Middleby Cooking Systems Group Oven PS520E User Manual

PS520-Series Electric Ovens:English  
installation  
& operation  
manual  
PS520-Series OVENS  
Model PS520E  
PS520 Single  
PS520 Triple  
PS520 Double  
Part No., 52358  
090/6  
©2006 Middleby Marshall Inc.  
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Model No.________________________ Serial No._______________ Installation Date __________  
MIDDLEBY MARSHALL INC.  
MIDDLEBY MARSHALL  
No Quibble Limited Warranty  
OVEN LIMITED WARRANTY (Non-U.S.A.)  
(U.S.A. Only)  
The Seller warrants equipment manufactured by it to be free from defects  
in material and workmanship for which it is responsible. The Seller’s ob-  
Middelby Marshall, Hereinafter referred to as “The Seller”,  
warrants equipment manufactures by it to be free from defects  
in materials and workmanship for which it is responsible. The  
seller’s obligation under thus warranty shall be limited to  
replacing or repairing, at seller’s option, without charge, any  
part found to be defective and any labor and material expense  
incurred by seller in repairing or replacing such part. Such  
warranty shall be limited to the original purchase of (1) one year  
from date of original installation or 18 months from date of  
purchase, whichever is earlier, provided that terms of payment  
have been fully met.  
ligation under this warranty shall be limited to replacing or repairing, at  
Seller’s option, without charge, F.O.B. Seller’s factory, any part found to  
be defective and any labor and material expense incurred by Seller in  
repairing or replacing such part. Such warranty is limited to a period of  
one year from date of original installation or 15 months from date of ship-  
ment from Seller’s factory, whichever is earlier, provided that terms of  
payment have been fully met. All labor shall be performed during regular  
working hours. Overtime premium will be charged to the Buyer.  
This warranty is not valid unless equipment is installed, started and dem-  
onstrated under the supervision of a factory-authorized installer.  
Normal maintenance functions, including lubrication, adjustment of air-  
flow, thermostats, door mechanisms, microswitches, burners and pilot  
burners, and replacement of light bulbs, fuses and indicating lights, are  
not covered by warranty.  
This warranty is valid only if the equipment is installed, started,  
and demonstrated under the supervision of a factory-authorized  
installer.  
Normal maintenance functions, including lubrication, cleaning,  
or customer abuse, are not covered by this no quibble warranty.  
Any repairs or replacements of defective parts shall be performed by  
Seller’s authorized service personnel. Seller shall not be responsible for  
any costs incurred if the work is performed by other than Seller’s autho-  
rized service personnel.  
Seller shall be responsible only for repairs or replacements of  
defective parts performed by Seller’s authorized service  
personnel. Authorized service agencies are located in principal  
cities throughout the contiguous United States and Hawaii. The  
warranty is valid in the 50 Unites States and is void elsewhere  
unless the product is purchased through Middleby International  
with warranty included.  
When returning any part under warranty, the part must be intact and com-  
plete, without evidence of misuse or abuse, freight prepaid.  
Seller shall not be liable for consequential damages of any kind which  
occur during the course of installation of equipment, or which result from  
the use or misuse by Buyer, its employees or others of the equipment  
supplied hereunder, and Buyer’s sole and exclusive remedy against Seller  
for any breach of the forgoing warranty or otherwise shall be for the repair  
or replacement of the equipment or parts thereof affected by such breach.  
The foregoing warranty is exclusive and in lieu of all other  
warranties, expressed or implied. There are no implied  
warranties of merchantability or fitness for a particular  
purpose.  
The foregoing warranty shall be valid and binding upon Seller if and only  
if Buyer loads, operates and maintains the equipment supplied hereunder  
in accordance with the instruction manual provided to Buyer. Seller does  
not guarantee the process of manufacture by Buyer or the quality of prod-  
uct to be produced by the equipment supplied hereunder and Seller shall  
not be liable for any prospective or lost profits of Buyer.  
The foregoing shall be Seller’s sole and exclusive obligation  
and Buyer’s sole and exclusive remedy for any action, including  
breach of contract or negligence. In no event shall Seller be liable  
for a sum in excess of the purchase price of the item. Seller shall  
not be liable for any prospective or lost profits of Buyer.  
THE FOREGOING WARRANTY IS EXCLUSIVE AND IN LIEU OF  
ALL OTHER EXPRESS AND IMPLIED WARRANTIES WHATSO-  
EVER. SPECIFICALLYTHEREARE NO IMPLIED WARRANTIES OF  
MERCHANTABILITY OR OF FITNESS FOR A PARTICULAR PUR-  
POSE.  
This warranty is effective on Middleby Marshall equipment  
sold on, or after February 15, 1995.  
The foregoing shall be Seller’s sole and exclusive obligation and Buyer’s  
sole and exclusive remedy for any action, whether in breach of contract or  
negligence. In no event shall Seller be liable for a sum in excess of the  
purchase price of the item  
©2006 Middleby Marshall, A Middleby Company  
The Middleby Marshall logo is a registered trademark of Middleby Marshall, A Middleby Company  
Middleby Marshall Inc. - 1400 Toastmaster Drive - Elgin, Illinois 60120-9272 - (847) 741-3300 - Fax: (847) 741-4406  
iii  
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Table of Contents  
(continued)  
Table of Contents  
SECTION 1 - DESCRIPTION  
SECTION 4 - MAINTENANCE  
I. MODEL IDENTIFICATION ............................................ 1  
Series PS520 Electrical Specifications............................. 2  
II. COMPONENT FUNCTION .......................................... 3  
A. Conveyor Motor and Conveyor Belt ......................... 3  
B. Blower Fan ............................................................... 3  
C. Electric Heaters ........................................................ 3  
D. Cooling Fan .............................................................. 3  
E. Air Fingers and Blank Plates - Figure 4-8 & 4-14 ..... 3  
I. MAINTENANCE - DAILY............................................. 16  
A. Exterior ................................................................... 17  
B. Cooling Fan ............................................................ 17  
C. Conveyor Belt......................................................... 17  
D. Crumb Pan ............................................................. 17  
II. MAINTENANCE - MONTHLY .................................... 18  
A. Removing Conveyor From Oven For Cleaning ...... 18  
B. Air Fingers Disassembly For Cleaning ................... 20  
C. Reassembly of Air Fingers ..................................... 21  
D. Reinstall End Plugs ................................................ 23  
E. Conveyor Reassembly Into Oven........................... 24  
F. Checking Conveyor Belt Tension ........................... 24  
G. Conveyor Belt Link Removal.................................. 25  
