidate your factory warranty. For your safety and to avoid  
electrical shock, please observe all safety notes and precautions detailed throughout this  
manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353  
(WELD).  
TEST DESCRIPTION  
This procedure will disable the high frequency circuit. The technician will then be able to  
take voltage measurements without the possibility of high frequency damage to his test  
equipment.  
MATERIALS NEEDED  
3/8" Nut driver  
Electrical insulating tape  
This procedure takes approximately 8 minutes to perform.  
WARNING  
HIGH VOLTAGE IS STILL PRESENT IN THE HIGH FREQUENCY CIRCUIT.  
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F-19  
F-19  
TROUBLESHOOTING & REPAIR  
HIGH FREQUENCY CIRCUIT DISABLE PROCEDURE (continued)  
FIGURE F.1 – SPARK GAP ASSEMBLY  
LEADS  
ATTACH  
HERE  
.015 Spark Gap  
RIGHT SIDE VIEW OF MACHINE  
PROCEDURE  
WARNING  
1. Remove the input power to the TIG 275  
machine.  
When power is applied to the  
machine there is a very high  
voltage present at these leads.  
2. Using the 3/8” nut driver, remove the right  
side case cover.  
3. Locate the Spark Gap Assembly at the lower  
right side of the machine. See Figure F.1.  
4. Carefully remove the two leads and washers  
from the Spark Gap Assembly.  
6. When voltage testing and scope measure-  
ments are complete, attach the two leads  
and washers to the Spark Gap Assembly.  
NOTE: Make sure insulation is still in place.  
5. Insulate the leads from each other and from  
the case.  
7. Reassemble the right side case cover.  
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F-20  
F-20  
TROUBLESHOOTING & REPAIR  
T1 MAIN TRANSFORMER TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshoot-  
ing assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
This test will determine if the correct voltage is being applied to the primary of the T1 trans-  
former and also if the correct voltages are being induced on the secondary windings of the  
transformer.  
MATERIALS NEEDED  
Volt/Ohmmeter (Multimeter)  
TIG 275 Wiring Diagrams  
3/8” Nut driver  
This procedure takes approximately 15 minutes to perform.  
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F-21  
F-21  
TROUBLESHOOTING & REPAIR  
T1 MAIN TRANSFORMER TEST (continued)  
FIGURE F.2 – PLUG J8 LOCATION ON CONTROL BOARD  
S-W TIG 275 CONTROL  
PIN 13 (LEAD #211A)  
PIN 14 (LEAD #212)  
PIN 12 (LEAD #232A)  
PIN 9 (LEAD #209)  
J8  
PIN 6 (LEAD #201)  
PIN 4 (LEAD #204)  
PIN 1 (LEAD #210)  
PIN 2 (LEAD #231)  
TEST PROCEDURE  
1. Remove main supply power to the machine.  
4. Carefully apply the correct input power mak-  
ing certain the reconnect configuration at the  
reconnect panel is correct for the input volt-  
age applied. Turn the TIG 275 ON.  
2. Using the 3/8” nut driver, remove the case  
left and right side covers.  
3. Locate plug J8 on the control board. See  
Figure F.2.  
5. Using the voltmeter, carefully test for the cor-  
rect transformer secondary voltages per  
Table F.1.  
WARNING  
ELECTRIC SHOCK can  
kill.  
• With input power ON, there are  
high voltages inside the  
machine. Do not reach into the  
machine or touch any internal  
part.  
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F-22  
F-22  
TROUBLESHOOTING & REPAIR  
T1 MAIN TRANSFORMER TEST (continued)  
6. If all of the secondary voltages are correct, the  
T1 transformer is functioning properly.  
a. If all of the secondary voltages are missing  
or incorrect, make certain that the correct  
input voltage is being applied to the correct  
primary leads. See Table F.1.  
b. If the correct input voltage is being applied  
to the primary leads and any or all of the  
secondary voltages are incorrect, the T1  
transformer may be faulty. See Main  
Transformer and Output Choke  
Removal and Replacement. Also check  
the leads for broken or loose connections  
between plug J8 and the T1 transformer.  
7. Replace the case side covers.  
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F-23  
F-23  
TROUBLESHOOTING & REPAIR  
T1 MAIN TRANSFORMER TEST (continued)  
TABLE F.1.  
T1 TRANSFORMER VOLTAGES  
TEST POINTS  
ACCEPTABLE VOLTAGES  
SECONDARY WINDINGS  
SECONDARY VOLTAGES  
PLUG J8 PIN 1 (LEAD #210)  
TO  
PLUG J8 PIN 9 (LEAD #209)  
18 VAC  
PLUG J8 PIN 6 (LEAD #201)  
TO  
PLUG J8 PIN 4 (LEAD #204)  
18 VAC  
PLUG J8 PIN 2 (LEAD #231)  
TO  
PLUG J8 PIN 12 (LEAD #232A)  
115 VAC  
PLUG J8 PIN 13 (LEAD #211A)  
TO  
PLUG J8 PIN 14 (LEAD #212)  
23 VAC  
78 VAC  
X1 TO X2  
PRIMARY WINDINGS1  
H1 TO H2  
PRIMARY VOLTAGES  
208 VAC  
H1 TO H3  
230 VAC  
H1 TO H4  
460 VAC  
NOTE: If the input voltages vary, the secondary voltages will vary accordingly.  
1Based on 208/230/460 models. For other voltage models refer to appropriate wiring diagram.  
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F-24  
F-24  
TROUBLESHOOTING & REPAIR  
GAS (WATER) SOLENOID TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshoot-  
ing assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
This procedure will help the technician to determine if the solenoid is receiving the correct volt-  
age and also if the solenoid is functional.  
MATERIALS NEEDED  
3/8” Nut driver  
Volt/Ohmmeter (Multimeter)  
Isolated 115 VAC power supply  
This procedure takes approximately 10 minutes to perform.  
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F-25  
F-25  
TROUBLESHOOTING & REPAIR  
GAS (WATER) SOLENOID TEST (continued)  
FIGURE F.3 – GAS SOLENOID LOCATION  
LEFT SIDE  
INTERNAL  
PANEL  
GAS  
SOLENOID  
CASE BACK  
CONTROL  
BOARD  
TEST PROCEDURE  
1. Remove input power to the TIG 275  
leads (#234 and #235). If the correct volt-  
age is present, the solenoid should activate  
and gas should flow.  
machine.  
2. Remove the left case side.  
8. If voltage is present at leads #234 and #235  
and the solenoid does not activate, the  
solenoid may be defective. The solenoid  
can be further checked by removing leads  
#234 and #235 from the solenoid and  
applying the external isolated 115 VAC sup-  
ply to the solenoid terminals. If the solenoid  
activates with the external supply but not  
when powered by the control board, the  
problem may be in the control board. If you  
hear solenoid activation but there is still no  
gas flow, check for restrictions in the line.  
3. Perform the High Frequency Circuit  
Disable Procedure.  
4. Locate the gas solenoid. See Figure F.3.  
5. Put the mode switch S3 in the 2-Step TIG  
position.  
WARNING  
ELECTRIC SHOCK can  
kill.  
9. When the test is complete, replace leads  
#234 and #235.  
• With input power ON, there are  
high voltages inside the  
machine. Do not reach into the  
machine or touch any internal  
part.  
10. Reassemble the two leads previously  
removed in the High Frequency Circuit  
Disable Procedure.  
11. Reassemble the left case side.  
6. Apply the correct input power to the TIG  
275.  
12. If a water solenoid is used, it can be tested  
using the same procedures.  
7. Activate the torch trigger and check for  
approximately 115 VAC at the solenoid  
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F-26  
F-26  
TROUBLESHOOTING & REPAIR  
STATIC SCR TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshoot-  
ing assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
The Static SCR Test is a quick check to determine if an SCR is shorted or “leaky.” See  
machine waveform section for normal and abnormal SCR waveforms.  
MATERIALS NEEDED  
Analog Ohmmeter (Multimeter)  
TIG 275 Wiring Diagrams  
SCR Heat Sink Assembly Drawing  
3/8” Nut driver  
This procedure takes approximately 12 minutes to perform.  
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F-27  
F-27  
TROUBLESHOOTING & REPAIR  
STATIC SCR TEST (continued)  
FIGURE F.4 – PLUG J1 LOCATION ON CONTROL BOARD  
S-W TIG 275 CONTROL  
J1  
J8  
TEST PROCEDURE  
1. Remove main supply power to the TIG 275  
and remove the case top and left side.  
2. Locate and remove plug J1 from the control  
board. See Figure F.4.  
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F-28  
F-28  
TROUBLESHOOTING & REPAIR  
STATIC SCR TEST (continued)  
FIGURE F.5 – SCR TEST POINTS  
DIODE D1  
SCR3 CATHODE  
SCR4 CATHODE  
SCR1 ANODE  
SCR3 / SCR4 ANODE  
SCR2 ANODE  
SCR1 / SCR2 CATHODE  
3. Using an analog ohmmeter, test the resis-  
tance from anode to cathode of SCR1.  
Reverse the meter leads and check from  
cathode to anode of SCR1. See Figure F.5.  
If a low resistance is indicated in either  
direction, SCR1 is faulty. Replace the SCR  
5. To further check the SCR’s functions, use an  
SCR tester and proceed to the Active SCR  
Test.  
NOTE: Also check diode D1.  
6. Replace plug J1 on the control board.  
7. Replace the case top and left side.  
Bridge Assembly.  
See SCR Bridge  
Assembly Removal and Replacement.  
4. Repeat Step #3 testing SCR2, SCR3 and  
SCR4.  
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F-29  
F-29  
TROUBLESHOOTING & REPAIR  
ACTIVE SCR TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshoot-  
ing assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
DESCRIPTION  
The Active SCR Test will determine if the device is able to be gated “ON” and conduct current  
from anode to cathode.  
MATERIALS NEEDED  
An SCR tester as outlined in this procedure  
TIG 275 Wiring Diagram  
3/8” Nut driver  
This procedure takes approximately 20 minutes to perform.  
