Fluke VICTOREEN 875 User Manual

Victoreen® 875  
High Range Containment Monitor  
Operators Manual  
February 2005  
Manual No. 877-1-1 Rev. 9  
©2004, 2005 Fluke Corporation, All rights reserved. Printed in U.S.A.  
All product names are trademarks of their respective companies  
Table of Contents  
Section 1:  
1.1  
Introduction................................................................................................ 1-1  
General Description..................................................................................... 1-1  
Specifications............................................................................................... 1-1  
Equipment Overview.................................................................................... 1-3  
Receiving Inspection.................................................................................... 1-8  
Storage ........................................................................................................ 1-9  
Procedures, Warnings, and Cautions .......................................................... 1-9  
1.2  
1.3  
1.4  
1.5  
1.6  
Section 2:  
2.1  
Installation.................................................................................................. 2-1  
Installation.................................................................................................... 2-1  
Cable and Wiring Installation ....................................................................... 2-3  
2.2  
Section 3:  
3.1  
Operation.................................................................................................... 3-1  
Operation..................................................................................................... 3-1  
Section 4:  
4.1  
Operation.................................................................................................... 4-1  
Functional Description ................................................................................. 4-1  
Readout Module 876A-1.............................................................................. 4-1  
4.2  
Section 5:  
5.1  
Maintenance, Calibration, and Troubleshooting..................................... 5-1  
Maintenance ................................................................................................ 5-1  
Calibration.................................................................................................... 5-1  
Troubleshooting........................................................................................... 5-3  
Power Supply Measurements...................................................................... 5-4  
Signal Input Circuit....................................................................................... 5-4  
Metering Circuit............................................................................................ 5-5  
The Alarm Circuits ....................................................................................... 5-5  
High Alarm Circuit........................................................................................ 5-6  
Muting Stages of the Alarm Circuits............................................................. 5-6  
ESC Board................................................................................................... 5-7  
Overall Fail Circuitry Associated with the ECS Test .................................... 5-9  
Starting with Pins M and P on the Power Supply Schematic ....................... 5-9  
Starting with Terminal H on Relay Driver Board .......................................... 5-9  
Provision of Inputs to Terminals M and P on the Power Supply Board........ 5-9  
Outputs of U206 Pulse Generator on the ECS Board................................ 5-10  
Operation of the Latch Circuit .................................................................... 5-10  
5.2  
5.3  
5.4  
5.5  
5.6  
5.7  
5.8  
5.9  
5.10  
5.11  
5.12  
5.13  
5.14  
5.15  
5.16  
i
Appendix A: Calibration and Test Procedures..............................................................A-1  
A.1  
A.2  
Calibration Procedures ................................................................................A-1  
Test Procedures ..........................................................................................A-1  
Appendix B: Cable and Pull Box Procedures................................................................B-1  
B.1 Cable and Pull Box Procedures...................................................................B-1  
Appendix C: Applicable Drawings and Bill of Materials...............................................C-1  
C.1  
C.2  
Applicable Drawings ....................................................................................C-1  
Bill of Materials ............................................................................................C-3  
ii  
Introduction  
General Description  
1
Section 1  
Introduction  
1.1 General Description  
Containment Monitor 875  
NOTE  
The 875 Containment Monitor has been qualified  
for use in Nuclear Safety related applications.  
Qualification Test Reports, 950.301, 950.308A, and  
950.310A define the parameters that have been  
verified by test and are available for purchase.  
Containment Monitor 875 functions as an accident monitor for reactor containments, refer to Figure 1-1. It  
consists of the 877-1 Ion Chamber Detector that is located within the reactor containment, and the 876A-1  
Readout Module that is contained in a rack in the control room. The readout module contains a power  
supply that provides the necessary power both for itself and the detector. The readout module is  
connected to the detector by two cables, a coaxial high voltage cable and a coaxial signal cable.  
Specifications for the detector and readout module are contained below.  
1.2 Specifications  
Detector 877-1  
Radiation Detected  
Range  
Photons above 60 keV  
1 R/h to 1E7 R/h  
Energy Response  
Chamber Construction  
± 20% from 80 keV to 2 MeV  
Stacked parallel plate, 316 stainless steel housing, 3  
terminal, guarded ion chamber  
Saturation  
>80% up to full scale on instrument  
450 to 550 VDC  
Collection Voltage  
Current Output  
7E-11 to 7E-4 Amp/R/Hr (nominal)  
435 picofarads (nominal)  
Chamber Capacitance  
Voltage Withstand and Leakage  
5E10-5 amperes @ 500 VDC between either ground and  
connector pins  
Capacitance  
Approximately 430 pf  
1-1  
Victoreen 875  
Operators Manual  
Hermetic Integrity  
1E10-5 cm3 of helium per second @ one standard  
atmosphere  
Chamber Fill Gas  
Nitrogen/helium (2%) at atmospheric pressure  
Dimensions (W x H x D) with Mounting Bracket  
9.25 x 12.5 x 10.06 in  
(234.95 x 317.5 x 255.52 mm)  
Weight  
Approximately 18 lb (8.17 kg)  
40° to 160°F (4° to 71°C)  
Temperature, Storage  
Temperature, Operating  
40° to 160°F (4° to 71°C)  
375°F (180°C) peak, accident, 3 hours  
Relative Humidity  
Total Integrated Dose  
Chemical Spray  
100% (waterproof)  
2E8 Rads + 10% margin, 60Co  
0.45 Gallons/minute/ft2 (0.28 molar H3BO3, 3000 ppm  
Boron, and NaOH; ph of 11, 24 hrs  
LOCA Test Duration  
28 days  
(Consult Fluke Biomedical, Radiation Management Services, for a complete description of Qualification  
Test Results)  
Readout Module 876A-1  
Range  
1 to 107 R/h  
Input Current  
Minimum: 6.5 to 7.5 x 10-11  
A
Maximum: 6.5 to 7.5 x 10-4 A  
Recorder Output  
optional)  
0 to +1 VDC, logarithmic (0 - 10 mV and 0 5 V  
Computer Output  
optional)  
0 to +5 VDC, logarithmic (0 - 100 mV and 0 - 50 mV  
(Other Outputs Available Upon Request)  
System Accuracy (during "all" conditions)  
Power Requirements:  
Accumulative @ Meter +36% of input radiation  
Analog Outputs +28% of input radiation  
a) AC Voltage: 108 to 132 VAC, RMS @ 60 ± 3 Hz  
b) Battery Power: 22 to 32 VDC @ 600 mA DC  
maximum  
Temperature Coefficient  
Dimensions (W x H x D)  
0.40%/°C, + 0.25 R/h/°C  
8.46 x 5.25 x 15.21 in  
(214.88 x 133.35 x 386.33 mm)  
Weight  
20 lbs (9.07 kg)  
Environmental Parameters  
Temperature (Storage): 40° to 140°F (4° to 60°C)  
Temperature (Operating): 40° to 120°F (4° to 49°C)  
1-2  
Introduction  
Specifications  
1
Relative Humidity (Storage): 0 to 95% (non-  
condensation)  
Relative Humidity (Operating): 0 to 90% (non-  
condensation)  
Irradiation: 3.5 to 1 x 103 Rads @ 60°C integrated over  
40 years life.  
Mounting  
876-1-55, Rack Chassis  
Available Options (consult factory)  
876A-100: Readout, for use with digital systems  
Outputs: 0 - 100 mV  
0 - 50 mV  
0 - 10 mV  
0 - 5 V  
Figure 1-2 illustrates the typical energy response for the detector, Figure 1-3 illustrates typical linearity for  
the detector and Figure 1-4 illustrates radiation input versus meter reading.  
1.3 Equipment Overview  
High-Range Containment Monitor Detector (877-1)  
The high-range containment monitor detector is an ion chamber detector that has the appearance of a  
six-inch diameter domed cylinder about seven inches long. Inside the cylinder are two flange-mounted  
electrodes consisting of 31 flat, disk-shaped plates, each about four inches in diameter, stacked, and  
mounted on disk rods. The assembly has the appearance of a large air capacitor. The mounting posts are  
attached to the mounting flange through insulating spacers, so the flange and housing will be neutral with  
respect to the charges applied to the electrodes.  
The whole assembly is covered by the six-inch diameter housing which contacts only the neutral  
mounting flange. The mounting flange is pierced by three holes. One hole supports the exhaust tube used  
for exhausting and back filling the chamber. The other two support two 2-pin connectors, one for each  
electrode. One pin in each pair is connected to the neutral mounting flange. When the coaxial signal  
cable is connected to this connector, the cable shield is connected to the neutral pin.  
The entire chamber is filled with a mixture of helium and nitrogen at atmospheric pressure and sealed.  
For further information refer to Section 4, Functional Description.  
Readout Module (876A-1)  
The 876A-1 Readout Module is designed to give an indication, on an analog meter, of radiation levels  
within the containment area. The readout is composed of an analog meter, indicator lights and operating  
switches. The meter has a range of 1 to 107 R/h and is controlled by an eight position rotary switch. The  
readout is mounted in the 876-1-55 Rack Chassis located in the control room.  
For further information refer to Section 4, Functional Description.  