H. Attaching Drive Chain ............................................ 26  
III. MAINTENANCE - EVERY 3 MONTHS ..................... 27  
A. Electrical Terminals ................................................ 27  
B. Ventilation............................................................... 27  
IV. MAINTENANCE - EVERY 6 MONTHS ..................... 27  
Key Spare Parts Kits................................................... 28  
SECTION 2 - INSTALLATION  
I. UNLOADING ................................................................. 4  
PS520 Oven Installation  
Required Kits And Equipment ................................... 5  
Oven Dimensions - Single, Double, Triple ................... 6  
Utility Rough In Dimensions and Positioning  
For PS520 Series Ovens .......................................... 7  
Circuit Breaker .............................................................. 7  
Electrical Specifications ................................................ 7  
Electrical Rating ............................................................ 7  
Supply Wire .................................................................. 7  
Suggested..................................................................... 7  
II. VENTILATION GUIDELINES ....................................... 7  
III. ELECTRICAL CONNECTION INFORMATION FOR  
PS520-SERIES OVENS ........................................... 8  
IV. ELECTRIC SUPPLY FOR ELECTRIC-HEATED  
OVENS...................................................................... 8  
SECTION 5 - TROUBLESHOOTING CHARTS  
Trouble Shooting Charts ............................................. 29  
SECTION 6 - ELECTRICAL SCHEMATIC  
Wiring Diagram, E208-240V 50/60 Hz 1Ph ................ 30  
Wiring Diagram, E380-480V 50/60 Hz 1 Ph ............... 31  
Wiring Diagram, E230-240V CE, 1Ph......................... 32  
Wiring Diagram, E380-400V CE, 1Ph......................... 33  
Wiring Diagram, E380-400V CE, 3Ph......................... 34  
SECTION 3 - OPERATION  
I. CONTROL FUNCTIONS ............................................... 9  
II. COMPONENT FUNCTIONS ...................................... 10  
A. Door Safety Switch ................................................. 10  
B. Blower Switch ......................................................... 10  
C. Heat Switch ............................................................ 10  
D. Temperature Controller .......................................... 10  
E. Conveyor ................................................................ 11  
Measuring Conveyor Speed ....................................... 11  
III. STEP-BY-STEP OPERATION .................................. 12  
A. Start-up Procedures ............................................... 12  
Daily Start-up .......................................................... 12  
Power Failure .......................................................... 12  
B. Shutdown Procedure .............................................. 12  
IV. NORMAL OPERATION - STEP-BY-STEP ............... 13  
A. Daily Start-up Procedure ........................................ 13  
B. Daily Shutdown Procedure ..................................... 13  
V. QUICK REFERENCE: TROUBLESHOOTING .......... 15  
iv  
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SECTION 1  
DESCRIPTION  
SECTION 1  
DESCRIPTION  
I. MODEL IDENTIFICATION  
The Mideleby Marshall PS520-Series may be used  
either as a single oven or stacked for use as a double  
or triple ovens.  
A single PS520-Series Oven (Figure 1-1) is mounted  
on a base pad with legs. A double oven (Figure 1-2)  
consists of two, stacked, single ovens. A triple oven  
(Figure 1-3) consists of three stacked single ovens.  
The lower oven is mounted on a base pad.  
Figure 1-1. Single PS520 Oven  
On a double or triple oven, the ovens operate indepen-  
dently. All ovens use identical controls and compo-  
nents. One oven can be cleaned or serviced, while the  
others are operating.  
Figure 1-2. Double PS520 Oven  
Figure 1-3. Triple PS520 Oven  
1
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SECTION 1  
DESCRIPTION  
PS520 SERIES OVEN SPECIFICATIONS  
Conveyor Belt Width  
18.00” (457mm)  
20.00” (5098mm)  
Heating Zone Length  
Baking Area Square Feet  
Overall Dimensions  
2.5 sq ft (.023 sq. m.)  
Standard Single Oven w/Legs  
42.00” (1067mm) L x  
35.21” (894mm) W x  
21.72” (786mm) H x  
Overall Dimensions  
Double Oven  
42.00” (1067mm) L x  
35.21” (894mm) W x  
37.27” (947mm) H x  
Overall dimensions  
Triple Oven  
42.00” (1067mm) L x  
35.21” (894mm) W x  
52.82” (1342mm) H x  
250 lbs (93.3kg)  
325 lbs (121.3kg)  
8.3 kW/hr  
Weight of Single Oven  
Shipping Weight  
Operating Range  
Maximum Operating temperature  
Warm-up Time  
5500F (2870C)  
20 min.  
Belt Speed Limits  
1-10 minutes  
SERIES PS520 ELECTRICAL SPECIFICATIONS  
Main Blower &  
Control Circuit  
Voltage  
Phase  
Frequency  
Amperage  
Draw  
Poles  
Wires  
Elements Voltage  
All Models  
208-240V  
208-240V  
1 Ph  
50/60 Hz  
See Below  
2 Pole  
3 Wire  
(2 hot, 1 grd)  
Heater Amperage  
Voltage  
kW  
8.3  
7.6  
8.3  
Amp  
208  
230  
240  
39.9  
33.0  
34.6  
Non-CE  
380V  
480V  
230-240V  
208-240V  
230-240V  
1 Ph  
1 Ph  
1 Ph  
50/60 Hz  
50/60 Hz  
50/60 Hz  
See Below  
Heater Amperage  
3 Pole  
3 Pole  
2 Pole  
4 Wire  
(2 hot, 1 neut, 1 grd)  
Voltage  
380  
kW  
8.3  
Amp  
21.8  
Domestic/Non-CE  
CE Only  
See Below  
Heater Amperage  
4 Wire  
(2 hot, 1 neut, 1 grd)  
Voltage  
480  
kW  
8.3  
Amp  
17.3  
380-400V  
See Below  
3 Wire  
Heater Amperage  
(2 hot, 1 grd)  
Voltage  
380  
400  
kW  
8.3  
8.3  
Amp  
21.8  
23.0  
3 Ph  
50/60 Hz  
See Below  
4 Pole  
N
5 Wire  
(3 hot, 1 neut, 1 grd)  
Heater Amperage  
Voltage kW L1 L2 L3  
380  
400  
8.3 21.8 21.8 1.2 1.2  
9.2 23.0 23.0 1.2 1.2  
NOTE  
Wiring Diagrams are contained in Section 6 of this manual and are also located inside the  
oven at the bottom of the control panel.  
This Manual Must Be Kept For Future Reference  
2
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SECTION 1  
DESCRIPTION  
II. COMPONENT FUNCTION  
A. Conveyor Motor and Conveyor Belt  
Blower Motor  
The conveyor belt is driven by a variable-speed electric  
motor (figure 1-5) operating through a gear reducer. The  
motor speed is controlled by a digital control. The  
stainless-steel wire belt can travel in either direction at  
variable rates ranging from 1 minute to 10 minutes; this  
is the time that a product can take to pass trough the  
oven.  
B. Blower Fan  
The blower fans are located at the rear of the oven. These  
blowers force heated air through the air fingers. The  
BLOWER switch must be set to “ON” or “I” for oven warm-  
up and baking.  
C. Electric Heaters  
Stand off  
Cooling Fan  
There is one heater element mounted on the inside of  
the rear panel. The element is connected to an electrical  
control which is energized by the temperature controller.  
Figure 1-4 Blower Assembly  
D. Cooling Fan - See Figure 1-4  
The cooling fan is located in the back of the oven. The  
cooling fan draws air through its grille, blowing it through  
the blower motor compartment and the control  
compartments into the oven top and exhausted out the  
front louvers.  