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F-30  
F-30  
TROUBLESHOOTING & REPAIR  
ACTIVE SCR TEST (continued)  
FIGURE F.6 – PLUG J1 LOCATION ON CONTROL BOARD  
S-W TIG 275 CONTROL  
J1  
J8  
TEST PROCEDURE  
1. Remove main supply power to the TIG 275  
machine.  
4. Construct the circuit outlined in Figure F.7.  
One 6V lantern battery can be used.  
Resistor values are ± 10%. The voltmeter  
scale should be low, approximately 0-5 or 0-  
10 volts.  
2. Locate and remove plug J1 from the control  
board. See Figure F.6.  
3. Perform the following test for all four SCRs.  
5. Battery Test – Check the battery by shorting  
leads (A) and (C) and then close switch SW-  
1. Replace the battery if voltage is less than  
4.5 volts.  
See Figure F.8.  
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F-31  
F-31  
TROUBLESHOOTING & REPAIR  
ACTIVE SCR TEST (continued)  
FIGURE F.7 – ACTIVE SCR TEST SETUP  
SW1  
R2  
V
R1  
SW2  
6volt  
Lantern  
Battery  
A
G
SCR  
under  
test  
C
R1 = 4 ohms / 10 watts  
R2 = 3 ohms / 10 watts  
Resistor valves are ± 10%  
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F-32  
F-32  
TROUBLESHOOTING & REPAIR  
ACTIVE SCR TEST (continued)  
FIGURE F.8 – SCR GATE LOCATIONS  
DIODE D1  
SCR3 CATHODE  
SCR4 CATHODE  
SCR1 ANODE  
SCR3 / SCR4 ANODE  
SCR2 ANODE  
SCR1 / SCR2 CATHODE  
6. Connect SCR into the test circuit as shown in  
Figure F.7: (A) lead to anode (C) lead to cath-  
ode and (G) lead to the gate.  
9. Open switch SW-1, disconnect the gate lead  
(G) and reverse the (A) and (C) leads on the  
SCR. Close switch SW-1. The voltmeter  
should read zero. If the voltage is higher  
than zero, the SCR is shorted.  
7. Close switch SW-1 (Switch SW-2 should be  
open). The voltmeter should read zero. If the  
voltmeter reads higher than zero, the SCR is  
shorted.  
10. Replace the SCR Bridge Assembly if any  
SCRs do not pass the test in Step #3. See  
SCR Bridge Assembly Removal and  
Replacement.  
8. With switch SW-1 closed, close switch SW-2  
for two seconds and release. The voltmeter  
should read 3 to 6 volts before and after  
switch SW-2 is released. If the voltmeter does  
not read, or reads only while SW-2 is  
depressed, the SCR or battery is defective.  
(Repeat Battery Test Procedure described in  
Step 5.)  
11. Replace plug J1 on the control board.  
12. Replace the case sides and top.  
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F-33  
F-33  
TROUBLESHOOTING & REPAIR  
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM  
AC TIG MODE  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
2 ms  
50 V  
This is the typical AC output voltage  
waveform generated from a properly  
operating machine. Note that each  
vertical division represents 50 volts  
and that each horizontal division rep-  
resents 2 milliseconds in time.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
NOTE: AC balance control set at  
“Balanced” position.  
SCOPE SETTINGS  
Volts/Div....................50 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-34  
F-34  
TROUBLESHOOTING & REPAIR  
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM  
DC TIG MODE  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
50 V  
2 ms  
This is the typical DC (+) output volt-  
age waveform generated from a prop-  
erly operating machine. Note that  
each vertical division represents 50  
volts and that each horizontal division  
represents 2 milliseconds in time.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
SCOPE SETTINGS  
Volts/Div....................50 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-35  
F-35  
TROUBLESHOOTING & REPAIR  
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM  
AC STICK MODE  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
50 V  
2 ms  
This is the typical AC output voltage  
waveform generated from a properly  
operating machine. Note that each  
vertical division represents 50 volts  
and that each horizontal division rep-  
resents 2 milliseconds in time.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
SCOPE SETTINGS  
Volts/Div....................50 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-36  
F-36  
TROUBLESHOOTING & REPAIR  
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM  
DC STICK MODE  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
50 V  
2 ms  
This is the typical DC (+) output volt-  
age waveform generated from a prop-  
erly operating machine. Note that  
each vertical division represents 50  
volts and that each horizontal division  
represents 2 milliseconds in time.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
SCOPE SETTINGS  
Volts/Div....................50 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-37  
F-37  
TROUBLESHOOTING & REPAIR  
TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED  
AC TIG MODE  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
20 V  
2 ms  
MACHINE LOADED TO 255 AMPS  
AT 30 VAC.  
This is the typical AC output voltage  
waveform generated from a properly  
operating machine. Note that each  
vertical division represents 20 volts  
and that each horizontal division rep-  
resents 2 milliseconds in time. The  
machine was loaded with a resistance  
grid bank.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
NOTE: AC balance control set at  
“Balanced” position.  
SCOPE SETTINGS  
Volts/Div....................20 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-38  
F-38  
TROUBLESHOOTING & REPAIR  
TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED  
DC TIG MODE  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
20 V  
2 ms  
MACHINE LOADED TO 275 AMPS  
AT 31 VDC.  
This is the typical DC (+) output volt-  
age waveform generated from a prop-  
erly operating machine. Note that  
each vertical division represents 20  
volts and that each horizontal division  
represents 2 milliseconds in time. The  
machine was loaded with a resistance  
grid bank.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
SCOPE SETTINGS  
Volts/Div....................20 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-39  
F-39  
TROUBLESHOOTING & REPAIR  
TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED  
AC STICK MODE  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
20 V  
2 ms  
MACHINE LOADED TO 275 AMPS  
AT 31 VDC.  
This is the typical AC output voltage  
waveform generated from a properly  
operating machine. Note that each  
vertical division represents 20 volts  
and that each horizontal division rep-  
resents 2 milliseconds in time. The  
machine was loaded with a resistance  
grid bank.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
SCOPE SETTINGS  
Volts/Div....................20 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-40  
F-40  
TROUBLESHOOTING & REPAIR  
TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED  
DC STICK MODE  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
20 V  
2 ms  
MACHINE LOADED TO 275 AMPS  
AT 31 VDC.  
This is the typical AC output voltage  
waveform generated from a properly  
operating machine. Note that each  
vertical division represents 20 volts  
and that each horizontal division rep-  
resents 2 milliseconds in time. The  
machine was loaded with a resistance  
grid bank.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
SCOPE SETTINGS  
Volts/Div....................20 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-41  
F-41  
TROUBLESHOOTING & REPAIR  
ABNORMAL OPEN CIRCUIT VOLTAGE - DC TIG MODE  
ONE OUTPUT SCR NOT FUNCTIONING  
CAUTION  
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.  
• Perform all voltage and waveform checks with high frequency circuit OFF.  
• Perform High Frequency Disable Procedure.  
0 V  
50 V  
2 ms  
This is NOT the typical DC (+) output  
voltage waveform. One output SCR is  
not functioning. Note the “gap” in the  
waveform. One SCR gate was dis-  
connected to simulate an open or non-  
functioning output SCR. Note that  
each vertical division represents 50  
volts and that each horizontal division  
represents 2 milliseconds in time.  
NOTE: Scope probes connected at  
machine output terminals: (+) probe to  
electrode, (–) probe to work.  
SCOPE SETTINGS  
Volts/Div....................50 V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling.............................DC  
Trigger.........................Internal  
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F-42  
F-42  
TROUBLESHOOTING & REPAIR  
HIGH VOLTAGE TRANSFORMER REMOVAL  
AND REPLACEMENT  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshoot-  
ing assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
DESCRIPTION  
This procedure will aid the technician in the removal and replacement of the high voltage  
transformer.  
MATERIALS NEEDED  
3/8” Nut driver  
Needle nose pliers  
Phillips head screw driver  
Wire cutters  
This procedure takes approximately 25 minutes to perform.  
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F-43  
F-43  
TROUBLESHOOTING & REPAIR  
HIGH VOLTAGE TRANSFORMER REMOVAL  
AND REPLACEMENT (continued)  
FIGURE F.9 – SECONDARY LEADS AT HIGH FREQUENCY STARTER BOARD  
SQUARE  
W
A
VE  
TIG  
275  
TRANSFORMER  
SECONDARY  
LEADS  
REMOVAL PROCEDURE  
1. Remove input power to the TIG 275 machine.  
6. Using the phillips head screw driver, remove  
the front mounting screw from the base of the  
high voltage transformer. Take note of insula-  
tor placement for reassembly.  
2. Using the 3/8” nut driver, remove the case  
sides.  
3. With the needle nose pliers, remove the two  
secondary leads from the quick-connects on  
the high frequency arc starter board assem-  
bly. See Figure F.9.  
7. With the phillips head screw driver, loosen the  
two rear mounting screws.  
8. Carefully slide the transformer forward and  
remove it from the TIG 275 machine.  
4. Disconnect the in-line splice quick connect  
from one primary lead to lead #238. Cut any  
necessary cable ties.  
5. Remove the lead splice from the other prima-  
ry lead that is connected to lead #237, C6  
capacitor and R5 resistor. See the Wiring  
Diagram. Cut any necessary cable ties.  
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F-44  
F-44  
TROUBLESHOOTING & REPAIR  
HIGH VOLTAGE TRANSFORMER REMOVAL  
AND REPLACEMENT (continued)  
FIGURE F.10 – HIGH VOLTAGE TRANSFORMER MOUNTING INSULATORS  
SLOTTED REAR  
MOUNTING INSULATORS  
FRONT MOUNTING  
INSULATOR  
REPLACEMENT PROCEDURE  
1. Carefully position the new high voltage trans-  
former in place in the two rear mounting insu-  
lators. See Figure F.10.  