Rack Chassis (876-1-55)  
The 876-1-55 Rack Chassis permits mounting of two readout modules or one readout module and one  
optical isolator in a 19-inch wide RETMA equipment rack. The panel height is 5.21 inches.  
For further information refer to applicable drawing located in Appendix C.  
1-3  
Victoreen 875  
Operators Manual  
Pull Box Assembly (878-12-5)  
The 878-12-5 Pull Box Assembly is designed to allow for thermal expansion of the detector cables and to  
provide a service loop. Various optional pull-box configurations are available per Table 1-1. For more  
information refer to Section 2, Appendix B, and Appendix C.  
Table 1-1.  
Pull-box Variations  
Outlet, Size and  
Location  
Model  
Inlet, Size and Location  
Inlet/Outlet Orientation  
878-12  
1" 270°  
1" MNPT 270°  
1" MNPT 270°  
1" 270°  
2, ¾", 90°  
180°  
180°  
180°  
180°  
90°  
878-12-M 1  
878-12-M2  
878-12-M3  
878-12-M4  
878-12-M5  
878-12-M6  
878-12-M7  
878-12-M8  
878-12-M9  
2, ¾", 90°  
2, 1", 90°  
1, 1", 90°  
1" 270°  
1, 1", 90°  
¾" 270°  
2, ¾", 90  
180°  
90°  
2, ¾" 0°/360°  
1" MNPT 270°  
2, ¾", 0°  
2, ¾", 90  
2, ¾", 90  
90°  
1,1", MNPT, 90°  
1, ¾" MNPT, 120°  
1, ½" MNPT, 210°  
2, ¾ 90°  
90°  
1,1" MNPT 90°  
150°  
210°  
0°  
878-12-M10  
878-12-M11  
878-12-M12  
1,1" MNPT  
2, ¾", 90°  
2, ¾", 270°  
1,1" MNPT 90°  
1" MNPT, 0°  
0°  
90°  
Flexible Tubing (878-12-30TAB)  
1.0 inch diameter flexible stainless steel tubing is available in various lengths to interconnect the 877-1  
Detector to the first pull-box.  
Cables/Connectors/Panel  
In-Containment Cable: (878-1-9-TAB)  
Ex-Containment Cable: (50-103-TAB)  
Replacement Detector Connector Kit: (878-7-5)  
Blank Panel: (844-8-5)  
Optional Equipment  
The following optional equipment is available:  
878-10 Field Calibrator - 250 mCi 137Cs  
1-4  
Introduction  
Equipment Overview  
1
Figure 1-1.High-Range Containment Monitor 875  
1-5  
Victoreen 875  
Operators Manual  
Figure 1-2.Typical Energy Response Curve – Detector 877-1  
1-6  
Introduction  
Equipment Overview  
1
Figure 1-3.Typical Linearity Detector 877-1  
Figure 1-4.Radiation Input vs. Meter Reading (Calculated Curve)  
1-7  
Victoreen 875  
Operators Manual  
Figure 1-5.High-Range Detector, Recommended Installation  
1.4 Receiving Inspection  
Upon receipt of the unit:  
1. Inspect the carton(s) and contents for damage. If damage is evident, file a claim with the carrier and  
notify Fluke Biomedical, Radiation Management Services at 440.248.9300.  
2. Remove the contents from the packing material.  
3. Verify that all items listed on the packing list have been received and are in good condition.  
NOTE  
If any of the listed items are missing or damaged,  
notify Fluke Biomedical.  
1-8  
Introduction  
1
Storage  
1.5 Storage  
Storage of Victoreen instruments must comply with level B storage requirements as outlined in ANSI  
N45.2.2 (1972) Section 6.1.2(.2). The storage area shall comply with ANSI N45.2.2 (1972) Section 6.2  
Storage Area, paragraphs 6.2.1 through 6.2.5. Housekeeping shall conform to ANSI N45.2.3 (1972).  
Level B components shall be stored within a fire resistant, tear resistant, weather tight enclosure in a well-  
ventilated building.  
Storage of Victoreen instruments must comply with the following:  
1. Inspection and examination of items in storage must be in accordance with ANSI N45.2.2 (1972)  
Section 6.4.1.  
2. Requirements for proper storage must be documented and written procedures or instructions must  
be established.  
3. In the event of fire, post-fire evaluation must be in accordance with ANSI N45.2.2 (1972), Section  
6.4.3.  
4. Removal of items from storage must be in accordance with ANSI N45.2.2 (1972), Sections 6.5 and  
6.6.  
1.6 Procedures, Warnings, and Cautions  
The equipment described in this manual is intended to be used for the detection and measurement of  
ionizing radiation. It should be used only by persons who have been trained in the proper interpretation of  
its readings and the appropriate safety procedures to be followed in the presence of radiation.  
Although the equipment described in this manual is designed and manufactured in compliance with all  
applicable safety standards, certain hazards are inherent in the use of electronic and radiometric  
equipment.  
WARNINGS and CAUTIONS are presented throughout this document to alert the user to potentially  
hazardous situations. A WARNING is a precautionary message preceding an operation that has the  
potential to cause personal injury or death. A CAUTION is a precautionary message preceding an  
operation that has the potential to cause permanent damage to the equipment and/or loss of data.  
Failure to comply with WARNINGS and CAUTIONS is at the user's own risk and is sufficient cause to  
terminate the warranty agreement between Fluke Biomedical and the customer.  
Adequate warnings are included in this manual and on the product itself to cover hazards that may be  
encountered in normal use and servicing of this equipment. No other procedures are warranted by Fluke  
Biomedical. It shall be the owner’s or user's responsibility to see to it that the procedures described here  
are meticulously followed, and especially that WARNINGS and CAUTIONS are heeded. Failure on the  
part of the owner or user in any way to follow the prescribed procedures shall absolve Fluke Biomedical  
and its agents from any resulting liability.  
Indicated battery and other operational tests must be performed prior to each use to assure that the  
instrument is functioning properly. If applicable, failure to conduct periodic performance tests in  
accordance with ANSI N323-1978 (R1983) Radiation Protection Instrumentation Test and Calibration,  
paragraphs 4.6 and 5.4, and to keep records thereof in accordance with paragraph 4.5 of the same  
standard, could result in erroneous readings or potential danger. ANSI N323-1978 becomes, by this  
reference, a part of this operating procedure.  
1-9  
Victoreen 875  
Operators Manual  
(Blank page)  
Installation  
Installation  
2
Section 2  
Installation  
2.1 Installation  
Installation of the monitoring system consists of selecting suitable mounting sites for each component of  
the system, mounting each of the components, and connecting the components into the system  
configuration.  
Installation of this system is as follows:  
NOTE  
Refer to the applicable drawings in Appendix C for  
further installation Instructions.  
Rack Chassis  
The 876-1-55 Rack Chassis is a standard 19-inch chassis with a flame barrier. When seismic qualification  
is required for the readout, seismic support brackets (P/N 876-1-114) are needed to support the rear of  
the rack chassis. The brackets are designed to mount on the 19-inch qualified equipment rack.  
Recommended mounting is shown on drawings GEL876-1-55, and 876-1-114.  
Readout Module  
Readout Module 876A-1 is designed to fit into one-half of an 876-1-55 Rack Chassis. Insert the readout  
module in the rack chassis (see drawing GEL876A-1), then insert and tighten the two holding screws in  
the rear flanges of the rack chassis. The pawl fastener on the front panel of the readout must be  
tightened.  
Optical Isolator (No longer manufactured, consult factory)  
Detector  
NOTE  
The detector case MUST BE PHYSICALLY  
GROUNDED TO EARTH GROUND. The readout  
instrument circuit common SHOULD NOT be  
grounded to earth ground.  
The 877-1 Detector is designed to mount on the containment wall. A mounting bracket attached to the  
detector has four holes that are used for mounting. Studs must be placed in the containment wall before  
mounting the detector. Dimensions for the studs are the same as the dimensions of the holes in the  
mounting bracket (refer to drawing GEL877-1). Recommended studs are 5/16 inch Grade 5. No lock  
washers are to be used and recommended torque for the nuts is 18 ft. lbs. Orient the detector so that the  
cable connectors are on the underside. Attach the detector to the mounting bracket with the four clamps  
provided, securing the bolts with a torque of 132 in. lbs. (Figure 1-5 and GEL877-1).  
Pull Box  
A cable pull box is required to allow for thermal expansion of the detector cables and to provide a service  
loop. The pull box (drawing 878-12-5) is a typical type that mounts to the containment wall. It should be  
mounted directly below the detector as shown in Figure 1-1. Depending on actual detector location, more  
than one pull box may be necessary.  
2-1  
Victoreen 875  
Operators Manual  
NOTE  
Under potential L.O.C.A. conditions of pressure and  
temperature, the cable may expand as much as 11  
inches per 100 feet.  
The distance from the pull box to the detector will be determined by the amount of flex hose used to seal  
the detector cables. Additional information is found in the paragraph below Cable Sealing and in CABLE-  
877 and 878-12-3 procedures in Appendix B.  
Once the cables have been pulled and tested, the pull box cover must be bolted shut. To bolt the pull box  
shut, follow the steps outlined in procedure 878-12-3 in Appendix B. Pull box material type and grade is  
304 stainless steel.  