E. Air Fingers and Blank Plates - See Figure 4-8, 4-  
14  
E1. Air fingers  
An Air Finger Assembly is made up of three parts:  
1. Outer Plate - The Outer Plate is the removable  
covering with tapered holes, which direct the air stream  
onto the product being baked.  
2. Inner Plate - The perforated Inner Plate is vital in  
forming the unique air jets. It must be assembled into  
the manifold with it’s holes aligned with the holes of the  
outer plate.  
3. Manifold - the Manifold is the assembly which slides  
on the tracks into the oven plenum.  
Conveyor Drive Motor  
Left Control Box  
Figure 1-5 Machinery Compartment  
Components  
3
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SECTION 2  
INSTALLATION  
SECTION 2  
INSTALLATION  
NOTE: The oven, when installed, must be electrically  
grounded in accordance with local codes, or in the  
absence of local codes, with the National Electrical Code  
(NEC), or ANSI/NFPA70  
I. UNLOADING  
Your Middleby Marshall PS520-Series Oven is  
shipped partially assembled. It will arrive in a carton on  
a crate.  
Carton size for a PS520-Series Oven is:  
44-1/4” (112mm) Long x  
37-1/2” (953mm) Wide x  
23” (584mm) High x  
NOTE  
There must be adequate clearance between  
the oven and any adjacent combustible  
construction. Clearance must also provide for  
servicing and for operation.  
The crate and carton MUST be examined before  
signing the Bill of Lading. Report any visible damage  
to the transport company, and check for the proper  
number of crates. If apparent damage is found, make  
arrangements to file a claim against the carrier.  
Surface Interstate Commerce Regulations (U.S.A.)  
require that the claim must be initiated by the con-  
signee within 10 days from the date that the shipment  
is received.  
CAUTION  
It is recommended that the oven be placed  
under a ventilation hood for adequate air  
supply and ventilation.  
CAUTION  
Do not obstruct the flow of ventilation air to  
and from your oven. Do not obstruct the fan  
holes in the rear of the unit.  
CAUTION  
On ovens with the Machinery Drive  
Compartment located at the RIGHT end, a  
minimum clearance of 0” to a left side wall,  
18” to a right side wall and 6” from a back wall  
to air openings at the rear of the oven must be  
maintained.  
For servicing and cleaning, a minimum of 18”  
clearance from all walls is recommended.  
4
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SECTION 2  
INSTALLATION  
PARTS LIST FOR SERIES PS520 ELECTRIC OVEN  
INSTALLATION KIT  
Single and Double Stack Ovens  
P/N 48397  
Item  
NO.  
1
2
3
4
5
6
6
QTY  
PART NO.  
3101908  
48392  
DESCRIPTION  
Leg 4” AD FT  
Insulation Bottom Tray  
4
2
1
1
4
1
1
48394  
Bottom Tray Weldment  
48396  
Top cover  
51387  
52358  
59476  
Screw MSSLT Thread 8-32 x 1/2, 18-8  
Installation & Operation Manual - English  
Installation & Operation Manual - French  
PARTS LIST FOR SERIES PS520 ELECTRIC OVEN  
INSTALLATION KIT  
Triple Stack Ovens  
P/N 54593  
Item  
NO.  
1
2
3
4
5
6
6
QTY  
PART NO.  
48392  
48394  
48396  
51387  
M3828  
52358  
DESCRIPTION  
Insulation Bottom Tray  
Bottom Tray Weldment  
Top cover  
Screw MSSLT Thread 8-32 x 1/2, 18-8  
Pin, Alignment  
Installation & Operation Manual - English  
Installation & Operation Manual - French  
2
1
1
4
4
1
1
59476  
5
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SECTION 2  
INSTALLATION  
Figure 2-5. MODEL PS520 SINGLE OVEN DIMENSIONS  
1
The Opening Height is Adjustable  
from 2-1/4 inch minimum to 3-3/4  
inch maximum in 1/2 inch  
increments.  
Figure 2-6. MODEL PS520 DOUBLE OVEN DIMENSIONS  
Figure 2-7. MODEL PS520 TRIPLE OVEN DIMENSIONS  
6
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SECTION 2  
INSTALLATION  
UTILITY ROUGH-IN DIMENSIONS AND POSITIONING  
FOR PS520 SERIES OVENS  
WARNING  
DO NOT USE CONDUIT OR GAS LINE FOR  
GROUNDING CONNECTION  
To Oven  
CAUTION  
IT IS RECOMMENDED THAT THE OVEN BE  
PLACED UNDER A VENTILATION HOOD  
FOR ADEQUATE AIR SUPPLY AND  
VENTILATION  
To Oven  
ELECTRIC SUPPLY TO BE  
PROVIDED BY CUSTOMER  
CIRCUIT BREAKER  
Separate circuit breaker with lockout/tagout electrical  
shutoff for each oven. Wire each oven separately.  
Suggested dimensions are shown; utility code  
requirements supercede any factors shown.  
50 amp circuit breaker for 208-240V, or 30 Amp circuit  
breaker for 380-480V.  
Figure 2-9. Typical PS520-Series Oven(s)  
Installation  
ELECTRICAL SPECIFICATIONS  
ALL MODELS:  
ELECTRICAL RATING  
•208V main blower motors and elements, 1 Ph, 39.9  
Amp draw, 50/60 Hz, 208V control circuit, 2 pole,  
3 wire system per oven (2 hot, 1 grd).  
•230V main blower motors and elements, 1 Ph, 33.0  
Amp draw, 50/60 Hz, 230V control circuit, 2 pole,  
3 wire system per oven (2 hot, 1 grd).  
7.6 - 9.2 kW/hr  
SUPPLY WIRING  
Supply wire size must be in accordance with the National  
Electrical Code (current edition) and must be in compliance  
with local codes.  
SUGGESTED  
•240V main blower motors and elements, 1 Ph, 34.6  
Amp draw, 50/60 Hz, 208-240V control circuit, 2 pole,  
3 wire system per oven (2 hot, 1 grd).  
If space permits, service should be located near the control  
console end of the oven(s) to allow convenient access to  
safety switches.  
Non-CE:  
•380V elements, 1 Ph, 21.8 Amp draw, 50/60 Hz, 208-  
240V control circuit and main blower motor, 3 pole,  
4 wire system per oven (2 hot, 1 neut, 1 grd).  
CAUTION  
UNIT MUST HAVE AIR VENT PLATES  
INSTALLED OR WARRANTY WILL BE VOID.  
Domestic and Non-CE:  
•480V elements, 1 Ph, 17.3 Amp draw, 50/60 Hz, 208-  
240V control circuit and main blower motor, 3 pole,  
4 wire system per oven (2 hot, 1 neut, 1 grd)  
II. VENTILATION  
A mechanically driven ventilation system is required for  
the PS520 Series Middleby Marshall conveyorized electric  
ovens.  