4. Reconnect the two primary leads.  
5. Reconnect the two secondary leads to the  
high frequency arc starter board assembly.  
2. Install the front mounting insulator and mount-  
ing screw.  
6. Replace any previously removed cable ties.  
7. Replace the case sides.  
3. Using the phillips head screw driver, tighten all  
three mounting screws making certain the  
insulators are positioned correctly.  
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F-45  
F-45  
TROUBLESHOOTING & REPAIR  
SCR BRIDGE ASSEMBLY REMOVAL AND REPLACEMENT  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshoot-  
ing assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
DESCRIPTION  
The following procedure will aid the technician in removing the SCRs from the output rectifier  
heat sink for maintenance or replacement.  
MATERIALS NEEDED  
3/8” Nut driver  
1/2” Wrench  
7/16” Wrench  
3/8” Wrench  
Penetrax A13 joint compound  
This procedure takes approximately 40 minutes to perform.  
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F-46  
F-46  
TROUBLESHOOTING & REPAIR  
SCR BRIDGE ASSEMBLY REMOVAL AND REPLACEMENT (continued)  
FIGURE F.11 – RECEPTACLE/CIRCUIT BREAKER LEADS  
CASE BACK SCREW  
CASE BACK  
SCREW  
CASE  
BACK  
CIRCUIT  
BREAKER  
RECEPTACLE  
PROCEDURE  
NOTE: “Left” and “right” are from the rear of the  
machine looking in.  
2. Using the 3/8” nut driver, remove the case  
sides and top.  
1. Remove input power to the TIG 275 machine.  
3. Using the 3/8” nut driver, remove the nine  
screws from the case back.  
FIGURE F.12 – FAN MOTOR BRACKET ASSEMBLY MOUNTING  
FAN  
MOTOR  
BRACKET  
ASSEMBLY  
MOUNTING  
SCREWS  
(3)  
SQUARE  
W
A
VE  
TIG  
275  
INTERNAL  
GLASTIC  
DIVIDER  
4. Carefully remove the case back and set aside.  
NOTE: The receptacle and circuit breaker  
leads will still be attached. See Figure F.11.  
6. Carefully pull the fan assembly away to allow  
access to the SCR Bridge Assembly. Support  
the fan assembly so as not to stress the fan  
motor leads. It is not necessary to disconnect  
the fan motor leads.  
5. With the 3/8” nut driver, remove the three  
screws mounting the fan motor bracket  
assembly to the internal glastic divider panel.  
See Figure F.12.  
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F-47  
F-47  
TROUBLESHOOTING & REPAIR  
SCR BRIDGE ASSEMBLY REMOVAL AND REPLACEMENT (continued)  
FIGURE F.13 – SCR BRIDGE CONNECTIONS  
"POS" LEAD (STEP 7)  
"NEG" IN SLEAVING  
(STEP 8)  
LEAD  
#217  
SHUNT & #220 LEAD  
LOCATIONS (STEP 11)  
LEAD #216  
"B"  
(STEP 12)  
X2 LEAD LOCATION  
(STEP 10)  
For Steps 7-13, see Figure F.13.  
7. Using the 7/16” wrench, label and remove the  
“POS” lead from the left side heat sink assem-  
bly. It is not necessary to remove the #218  
lead.  
11. With the 7/16” wrench, remove the shunt and  
one #220 lead from the right side negative  
heat sink assembly. It is not necessary to  
remove the other #220 lead.  
8. Using the 7/16” wrench, label and remove the  
“NEG” lead from the D1 diode pigtail.  
NOTE: It will be necessary to remove the  
sleeve insulation to gain access to the con-  
nection.  
12. Using the 1/2” wrench, remove the “B” lead  
from the AC left side heat sink. It is not nec-  
essary to remove the copper jumper or the  
#217 lead.  
13. Using the 3/8” wrench, remove the four  
mounting screws holding the SCR Bridge  
Assembly to the transformer iron assembly.  
9. Remove plug J1 from the control board. Also  
remove the plug and lead harness from the  
internal divider panel.  
14. Carefully remove the SCR Bridge assembly  
from the machine.  
10. With the 1/2” wrench, remove the X2 trans-  
former secondary lead from the right side  
heat sink assembly. It is not necessary to  
remove the jumper lead or the #216 lead.  
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F-48  
F-48  
TROUBLESHOOTING & REPAIR  
SCR BRIDGE ASSEMBLY REMOVAL AND REPLACEMENT (continued)  
REPLACEMENT PROCEDURE  
Refer to Figures F.11 - F.13.  
1. Carefully place the new SCR bridge assembly  
in position in the TIG 275.  
2. Using the 3/8” wrench, install the four mount-  
ing screws.  
Use Penetrox A13 joint compound on all alu-  
minum connections.  
3. Assemble lead “B” onto the AC left heat sink.  
4. Assemble the shunt to the right side negative  
heat sink.  
5. Assemble the X2 transformer secondary lead  
onto the right side heat sink.  
6. Feed the J1 plug and harness through the  
internal divider and install the plug into the  
control board.  
7. Assembly the “NEG” lead to the D1 diode pig-  
tail. Replace and secure sleeve insulation.  
8. Assemble the “POS” lead to the left side heat  
sink.  
9. Carefully position the fan motor assembly into  
place.  
10. Attach the fan motor assembly onto the glas-  
tic divider using the three screws previously  
removed.  
11. Carefully position the case back into place,  
being careful not to disconnect the leads  
from the circuit breaker or receptacle.  
12. Secure the case back with the nine screws  
previously removed.  
13. Assemble the case sides and top.  
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F-49  
F-49  
TROUBLESHOOTING & REPAIR  
POLARITY SWITCH REMOVAL AND REPLACEMENT  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshoot-  
ing assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
DESCRIPTION  
This procedure will aid the technician in the removal and replacement of the polarity switch.  
MATERIALS NEEDED  
3/8” Nut driver  
1/2” Wrench  
7/16” Wrench  
Phillips head screw driver  
5/64” Allen type wrench  
Needle nose pliers  
Slot head screw driver (2 required)  
Wiring diagram  
This procedure takes approximately 60 minutes to perform.  
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F-50  
F-50  
TROUBLESHOOTING & REPAIR  
POLARITY SWITCH REMOVAL AND REPLACEMENT (continued)  
FIGURE F.14 – NAMEPLATE REMOVAL  
POLARITY  
SWITCH  
CASE FRONT PANEL  
NAMEPLATE  
OUTPUT  
CONTROL  
KNOB  
AMPERAGE  
AC W  
ALLEN  
SCREW  
BALANCE  
A
AMPS  
VE  
VOL  
TS  
POST FLOW  
DOWN SLOPE  
TIME  
THERMAL  
PROTECTION  
POWER  
CONTROL  
KNOBS  
ON  
OFF  
REMOTE  
SQUARE  
T
O
W
WORK  
W
A
VE  
A
TER OUT  
TIG  
ELECTRODE  
W
A
275  
TER IN  
SCREW  
POLARITY  
SWITCH  
HANDLE  
PROCEDURE  
1. Remove the input power to the TIG 275  
machine.  
5. With the 2 slot head screw drivers, carefully  
pry the polarity switch handle from the shaft.  
2. Using the 3/8” nut driver, remove the case  
sides and top. For Steps 3-8, see Figure F.14.  
6. Using the small slot head screw driver,  
remove the three small control knobs.  
3. Using the 5/64” allen type wrench, remove the  
output control knob.  
7. Remove the seven plastic snap rivets holding  
the nameplate to the case front.  
4. Using the phillips head screw driver, remove  
the screw from the polarity switch handle.  
8. Remove the nameplate.  
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F-51  
F-51  
TROUBLESHOOTING & REPAIR  
POLARITY SWITCH REMOVAL AND REPLACEMENT (continued)  
FIGURE F.15 – POLARITY SWITCH CONNECTIONS  
B
CHOKE  
NEG  
253  
POS  
MICRO SWITCH  
LEADS  
X1  
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F-52  
F-52  
TROUBLESHOOTING & REPAIR  
POLARITY SWITCH REMOVAL AND REPLACEMENT (continued)  
FIGURE F.16 – POLARITY SWITCH WIRING DIAGRAM  
H4 (460V)  
H3 (230V)  
H2 (208V)  
H1  
232A  
211A  
232  
211B  
211  
R8  
W 209  
W X10  
18VAC  
B X9  
T1  
S
F
R 210  
W 201  
X1  
78VAC  
X2  
W 221  
R 222  
W X7  
S
F
18VAC  
W 204  
B 232  
232B  
W X8  
B X3  
115VAC  
CB  
115VAC  
232C  
C7  
CB  
231B  
B X4  
X5  
23VAC  
B 231  
211  
SCR1  
G1  
(+)  
218  
POS  
212  
X6  
G2  
SCR2  
POLARITY SWITCH  
AC A-C, D-E, B-F  
MICRO SWITCH  
OPEN  
L1  
DC+ B-D, C-E, A-F, G-H CLOSED  
DC- B-D, A-E, C-F, G-H CLOSED  
217  
G3  
FRONT GANG  
D
MICRO-SWITCH  
REAR GANG  
B
B
D2  
S2A  
NO  
H
NC  
E
F
A
SCR3  
G
220  
220A  
C
(-)  
POS  
D1  
B
X1  
SCR4  
G4  
X2  
S2  
POLARITY  
SWITCH  
216  
(REAR VIEW, SHOWN  
IN AC POSITION)  
R7  
253  
R6  
BYPASS /  
STABILIZER  
PC BOARD  
247  
S
L3  
C5  
SPARK  
GAP  
115VAC  
T2  
T3  
F
L4  
ARC STARTER AS'BLY  
ELECTRODE  
WORK  
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F-53  
F-53  
TROUBLESHOOTING & REPAIR  
POLARITY SWITCH REMOVAL AND REPLACEMENT (continued)  
For Steps 9--17, see Figure F.15 and F.16.  
17. Remove the cable tie that holds the thermal  
protection light leads to the polarity switch.  