Cable Sealing  
In-containment cable is 878-1-9. This is special cable designed to withstand the potential high radiation  
that may exist following a L.O.C.A. or similar event. In order to withstand the high pressure and moisture  
generated during such an event, the entire cable length must be sealed so that moisture will not come in  
contact with the cable. Cable specifications are listed below.  
Specifications for Cable 878-1-9  
Conductor  
Insulation  
Shield  
#24 AWG, 19/36 Tinned Copper  
Tefzel (BIWF)  
#36 AWG, Tinned copper brand, 90% Coverage  
Tefzel (BIWF)  
Jacket  
Outside Diameter  
0.250 to 0.295 in  
(6.35 to 7.49 mm)  
Impedance  
75 ohms nominal  
22 pf/ft nominal  
7000 V minimum  
2300 V maximum  
Capacitance  
Dielectric Strength  
Operating Voltage  
The following guidelines are based on the sealing method used during the qualification test. Stainless  
steel Flex Hose 878-12-30, ¾ inch diameter x 18.5 inches long (with welded Swagelok connectors)  
should be installed between the detector and pull box. Stainless steel tubing (¾ inch diameter) should be  
installed from the pull box to the penetration for each cable. If a common stainless steel tubing run is  
used, a one (1) inch diameter tube is recommended.  
NOTE  
Seismic support and the sealing technique at  
penetration vary with plant requirements.  
Techniques and materials used are the customer's  
responsibility.  
Attach the stainless steel tubing to the pull box with compression fittings (¾ inch) and, after finger  
tightening, tighten at least 1-¼ turns. The flex hose connection at the pull box is installed in the same  
manner. The detector end of the flex hose is swaged to the cable connector backshell. This should not be  
2-2  
Installation  
Installation  
2
done until cable is pulled and tested. (Refer to the procedure Cable-877, in Appendix B, for more  
information.)  
NOTE  
Minimum bend radius of the 878-1-9 cable is four  
inches. When bending conduit or flex hose, take  
this into consideration. Typical bend radius for P/N  
878-12-30 is ¾ inch; stainless steel flex house is 12  
inches.  
2.2 Cable and Wiring Installation  
Detector Cable Inside Containment  
Detector cables used inside containment are to be installed and terminated according to procedure  
Cable-877, in Appendix B. Do not allow any moisture or contaminants to deposit on the connectors used  
for installing cables due to the potential for electrical leakage. Because the detector transmits extremely  
small current signals, no terminal block connections are acceptable in the penetration. Signal conductor  
must be shielded but not grounded (qualified butt splices are acceptable). Refer to drawing GEL875-1 for  
electrical connections and to 878-1-9 for cable data.  
CAUTION  
The detector and readout must not be connected  
during the following test.  
Detector Test After Installation  
Testing of detector cables after installation is required. A leakage test from the center conductor to the  
shield should yield better than 1000 megohms at 1000 VDC.  
Typical resistance of the center conductor is 0.022 ohm per foot at 20°C (68°F).  
Detector Cable Outside Containment  
Detector cables used outside containment should be a qualified coaxial type RG 59/U. Ideally, the cable  
should connect directly from the penetration to the appropriate connectors on Readout Module 876A-1.  
Terminal block connections and unshielded center conductors are not acceptable for installation. Fluke  
Biomedical recommends that cable 50-103 be used. Typical wiring is shown on drawing GEL 875-1. After  
installation, testing is required as described in the previous paragraph. Specifications for cable used  
outside containment are listed below. Refer to drawing 50-103 for additional data.  
Specifications for Cable 50-103  
Type  
RG 59/U, alternate  
Conductor  
Insulation  
Flame Tape  
Shield  
19/36 Tinned copper  
Cross-linked polyethylene  
Mica tape  
#36 AWG, 92% coverage  
0.001 inch (0.03 mm) mylar  
Bostrad 7 (CSPE)  
Insulation Wrap  
Jacket Type  
2-3  
Victoreen 875  
Operators Manual  
Thickness  
0.015 inch (0.38 mm) nominal  
0.217 inch (5.51 mm) nominal  
75 ohms nominal  
Outer Diameter  
Impedance  
Capacitance  
22 pf/ft nominal  
Ancillary Wiring  
Ancillary wiring for computer, recorder, power and alarm contacts are installed according to drawing GEL  
875-1 and Table 2-1 which indicates connector pin designations.  
Table 2-1.  
Installation  
Computer & Recorder  
Function  
Ground  
Ground  
J3  
D
F
Computer  
E
Recorder  
C
All Alarms on P2  
Normal Operation *  
Shelf State  
Alert Alarm I  
Alert Alarm II  
High Alarm I  
High Alarm II  
Fail Alarm I  
Fail Alarm II  
N
P
R
D
E
F
S
T
U
G
H
J
K
L
M
A
B
C
NO  
C
NC  
NO  
C
NC  
NO  
C
NC  
NO  
C
NC  
NO  
C
NC  
NO  
NC  
C
NO  
NC  
C
NO  
NC  
C
NO  
NC  
C
NO  
NC  
C
NO  
NC  
C
C
NC  
NO  
Power Connections (P1)  
Line  
Neutral  
Chassis Ground  
A
B
C
* Relays are Fail Safe, i.e. energized for normal operation. Relays de-energize during an alarm condition.  
NO = Normally open  
C = Common  
NC = Normally closed  
2-4  
Operation  
Operation  
3
Section 3  
Operation  
3.1 Operation  
Once installation is completed, operation is fully automatic. The 876A-1 Readout Module continuously  
indicates the level of radioactivity measured at the detector site. When the radiation level exceeds an  
alarm set point, an alarm is actuated.  
The following steps explain how to operate the 875 monitor:  
1. Turn the function switch to the TEST position, and press and release the Electronic Check Source  
(ECS) push button. About four seconds later, the SAFE-RESET light should come on. Then press  
and hold the CHANNEL TEST push button. The ALERT, HIGH, and CHANNEL TEST lamps should  
light immediately.  
NOTE  
When channel test is pressed, the high and alert  
alarm relays are deactivated. (Their coils are de-  
energized). The wiring of the channel test circuit is  
such that the channel test lamp will not light unless  
the alarm relay contacts are in the deactivated or  
tripped state. This is for the purpose of assuring  
that an actual contact state change has occurred,  
identifying that the channel is in the test mode.  
Reconciling these alarm conditions is the user's  
responsibility, since the remote alarms are not  
included in the standard containment monitor  
system.  
2. Release the CHANNEL TEST push button. The SAFE-RESET lamp should stay on. Either or both  
of the HIGH (red) and ALERT (yellow) lamps may stay on or go out depending on the alarm reset  
mode chosen by the installation of jumpers on the alarm circuit board. The monitor is supplied with  
the manual reset mode selected.  
3. To reset any alarm light, press the SAFE-RESET push button. If conditions are normal, the light will  
go out.  
4. Switch the function switch to the ALL position.  
5. Again press the ECS push button. The panel meter indicator should go to a reading of about 103  
R/h and the green SAFE-RESET light stays on in the operating condition. If the panel meter shows  
little or no deflection at the pressing of the ECS push button, the green light should go out four  
seconds after the ECS push button is pressed. In this case, follow troubleshooting procedures.  
6. To set the alert and high alarm adjustments, remove two screws in the rear of the chassis, loosen  
the knurled knob on the front of the chassis, and slide the module forward part way out of the rack  
to reveal the adjustment potentiometers R513 and R509 on the relay driver printed circuit board. To  
adjust the HIGH alarm, depress the red HIGH push button and adjust R513 (drawing 876A-1-75A)  
until the meter indicates the desired alarm level. To adjust the ALERT alarm, depress the yellow  
ALERT push button and adjust R509 (drawing 876A-1-75A) until the meter indicates the desired  
3-1  
Victoreen 875  
Operators Manual  
alarm level. Return the module to its proper position in the rack. Tighten the rear holding screws.  
Tighten the knurled holding knob on the front. Return the module to service.  
During normal operation, the radiation field is usually less than 1 R/h (the lower limit of detection of the  
high range detector) and the analog meter display will be at the low end of the meter scale.  
Figure 3-1.Readout Module 876A-1, Front and Rear View (reference only, not to scale)  
3-2  
Function Description  
Functional Description  
4
Section 4  
Function Description  
4.1 Functional Description  
High-Range Containment Monitor Detector 877-1  
The high-range containment monitor detector is an ion chamber detector that has the appearance of a  
six-inch diameter domed cylinder about seven inches long, mounted on an L shaped bracket. Inside the  
cylinder are two flange-mounted electrodes consisting of 31 flat, disk-shaped plates, each about four  
inches in diameter, stacked, and mounted on disk rods. The 31 disks form two groups, interleaved with  
each other, 16 collection disks and 15 signal disks. Because of the interleaving, they appear as only one  
stack, but the collection disks are mounted on three collection disk-posts and the signal disks on three  
signal disk-posts. Spacers on the posts keep the disks separated so they do not come in contact, and  
clearance holes in the disks allow posts of the opposite polarity to pass through without contact. The  
assembly has the appearance of a large air capacitor. The mounting posts are attached to the mounting  
flange through insulating spacers, so the flange and housing will be neutral with respect to the charges  
applied to the electrodes. The collecting diskposts are elongated beyond the last collecting disk to support  
a cup-shaped liner having the same potential as the collecting disks, thus becoming part of the collector.  