CE Only:  
•380V elements, 1 Ph, 21.8 Amp draw, 50/60 Hz, 208-  
240V control circuit and main blower motor, 2 pole,  
3 wire system per oven (2 hot, 1 grd).  
•400V elements, 1 Ph, 23.0 Amp draw, 50/60 Hz, 208-  
240V control circuit and main blower motor, 2 pole,  
3 wire system per oven (2 hot, 1 grd)  
•380V elements, 3 Ph, 21.8/21.8/1.2 Amp draw, 50/60  
Hz, 5 pole, 4 wire system per oven (3 hot, 1 neut, 1  
grd).  
Local codes and conditions vary greatly from one area to  
another and must be complied with. Following are the  
suggested requirements for good ventilation. Please  
remember these are recommendations or guidelines, you  
may have a special condition or problem that will require  
the services of a ventilation engineer or specialist. Proper  
ventilation is the oven owner’s responsibility. Improper  
ventilation can inhibit oven performance.  
•400V elements, 3 Ph, 23.0/23.0/1.2 Amp draw, 50/60  
Hz, 5 pole, 4 wire system per oven (3 hot, 1 neut, 1  
grd)  
Please Note: There are now two “stand off” “C”  
channels that must be installed in the field (See Section  
1: Figure 1-4, page 3 for reference)  
Do NOT use conduit for ground.  
7
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SECTION 2  
INSTALLATION  
These “C” Channel brackets are installed in the vertical  
plane using existing screws to support these ‘C”  
Channels using the upper and lower Key Hole openings  
in the ‘C’ Channels. The “C” Channels are identical and  
once installed will allow ample amounts of air through  
the cooling fan mounted on the rear side of the oven by  
keeping the oven away from the rear wall.  
A fused disconnect switch or a main circuit breaker  
(customer supplied) MUST be installed in the electric  
supply line for each oven; it is recommended that this  
switch/circuit breaker have lockout/tagout capability. The  
electric supply connection must meet all national and  
local electrical code requirements. Copper is the  
recommended material for the electrical supply  
conductors.  
III. ELECTRICAL CONNECTION INFORMATION  
FOR PS520-SERIES OVENS.  
IV. ELECTRIC SUPPLY FOR ELECTRICALLY  
HEATED OVENS  
WARNING  
Power requirements for electrically heated ovens are  
usually 208-240VAC, 1-phase, 3 wire (2 ‘hot’, 1 ground),  
although ovens built for export can have power  
requirements of 380VAC and 480VAC. (These ovens  
have a 4-wire or 5-wire system.) A 1.5” (38mm) diameter  
cutout/hole in the back of the machinery compartment  
provides access for the electrical supply connections on  
380V and 480V units. 208V and 240V units have a cord  
and plug. Using flexible cable(s) for the electrical power  
supply conductors requires a 2” (51mm) strain-relief fitting  
(not furnished) to enable safe access to the terminal block  
from which oven power is distributed.  
Authorized supplier personnel normally  
accomplish the connection for the ventilation  
system, electric supply, as arranged by the  
customer. Following these connections, the  
factory-authorized installer can perform the  
initial start-up of the oven.  
Check the oven data plate (Figure 2-10) before making  
any electric supply connections. Electric supply  
connections must agree with data on the oven data plate.  
NOTE: The electric supply installation must satisfy the  
requirements of the appropriate statutory authority, such  
as the National Electrical Code (NEC), ANSI/NFPA70,  
(U.S.A); the Canadian Electrical Code, CSA C22:2; the  
Australian Code AG601; or other applicable regulations.  
The supply conductors must be of the size and material  
(copper) recommended to provide the current require;  
(refer to the data plate for the ampere specifications).  
Typical specifications for each PS520-Series Oven are  
208-240V, 1-phase, 3 wire, 8.3kW; this oven requires  
50 ampere service. A PS520-Series Double Oven (Figure  
1-2) installation would require two 50 ampere service  
connections, one for each oven; the 8.3kW power  
consumption also doubles for such an installation to  
16.6kW.  
The 208V, 230V or 240V AC electrically heated oven  
uses two legs of the supplied power to provide 208V,  
230V or 240V AC power for the oven control circuitry  
ELECTRICAL  
INLET  
Figure 2-11. Junction Connection Box  
Figure 2-10. Typical Electric Oven Data Plate  
8
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SECTION 3  
OPERATION  
SECTION 3  
OPERATION  
I. CONTROL FUNCTIONS  
Blower  
Switch  
Heat  
Switch  
Temperature  
Controller  
Conveyor  
Speed  
Control  
Conveyor  
Switch  
Figure 3-1. PS520-Series Oven Control Functions  
WARNING  
A possibility of injury from rotating parts and electric  
shock exists in the oven. Never disassemble or  
clean the oven with the BLOWER switch or any  
other oven control turned “ON” or “I”. Turn “OFF” or  
“O” and lockout or tagout all electric power to the  
oven before attempting to clean or service the oven.  
9
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SECTION 3  
OPERATION  
If the temperature of the oven is over 2000F (930C) the  
main blower will continue to run after the blower switch  
is turned to the “OFF” or “O” position.  
II. COMPONENT INFORMATION AND  
LOCATION (Figures 3-1 and 3-2)  
A. Door Safety Switch  
C. Heat Switch  
The Door Safety Switch is located at the lower right side  
of the control panel opening. Opening the control panel  
door permits this switch to open, disconnecting power  
to all electrical controls.  
Turning the HEAT switch to “ON” or “I” will energize the  
electric heating system. This switch is in series with the  
blower fan motor and high temperature override switch.  
Both switches must be closed before the heating  
elements can be energized.  
CAUTION  
Do NOT touch the wires going to this  
safety switch. Current is always present.  
D. Temperature Controller  
The temperature controller is a solid-state, PID type to  
maintain the operator-set temperature. The temperature  
controller continuously monitors the oven temperature  
and turns on the modulating solid state relay controller.  
The heat is on for the time required to maintain a  
consistent oven temperature.  
B. Blower Switch  
The blower switch has two positions. The switch must  
be “ON” or “I” for the main blowers to come on and permit  
the oven to run. The fan circulates the air throughout the  
oven and must stay on during baking and during the  
cool down cycle above 2000F (930C) to prevent blower  
bearing damage. To protect the blower motor and  
bearings a thermostatic override is built into the oven.  
The temperature controller contains a low-limit switch  
which allows the oven to cool down to 2000F (930C)  
before shutting off the blower. A high-limit indication  
(ALM1) will appear on the display if the oven reaches  
6500F (3430C).  
Door Safety  
Switch  
Temperature  
Controller  
Conveyor Speed  
Digital Control  
Conveyor Speed  
Control Module  
Conveyor  
Drive Motor  
Figure 3-2. Interior View of Control Console  
10  
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SECTION 3  
OPERATION  
E. Conveyor  
The on-off switch for the conveyor motor is on the  
digital control panel. Also on the control panel is the  
digital conveyor speed control. The digital control can  
be adjusted from 1-10 minutes bake time (conveyor  
speed). Refer to Figure 3-3.  