9. With the 1/2” wrench, remove the “POS” flex  
lead from the polarity switch. See the Wiring  
Diagram. Label lead and connection point  
for reassembly.  
18. With the 7/16” wrench, remove the two nuts  
and washers that hold the polarity switch to  
the front panel. See Figure F.14.  
10. With the 1/2” wrench, remove the “B” flex  
lead from the polarity switch. This lead con-  
nects to the AC plate on the SCR bridge.  
See Wiring Diagram. Label lead and con-  
nection point for reassembly.  
19. Carefully remove the polarity switch assem-  
bly from the machine.  
Replacement Procedure  
11. Using the 1/2” wrench, remove the “NEG”  
flex lead from the rear gang of the polarity  
switch. This lead connects to the D1 diode  
on the SCR bridge. See the Wiring Diagram.  
Label lead and connection point for reassem-  
bly. Also label and remove the D2 diode heat  
sink assembly.  
Refer to Figures F.14 - F.16.  
1. Mount the polarity switch to the front panel  
with two nuts and washers.  
2. Replace the cable tie holding the thermal pro-  
tection light leads to the polarity switch.  
3. Resolder leads #275C and #312 to the  
microswitch.  
12. Using the 1/2” wrench, remove the flex lead  
from the polarity switch. This lead connects  
to the high frequency transformer coil and  
the by-pass board. See the Wiring Diagram.  
Label lead and connection point for  
reassembly. Also remove lead #252.  
4. Attach the following leads to the polarity  
switch. See Figures F.15 and F.16.  
• X1 secondary lead  
• choke lead  
13. Using the 1/2” wrench, remove the other flex  
lead from the polarity switch. This lead con-  
nects to the upper terminal on the by-pass  
and the “work” output terminal lead. See the  
Wiring Diagram. Label lead and connection  
point for reassembly. Also remove lead  
#253.  
• #253 and flex lead  
• #252 and flex lead  
• NEG lead (at rear gang)  
• POS lead  
• B lead  
14. Using the 1/2” wrench, remove the choke  
lead from the polarity switch. See the Wiring  
Diagram. Label lead and connection point  
for reassembly.  
5. Install the nameplate with 7 rivets.  
6. Re-install and secure the three small plastic  
control knobs.  
15. With the 1/2” wrench, remove the X1 sec-  
ondary lead from the polarity switch. See the  
Wiring Diagram. Label lead and connection  
point for reassembly.  
7. Install the polarity switch handle with the  
phillips head screw.  
8. Install the output control knob with the allen  
screw.  
16. Carefully unsolder the two leads (#275C and  
#312) from the microswitch located on the  
polarity switch assembly. See the Wiring  
Diagram. Label leads and connections  
points for reassembly.  
9. Install the case top and sides.  
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F-54  
F-54  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY  
REMOVAL AND REPLACEMENT  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshoot-  
ing assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
DESCRIPTION  
This procedure will aid the technician in the removal and replacement of the main transformer  
and choke assembly.  
MATERIALS NEEDED  
3/8” Nut driver  
5/16” Nut driver  
1/2” Wrench  
Wire cutters  
Molex extraction tool # HT60630B  
This procedure takes approximately 2 hours to perform.  
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F-55  
F-55  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY  
REMOVAL AND REPLACEMENT (continued)  
FIGURE F.17 – PLUG J8 LOCATION ON CONTROL BOARD  
S-W TIG 275 CONTROL  
PIN 13 (LEAD #211A)  
PIN 14 (LEAD #212)  
PIN 12 (LEAD #232A)  
PIN 9 (LEAD #209)  
J8  
PIN 6 (LEAD #201)  
PIN 4 (LEAD #204)  
PIN 1 (LEAD #210)  
PIN 2 (LEAD #231)  
PROCEDURE  
1. Remove the input power to the TIG 275  
machine.  
6. Using the mini-molex extraction tool, remove  
the following six leads from plug J8. See  
Figure F.17 for lead locations. Cut any nec-  
essary cable ties. Note lead and pin place-  
ment for reassembly.  
2. Perform the SCR Bridge Assembly Removal  
Procedure.  
3. Label and remove lead #232B from the circuit  
breaker located on the case back.  
#212, #201, #204, #209, #210, #231  
7. Disconnect lead #232A at the quick-connect.  
8. Disconnect lead #211 at the quick-connect.  
4. Label and remove lead #231B from the recep-  
tacle located on the case back.  
5. Remove Plug J8 from the control board. See  
Figure F.17.  
9. Feed the disconnected leads through the  
internal baffle along with leads #232B and  
231B.  
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F-56  
F-56  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY  
REMOVAL AND REPLACEMENT (continued)  
FIGURE F.18 – TRANSFORMER CONNECTIONS  
GLASTIC CHOKE  
BAFFLES  
CHOKE  
LEAD  
LEFT SIDE  
INTERNAL  
PANEL  
LIFT BAIL  
BAFFLE  
GLASTIC  
RECONNECT  
PANEL  
(LEFT SIDE)  
TRANSFORMER  
PRIMARY LEADS -  
CONNECTION  
POINTS  
SQUARE  
W
A
VE  
TIG  
275  
SCREW (1)  
TRANSFORMER  
MOUNTING  
STUD (4)  
SCREW (2)  
H1 PRIMARY LEAD  
CONNECTION AT  
INPUT LINE SWITCH  
(LOCATION)  
10. Using the 7/16” wrench, disconnect the  
transformer primary leads from the recon-  
nect studs. See the Wiring Diagram and  
Figure F.18. Label the leads for reassembly.  
15. Clear the glastic choke baffle and associated  
leads for transformer removal.  
16. With the 3/8” wrench, disconnect the H1 pri-  
mary lead from the input line switch.  
11. Using the 5/16” nut driver, remove the one  
screw from the lower front corner of the glas-  
tic reconnect panel.  
17. Using the 1/2” wrench, disconnect the choke  
lead from the polarity switch. See the Wiring  
Diagram and Figure F.19.  
Label for  
12. Remove the H1 capacitor lead from the  
capacitor terminal.  
reassembly.  
18. Using the 1/2” wrench, disconnect the X1  
transformer secondary lead from the polarity  
switch. Label for reassembly. See Figure  
F.19.  
13. Using the 5/16” nut driver, remove the four  
screws from the glastic choke baffles.  
14. Remove the glastic reconnect panel by lifting  
up on the choke baffle and sliding the recon-  
nect panel away from the machine. (Clear  
all leads.)  
19. Using the 3/8” nut driver, remove the screw  
holding the left side internal panel to the  
metal lift bail baffle. See Figure F.18.  
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F-57  
F-57  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY  
REMOVAL AND REPLACEMENT (continued)  
FIGURE F.19 – POLARITY SWITCH CONNECTIONS  
B
CHOKE  
NEG  
253  
POS  
MICRO SWITCH  
LEADS  
X1  
20. Using the 3/8” wrench, remove the two  
screws holding the left side panel to the base  
of the machine. See Figure F.18.  
25. Remove lead #315 and #316 from the X1  
secondary lead thermostat. See the Wiring  
Diagram.  
21. With the 1/2” wrench, disconnect the shunt  
assembly from the choke lead.  
26. Disconnect the primary thermostat lead  
splices #313 and #315. See the Wiring  
Diagram.  
22. Carefully slide the panel away from the  
transformer about two inches.  
27. With the 9/16” wrench, remove the four nuts  
from the transformer mounting studs. See  
Figure F.18.  
23. Remove the left side choke glastic baffle.  
24. Remove leads #314 and #316 from the  
choke thermostat. See the Wiring Diagram.  
28. Carefully lift the transformer and choke  
assembly from the machine base. Clear all  
leads.  
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F-58  
F-58  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY  
REMOVAL AND REPLACEMENT (continued)  
Reassembly Procedure  
Refer to Figures F.17 - F.19.  
1. Set the transformer onto the four mounting  
studs on the base. Attach the four nuts.  
8. Fit the choke baffle and glastic reconnect  
panel together and attach them with screws.  
2. Connect the lead splices to the three ther-  
mostats:  
9. Attach the H1 capacitor lead to the capacitor  
terminal.  
• #313 and #315 to the primary thermostat.  
10. Connect the transformer primary leads to the  
reconnect panel studs.  
• #315 and #316 to the X1 secondary ther-  
mostat  
11. Feed the following leads through the internal  
panel and attach them as follows:  
• #314 and #316 to the choke thermostat.  
• #211 and #232A at the quick-connects  
• #231B to the receptacle  
3. Attach the shunt assembly to the choke lead.  
4. Attach the lead side panel to the base with  
two screws.  
• 232B to the circuit breaker  
5. Attach the left side panel to the metal lift bail  
baffle.  
• #212, #201, #204, #209, #210, #231 at  
molex plug J8. See Figure F.17.  
6. Connect the X1 transformer lead and the  
choke lead to the polarity switch.  
• Install plug J8 into the control board.  
12. Install necessary cable ties.  
7. Connect the H1 primary lead to the input line  
switch.  
13. Perform the SCR Bridge Assembly  
reassembly procedure.  
SQUARE WAVE TIG 275  
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F-59  
F-59  
TROUBLESHOOTING & REPAIR  
RETEST AFTER REPAIR  
Should a machine under test be rejected for any reason requiring the removal of any mechanical part that could  
affect the machine’s electrical characteristics, or if any electrical components are repaired or replaced, the machine  
must be retested.  