The whole assembly is covered by the six-inch diameter housing which contacts only the neutral  
mounting flange. The mounting flange is pierced by three holes. One hole supports the exhaust tube used  
for exhausting and back filling the chamber. The other two support two 2-pin connectors, one for each  
electrode. One pin in each pair is connected to the neutral mounting flange. When the coaxial signal  
cable is connected to this connector, the cable shield is connected to the neutral pin.  
The entire chamber is filled with a mixture of helium (2%) and nitrogen at atmospheric pressure and  
sealed.  
CAUTION  
The seal on this chamber must not be broken. To  
do so would alter the calibration and specified  
energy response of the system.  
4.2 Readout Module 876A-1  
NOTE  
Drawings 876A-1-3H and 876-1-3A serve as  
interconnecting diagrams for tracing signals  
between printed circuit boards. In addition, drawing  
876-1-3A contains the main power supply  
4-1  
Victoreen 875  
Operators Manual  
PreamplifierIMeter Printed Circuit Board (P/N 876A-1-86, Schematic 876A-1-3E)  
The detector current, measuring from 7 x 10-11 to 7 x 10-4 amperes respectively, at the bottom and top of  
the reading range, enters the readout on rear panel connector J1. From the rear panel, the ion chamber  
current enters the preamplifier circuit through terminal J302. It passes to U301, a seven-decade  
logarithmic amplifier, where it produces an output voltage of 5 V for minimum currents and -2.6 V for  
maximum currents. This voltage can be monitored at TP501, on the relay driver PC Board.  
Q301A and Q301B have their bases connected to their collectors, so that they operate as diodes. Q301  
limits over-range inputs to U301. Q302A is a lower-level clamp on the input to logarithmic amplifier U301,  
keeping the current from falling below 1 % of the lower limit of sensitivity. This limiting of the low level  
current speeds the response of the logarithmic amplifier. The output of U301appears on terminal 13 of  
J301. This terminal is connected to terminal 13 of J103 on the motherboard by a ribbon cable. From this  
point, connection is made to terminal 14, J106 of the relay driver printed circuit board. This terminal is  
effectively the point of input to the meter circuit and high and alert alarm circuits.  
Amplifier and meter circuits can be tested by turning the function switch to TEST and depressing the  
CHANNEL TEST push button on the front panel. This applies 15 volts to a circuit of which Q302B is a  
series element; the purpose is to generate an input current for U301 (at pin 2) such that panel meter  
M401 will be driven full scale.  
Panel meter M401 may be switched into anyone of six positions of different sensitivity. The meter current  
is determined by the voltage applied to pin 10 of U401 from pin 3 of J401. U401 is driven in turn by U501  
of the relay driver printed circuit board. Connection is made from terminal 12 of the relay driver printed  
circuit board to terminal 3, J401 of the preamplifier metering printed circuit board through pins 11 and 14,  
J101 of the switchboard (drawing 876-1-3J) so that the signal path may be interrupted when it is desired  
to use the meter for alarm setpoint checks.  
One of the six sensitivity positions, the ALL position, displays all seven decades on the red meter scale.  
Each of the other positions expands the scale to achieve a three-decade display on the black scale. In  
addition there is a TEST position and an OFF position. The TEST position is also a seven-decade meter.  
Power Supplies  
Mother Board Power Supplies (P/N 876-1-78, Schematic 876-1-3A)  
T101 acts as a step down transformer producing an output voltage of 24 VDC. This is rectified in the full-  
wave rectifier consisting of four diodes, CR101 through CR104. The 0.1 microfarad capacitors on the AC  
input suppress spikes and limit noise. The output of this 24-volt supply provides the power to both the  
positive and negative power supplies on the power supply printed circuit board.  
Printed Circuit Board Power Supplies (P/N 876-1-89, Schematic 876-1-3C) (P/N 876-1-89A,  
Schematic 876-1-93A)  
Positive Power Supply  
Twenty-four (24) V power from the motherboard enters the power supply board on terminal 1. Integrated  
circuit U2 is a voltage regulator; +15 V comes out of pin 2 of U2. A second supply of +14 volts is provided  
through pass element Q1. This output serves relays, lights, and other high current circuit elements. It is  
current-limited through R29. The 14 V supply is monitored at TP3.  
Negative Power Supply  
Transistors Q7 and Q8 make up a free-running multivibrator with a 9 kHz repetition rate, which is powered  
by the unregulated 24 volts from the motherboard power supply. Q6 acts as a current limiter for this  
multivibrator. U1, pins 8, 9, and 10, and Q5 accept its output and act as a driver stage for the rectifier  
which follows. This rectifier consists of CR4 and CR5, and produces a negative voltage, which should be  
about -21 VAC, and can be measured at TP5. Voltage regulator U1 (located on the 876-1-89A add-on PC  
board) takes this voltage as an input, and delivers a -10 V regulated voltage, which is obtained from  
terminal K of the board, and can be monitored at TP4.  
4-2  
Function Description  
Readout Module876A-1  
4
High Voltage Power Supply Normal Operation (non-ECS Test)  
The multivibrator circuit of Q7 and Q8 also supplies the input to the high voltage generator. Two of the  
transistors of U1 act as buffers between the multivibrator and the high voltage circuit. Q4 and Q3 serve an  
output driving stage for the primary of high voltage transformer T1. The input to T1 is a square wave,  
approximately 12.5 V peak to peak. T1 has a step-up ratio of approximately 20: 1. C22, CR15, CR14, and  
C20 form a voltage doubler that gives a DC output of approximately 525 volts. The resistor capacitor  
circuit R42, R43, and R44, and C17, C18, and C19 serve for further filtering, and ultimately a 506 volt  
output is delivered at J1.  
R37, R40 and R41 form a voltage divider across the 515 V input to the resistor capacitor filter. The  
voltage at the junction of R37 and R40 is the input to OP AMP U2 pins 6 through series resistor R39. Pins  
5 and 6 of U2 are the inputs to a difference amplifier, which acts to produce additional regulation of the  
high voltage.  
U2 (pins 1, 2, 3) is used as a logic circuit in the SAFE/FAIL circuit of the monitor, refer to FAIL/SAFE  
Comparison Circuit on Power Supply Board for additional information. In addition to the 6.2 V  
reference signal, a voltage will be present at terminal P that comes from terminal 8 of the ECS board  
during the ECS test, and a muting signal will also be present at terminal M. This circuit is a part of a  
complex checking circuit during the ECS test, and is described in more detail in the "FAIL/SAFE"  
paragraph.  
Operation of High Voltage Supply During ECS Test  
A low voltage ramp (approximately 0 to 6.2 V) from the ECS board enters the power supply board on  
terminal 12, and proceeds through a series of auxiliary circuits to give a ramp of the same waveshape on  
the center-tap of the primary of high voltage transformer T1, which point is also the source of power to the  
driving circuit Q3 and Q4. As a result of this variation of the voltage at the center-tap, the amplitude of the  
current in the primary varies accordingly, and ultimately the voltage output at J1 varies from 0 to 506  
volts, linearly with time. This high voltage ramp generates the current in the detector circuit during the  
ECS test period.  
FAIL/SAFE Comparison Circuit on Power Supply Board  
The comparison circuit on the power supply board, consisting of U2, pins 1, 2, and 3 has two functions:  
The first function, a monitoring of the high voltage, is in operation at all times except during the ECS test.  
If this voltage falls below 80% of its rated value, (roughly, from 500 to 400 volts), the FAIL/SAFE circuit  
will go out, and the FAIL relay will de-energize. During this period, a steady 6.2 volts, which is input on  
terminal 13, serves as a comparison voltage. The voltage on pin 2 is proportional to the high voltage  
through a high ratio voltage divider.  
The second function, a monitoring of the result of the ECS test, is in operation during this test. During this  
period, the high voltage falls well below 400 volts (actually, practically to zero) so the monitoring of the  
high voltage as in the above paragraph is inapplicable. Instead, the following are the input and output  
conditions.  
On pin 2 there is impressed a positive 15-volt signal that lasts for the duration of the ECS test (6.0  
seconds). The voltage on terminal M is 15 volts during the ECS test and zero at all other times. The wave  
shape that creates this condition on terminal M is called the muting signal wave shape. It will override  
whatever voltage would otherwise be present through the high ratio voltage divider from J1.  
On pin 3 of the comparison circuit there is impressed a DC voltage that is either 6.2 volts (safe condition)  
or 15 volts (fail condition). This voltage arrives on terminal P of the power supply board from a latch circuit  
on the ECS board, which circuit will be described in connection with that board. A safe condition causes  
the output on terminal N (from pin 1 of U2) to be -10 volts; a fail condition causes it to be +15 volts.  
Terminal N is connected to the SAFE/FAIL circuit on the relay driver board, which controls the action of  
the fail relay and the SAFE-RESET green lamp on the panel. A fail condition causes the green lamp to go  
out and de-energizes the fail relay, although the muting signal delays these actions until the end of the six  
(6) second ECS test period. For the safe condition the green light is on, and the fail relay is energized.  