Conveyor speed is measured by the amount of time it  
takes for an item to go through the bake chamber of  
the oven.  
Seconds  
Minutes  
MEASURING CONVEYOR SPEED  
Figure 3-3. Conveyor Speed Digital Control  
See Figure 3-4 and 3-5.  
To check conveyor speed, place a product item at the  
entrance end of the baking chamber as shown. Time  
how long it takes for the leading edge of the item to go  
from the entrance end of the baking chamber to the  
exit end. This should be the conveyor speed shown on  
the conveyor speed digital control.  
NOTE: In Figure 3-4 and 3-5, the oven shown is with  
the conveyor running left to right.  
WARNING  
A possibility of injury from rotating parts and electric  
shock exists in the oven. Never disassemble or  
clean the oven with the BLOWER switch or any  
other oven control turned “ON” or “I”. Turn “OFF” or  
“O” and lockout or tagout all electric power to the  
oven before attempting to clean or service the oven.  
Figure 3-4. Product at entrance end of baking  
chamber - BEGINNING OF TIMING  
Figure 3-5. Product at exit end of baking  
chamber - END OF TIMING  
11  
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SECTION 3  
OPERATION  
4. Set the temperature controller to the desired baking  
temperature.  
WARNING  
OVEN MUST BE KEPT CLEAR OF  
COMBUSTIBLES AT ALL TIMES  
NOTE: For complete temperature controller operation  
instructions refer to Step C.  
III. STEP-BY-STEP OPERATION  
5. Turn the HEAT switch (see Figure 3-6) to the “ON” or “I”  
position. This completes a circuit to supply electric power  
to the electric heating system.  
A. Start-up Procedure  
Daily Start-up  
1. Turn the BLOWER switch (Figure 3-6) to the “ON” or “I”  
position. This starts the main blower fan and the cooling  
fans. This blower circulates air through the air fingers and  
must stay on during the cooking or baking process.  
6. Oven will reach baking temperature of 5000F (2320C) in  
approximately 20 minutes. Allow the oven to cycle for 30  
minutes after it has reached desired baking temperature.  
The oven is now ready for baking.  
2. Check to see if the cooling fans (see Figure 4-1 page  
13) are operating when the blower switch (see Figure 3-6)  
is turned “ON” or “I”. The cooling fans cool the control  
components and blower motor. The cooling fans, located  
at the rear of the oven blows air into and through the  
cabinet. Air is exhausted through the front of the cabinet  
and also out the front of the oven. Refer to Daily  
Maintenance Section for fan intake checking procedure.  
POWER FAILURE  
In case of power failure, turn off all switches and remove  
product. After power has been reestablished follow normal  
start-up procedure.  
B. Shutdown Procedure  
1. Turn the BLOWER and HEAT switches to “OFF” or “O”.  
IMPORTANT NOTICE  
The cooling fan operates when the BLOWER  
switch is turned “ON” or “I”. It must operate to  
keep the control console below 1400F (600C)  
NOTE: The blowers will remain on until the oven  
temperature cools down to 2000F (930C) at which time they  
will stop automatically.  
3. Turn the CONVEYOR switch (see Figure 3-6) to the  
“ON” or “I” position. This starts the conveyor belt moving  
through the oven. Set the conveyer speed for the desired  
baking time. Refer to the following Procedures E, F and G.  
2. Make certain that there are no products left on the  
conveyor inside the oven. Turn the CONVEYOR switch to  
“OFF” or “O”  
Figure 3-6. Control Panel  
12  
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SECTION 3  
OPERATION  
IV. NORMAL OPERATION - STEP-BY-STEP  
7. Wait for the oven to heat to the setpoint temperature.  
Higher setpoint temperatures will require a longer wait.  
The oven cavity can reach a temperature of 5000F (2320C)  
in approximately 15 minutes.  
A. Daily Start-up Procedure  
1. Check that the circuit breaker/fused disconnect is in the on  
position.  
8. (Optional) Press the  
2. Turn the “BLOWER”  
Temperature  
key to  
switch to the “ON”  
or “I” position.  
show the Actual Tem-  
perature in the display,  
and wait for the “AC-  
TUAL TEMP” light to turn  
on. This allows you to  
monitor the oven tem-  
perature as it rises to the  
setpoint.  
3. Turn the “CONVEYOR”  
switch to the “ON” or  
“I” position.  
9. Allow the oven to preheat for 10 minutes after it has  
reached the set point temperature.  
4. If necessary, adjust the  
conveyor speed setting  
B. DAILY SHUTDOWN PROCEDURE  
by pressing the  
or  
1. Turn the “HEAT”  
and “BLOWER”  
pushbuttons on the con-  
veyor speed controller to  
change the displayed  
bake time.  
switches to the “OFF” or  
“O” position. Note the  
blowers will remain in  
operation until the oven  
has cooled to below  
2000F (930C).  
5. Adjust the temperature  
controller to a desired set  
temperature, if neces-  
sary.  
Press the Set Point  
and Unlock keys at  
the same time. Wait  
for the “SET PT” light  
to turn on.  
2. Make certain that there  
are no products left on the  
conveyor inside the oven.  
Turn the “CONVEYOR”  
switch to the “OFF”  
or “O” position.  
Press the Up Arrow  
and Down Arrow  
Keys as necessary  
to adjust the set-  
point.  
3. After the oven has cooled and the blowers have turned  
off, switch the circuit breakers/fused disconnect to the  
“OFF” or “O” position.  
6. Turn the “HEAT”  
switch to the “ON” or “I”  
position, and wait for the  
“HEAT ON” light to turn  
on.  
CAUTION  
In case of power failure, turn all switches to the “OFF” or  
“O” position and remove the product. After the power has  
been restored, perform the normal start-up procedure. IF  
THE OVEN WAS SWITCHED OFF FOR LESS THAN (5)  
FIVE MINUTES, WAIT FOR AT LEAST (5) FIVE  
MINUTES BEFORE RESTARTING THE OVEN.  
13  
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SECTION 3  
OPERATION  
Display  
“HEAT ON”  
Shows the Set Point or  
the Actual Temperature  
in degrees Fahrenheit (F)  
or Celsius (C).  
Light  
Lights when the burner is  
in operation.  
“SP LOCK”  
“SET  
PT”(setpoint)  
Light  
Lights when the set point  
is locked out from  
Light  
Lights when the set  
point is shown in the  
display  
changes. This setting can  
only be changed by  
service personnel.  
OVERTEMP  
“ACTUAL TEMP”  
Light  
Light  
Lights when the oven  
temperature is greater than  
6500F (3430C). Refer to  
Quick Reference;  
Lights when the Actual  
Temperature is shown in  
the display.  
Troubleshooting in this  
section.  
Service Key  
Service use only  
Temperature  
Key  
Press this key once to view  
the Actual Temperature in  
the Display  
Unlock Key  
Up Arrow and Down  
Set Point Key  
Press this key together  
with the Unlock Key to  
allow the Set Point to be  
changed. Changes can  
only be made for 60  
seconds.  