INPUT IDLE AMPS  
Input Volts/Hertz  
Maximum Idle Amps  
Maximum Idle Amps  
(without PFC)  
(with PFC)  
208/60  
230/60  
460/60  
5
4
2
38  
35  
18  
OPEN CIRCUIT VOLTAGES  
STICK MODE OCV  
AC 70 - 74 VAC  
DC 56.5 - 61.5 VDC  
TIG MODE OCV  
AC 70 - 76 VAC  
DC 59 - 67 VDC  
MAXIMUM ACCEPTABLE OUTPUT VOLTAGE -  
AT MINIMUM OUTPUT SETTINGS  
DC TIG Mode  
5 Amps @ 13 Volts  
MINIMUM ACCEPTABLE OUTPUT VOLTAGE -  
AT MAXIMUM OUTPUT SETTING  
DC TIG Mode  
300 Amps @ 32 Volts  
RECOMMENDED METERS FOR MACHINE OUTPUT TESTS  
VOLTMETER: AC and DC True RMS Meter - Fluke 8922A or equivalent  
AMMETER: Columbia Type AX AC or DC Tong Ammeter  
IMPORTANT: IF OTHER TYPE METERS ARE USED, RESULTS MAY NOT BE ACCURATE.  
SQUARE WAVE TIG 275  
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F-60  
F-60  
NOTES  
SQUARE WAVE TIG 275  
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G-1  
G-1  
ELECTRICAL DIAGRAMS  
TABLE OF CONTENTS  
ELECTRICAL DIAGRAMS SECTION  
Electrical Diagrams Section ..........................................................................................Section G  
Wiring Diagram (L10747).............................................................................................................G-2  
Wiring Diagram (L10747-2) .........................................................................................................G-3  
Control Board Schmatic (G3358-1) .............................................................................................G-4  
Control Board Schmatic (G3358-2) .............................................................................................G-5  
Display Board Schematic (L10768).............................................................................................G-6  
Bypass Board Schematic (S22530).............................................................................................G-7  
Display Board Layout (L10770-1)................................................................................................G-8  
Control Board Layout (G3360-1) .................................................................................................G-9  
Bypass Board Layout (L10121-1)..............................................................................................G-10  
SQUARE WAVE TIG 275  
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G-2  
G-2  
ELECTRICAL DIAGRAMS  
Wiring Diagram (L10747)  
2 7 5 C  
N E G  
2 5 2  
N E G  
2 7 7 A  
3 1 5  
A
B
F
C
E
D
3 1 3  
3 1 4  
2 0 9 W  
2 1 0 R  
2 3 5  
W
R
2 2 1 ( + )  
2 2 2 ( - )  
2 3 1 B  
2 3 8  
2 3 4  
2 3 2 B A  
2 0 4 W  
2 1 6  
G 4  
2 1 1 A  
W
2 3 6  
2 1 8  
G 1  
2 1 2  
2 0 1  
2 2 0 A  
G 2  
2 4 7  
2 2 0  
2 1 7  
G 3  
2 6 0  
2 6 1  
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your  
code is pasted inside one of the enclosure panels of your machine.  
SQUARE WAVE TIG 275  
L10747  
7-24-98  
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G-3  
G-3  
ELECTRICAL DIAGRAMS  
Wiring Diagram (L10747-2)  
2 7 5 C  
N E G  
2 5 2  
N E G  
2 7 7 A  
3 1 5  
A
B
F
C
E
D
3 1 3  
3 1 4  
2 0 9 W  
2 1 0 R  
2 3 5  
W
R
2 2 1 ( + )  
2 2 2 ( - )  
2 3 1 B  
2 3 8  
2 3 4  
2 3 2 B A  
2 0 4 W  
2 1 6  
G 4  
2 1 1 A  
W
2 3 6  
2 1 8  
G 1  
2 1 2  
2 0 1  
2 2 0 A  
G 2  
2 4 7  
2 2 0  
2 1 7  
G 3  
2 6 0  
2 6 1  
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your  
code is pasted inside one of the enclosure panels of your machine.  
SQUARE WAVE TIG 275  
L10747-2  
C-UF  
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G-4  
G-4  
ELECTRICAL DIAGRAMS  
Control Board Schematic (G3358-1)  
+15V  
10.0K  
R217  
PT_Vsp  
R209  
221K  
SW_15V  
CLEANNING  
SCR 2,  
DZ13  
J1  
SCR DRIVING CIRCUIT  
D20  
4
13  
12  
8
R206  
10.0K  
X5  
C93  
05.01 V  
C105  
.0047  
50V  
1N4936  
Q22  
47.5  
R99  
C96  
.0047  
50V  
R208  
4.75K  
2N4401  
3
3.3V  
1W  
1
D46 1N4936  
Q19  
C44  
50V  
47.5  
R98  
T1  
2N4401  
GATE SCR  
3
0.2mH  
SW_GND  
R190  
18.2K  
47.5  
R96  
T1  
.0047  
D45 1N4936  
4
850uS PULSE WIDTH LIMIT  
2
SW_15V  
0.2mH  
R189  
39.2K  
13  
J1  
4
47.5  
R97  
D44 1N4936  
11  
2N4403  
Q17  
J1  
6
D14  
X6  
1
12  
1N4936  
3
9
8
47.5  
X8  
2
5
SW_GND  
10  
X6  
R100  
D
S
2
3
C45  
.0047  
50V  
50 KHz OSCILATOR  
C89  
820p  
50V  
T1  
47.5  
R103  
C76  
.0047  
50V  
Q8  
PHASE FIRE  
0.2mH  
50KHz 75% DUTY CYCLE  
GATE SCR  
1
6
5
1
15A  
60V  
1
OFF SHEET CONNECTIONS  
Q15  
4
3
47.5  
R102  
R147  
100  
6
X8  
X6  
2
R198  
10.0K  
2N4401  
G
REFER TO SHEET  
2
DZ11  
15V  
1W  
47.5  
R101  
C85  
100p  
100V  
C67  
330p  
100V  
SW_GND  
SW_15V  
(ALL CONNECTIONS ARE SINGLE POINT)  
1
J1  
3
T2  
D21  
47.5  
1N4936  
0.2mH  
OUTPUT_ENABLE  
SW_15V  
Q12  
3
R109  
SW_GND  
2N4401  
SW_GND  
2
47.5  
R111  
C46  
.0047  
50V  
T2  
PENETRATION  
GATE SCR  
2
0.2mH  
SCR 1,  
3
47.5  
R110  
PHASE_FIRE  
LINE_SYNC  
4
J1  
2
47.5  
R108  
2N4403  
Q13  
J1  
5
D22  
D
2
3
6
5
47.5  
C81  
.0047  
50V  
SW_GND  
Q9  
1N4936  
Q16  
2N4401  
4
5
X6  
R200  
10.0K  
R106  
15A  
60V  
1
R174  
100  
C47  
.0047  
50V  
PHASE_A  
PHASE_B  
47.5  
R104  
T2  
G
S
0.2mH  
C73  
GATE SCR  
4
DZ9  
15V  
1W  
C86  
100p  
100V  
330p  
100V  
47.5  
R107  
6
J1  
1
47.5  
R105  
SW_GND  
SW_GND  
+15V  
13  
12  
11  
X8  
PHASE  
(PENETRATION)  
B
PHASE  
(CLEANNING)  
A
+15V  
22.1K  
R207  
9
8
J1  
7
10  
X8  
Q21  
2N4401  
PHASE DETECTOR  
1
2
X5  
C7  
.1  
400V  
C8  
.1  
400V  
C10  
C9  
.1  
400V  
.1  
C102  
.1  
50V  
C94  
.0047  
50V  
400V  
D55  
1N4936  
Q20  
R218  
10.0K  
2N4401  
LINE SYNC.  
TP6  
150V  
80J  
DZ14  
5.1V  
1W  
C101  
C98  
.0047  
50V  
D54  
1N4936  
TP2  
130V  
90J  
TP4  
130V  
90J  
PT_Vsp  
L_5V  
TP3  
130V  
90J  
TP1  
+5V  
.0047  
50V  
130V  
+15V  
SW_15V  
R589  
1.00K  
90J  
D47  
X7  
R34  
IN  
OUT  
D48  
1N5402  
1.00K  
D52  
D49  
1N5402  
1N5402  
GND  
R452  
SCR SNUBBER CIRCUIT  
1.00K  
R598  
1
C17  
C77  
SOME OR ALL OF THESE  
RESISTORS MAY NOT PRESENT  
C12  
4.7  
35V  
9
R194  
J8  
8
X2  
+
C82  
100  
50V  
t
2.7  
5W  
C60  
REF  
.25  
C99  
.0047  
1400V  
TL431  
6
18VAC  
1
35V  
D42  
1000  
C83  
.05  
600V  
J8  
D50  
D51  
1N5402  
L_GND  
SW_GND  
J2  
J2  
J6  
1
J3  
J3  
J3  
J3  
3
4
3
4
5
6
J6  
2
+15V  
L_5V  
SW_15V  
14  
11  
10  
X5  
LAST NO. USED  
GENERAL INFORMATION  
R- 637  
818  
X- 17  
OCI-  
4
14  
14  
4
14  
4
4
14  
14  
C-  
6
4
14  
28  
ELECTRICAL SYMBOLS PER E1537  
D- 99  
TRI-  
CAPACITORS  
RESISTORS  
DIODES  
=
MFD  
(
.022/50V  
1/4W  
UNLESS OTHERWISE SPECIFIED)  
UNLESS OTHERWISE SPECIFIED)  
DZ- 39  
X5  
C185  
0.1  
50V  
C186  
C187  
0.1  
50V  
C87  
0.1  
50V  
C97  
0.1  
50V  
C232  
0.1  
50V  
C233  
0.1  
50V  
C92  
0.1  
50V  
X8  
X6  
LABELS  
Q- 41  
=
Ohms  
(
C16  
0.1  
50V  
0.1  
C230  
0.1  
50V  
C231  
2700p  
50V  
C229  
X1  
X9  
X10  
X11  
X13  
X14  
X17  
X16  
X12  
=
1A, 400V  
(UNLESS OTHERWISE SPECIFIED)  
50V  
4.7  
SUPPLY  
VOLTAGE NET  
4093B  
7
4093B  
35V  
LT1014  
11  
LM224  
11  
4066B  
7
LM224  
11  
LM224  
4066B  
7
4066B  
J1:  
J2:  
J3:  
8
4
4
PIN  
PIN  
PIN  
J6:  
J7:  
4
8
PIN  
PIN  
4066B  
MC68HC705  
POWER SUPPLY SOURCE POINT  
COMMON CONNECTION  
G3358_2BA  
SHEET  
J7A:  
8
PIN  
7
11  
7
7
7
14  
J4: 10 PIN  
J5: 14 PIN  
J8: 16 PIN  
1
FRAME CONNECTION  
SW_GND  
L_GND  
EARTH GROUND CONNECTION  
NOTES  
:
N.A. SINCE COMPONENTS OR CIRCUITRY ON  
A
PRINTED CIRCUIT BOARD MAY CHANGE  
WITHOUT AFFECTING THE INTERCHANGEABILITY OF COMPLETE BOARD, THIS DIAGRAM MAY  
A
NOT SHOW THE EXACT COMPONENTS OR CIRCUITRY OF CONTROLS HAVING  
NUMBER.  