4-3  
Victoreen 875  
Operators Manual  
PreamplifierIMeter Board Power Supply (P/N 876-1-86, Schematic 876-1-3E)  
A +6.2 V power supply contained on the preamplifier meter board has as its input the +15 V from the  
power supply board. Integrated circuit U401, pins 12, 13, and 14 is a voltage regulator with diode U402  
providing a stable reference voltage. The output is adjustable by R413.  
Relay Driver Printed Circuit Board (P/N 876A-1-75A, Schematic 876A-1-3B)  
The signal input to the relay driver printed circuit board which is taken from pin 13 of the preamplifier  
meter may be monitored at this point through test point TP501. The signal enters pin 13 of OP AMP  
U501, and the output is taken from pin 14. The gain of this amplifier stage can be adjusted by  
potentiometer R503. The output of the OP AMP can be monitored at TP502; it provides inputs to:  
High Alarm circuit  
Alert Alarm circuit  
Meter buffer amplifier circuit  
Recorder/Computer drivers  
High Alarm Circuit  
The signal output to the high alarm circuit enter OP AMP U502 on pin 5. This is a difference amplifier,  
whose other input (pin 6) is determined by the setting of potentiometer R513. The main purpose of this  
stage is to control the high alarm threshold.  
The output of the comparison OP AMP is connected, through diode CR504, to pin 6 of U503, which acts  
mainly as a power stage for the HIGH ALARM (red) panel light. The output of this stage (pin 7) also  
serves as the input to the high alarm relay driver stage U503, whose main function is to drive relay K502.  
The input to the high alarm relay driver stage of U503 is on pin 9, and the output is taken from pin 8.  
Relay K502 is energized in the non-alarm state, and a signal above threshold serves to de-energize it.  
There is a red HIGH ALARM jumper connected to the collector (pin 8) of the relay driver U503. The  
following options are available with the presence or absence of the jumper when the radiation level  
exceeds the threshold and triggers the alarm:  
Manual Reset - The alarm will continue to be activated even after the radiation level recedes below  
threshold until the SAFE/RESET indicator push button on the panel is depressed. This option occurs  
with the jumper in place.  
Automatic Reset - The alarm will continue to be activated only as long as the radiation exceeds the  
threshold level. This option occurs with the jumper removed.  
The red warning light acts similarly to the alarms. It lights when the alarm relay is de-energized.  
Each relay contains four Form C contacts, but only two of the four are accessible through the rear  
connector.  
The connection to the red panel warning light is from terminal 3 of the printed circuit board, which is  
connected to the collector (pin 7) of U503 through resistor R521.  
Alert Alarm Circuit  
The signal input to the alert alarm circuit enters OP AMP U502 on pin 3. This is a difference amplifier,  
whose other input (pin 2) is determined by the setting of potentiometer R509. The main purpose of this  
stage is to control the alert alarm threshold. The output of the comparison OP AMP is connected, through  
diode CR501, to pin 13 of U503, which acts mainly as a power stage for the Alert (yellow) panel light. The  
output of this stage (pin 14) also serves as the input to the alert alarm relay driver stage U503, whose  
main function is to drive relay K501. The input to the alert alarm relay driver stage of U503 is on pin 2,  
and the output to the relay is taken from pin 1. Relay K501 is energized in the non-alarm state, and a  
signal above threshold serves to de-energize it.  
4-4  
Function Description  
Readout Module876A-1  
4
There is a yellow ALERT ALARM jumper connected to the collector (pin 1) of the alert alarm relay driver  
stage of U503. The following options are available with the presence or absence of the jumper when the  
radiation level exceeds the threshold and triggers the alarm:  
Manual Reset - The alarm will continue to be activated even after the radiation level recedes below  
threshold until the SAE/RESET indicator push button on the panel is depressed. This action occurs with  
the jumper in place.  
Automatic Reset - The alarm will continue to be activated only as long as the radiation exceeds the  
threshold level. This action occurs with the jumper removed.  
The yellow warning light acts similarly to the alarms. It lights when the alarm relay is de-energized.  
Each relay contains four Form C contacts, but only two of them are accessible from the rear connector.  
The connection to the yellow panel warning light is from terminal 2 of the printed circuit board, which is  
connected to the collector (pin 14) of U503 through R526.  
Fail/Safe Circuit  
Input to the fail/safe circuit comes from pin 1 of U2 on the power supply board, entering the relay driver  
board on pin H of the relay driver printed circuit board. The input is a DC voltage that is either high (15 V)  
or low (0 V); if it is low, relay K3 is energized (non-alarm condition). If the signal is high, the green  
SAFE/RESET lamp will go off and the relay is de-energized, indicating a fault somewhere in the system.  
The circuit consists basically of two inverters in tandem so the voltage on the collector of Q502 is  
approximately the same as the input voltage, the diode CR508 preventing current flow through the  
solenoid if the collector is slightly higher than the 14 V at the other end of the solenoid coil.  
Recorders and Computer Buffers  
Provisions have been made for delivering DC output voltages to a recorder and computer for further  
processing. The buffers are located on the relay driver board. If a commercial device is to be connected, a  
signal isolator must be installed between the device and the 876A-1 Readout Module output. Inputs to  
both computer and recorder buffers arrive at pin R of the relay driver printed circuit board, coming from  
terminal 3 on the ECS printed circuit board. The computer buffer consists of and OP AMP using pins 1, 2  
and 3 of U501, the output being taken off the relay driver board at pins 4 (+) and 2 (-) of P502. Resistors  
R532 and R533 act as voltage dividers for the output. Their values for standard usage and available  
options are shown in Table 4-1.  
The recorder buffer consists of an OP AMP using pins 5, 6 and 7 of U501, the output being taken off the  
relay driver board at pins 1 (+) and 3 (-) of P502. Resistors R530 and R531 act as voltage dividers for the  
output. Their value for standard usage and available options are shown in Table 4-1. Both buffers are  
disabled during the ECS test by a switching circuit on the ECS board, so that the ECS current is not  
recorded. This circuit consists of Q201 and Q202 on the ECS board and is activated by a muting voltage  
during the ECS test.  
Table 4-1.  
Resistance Options for Voltage Dividers  
Resistor  
Std.  
Option 1  
Option 2  
0 – 5 V  
Option 3  
0 – 5V  
Recorder  
Voltage  
0 – 1 V  
0 – 10 mV  
R530  
R531  
1 kilohm  
119.8 kilohms  
200 ohms  
200 ohms  
1 kilohm  
200 ohms  
1 kilohm  
200 ohms  
Computer  
Voltage  
0 – 5 V  
1 – 100 mV  
0 – 50 mV  
0 – 5 V  
R532  
R533  
200 ohms  
1 kilohm  
11.8 kilohms  
200 ohms  
23.8 kilohms  
200 ohms  
200 ohms  
1 kilohm  
Pen Clamp  
4-5  
Victoreen 875  
Operators Manual  
The pen clamp circuit is a clamping circuit consisting of U501, pins 8, 9 and 10 and diode CR502. It  
prevents pin 9 from going negative. The purpose of this is to prevent the recorder pen from being jammed  
against the baseline.  
Electronic Check Source (ECS) Printed Circuit Board (P/N 876A-1-92, Schematic 876A-1-  
30)  
Due to the range of the detector (1 to 10E7 R/h), a remotely activated radioactive check source is  
impractical, since the source activity would be high and the shielding necessary for this source would  
effect detector energy response. For this reason, an electronic check source is provided. During check  
source operation, the detector remains connected to the system as a passive capacitive element. Since  
the current-voltage relation in a capacitor is such that the current is proportional to the rate of change of  
the applied voltage, an applied voltage, in the form of a linear ramp, will produce a steady current. It is this  
current which is read during the ECS test.  
The ECS board (drawing 876A-1-3D) has two main functions: 1. To generate the low voltage ramp which,  
in the high voltage supply, develops the high voltage ramp responsible for the test current in the detector  
during the ECS test. 2. To monitor the current flowing during the ECS test, and recognize whether the test  
signifies a passing of failing condition in the circuits of the unit. One of the circuits involved in this  
monitoring process is actually on the power supply printed circuit board.  
The voltage ramp which develops the detector current during the ECS test rises from 0 to 506 volts over  
three seconds, so that the rate of change of voltage is approximately 170 V/second. The capacitance of  
the detector is approximately 435 picofarads and therefore, the steady current during the rise of the  
voltage ramp is approximately 7 x 10-8 amperes, which puts the panel meter at about one-third full scale.  
The ramp occurs when ECS is initiated for a period of about six (6) seconds, during which time the  
system is not acting as a radiation monitor.  
The ECS test may be initiated at the will of the operator. For this purpose there is a manually operated  
ECS push button. If the ECS test is not initiated by the operator, it will take place automatically every 17.1  
minutes. After each manually initiated test, the automatic circuits are reset so that a test will be initiated  
17.1 minutes later.  
In addition to causing visual alarms and relay de-energizing if circuit failures are found, the ECS test  
affects the panel meter as in the three cases described below. It is the processing of the voltage read by  
the panel meter during the ECS test that is responsible for the action of the circuits directly involved in  
driving the visual (green light) and relay (fail) alarm circuits. Recorder and computer outputs are muted  
during the ECS and will indicate zero while the test is in progress, approximately six (6) seconds.  