Press this key together  
with the Set Point Key to  
allow the Set Point to be  
changed. Changes can  
only be made for 60  
seconds.  
Arrow Keys  
Press these keys to adjust  
the Set Point up or down. If  
the Set Point will not  
change, refer to Set Point  
Key and Unlock Key in this  
section  
14  
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SECTION 3  
OPERATION  
V. QUICK REFERENCE: TROUBLESHOOTING  
SYMPTOM  
PROBLEM  
SOLUTION  
light is lit,  
food product is  
undercooked  
The oven temperature ex-  
ceeded 6500F (3430C), and  
the burner was automati-  
cally shut down  
Follow the procedures under Daily Shutdown Procedures  
in this section to shut down the oven. Contact your  
Middleby Marshall Authorized ServiceAgent to determine  
and correct the cause of the condition to prevent damage  
to the oven.  
Electrical power may not be  
reaching the oven, or the  
controls may be set incor-  
rectly.  
Check that the circuit breaker/fused disconnect is turned  
on.  
Oven will not turn on  
at all  
Check that the “BLOWER”  
position.  
Switch is in the “ON” or “I”  
Turn the “HEAT”  
,
“BLOWER”  
,
and  
The oven did not reach  
2000F (930F) within 15 min-  
utes of start-up, and the  
oven has stopped heating.  
“CONVEYOR”  
switches to the “OFF” or “O” position.  
Wait for AT LEAST FIVE MINUTES before restarting the  
oven.  
Repeat the daily procedure.  
appears in display,  
oven is not heating  
Check that the Set Point is correctly set.  
Controls may be set incor-  
rectly  
Oven will not heat  
Check that both “BLOWER”  
and “HEAT”  
switches are in the “ON” or “I” position.  
Wait for AT LEAST FIVE MINUTES before restarting the  
oven.  
Repeat the Daily Start-up procedure. Check that the Set  
Point is above 2000F (930C)  
Turn the oven to the “OFF” or “O” position, and allow to  
cool. Disconnect electrical power to the oven.  
Refer to Section 4, Maintenance, for instructions on  
reassembling the air fingers.  
Air fingers may have been  
reassembled incorrectly af-  
ter cleaning.  
Oven is operating, but  
little or no air is  
blowing from air  
fingers  
Turn the oven to the “OFF” or “O” position, and allow to  
cool. Disconnect electrical power to the oven.  
Check if the conveyor is blocked by an object inside the  
oven.  
Refer to Section 4, Maintenance, for instructions on  
checking the conveyor and drive chain tension.  
Conveyor may be jammed  
on an object in the oven, or  
conveyor belt or drive chain  
tension may be incorrect.  
Conveyor moves with  
a jerky motion, or will  
not move at all  
Check that the set temperature and bake time settings  
are correct.  
Controls may be set incor-  
rectly  
Food products are  
overcooked or  
undercooked  
IF THESE STEPS FAIL TO RESOLVE THE PROBLEM, CONTACT YOUR LOCAL MIDDLEBY MARSHALL  
AUTHORIZED SERVICE AGENT. A SERVICE AGENCY DIRECTORY IS SUPPLIED WITH YOUR OVEN.  
15  
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SECTION 4  
MAINTENANCE  
SECTION 4  
MAINTENANCE  
WARNING  
Possibility of injury from rotating parts and electrical  
shock exist in this oven. Turn off and lockout or tagout  
electrical supply to oven(s) before attempting to  
disassemble, clean or service oven(s). Never  
disassemble or clean the oven with the blower switch or  
any other part of the oven turned on.  
WARNING  
Before performing any maintenance work or cleaning,  
turn main power switch off.  
CAUTION  
When cleaning do not use any abrasive cleaning  
materials or water spray, wipe clean only. Never use a  
water hose or pressurized steam cleaning equipment  
when cleaning this oven.  
NOTICE  
If the oven is to be removed from it’s installed location  
for servicing, perform the following procedure:  
1. Switch off the oven and allow it to cool, DO NOT  
service the oven while it is warm.  
2. Turn off main circuit breakers and disconnect  
connector from oven.  
3. Move oven to desired location for servicing.  
4. When servicing is complete, move oven to original  
location.  
5. Adjust legs to level oven.  
6. Connect electrical connectors to oven.  
7. Turn on main circuit breaker.  
8. Follow normal start-up instructions.  
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SECTION 4  
MAINTENANCE  
D. Crumb Pans (Figure 4-2)  
WARNING  
I. MAINTENANCE - DAILY  
A. Exterior  
Everyday you should clean the outside of the oven with  
a soft cloth and mild detergent.  
Crumb pan is extremely hot while oven is operating.  
Allow oven to cool before removing crumb pan.  
When oven is cool remove and clean the crumb pan at  
each end of the oven. Each crumb pan can be removed  
by sliding it out, as shown in Figure 4-2. Reinstall the  
crumb pans after cleaning.  
WARNING  
Never use a water hose or pressurized steam  
cleaning equipment when cleaning the oven.  
B. Cooling Fan  
Cooling Fan Grille  
1. ONE COOLING FAN GRILLE AT THE REAR OF THE  
OVEN MUST CLEANED DAILY - Clean grille with a stiff  
nylon type brush.  
2. Check the air intake of the cooling fan daily. The best  
time to check is right after starting the oven.  
IMPORTANT NOTE  
The cooling fan operates when the blower switch  
is turned to “ON” or “I”. It must operate to keep  
the electrical control cabinet below 1400F (600C).  
Figure 4-1. Oven Cooling Fans  
WARNING  
IF FAN BLADE IS NOT ROTATING, BROKEN,  
OR FAN ASSEMBLY IS MISSING FROM MAIN  
BLOWER MOTOR SHAFT, DO NOT OPERATE  
OVEN. REPLACE COOLING FAN BLADE  
BEFORE OPERATING OVEN. Serious damage  
could be done to the burner blower motor and/or  
solid-state electrical components if oven is  
operated while cooling fan is not running or vent  
grille is plugged.  
3. Using a stiff nylon brush clean control compartment  
vent grille.  
C. Conveyor Belt (Figure 4-2)  
Everyday, just after starting the oven, stand at the  
unloading end of the conveyor, and with a brush, remove  
food particles (crumbs etc.) clinging to the conveyor belt,  
brushing them into the crumb pan.  
Figure 4-2. Conveyor Belt and  
Crumb Pan Cleaning  
17  
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SECTION 4  
MAINTENANCE  
react with the aluminized finger manifold surfaces.  
II. MAINTENANCE - MONTHLY  
NOTE: The oven interior may require cleaning more than once a  
month depending on the volume of baking. To clean the interior , you  
have to disassemble some parts of the oven.  
You can order non-caustic cleaner from your local  
authorized Middleby Marshall Parts Distributor in the  
quantities listed below  
When cleaning your PS520-Series Oven note the following:  
Part#  
Quantity  
PRECAUTIONS-  
1. Do not use excessive water or saturation of oven  
insulation will occur.  