A
COMMON CODE  
G3358-1  
7-24-98  
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not  
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result  
SQUARE WAVE TIG 275  
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.  
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G-5  
G-5  
ELECTRICAL DIAGRAMS  
Control Board Schematic (G3358-2)  
THERMAL LED  
N_5V  
BACKGROUND  
SUPPLY  
(+)  
L_5V  
8
23 VAC  
L_5V  
SOLENOID  
HV XFMR  
1.50K  
R592  
J8  
LOCAL CONTROL POT  
+15V  
R593  
267  
(-)  
C263  
.0047  
1400V  
R503  
FAN  
14  
13  
D91  
THERMAL SHUTDOWN CIRCUIT  
PT_Vsp  
5
J5  
100K  
Vdd  
L12  
.39mH  
R590  
6.81K  
TSTAT  
+5V  
+15V  
115VAC  
FAN  
7
15  
C181  
J8  
J8  
1
6
4
3
16  
Q37  
1.0  
X15  
RES  
.0047  
C218  
0.1  
50V  
C260  
C261  
J8  
J8  
2N4401  
J8  
R504  
1.00K  
35V  
1400V  
OCI6  
3043  
1
2
10.0K  
R613  
MT2  
MT1  
1
2
S-8054HN  
J5  
TRI4  
C219  
C217  
0.1  
Vss  
2
9
5
J5  
J5  
3
10  
11  
10  
12  
J3  
J3  
2
50V  
G
C2  
C198  
0.1  
L_GND  
TP5  
J8  
J5  
J8  
175V  
J8  
J8  
J8  
J5  
J8  
R437  
267  
C262  
50V  
C158  
.0047  
1400V  
R322  
47.5  
.0047  
+15V  
FAN DRIVING CIRCUIT  
C173  
3300  
50V  
+5V  
1
6
4
DZ4  
R502  
1.00M  
Y1  
L_GND  
t
+
1400V  
C180  
.0047  
1400V  
3.3V  
1W  
TRI3  
G
MT2  
120J  
C170  
OCI4  
3043  
R321  
47.5  
C257  
R595  
C103  
.0047  
1400V  
R594  
1.00K  
C108  
.0047  
PTC1  
56  
C104  
10.0K  
R596  
MT1  
2
4.0MHz  
130  
.0047  
C193  
0.1  
50V  
C258  
1400V  
1400V  
C171  
C172  
.1  
400V  
C174  
3300  
50V  
DZ29  
C40  
6
5
C214  
C215  
22p  
C1  
Q1  
DZ36  
15V  
5W  
R597  
10.0K  
10.0K  
R585  
R326  
2.67K  
22p  
100V  
7
D90  
20.0  
C152  
0.1  
X13  
100V  
C36  
R438  
DZ1  
4
8
4
R472  
3.32K  
Q27  
2N4403  
2N4401  
50V  
MACH_PRESET  
J7A  
J7A  
J7  
1.00K  
4.75K  
15V  
+15V  
ROBOTIC  
INTERFACE  
D70  
Q24  
2N4401  
5.1V  
1W  
1W  
R587  
C19  
BACKGROUND CURRENT  
HF DRIVING CIRCUIT  
X16  
13  
DZ20  
C207  
1
2
C169  
20.0  
0.1  
L_GND  
5.1V  
1W  
R588  
50V  
AMPTROL  
INTERFACE  
R196  
267  
+5V  
5
6
R549  
100K  
X5  
R197  
267  
1.50K  
R186  
8
+15V  
J8  
DZ35  
15V  
J7  
R215  
4
C62  
REMOTE PROTECTION  
D9  
D17  
ARC_SENSED  
(+)  
1
6
.05  
1W  
1.00K  
5
5
C255  
X16  
600V  
MT2  
MT1  
J7A  
TRI1  
L5  
OCI2  
3043  
1
6
4
R216  
1.00K  
18VAC  
C75  
MT2  
MT1  
TRI2  
C106  
C79  
OCI3  
3043  
G
.39mH  
A
J7  
J7A  
C107  
.0047  
3000V  
OCI1  
2
4
.0047  
C38  
PULSER SUPPLY:  
Set control pot at max.  
J8  
1400V  
C91  
CNY17-3  
G
ROBOTIC  
CONTROL  
R118  
1
1
6
C84  
.1  
20  
4.2V  
4.8V  
@
@
70mA  
50mA  
PTC3  
1
5
2
L4  
50V  
1.00K  
C100  
Trigger open  
R316  
221  
9
8
C39  
400V  
.39mH  
J7  
R117  
+
C95  
t
B
56  
R205  
1.00K  
.0047  
close  
6
J7A  
1.00K  
35V  
1.0  
ROBOTIC  
GND  
DZ38  
2
6
4
R317  
221  
2
2
3000V  
D12  
D13  
L3  
DZ37  
Q18  
D77  
L2  
C63  
.05  
600V  
2N4401  
R211  
C153  
0.1  
50V  
J7  
J7  
10V  
5W  
R178  
6.81K  
R542  
6.81K  
1.0  
35V  
MACH  
3
5.1V  
1W  
28  
.39mH  
1A  
C
J7  
1
1.00K  
R318  
221  
The snubber is needed for TRI1 to prevent  
HI-FREQ. turning on when noise coupled through  
AC line or when switching power switch on  
.39mH  
/RESET  
Vdd  
/IRQ  
D76  
Q11  
TRIGGER CIRCUIT  
C80  
.0047  
3000V  
C65  
C72  
2N4401  
24  
15  
27  
26  
22  
18  
16  
25  
19  
20  
21  
2
5
C54  
150p  
50V  
C88  
.0047  
3000V  
TCMP  
VRH/PC7  
OSC1  
/SHUTDOWN  
BG_CURRENT  
GAS  
R505  
4.75K  
.0047  
1400V  
C74  
AMPTROL  
and off.  
R319  
221  
TRIGGER  
PA5  
GAS DRIVING CIRCUIT  
L1  
GAS  
PULSER  
CHASSIS CONNECTION  
F
13  
6
6
PB7/SCK  
PB6/SDI  
PA0  
+15V  
GND  
J7  
7
C190  
.0047  
12  
10  
9
.39mH  
OSC2  
PC0  
HF  
C66  
.0047  
3000V  
HF  
/TRIGGER  
3000V  
R614  
4.75K  
2_STEP  
2_STEP  
REMOTE PROTECTION  
PULSER_PRESET  
L6  
MODE  
AN2/PC4  
AN0/PC6  
PD7  
PA1  
PA2  
START  
START  
ARC_SENSED  
(-)  
8
POSTFLOW  
AC  
UP_SLOPE  
LOC_REM  
ARC_SENSED  
OUTPUT_ENABLE  
STICK  
UP_SLOPE  
.39mH  
Q40  
2N4401  
J7A  
J7A  
D95  
GND  
3
4
PA6  
LOC_REM  
R580  
6.81K  
6
FAN  
REM_SENSE  
SOFT_START  
AN3/PC3  
PC2  
PA4  
ROBOT  
11  
3
TRIGGER  
PB5/SD0  
PA7  
+5V  
FAN  
PC1  
J7A  
7
17  
14  
7
CURRENT_FB  
AN1/PC5  
Vss  
PA3  
/SENSE_ENABLE  
FILTER_CAP  
OUTPUT_ENABLE  
23  
X12  
PD5  
CTRL POT AUTO CONNECTION  
MC68HC705  
R499  
2_STEP  
4_STEP  
J5  
J5  
J5  
10.0K  
8
+15V  
ARC_SENSED  
L11  
.39mH  
X17  
12  
6
R500  
475  
R632  
STICK  
R576  
2
PULSER_PRESET  
+15V  
1
6.81K  
C244  
.0047  
4.75K  
13  
REM_SENSE  
X17  
X17  
3000V  
X14  
STICK  
+5V  
DZ21  
5.1V  
1W  
R633  
332K  
GND  
C213  
14  
10  
11  
8
9
R476  
2.21K  
SHUNT_CURRENT  
10  
11  
4.7  
J5  
C272  
35V  
12  
6
4.7  
REM_SENSE  
PULSER  
12  
R513  
10.0K  
R629  
47.5K  
35V  
+15V  
/SENSE_ENABLE  
820p  
50V  
C223  
DZ24  
5.1V  
1W  
D88  
C224  
0.1  
50V  
+15V  
Q34  
10  
R572  
6.81K  
2N4401  
L10  
.39mH  
POSTFLOW  
X13  
X5  
J5  
8
9
8
7
R506  
4.75K  
9
R517  
1.00K  
R514  
47.5K  
DZ22  
4
C243  
D98  
C220  
J5  
R515  
.0047  
5.1V  
1W  
4.7  
MACH  
3000V  
+15V  
1.00K  
35V  
C225  
13  
47p  
GND  
X1  
MACH  
14  
100V  
5
2N4401  
Q38  
R516  
1.00K  
1
12  
C212  
+15V  
+15V  
3
4
OCI5  
1CNY17-3  
J4  
J4  
0.1  
R468  
1.50K  
MACH_PRESET  
C14  
4.7  
35V  
2
5
50V  
+5V  
AC  
+15V  
X17  
C13  
+15V  
STICK  
9
2
6
4
R634  
R635  
ROBOTIC ARC_SENSED  
C270  
0.1  
50V  
J4  
J4  
1.00K  
R636  
1.00K  
R637  
2_STEP  
13  
10  
ARC_SENSED  
Q41  
2N4401  
DZ39  
3.3V  
D97  
MAX FIRE ANGLE  
R466  
6.81K  
1
2
1.2V  
1.00K  
1.00K  
R618  
150  
D96  
L9  
D78  
3
2
C273  
0.1  
50V  
C274  
J5  
X14  
Q26  
R16  
13  
R508  
100  
R509  
0.1  
R469  
475K  
2N4401  
1
33.2K  
X1  
R485  
50V  
.39mH  
2_STEP  
Q29  
2N4401  
4.75K  
C221  
C271  
DC  
1W  
22.1K  
R28  
PRESET  
5.1V  
9
6
5
4.7  
35V  
C191  
AC  
1W  
33.2K  
R486  
15.0K  
C242  
.0047  
3000V  
8
C30  
C194  
150p  
DZ23  
PHASE FIRE  
X11  
7
C18  
.0047  
50V  
C27  
.0047  
50V  
D83  
X11  
0.1  
10  
L7  
R617  
10.0K  
WORK VOLT.  