Panel Meter Action During ECS Test  
The meter action to be expected during the test period with the containment monitor operating properly  
can best be explained by considering three initial conditions: 1) Panel meter is resting at extreme lower  
end of scale; 2) Panel meter on scale but below 103 R/h; 3) Meter above 103 R/h at start of test.  
1. Meter at extreme lower end of scale  
In this case, the meter needle should remain motionless for about 1 second, rise to 103 R/h and  
remain there for about three seconds, and then fall to its initial position.  
2. Meter on scale, but below 103 R/h  
In this case, the meter needle should fall to zero at the beginning of the test period. It will then rise  
to approximately one-third full scale, and remain in this position for about four seconds. After this, it  
will resume its original reading, with perhaps some slight negative overshoot.  
3. Meter above 103 R/h at start of test  
This case is quite similar to the above except that the meter may not fall to zero at the start of the  
test, and at the upswing, it will take a position higher than 103 R/h, the excess depending on the  
ambient radiation. It will ultimately resume the same position as before the test as in item 2 above.  
4-6  
Function Description  
Readout Module876A-1  
4
NOTE  
During the ECS test, all alarms are muted; that is,  
their operation is disabled until the completion of  
the test. During this six-second period there is no  
warning of a high radiation condition. If this  
situation is not tolerable, two containment monitors  
must be installed.  
Action of Green Safe/Reset Light and Alarm During ECS Test  
The behavior of the green SAFE/RESET panel light during the test is as follows:  
A pass condition is indicated by the green light remaining lighted throughout the test.  
A fail condition is indicated if the green light goes out at the end of the test.  
Circuit Actions at Manual and Automatic Initiation of ECS Test  
Whether the ECS test is initiated automatically or at the will of the operator, a trigger signal is delivered to  
pin 4 (manual) or pin 5 (automatic) of U206, whose output initiates the low voltage ramp generation.  
Automatic operation may be disabled by the removal of jumper 200A. The system will then respond only  
to the pressing of the ECS button.  
The circuit containing U201 (pins 5, 6, 7) and U208 (pins 11 and 12) constitutes a clock with a 0.976  
millisecond repetition rate. It is followed by counters U204 and U205. The action of U204 is entirely  
restricted to automatic control of the ECS test, as is the output from pin 1 of U205 (note that it may be  
open-circuited by the removal of jumper 200A). However, the outputs from pins 3, 5, and 6 have functions  
that enter into both manual and automatic action. In addition, they involve both the ramp-generation and  
monitoring functions of the ECS board, and also enter into the operation of two important auxiliary  
functions: 1) generation of a muting pulse, so that the alarms will not be set off during the ECS test and;  
2) re-initiation prevention--that is the prevention of malfunction on manual operation in case the operator  
inadvertently presses the ECS button more than once. The monitoring function is involved because the  
instant of generation of the latch-enable pulse occurs a precise time after the pressing of the ECS button  
initiates the test (toward the end of the test, when conditions have stabilized). The path from U205 pin 6  
to the latch-enable generator may be seen to involve the following points: 1) pin 10, U203; 2) pin 5, U207  
(input); 3) pin 6, U207 (output) and finally pin 11, U207, whose output drives the latch-enable generator  
Q205. The latch and latch enable functions will be explained with the monitoring circuits after the  
explanation of the ramp generation.  
Low Voltage Ramp Generator  
The elements that enter the generation of the low voltage ramp are U203, U208, U201, Q204, and  
associated capacitors, resistors, and diodes. U203 is an auxiliary element.  
At the arrival of the trigger, Q204 serves the purpose of reducing the voltage previously at terminal 5  
quickly to zero, at which instant the ramp-generator proper takes over. Basically, C210 is the charging  
capacitor, and the other components serve either as charging resistors or linear elements. Potentiometer  
R227, ramp voltage per second adjustment (RAMP V/SEC ADJUST), serves to determine the rate of  
charge of capacitor C210, and consequently, the rate of rise of the voltage applied to the detector plates.  
The ramp that is generated by the ramp generator appears at terminal 5, where its maximum is only 6.2  
volts. From terminal 5, it is connected to the high voltage generator on the power supply printed circuit  
board, where it controls the generation of the high voltage, as explained in the functional description of  
the power supply printed circuit board.  
Monitoring Circuits of The ECS Board  
The input to the monitoring circuits of the ECS board is on terminal 1, the output on terminal 8. The input  
on terminal 1 is effectively proportional to the current produced in the detector by the application of the  
4-7  
Victoreen 875  
Operators Manual  
high voltage ramp. The overall circuit that monitors the ECS test also includes U2, described with the  
power supplies; and the SAFE/FAIL circuit on the relay driver printed circuit board.  
Ultimately, by the action of R218, the charge integration adjustment potentiometer (CHARGE INTEG.  
ADJ.), charging capacitor C209, and other auxiliary elements, a DC voltage is produced on terminal 10 of  
U201, and an output voltage on pin 8 which results in an input to pin 10 of U208 which will be  
approximately zero if the system is operative, and approximately + 15 V it a malfunction is present, or on  
channel power-up before the first automatic or manually initiated ECS test.  
This signal is the input to the latch-and-flop circuit composed of the NOR circuits U202 (pins 1 to 13). The  
latch is quiescent until triggered near the end of the ECS test period by the latch-enable input on pin 1 of  
U202. This trigger voltage will cause the output (pin 10 of U202) to flop from a pass indication to a fail  
indication if a malfunction exists in the detector cable, or signal input circuit.  
If the system is operative, a voltage that is low (6.2 V) will appear at terminal 8; if the system has a  
malfunction, a voltage that is high (+15 V) will appear at this terminal (+15 V will appear momentarily  
immediately after power on). This voltage determines the action of a comparison circuit U4A, and the  
output of U4A determines the action of the SAFE/FAIL circuit.  
A block diagram of the entire monitoring circuit of the ECS test is shown in Figure 4-1.  
Figure 4-1.Block Diagram of ECS Test  
4-8  
Function Description  
Readout Module876A-1  
4
Safe/Reset Sub-circuits  
The three sub-circuits described below are all involved in the operation of the green SAFE/RESET lamp  
and its associated alarm:  
1. A latch for the SAFE/RESET lamp built around four NOR circuits of integrated circuit U202, with  
several auxiliary elements.  
2. A threshold detector U201 (pins 8, 9, and 10) ascertains by comparison with a standard voltage  
whether the current produced by the ECS ramp is sufficiently high.  
3. A one-shot multivibrator, U207, pins 9 to 15, which provides an enable signal to allow the latch  
circuit to flop from a pass to a fail condition if the signal from the threshold detector is a fail signal.  
This enable signal is necessary because the detector current during the ECS test is higher than the  
average normal radiation current. The monitoring circuits must therefore be examined just at the  
proper time, which is immediately after the cessation of the ECS current.  
It will be noted that a trigger signal from the counter U205 is applied to the base of Q207, whose collector  
is connected to Q203. . The purpose of this sub-circuit is to short-circuit capacitor C209, so that the  
integration of the ECS may proceed from a stable and repeatable starting point. If the system is a  
functioning properly, a 2.57 volt level will be present at terminal 1 at the top of the ramp, corresponding to  
the 103 R/h meter indication. If voltage at pin 1 is below 2.48 V at this point, ECS circuitry will indicate  
channel failure. See Figure 5-1 and drawing 876A-1-3D. This voltage, applied to the integrator circuit  
consisting of R218, R224, C209 and the OP AMP circuit U201, pins 12, 13 and 14, produces a linearly  
failing voltage of about 2 V/second at pin 14 of U201. This voltage begins just above 0 V. When it reaches  
-6.2 volts, a quick switching action takes place in U201, the important result being a sharp change in the  
output voltage (pin 8) from +15 to 0 volts. A low (approximately 0 V) input at pin 10 of U208 results  
ultimately in a safe report (green light stays on and the alarm relay is energized); whereas a high  
(approximately 15 V) input results in a fail report (green light goes out and alarm relay is de-energized).  
For any change in the output of the latch circuit (pin 10 of U202) an enable pulse is required. This signal  
is output by one-shot multivibrator U207, pin 9, which receives its input from one of the outputs of the  
muting multivibrator U207 (pins 1 to 8).  
Muting Circuits of ECS Board  
During ECS test, it is possible that the normal current generated by the ECS voltage ramp will exceed the  
trip-level chosen for the high and/or alert alarm circuits. To avoid an unwanted alarm, the alarm circuits  
are muted during the ECS test--that is the alarm circuits are made inactive, so that their lamps and alarm  
relays will not respond during the test. Effectively, this is done by generating voltage pulses in the ECS  
circuits which last for the duration of the test, and applying them at appropriate points in the alarm circuits  
on the relay driver board, so that the alarm circuitry will be momentarily disabled. Computer and recorder  
buffers are also muted during the ECS test.  
The circuits of the ECS board that generate the muting pulses are, to some degree, involved with the  
ramp-generating and monitoring circuits of the ECS board, since all must be in time synchronization.  