27170-0244  
27170-0246  
Case of Quarts (6)  
Case of Gallons (4)  
A. Removing Conveyor From Oven For Cleaning  
1. Remove entry and exit trays  
2. Do not use caustic oven cleaner or the aluminized  
finger manifold surfaces will be severely damaged.  
2. Loosen (do not remove) two screws on housing guard.  
3. Remove motor housing guard.  
When cleaning your oven, first remove all heavy debris  
with a vacuum cleaner. Use a damp cloth for light  
cleaning. For heavier cleaning of baked on grease and  
carbon deposits use a non-caustic cleaner that will not  
4. Lift conveyor and remove chain.  
Console  
Controls  
Removable Air Fingers  
(inside baking chamber)  
Temperature  
Controller  
Blower and Cooling  
Fan Motor  
Conveyor  
Speed  
Control  
Conveyor  
Motor  
(inside)  
Motor  
Housing  
Guard  
Removable  
Crumb Pan  
Adjustable  
Eyebrow  
Removable  
Conveyor  
Assembly  
Legs  
Figure 4-3  
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SECTION 4  
MAINTENANCE  
5. Lift other side of conveyor and push toward other  
side.  
6. Remove conveyor as shown.  
Figure 4-6  
Figure 4-4  
Figure 4-7  
CAUTION  
Figure 4-5  
Be careful no to bump the drive sprocket while  
handling the conveyor, to avoid damaging the  
drive shaft.  
19  
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SECTION 4  
MAINTENANCE  
B. Air Fingers Disassembly For cleaning  
1. As the air fingers are removed use a felt pen to mark  
all parts of the fingers. This includes the finger manifold,  
inner plate and the outer plate (see Figure 1-9). If a blank  
or choke plate is used, mark that plate also, Fingers are  
marked in the order shown; as viewed from the front of  
the oven. (The marks for an upper oven should be  
preceded with a “U”, example UB1, UT2, etc.)  
Standard Fingers  
2. Slide blank plates straight out.  
Figure 4-9  
Figure 4-8  
4. With air fingers out, place them in an upright position  
to remove the outer plate.  
5. Gently step on the lip of the finger and pull the outer  
plate off.  
3. Remove air fingers.  
NOTE: Some oven users require a custom finger  
arrangement where the quantity of air fingers may vary.  
You can remove the top and bottom fingers and blank  
plates from each or either end. It is highly recommended  
that each finger be marked before removing so it is placed  
in exactly the same position when reassembled (refer to  
step 1).  
Remove the air fingers, pull the finger at the back side-  
pull straight out.  
Figure 4-10  
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SECTION 4  
MAINTENANCE  
6. To remove the inner plate, pull the plate out and  
then up.  
C. Reassembly of Air Fingers  
1. Air fingers are made up of one inner plate, one  
outer plate and the finger housing manifold. Be sure to  
match up the markings (T1, T2, T3, etc.) on all parts of  
the air fingers as you are reassembling.  
Figure 4-11  
7. The outer finger plate is stainless steel and may be  
cleaned by either soaking in a hot, strong detergent  
solution or using a caustic cleaner. The conveyor belt  
can also be cleaned in the same way.  
Figure 4-14  
2. Reassemble the inner plate. Keep your fingers clear  
so you won’t pinch them. The inner plate of a finger  
will only go in one way because of its design.  
3. Replace the outer plate by placing your hands flat  
on the top of the plate and pushing down. Keep your  
fingers clear so you won’t pinch them.  
Figure 4-12. Standard Lower Finger  
Figure 4-15  
Figure 4-13. Standard Upper Finger  
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SECTION 4  
MAINTENANCE  
4 . Replace the air fingers by pushing in at the back  
side. Remember to replace them according to the  
numbers marked on them when they were removed.  
They must go back in the same way they came out.  
IMPORTANT: When inserting fingers the tab  
on the outer plate must be in the groove as  
shown in Figure 4-18. There is a blocking tab  
on the outside of the groove which will prevent  
inserting the finger in the groove if the outer  
plate is moved away from the flange of the  
finger.  
Figure 4-16  
Extended Lip  
Tab on  
Outer Plate  
Flange of  
Finger Manifold  
Tab on  
Outer Plate  
Figure 4-17  
22  
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SECTION 4  
MAINTENANCE  
5. Install fingers and blank plates correctly with edges interlocked and no space between edges.  
Correct -  
Edges Overlap  
Completely  
Top Finger  
Blank Plate  
Tab on Outer Plate of  
Finger Located in Groove  
Figure 4-18  
D. Reinstall End Plugs  
1. Reinstall lower end plug. Be sure to tighten the wing screw on the end plug.  
2. Reinstall conveyor.  
3. Reinstall upper end plug. Be sure to tighten two wing screws on the end plug..  
Figure 4-19  
23  
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SECTION 4  
MAINTENANCE  
E. Conveyor Reassembly Into Oven  
F. Checking Conveyor Belt Tension  
1. Lift conveyor and position it in the oven as shown.  
WARNING  
NOTE: Conveyor may be inserted into either end of  
the oven. If it is ti be installed from the non-drive end of  
the oven the drive sprocket assembly must be  
Oven conveyor belt must be cool when adjusting belt.  
Do not adjust belt if HOT.  
removed as shown in conveyor disassembly section.  
1. With the conveyor assembly in the oven, stand at  
one end of the conveyor and check tension by lifting  
the conveyor belt at the center of the oven chamber  
opening (see Figure 4-23). The belt should not lift  
higher then 1” to 2” (75mm to 102mm).  
2. If conveyor belt is still not under proper tension, an  
entire link must be removed. Use the following  
procedure “H. Conveyor Belt Link Removal” to  
remove a link. If conveyor belt is under proper tension  
proceed directly to “J. Attaching Drive Chain”.  
3. Newer model PS520-Series ovens have adjustment  
screws at the end to tighten the conveyor belt. If these  
adjustment screws are at their limit and belt tension is  
still not correct, loosen the adjustment screws,  
proceed to “H. Conveyor Belt Link Removal” to  
shorten the belt and then return to “F. Checking  
Conveyor Belt Tension” for proper adjustment. If belt  
is tensioned properly proceed directly to “J. Attaching  
Drive Chain”.  
Figure 4-21  
2. Reinstall the conveyor extension.  
Conveyor Extension  
Figure 4-22  
Figure 4-23  
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SECTION 4  
MAINTENANCE  
G. Conveyor Belt Link Removal  
4. Unhook the link to be removed.  
1. Using long nose pliers, an entire link can be  
removed with the conveyor assembly either in or out of  
the oven. Position master links at the end of the  
conveyor as shown in Figure 4-24.  
5. Pull up on the link section and remove. Do not  
discard the link removed as it may be used for making  
spare master links.  
NOT: If a section of the conveyor is being replaced it  
should be done now. Remove the links that need  
replacing and use the section of conveyor belt  
furnished in the installation kit to replace them.  
Master  
Links  
Figure 4-24  
2. Using long nose pliers, unhook master links at left  
end of conveyor as shown in Figure 4-25.  