R482  
15.0K  
50V  
221  
50V  
3
AC/DC  
MICRO-  
SWITCH  
GND  
.39mH  
J6  
C246  
C195  
.0047  
3000V  
C197  
R32  
D64  
R484  
22.1K  
C269  
0.1  
50V  
+15V  
-
+15V  
2N4401  
Q39  
.0047  
1400V  
L8  
2
3
UP_SLOPE  
ELECT.VOLT  
R600  
4
1N4936  
1
D1  
START  
.39mH  
J6  
Q5  
X11  
C196  
.0047  
3000V  
+15V  
Q2  
2.21K  
2N4401  
CURRENT CONTROL  
J2  
1
D72  
SHUNT CURRENT AMPLIFIER  
5
2N4401  
2_STEP  
5
6
R7  
R5  
C31  
STICK  
D7  
7
4
3
150  
1.00K  
X1  
R65  
.0047  
50V  
R547  
1.50K  
6.81K  
R568  
D87  
DZ2  
15V  
1W  
X16  
R570  
47.5K  
10.0K  
2N4401  
Q33  
3
R4  
Q28  
2N4401  
C6  
400A/200mV  
C4  
GND  
C5  
47p  
100V  
C37  
UP/DOWN SLOPE CIRCUIT  
820p  
1.00K  
10.0K  
R546  
.0047  
50V  
ELECT.VOLT  
WORK VOLT.  
5
8
X14  
UP_SLOPE  
J2  
2
50V  
J4  
J4  
R3  
R558  
221K  
5
3
4
221K  
4
R33  
SHUNT_CURRENT  
R491  
R492  
22.1K  
R543  
68.1K  
C234  
.0047  
50V  
J4  
J4  
+15V  
1.00K  
R493  
1.00K  
R494  
R480  
10.0  
OUTPUT_ENABLE  
9
1.00K  
1.00K  
+5V  
R544  
61.9K  
CURRENT CONTROL  
FILTER_CAP  
12  
LINE_SYNC  
6.81K  
D86  
6
C203  
47  
START  
6
7
R567  
47.5K  
R495  
1.00K  
R496  
1.00K  
1.00K  
ERROR AMPLIFIER CIRCUIT  
X10  
2N4401  
R565  
START  
J4  
J4  
R26  
221  
11  
10  
X14  
R626  
68.1K  
C21  
.0047  
50V  
R534  
1.00K  
35V  
R537  
1
2
10  
R13  
X10  
CLN  
D99  
R497  
1.00K  
R498  
1.00K  
AC  
8
8
13  
1.00K  
R536  
1.00K  
X1  
R22  
475  
R481  
PEN  
12  
12  
13  
Q32  
9
D2  
10.0K  
X13  
R27  
100  
R24  
8.25K  
R25  
X11  
R477  
C22  
C208  
14  
14  
221K  
R56  
0.1  
0.1  
1.00K  
2.21K  
C211  
0.1  
C238  
C25  
+15V  
13  
50V  
50V  
C209  
C29  
C28  
1.0  
35V  
C15  
C160  
0.1  
0.1  
50V  
47p  
C201  
50V  
50V  
.68  
100V  
C210  
6.81K  
D85  
50V  
UP_SLOPE  
C24  
R564  
4.75K  
0.1  
2N4401  
Q31  
R562  
R518  
50V  
+5V  
C165  
301  
.68  
X16  
50V  
2
X10  
AUTO  
X10  
10  
11  
12  
13  
C818  
0.1  
50V  
1
X9  
R541  
+15V  
C227  
3
4
9
8
14  
.68  
X13  
12  
OUTPUT_ENABLE  
PHASE_FIRE  
47.5K  
R561  
50V  
+5V  
SPARE PARTS AND IC POWER CONNECTION SHOW ON SHEET  
LAST NO. USED  
1
3
2.21K  
5
6
/AUTO  
2N4401  
R535  
1.00K  
Q30  
D84  
R528  
100K  
GENERAL INFORMATION  
BALANCE CONTROL  
+5V  
X-  
OCI-  
TRI-  
PTC-  
SEE SHEET  
R-  
C-  
D-  
DZ-  
Q-  
AUTO  
R520  
47.5K  
R527  
X5  
ELECTRICAL SYMBOLS PER E1537  
3
4
1.00M  
9
CAPACITORS  
RESISTORS  
DIODES  
=
MFD  
(
.022/50V  
1/4W  
UNLESS OTHERWISE SPECIFIED)  
UNLESS OTHERWISE SPECIFIED)  
C163  
LINE_SYNC  
PHASE_A  
1
LABELS  
SUPPLY  
=
Ohms  
(
8
J5  
R522  
100K  
X9  
47.5K  
R531  
100K  
R523  
5
11  
R410  
R464  
10.0K  
=
1A, 400V  
(UNLESS OTHERWISE SPECIFIED)  
3
2
10  
VOLTAGE NET  
X9  
J1:  
J2:  
J3:  
8
4
4
PIN  
PIN  
PIN  
J6:  
J7:  
4
8
PIN  
PIN  
10.0K  
7
X9  
1.2 Vref  
1
C183  
POWER SUPPLY SOURCE POINT  
COMMON CONNECTION  
R524  
100K  
6
0.1  
PHASE_B  
J7A:  
8
PIN  
C228  
G3358_2BA  
50V  
J4: 10 PIN  
J5: 14 PIN  
J8: 16 PIN  
FRAME CONNECTION  
R525  
26.7K  
R526  
100K  
AUTO  
SHEET  
2
EARTH GROUND CONNECTION  
BALANCE CONTROL CIRCUIT  
NOTES  
:
N.A. SINCE COMPONENTS OR CIRCUITRY ON  
WITHOUT AFFECTING THE INTERCHANGEABILITY OF  
A
PRINTED CIRCUIT BOARD MAY CHANGE  
COMPLETE BOARD, THIS DIAGRAM MAY  
A
NOT SHOW THE EXACT COMPONENTS OR CIRCUITRY OF CONTROLS HAVING  
NUMBER.  
A
COMMON CODE  
G3358-2  
7-24-98  
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not  
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result  
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.  
SQUARE WAVE TIG 275  
Download from Www.Somanuals.com. All Manuals Search And Download.  
G-6  
G-6  
ELECTRICAL DIAGRAMS  
Display Board Schematic (L10768)  
-Vsp  
R31  
R26  
R25  
15.0K  
J20  
1.00M  
100K  
C26  
VOLTS  
16  
7
6
5
4
2
a
ELECT.  