Generally speaking, however, the most important elements of the muting circuits are contained in  
integrated circuit U207 (pins 1 to 8) and integrated circuit U206 (pins 9 to 15). The muting pulse is a  
voltage which starts from zero, rises abruptly to +15 V, lasts about six seconds, and falls abruptly to zero.  
Initiation takes place on pin 5 of U207, and the output is taken from pin 13 of U208. The signal for muting  
the alarms appears on terminal 9 of the ECS board, but a second path leading to pin 12 of U203 serves  
the auxiliary purpose of preventing re-initiation of the manually generated trigger produced by pressing  
the ECS button on the panel.  
4-9  
Victoreen 875  
Operators Manual  
(Blank page)  
Maintenance, Calibration, and Troubleshooting  
5
Maintenance  
Section 5  
Maintenance, Calibration, and Troubleshooting  
5.1 Maintenance  
The monitor is designed to operate for long periods in the containment without attention. The following  
replacement schedule should keep the monitor in trouble-free operation.  
Every five years - Replace the 4200 microfarad electrolytic capacitor, P/N 92-3005-A (C1 01), and the RFI  
line filter, P/N 92-9015A (FL101), located on the 876-1-78 mother board of the 876A-1-108 or 876A-100  
Readout Module.  
Whenever detector cables are removed - Replace the nickel seals, P/N 877-1-60-1, on the detector  
connectors as described in the CABLE-877 procedure in Appendix A.  
5.2 Calibration  
The monitoring systems require calibration before placing them into service. In addition, they should be  
recalibrated at regular intervals during routine service. The length of time between calibration intervals  
should be determined by operations personnel. For further calibration information, refer to the applicable  
calibration procedure provided in Appendix A.  
The high-range containment area monitor underwent a complete electronic and isotopic calibration prior  
to leaving the Fluke Biomedical plant. The same electronic calibration procedure is supplied in this  
manual. Prior to primary isotopic calibration, the detector's hermetically must be verified. Primary isotopic  
calibration requires a highly radioactive source (greater than 400 curies) with National Bureau of  
Standards (NBS) traceability. As this is beyond the capability of most facilities to perform, the following  
method of verifying detector calibration is used:  
Detectors shall either be returned to Fluke Biomedical at a five (5) year interval from the date of delivery  
or the owner must establish a procedure to determine that the average A/R/h output current does not  
deviate from original factory calibration by more than ± 10%.  
To encompass Nureg-0737 guidelines, on-site in-situ calibration checks can be performed with the 878-  
10 High-Range Field Calibrator that is capable of producing a 10 R/h indication on the channel under  
test.  
Electronic alignment of the 876A Readout may be performed using Functional Test Procedure, TP876A-  
1-108 included in Appendix A, and the standard test equipment as listed in Table 5-1. Personnel must be  
fully knowledgeable in the operation of the readout prior to attempting to perform the test.  
NOTE  
Disconnect Detector 877-1 from Readout Module  
876A-1 by removing cables from J1 and J2 before  
starting electronic calibration.  
5-1  
Victoreen 875  
Operators Manual  
Table 5-1.  
Recommended Test Equipment  
Current Generator - Test Electrometer  
1 x 10-12 Amps to 1 x 10-3 Amps  
10-12 Amps ± 10%  
Range  
Accuracy, Current Generator  
10-11 Amps ± 3%  
10-10 to 10-7 Amps ± 2%  
10-7 to 10-3 Amps ± 0.2%  
± 0.2% ± 1 digit with integration time long enough to accumulate 3  
significant digits of volts indicated on display V/R ± 0.2% ± 1 digit  
Accuracy Test Electrometer  
Adjustable AC Voltage Source  
Low range 140 VAC, high-range 280 VAC  
60 Hz  
Maximum Voltage  
Frequency  
4 ½ Digit Digital Multimeter  
Fluke 8600A or equivalent  
Ranges  
+ 0 to 100 mV up to + 0 to 100 V (20% over-range)  
100 mV range: ± (0.05% of input ± 0.02% of range)  
all other ranges: ± (0.02% of input ± 0.01% of range)  
> 10 megohms  
Accuracy  
Input Impedance  
DC Voltage  
± 0.03%  
AC Voltage  
± 1%  
DC Current  
± 0.3%  
Trim Pot Adjustment Tool  
Carbon Composition Resistor  
10 kilohms, ½ W, 5%  
Small alligator clips  
Resistance  
Lead Connectors  
DC Power Supply  
Output Voltage  
0 to + 25 VDC  
Output Current  
0 to 600 mA  
Load Regulation  
Adjustable Current Limit  
0.01% ± 4 mV  
Down to 10 mA  
Multi-function Counter  
Fluke 1900A or equivalent  
Frequency  
5 Hz to 80 MHz (0.1 to 100 Hz Resolution)  
5 Hz to 1 MHz, single and multiple period averages  
(1 to 100 nsec resolution)  
Period  
Total Counts  
1 to 999,999 counts  
Test Procedure TP876A-1-108  
Factory test procedure, TP876A-1-108, contains this information necessary to perform electronic  
alignment of the 876A-1-108 Readout Module. This procedure is included in Appendix A.  
5-2  
Maintenance, Calibration, and Troubleshooting  
5
Troubleshooting  
5.3 Troubleshooting  
The 875 High-Range Containment Monitor is safety-related equipment. The monitor has been assembled  
by techniques and with parts selected for the reliability required in a nuclear application. Any repairs made  
to the detector or readout (other than replacement of parts listed in Section 5) may void the safety-related  
rating. The troubleshooting procedure that follows is a guide to isolating a fault in the system.  
Replacement of parts is at the printed circuit board level only. Printed circuit boards must be returned to  
Fluke Biomedical for service.  
There are two self-contained system tests available in Containment Monitor 875, the Channel Test and  
the ECS Test. In both cases, the procedure is to put a known input into the system, and to look for the  
desired output.  
There is an important difference between the Channel Test and the ECS Test: the former applies an input  
to the readout module (that is, to the first electronic circuit in the Containment Monitor); however, it does  
not test the detector or the cables connecting the detector to the readout module. In addition, the Channel  
Test applies a DC voltage, whereas the ECS Test applies a ramp voltage to the detector plates,  
monitoring the resultant current into the readout module.  
The digital multimeter mentioned in Table 5-1 of the calibration section is also recommended for  
troubleshooting.  
If the ECS Test gives a favorable result, the following conditions exist:  
1. The detector cannot have any appreciable malfunction.  
2. The cables must have continuity.  
3. The ECS board and power supply board must be operative.  
4. It is highly improbable that any malfunction exists in the fail/safe circuitry.  
5. The amplifier, meter and alarm circuitry must be operative.  
Essentially, the Channel Test verifies only #5 of the above. However, in doing so, it incidentally verifies all  
of the power supplies except the high voltage power supply.  
For clarity, troubleshooting is divided into six divisions:  
1. Power supplies  
2. Input circuit  
3. Meter circuit  
4. Alarm circuits  
5. ECS board  
6. Overall fail circuitry  
NOTE  
Disconnect Detector 877-1 from Readout Module  
876A-1 by removing cables from J1 and J2 before  
starting troubleshooting of readout module. The  
user will probably wish to disconnect the external  
alarms as well. It is the responsibility of the user to  
see that the alarms are not set off by disconnection.  
5-3  
Victoreen 875  
Operators Manual  
5.4 Power Supply Measurements (P/N 876-1-89 Schematic 876-1-3C)  
Turn the 876A-1 on by turning the function switch to the ALL position.  
CAUTION  
Allow all equipment, including the readout module,  
to warm up for at least 60 minutes before  
attempting any calibration.  
Adjust the mechanical zero of the panel meter (use mirror scale to avoid parallax error) so that the needle  
is centered on the first hash mark of the black expanded arc to within 0.50 needle width.  
Verify the output voltage of the power supplies as follows (See drawings 876-1-78 and 876-1-89).  
Mother Board (P/N 876-1-78, Schematic 876-1-3A)  
1. Connect the negative lead of the DMM to TP102.  
2. Probe TP101 with the positive lead of the DMM. The DMM should read +24 ± 3 VDC.  
Power Supply Printed Circuit Board (P/N 876-1-89, Schematic 876-1-3C)  
3. Probe TP5 (white) with the positive lead. The DMM should read -21 ± 2 VDC.  
4. Probe TP4 with the positive lead. The DMM should read -10.00 ± 0.01 VDC. Adjust R4 as  
necessary to correct this reading.  
5. Probe TP2 with the positive lead. The DMM should read + 15.0 ± 0.2 VDC. Adjust R5 as required to  
achieve correct readings.  
6. Probe TP3 with the positive lead. The DMM should read +14.3 ± 0.4 VDC.  
PreamplifierIMeter Board (P/N 876A-1-86, Schematic 876A-1-3E)  
7. Probe TP401 on preamplifier meter board with the positive lead. The DMM should read +6.200 ±  
0.001 VDC. Adjust R413 as necessary to correct this reading.  
Rear Panel  
8. Probe the back panel high voltage connector, J2. The DMM should read +506 ± 10 VDC.  
5.5 Signal Input Circuit  
(P/N 876A-1-35, Schematic 876A-1-92 & P/N 876A-1-75A, Schematic 876A-1-  
3B)  
The signal input circuit is partly on the preamplifier board, and partly on the relay driver board. It consists  
of logarithmic amplifier U301 and its associated circuitry (preamplifier meter board) and amplifier U501  
(relay driver board). The output of U501 provides the input for the meter circuit on the preamplifier meter  
board and the high and alert alarm circuits on the relay driver board. The alarm circuits are covered in the  
"Alarm Circuits" paragraph. The signal input circuit can be tested at two test points, using the CHANNEL  
TEST push button to provide a convenient input signal. Voltages at these points should be measured with  
no signal input.  