Figure 4-27  
NOTE: Before connecting the inside master links,  
notice that these links have a correct position (Figure  
4-28). The link at the right is in the correct (horns up)  
position for inserting into the conveyor belt. The horns  
facing down are in the incorrect position.  
Figure 4-25  
3. Remove the outside master links on the right and  
left sides of the conveyor belt as shown in Figure 4-26.  
Correct  
Position  
Incorrect  
Position  
Figure 4-28  
Figure 4-26  
25  
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SECTION 4  
MAINTENANCE  
6. Reconnecting the inside master links (Figure 4-29)  
H. Attaching Drive Chain  
1. If drive sprocket assembly was removed,  
reassemble it onto the conveyor drive shaft. Be sure  
flat on end of drive shaft aligns with set screw in  
conveyor shaft collar. Once in place tighten 3/32” set  
screw.  
2. Lift conveyor and install drive chain to conveyor  
drive sprocket and motor sprocket.  
Figure 4-29  
NOTE: The outside master links have right and left  
sides to them. The right edge master link has an open  
hook facing you as shown in Figure 4-30. This will  
match up with the outer edges of the conveyor belt.  
Remember this hook travels backwards on the  
conveyor.  
Figure 4-32  
3. The angle plate located on the underside of the  
conveyor must be against the lower end plug. This is  
true on both sides of the oven.  
Figure 4-30  
7. Reconnect the outside master links.  
8. Replace all parts removed from the oven.  
Crumb Pan  
Mounting Bracket  
Lower End Plug  
Figure 4-33  
Figure 4-31  
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SECTION 4  
MAINTENANCE  
4. Reattach conveyor guard to control panel and  
secure two screws.  
A. Electrical Terminals  
Open the control cabinet door by removing the three  
screws from the control cabinet door. Tighten all  
electrical control terminal screws as shown in Figure 4-  
35.  
Install both upper end plugs.  
Figure 4-34  
Figure 4-35  
B. Ventilation  
III. MAINTENANCE - EVERY 3 MONTHS  
Check that the air circulation throughout the oven is  
not blocked and is working properly.  
WARNING  
IV. MAINTENANCE - EVERY 6 MONTHS  
Shut OFF all electrical power and lockout/tagout  
the switch before attempting maintenance work.  
A. Check brushes on D.C. conveyor motor. When  
worn to less then 1/10” (2.4mm), replace the brushes.  
NOTE: It is recommended that the 3-month  
maintenance be performed by an authorized Middleby  
Marshall technician.  
B. Check your venting system.  
IMPORTANT NOTICES:  
• Installation of replacement parts requiring  
access to the interior of the oven is permitted  
only by an authorized service technician.  
• If there are any problems with the operation of  
the oven, the authorized service technician  
must be called.  
• It is suggested to obtain a service contract with  
a manufacturer’s authorized service technician.  
27  
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SECTION 4  
MAINTENANCE  
PS520-SERIES ELECTRIC OVEN KEY SPARE PARTS KIT  
ITEM  
PART NO.  
58504  
51402  
58390  
58323  
33812-5  
50715  
51017  
51958  
51961  
57408  
DESCRIPTION  
QUANTITY  
1
2
3
4
5
6
6
6
6
7
Kit, Temperature Control On/Off PID  
Relay, 100A  
1
1
1
1
3
1
1
1
1
1
Conveyor Drive Motor with 2 pole magnet  
Conveyor Speed control  
Thermocouple  
Heater Element, 208V  
Heater Element, 240V  
Heater Element, 380V  
Heater Element, 480V  
Contactor 65 amp 3-pole  
28  
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SECTION 5  
TROUBLESHOOTING  
SECTION 5  
TROUBLESHOOTING  
PROBLEM:  
PROBLEM:  
OVEN BLOWER AND CONVEYOR OPERATE,  
YET THE OVEN IS NOT HEATING  
PRODUCTS ARE OVERCOOKED  
OR UNDERCOOKED  
Reset the temperature controller  
to a new setting (above 2000F),  
after turning the BLOWER switch  
to off for 30 seconds.  
Check for correct  
setting of conveyor  
speed control.  
Check for correct  
setting on temperature  
controller  
Start the oven again. If the oven still does not  
heat, call your Middleby Marshall Service Agency.  
Set the conveyor  
speed control at  
correct setting.  
Turn temperature  
control to correct  
setting.  
PROBLEM:  
CONVEYOR WILL NOT HOLD PROPER  
SPEED OR WILL NOT RUN AT ALL  
Verify the food  
preparation process.  
If products still cook incorrectly,  
call your Middleby Marshall  
Service Agency.  
Check whether the conveyor is  
jammed on something in the oven.  
Check for proper tension of conveyor drive chain and  
conveyor belt. Refer to Section 4 for  
correct procedure.  
PROBLEM:  
OVEN DOES NOT HEAT  
Check that the conveyor  
drive sprocket is tight.  
Check to see if both BLOWER  
switch and HEAT switch are in  
the “ON” or “I” position.  
If conveyor still does not run correctly, contact  
your Middleby Marshall Service Agency.  
If oven does not heat, call your  
Middleby Marshall Service Agency  
PROBLEM:  
OVEN DOES NOT TURN ON WHEN ITS  
SWITCHES ARE TURNED ON  
PROBLEM:  
BLOWER MOTOR IS RUNNING, YET LITTLE  
OR NO AIR BLOWS FROM AIR FINGERS  
Check that all electric supply switches are set to  
the “ON” or “I” position. Then, start the oven.  
Air fingers reassembled incorrectly,  
after cleaning  
If oven still will not start, contact your Middleby  
Marshall Service Agency.  
Assemble air fingers correctly, after cleaning.  
Refer to Section 4 procedure, or call your  
Middleby Marshall Service Agency  
29  
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SECTION 6  
ELECTRICAL SCHEMATICS  
30  
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SECTION 6  
ELECTRICAL SCHEMATICS  
31  
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SECTION 6  
ELECTRICAL SCHEMATICS  
32  
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SECTION 6  
ELECTRICAL SCHEMATICS  
33  
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SECTION 6  
ELECTRICAL SCHEMATICS  
34  
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NOTES  
35  
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WARNING  
Improper installation, adjustment, alteration, service or  
maintenance can cause property damage, injury or death. Read  
the installation, operating and maintenance instructions  
thoroughly before installing or servicing this equipment.  
NOTICE  
During the warranty period. ALL parts replacement and servicing should be  
performed by your Middleby Marshall Authorized Service Agent. Service that is  
performed by parties other than your Middleby Marshall Authorized Service Agent  
may void your warranty.  
NOTICE  
Using any parts other than genuine Middleby Marshall factory manufactured parts  
relieves the manufacturer of all warranty and liabilities.  
NOTICE  
Middleby Marshall reserves the right to change specifications at any time.  
Middleby is proud to support the Commercial Food  
Equipment Service Association (CFESA). We  
recognize and applaud CFESA’s ongoing efforts to  
improve the quality of technical service in the industry.  
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406  
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