BANK4  
BANK3  
Vdd  
D14  
3
8
3
8
3
8
750p  
1000V  
D10  
D12  
D11  
X8  
8
2
3
15  
3
1
1
1
b
c
X7  
2
4
5
6
7
9
2
4
5
6
7
9
2
4
5
6
7
9
R30  
1
100K  
13  
9
BANK2  
BANK1  
d
C43  
N_GND  
D13  
.0047  
e
h
R37  
3000V  
R2  
CW  
DISP3  
DISP2  
DISP1  
17  
12  
11  
19  
14  
BANK5  
DATA IN  
CLOCK  
/ENABLE  
DATA OUT  
44.2K  
10  
10  
10  
10K  
Vss  
C25  
750p  
1000V  
R128  
221K  
VOLT  
20  
1
g
J20  
C53  
10  
18  
WORK  
f
5
8
Rx  
N_GND  
MC14489  
100p  
100V  
R33  
6
GAIN  
=
.042  
X7  
1.00M  
7
5
R121  
GAIN  
=
4
6.81K  
12  
13  
R42  
HI_VOLT_FB  
14  
C32  
47p  
100V  
1.00K  
X7  
16  
7
6
5
4
2
a
BANK4  
BANK3  
Vdd  
3
8
3
8
3
8
C29  
0.1  
X9  
AMPS  
2
R43  
15  
3
1
1
1
b
c
1.00K  
2
4
5
6
7
9
2
4
5
6
7
9
2
4
5
6
7
9
50V  
X10  
R45  
R46  
13  
9
BANK2  
BANK1  
BANK5  
d
15.0K  
15.0K  
L_GND  
e
h
DISP6  
DISP5  
DISP4  
17  
12  
11  
19  
14  
LO_VOLT_FB  
10  
10  
10  
R47  
GAIN  
=
.545  
DATA IN  
Vss  
3
1.00K  
20  
1
C33  
0.1  
50V  
CLOCK  
g
J20  
AMP  
R1  
10  
18  
X10  
/ENABLE  
DATA OUT  
f
HI_CUR_FB  
R41  
CUR_FB  
3
L_5V  
8
Rx  
CW  
10.0K  
5K  
L_GND  
MC14489  
C30  
+15V  
N_GND  
5
48  
25  
46  
47  
45  
19  
20  
17  
18  
1
MODA  
PD4  
Vdd  
20  
26  
31  
32  
33  
34  
35  
36  
37  
38  
16  
15  
14  
13  
12  
11  
11  
3
X10  
CLOCK  
LATCH  
DATA  
AS  
AD0  
AD1  
AD2  
AD3  
AD4  
AD5  
AD6  
AD7  
A8  
LE  
Vcc  
Q0  
2
PD5  
D0  
D1  
X11  
GAIN  
=
4
4
5
6
9
PD3  
Q1  
10  
7
R112  
R50  
HI_VOLT_FB  
PE2  
D2  
D3  
D4  
D5  
D6  
D7  
GND  
Q2  
Q3  
Q4  
Q5  
Q6  
Q7  
OE  
C34  
LO_CUR_FB  
8
332K  
1.00K  
LO_VOLT_FB  
HI_CUR_FB  
LO_CUR_FB  
8
R53  
47p  
X7  
PE3  
D16  
9
100V  
1.00K  
4
13  
14  
17  
12  
15  
16  
19  
1
R51  
C35  
0.1  
PE0  
1.00K  
PE1  
L_5V  
1
50V  
X10  
28  
AC  
PA7  
Vpp  
D0  
D1  
Vcc  
A0  
R52  
R122  
15.0K  
L_GND  
7
11  
10  
9
18  
10  
OUTPUT_ENABLE  
LINESYNC  
PA1  
15.0K  
6
12  
13  
15  
16  
17  
18  
19  
25  
24  
21  
IC1/PA2  
PD0  
A1  
74HC373  
42  
43  
44  
5
8
A9  
D2  
D3  
D4  
D5  
D6  
D7  
A8  
A9  
A10  
A11  
X1  
A2  
L_GND  
7
PD1  
A10  
A3  
J20  
6
PD2  
A11  
A4  
R55  
AC  
7
5
PA3  
A12  
A5  
10.0K  
6
8
4
C37  
0.1  
50V  
PA0  
A13  
A6  
+15V  
41  
40  
30  
29  
39  
10  
28  
27  
9
3
/IRQ  
A14  
A7  
X10  
20  
22  
27  
26  
2
/XIRQ  
XTAL  
EXTAL  
/RESET  
VRL  
R/W  
E
/CE  
/0E  
A14  
A13  
A12  
4
J20  
N_GND  
C20  
0.1  
OUTPUT_ENABLE  
R62  
L_GND  
A15  
R56  
4
L_5V  
4.75K  
R63  
4
23  
14  
50V  
PA4  
PA5  
PA6  
MODB  
+15V  
10.0K  
X7  
L_5V  
7
21  
3
C38  
0.1  
50V  
GND  
27C256  
+15V  
4.75K  
23  
X5  
2
L_GND  
Vss  
33074A  
11  
1
C21  
0.1  
50V  
X10  
68HC11A1  
22  
24  
3
VRH  
X12  
3
4
R59  
2
X4  
X4  
X4  
X4  
X4  
L_5V  
D15  
1N4936  
1.00M  
4
5
6
L_5V  
X12  
Y1  
N_GND  
L_5V  
1.00K  
R64  
5
6
C39  
C40  
8.0MHz  
130  
L_5V  
22p  
22p  
-Vsp  
D18  
1N4936  
C52  
1.0  
35V  
100V  
100V  
+15V  
C41  
0.1  
50V  
DZ1  
Vdd  
X6  
Q2  
9
8
J20  
/LINESYNC  
R116  
2N4401  
RES  
Q5  
L_GND  
R124  
R125  
R21  
R115  
2N4401  
6
4.75K  
14  
S-8054HN  
C42  
L_GND  
4.75K  
4.75K  
22.1K  
22.1K  
5.1V  
1W  
Vss  
X4  
C19  
0.1  
50V  
11  
13  
10  
12  
119 KHz OSC.  
C47  
C45  
100p  
100V  
+15V  
C46  
R4  
R8  
1
2
X4  
47.5  
R5  
47.5  
L_GND  
N_GND  
C13  
V_5V  
R9  
7
0.1  
+15V  
L_GND  
47.5  
47.5  
50V  
D3  
+15V  
L_5V  
Q1  
R6  
R10  
2N4401  
47.5  
47.5  
J20  
J20  
X2  
CONTROL BD 15V  
IN  
OUT  
C9  
R7  
R11  
C14  
820p  
50V  
1
C6  
C10  
1.0  
35V  
47.5  
47.5  
48  
28  
20  
14  
GND  
D7  
C2  
C1  
C5  
D2  
4.7  
1.0  
C50  
0.1  
50V  
X12  
C48  
0.1  
50V  
C49  
C18  
1.0  
35V  
35V  
35V  
X5  
X1  
X11  
0.1  
-Vsp  
74HC132  
50V  
68HC11A1  
23  
27C256  
14  
74HC373  
10  
C15  
1.0  
35V  
CONTROL BD GND  
L_5V  
Q3  
R12  
R16  
2N4401  
2
47.5  
R13  
47.5  
R17  
7
A_5V  
N_GND  
47.5  
R14  
47.5  
R18  
L_5V  
D9  
V_5V  
A_5V  
D4  
X3  
1N4936  
N_GND  
L_GND  
Vdd  
C16  
1.0  
35V  
47.5  
R15  
47.5  
R19  
2N4403  
Q4  
D8  
1N4936  
9
8
3
3
Vdd  
8
X12  
X12  
47.5  
47.5  
IN  
OUT  
C11  
10  
C8  
C7  
X8  
X9  
C22  
0.1  
50V  
C23  
0.1  
50V  
C24  
X10  
1.0  
GND  
C12  
1.0  
35V  
D6  
12  
13  
0.1  
35V  
11  
50V  
MC14489  
MC14489  
TCF6000  
1
Vss  
Vss  
14  
14  
ISOLATED CIRCUIT  
L_GND  
L_GND  
L_GND  
L10768  
7-24-98  
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not  
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result  
SQUARE WAVE TIG 275  
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.  
Download from Www.Somanuals.com. All Manuals Search And Download.  
G-7  
G-7  
ELECTRICAL DIAGRAMS  
Bypass Board Schematic (S22530)  
SQUARE WAVE TIG 275  
S22530  
7-12-96  
Download from Www.Somanuals.com. All Manuals Search And Download.  
G-8  
G-8  
ELECTRICAL DIAGRAMS  
Display Board Layout (L10770-1)  
L10770-1  
DISPLAY  
ITEM  
PART NO.  
DESCRIPTION  
REQ'D  
SQUARE WAVE TIG 275  
L10770-1  
7-24-98  
Download from Www.Somanuals.com. All Manuals Search And Download.  
G-9  
G-9  
ELECTRICAL DIAGRAMS  
REQ'D  
ITEM  
PART NO.  
DESCRIPTION  
ITEM  
REQ'D  
PART NO.  
DESCRIPTION  
R96  
R97  
R98  
R99  
R69  
R70  
R71  
R72  
R73  
R36  
R37  
R38  
R39  
R40  
G3360-1  
C44  
R100  
R101  
R102  
R103  
R74  
R75  
R76  
R77  
R78  
R41  
R42  
R43  
R44  
R45  
X6  
R209  
C93  
C92  
C45  
D14  
R79  
R80  
R81  
R82  
R83  
R46  
R47  
R48  
R49  
R50  
R104  
R105  
R106  
R107  
TP4  
C46  
R84  
R85  
R86  
R87  
R88  
R51  
R52  
R53  
R54  
R55  
XXXXXXXXX  
R108  
R109  
R110  
R111  
X8  
X5  
D22  
TP3  
XXXXXXX  
TP6  
C47  
DZ14  
C60  
D42  
R210  
R439  
C82  
C172  
D59  
X16  
R8  
R323  
R324  
R325  
D58  
X7  
D57  
D56  
C77  
C180  
C173  
R593  
OCI6  
X1  
C261  
C232  
X13  
R592  
R580  
D48  
D52  
D51  
D49  
DZ24  
R474  
R590  
C174  
DZ35  
C214  
C104  
C218  
Y1  
D50  
R504  
C219  
X10  
X11  
C103  
C108  
C215  
X12  
R195  
R181  
C75  
C185  
R587  
R588  
X14  
X X X  
X9  
OCI2  
C79  
DZ20  
R473  
Q38  
R476  
C200  
X X X  
R612  
R562  
R480  
R570  
C264  
R602  
R568  
C229  
R144  
X X X  
R452  
OCI3  
C203  
X X X  
C38  
R34  
R589  
Q36  
R569  
C249  
X X X  
X X X  
X X X  
X X X  
D9  
D94  
D93  
R114  
D17  
OCI5  
OCI1  
R469  
C194  
C17  
D454  
C106  
R327  
R14  
C65  
C62  
C63  
C242  
C243  
C244  
C193  
C198  
R490  
C158  
C197  
C196  
C2  
J3  
C190  
C212  
R472  
R499  
J7  
J7A  
J4  
J6  
J5  
G3360-1  
7-24-98  
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not  
available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result  
SQUARE WAVE TIG 275  
in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.  
Download from Www.Somanuals.com. All Manuals Search And Download.  
G-10  
G-10  
ELECTRICAL DIAGRAMS  
Bypass Board Layout (L10121-1)  
L10121-1 BYPASS STABILIZER  
ITEM  
REQ'D  
IDENTIFICATION  
PART NO.  
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your  
factory warranty. Individual Printed Circuit Board Components are not available from Lincoln Electric. This information is provided  
for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design  
and may result in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.  
SQUARE WAVE TIG 275  
L10121-1  
9-13-96  
Download from Www.Somanuals.com. All Manuals Search And Download.  
G-11  
G-11  
Notes  
SQUARE WAVE TIG 275  
Download from Www.Somanuals.com. All Manuals Search And Download.  

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