1. Disconnect the cable connecting the readout module to the detector. Turn the function switch to  
TEST.  
2. Measure the voltages at TP501 and TP502 under two conditions: 1) with no signal input; 2) with a  
signal input obtained by pressing the CHANNEL TEST push button.  
The voltages should be:  
No Signal  
Channel Test Signal  
5-4  
Maintenance, Calibration, and Troubleshooting  
5
Signal Input Circuit  
TP501  
TP502  
+5 V  
-1.5 V  
-2.8 V  
+6.3 V  
These voltages are approximate and actual values may differ somewhat. Any marked departures from  
these values is an indication of a malfunction.  
5.6 Metering Circuit (P/N 876A-1-3E, Schematic 876A-1-92)  
The signal circuit that drives the meter is U401 (Figure 5-2). This is a voltage follower whose output on pin  
9 should equal its input on pin 10.  
These signals vary from -1.5 V with no signal to +6.3 V with the CHANNEL TEST push button pressed.  
All other faults in the metering circuit should be detectable by resistance measurements.  
NOTE  
The preamplifier metering board contains a  
regulated power supply whose voltage is critical. It  
should measure 6.2 ± 0.001 V at TP401. It may be  
adjusted by R413.  
5.7 The Alarm Circuits (P/N 876A-1-75, Schematic 876A-1-3B)  
The alert and high alarm circuits differ only in very minor details, so for troubleshooting purposes, it will be  
sufficient to discuss them together. As a matter of fact, they are similar for troubleshooting purposes. E.g.  
the simplest way to eliminate certain problems is to replace printed circuit board 876A-1-75. Where the  
discussion is given in terms of particular pin numbers for definiteness, the alert alarm circuit is to be  
understood, but completely analogous procedures apply to the high alarm circuit. At some points, it is  
deemed sufficient to describe the voltage state as simply high or low; at other points, particular voltages  
have been given. The maximum high value is +15 V, and the minimum low value is -10 V.  
In the alert alarm circuit, if a measurement can be made directly on a pin of an OP AMP, a high reading  
will usually be close to +15 V, and a low reading close to -10 V. For example, the normal (low input  
current) voltage on pin 1 of U502 is -9.9 V (low) and the voltage at the same point is + 13.7 V when high.  
However, if the voltage is measured on the other side of the resistor R510, the high is only +1.45 V,  
whereas the low is still the same -9.9 V.  
If the Channel Test has shown the system to be operative, the following will be the voltage states at  
critical points in the signal chain between test point TP502 and relay K501:  
The following are measured voltages at critical points in the alert alarm circuit (muting stages are treated  
separately). Reset the alarm after every test.  
1) TP502  
0 to 6 V depending on strength of radiation  
Test Point  
2) Pin 1 U502  
*Normal  
Channel Test  
+13.7 V  
-9.8 V  
3) Junction of R510 and CR501 -9.8 V  
+1.45 V  
4) Pin 14 U503  
5) Pin 1 U503  
+14.1 V  
+0.08 V  
+0.2 V  
+13.7 V  
5-5  
Victoreen 875  
Operators Manual  
*Normal here signifies a small radiation signal so that the voltage at TP502 is close to zero volts.  
NOTE  
Both of the solenoids of the alert and high alarm  
circuits must operate for the CHANNEL TEST lamp  
to light.  
The lighting of the CHANNEL TEST lamp does not  
of itself show that the remote alarm contacts have  
closed (See Relay Driver Schematic, drawing  
876A-1-3B.)  
However,  
simple  
resistance  
measurements and reference to the relay driver  
schematic can assure that the output to the remote  
alarms is correct.  
5.8 High Alarm Circuit  
Troubleshooting in the high alarm circuit is completely analogous to that in the alert alarm circuit. Voltages  
may be slightly different because R513 may be set differently from R509. However, the high and low state  
should be recognizable.  
5.9 Muting Stages of the Alarm Circuits  
The muting stages of the alarm circuits (U502 pins 8, 9, 10 and pins 12, 13, 14) can cause trouble in two  
ways:  
1. They can fail to mute the alarm circuits during the ECS Test, thus causing the alarms to sound  
when this is undesired.  
2. They can mute the alarms when the alarms should sound. This is the more undesirable of the two  
possibilities.  
If the CHANNEL TEST lamp lights when the CHANNEL TEST push button is pressed, the second  
possibility is eliminated. Conversely, if it does not light, malfunction in the muting stages is among the  
problems that must be considered in addition to those in the signal chain (also a light burn-out).  
Critical voltages in one of the two muting OP AMPS of U502 are:  
Normal (Low Signal Level)  
Channel Test  
ECS TEST  
Pin 10  
Pin 9  
+2 V  
0 V  
+12.88 V*  
0 V  
+2 V  
+12 V*  
(Muting voltage)  
-9.8 V  
Pin 8  
+13.7 V  
13.7 V  
* An especially high voltage (12.88 V) is place on pin 10 during the Channel Test to overcome the +12 V  
that is placed on pin 9 during the ECS Test. Muting is not desired during the Channel Test. Although  
there is only a slight possibility that an automatically initiated ECS Test would take place during a Channel  
Test, it is desired to eliminate even this slight possibility.  
5-6  
Maintenance, Calibration, and Troubleshooting  
5
Muting Stages of the Alarm Circuits  
Conversely, during the ECS Test muting is definitely wanted, and the +12 V on pin 9 can easily overcome  
the +2 V on pin 10.  
5.10 ESC Board (P/N 876A-1-92, Schematic 876A-1-3D)  
The wave-shapes shown in Figure 5-1 should be sufficient for localization of malfunction on the ECS  
board. Test points A to S are shown on 876A-1-3D. The wave-shapes at the lettered test points are drawn  
to the same time scale and also synchronized in time.  
The wave-shape at the top of Figure 5-1 is the output at TP201. It is the main synchronizing waveshape  
for the lettered wave-shapes, but it is drawn to a different time scale.  
These wave-shapes are best used in connection with the discussion of the ECS circuitry.  
CAUTION  
Electrostatic discharge precautions should be  
followed when servicing the ECS board, due to the  
MOS FET devices located on it.  
5-7  
Victoreen 875  
Operators Manual  
U
PIN  
204  
205  
205  
1
6
3
205  
206  
1
7
203  
207  
10  
6
207  
9
5
CONN  
206  
10  
1
CONN  
0203  
208  
1
13  
201  
208  
8
3
202  
10  
Figure 5-1. Wave Shapes on the Electronic Check Source  
Board  
5-8  
Maintenance, Calibration, and Troubleshooting  
Overall Fail Circuitry Associated with the ECS Test  
5
5.11 Overall Fail Circuitry Associated with the ECS Test  
Because the ECS Test involves circuits on the switch printed circuit board, power supply printed circuit  
board and relay driver printed circuit board, as well as those on the ECS printed circuit board, a fairly  
detailed study of this overall circuitry has been included. The study is devoted not only to circuitry, but in  
great part to the interconnections between the printed circuit boards involved.  
5.12 Starting With Pins M and P on the Power Supply  
Schematic  
These pins are ultimately connected to the two inputs of OP AMP U2.  
The muting signal input, (15 V), is connected to pin 2 (-). It must pass through a diode to get to pin 2.  
There is also a second input to pin 2 from the high voltage 506 V. But the second input is connected to  
pin 2 by high resistance, and even if the high voltage falls to 0, the muting signal can overcome it, and  
prevent the circuit from going into an alarm condition.  
A voltage of either 0 V or 14 V is connected pin 3 (+) of the OP AMP. (There is also connected to pin 3 a  
resistor of 130 kilohms whose other end is at 6.2 V.) In the operation of the OP AMP, a 0 V input to pin 3  
is a pass condition (green light will stay on) and 14 V is a fail condition (green light will go off), and alarm  
relays will be de-energized.  
The output of the OP AMP goes from terminal N of the power supply board to the fail/safe circuit on the  
relay driver board, via terminal H.  
5.13 Starting With Terminal H on Relay Driver Board  
If the input on pin H is low (-9.25 V measured), the output on pin 4 of the K503 solenoid is low (0.148 V  
measured). When the input on pin H is high, the output is high (14.5 V measured). When pin 8 of U503 is  
low, the solenoid has almost 14 V across it and is energized; when pin 8 is high (U503 cut off), the  
solenoid has no voltage difference across it. The common point connecting the collector of Q501 and the  
base of Q502 has a high (SAFE) of only 0.8 V and a low of 0.03 V, but this change is enough to cause  
switching, since conduction in Q502 occurs when its base rises above 0.5 V.  
The output of the FAIL/SAFE circuit, on pin F, is connected directly to one terminal of the green lamp on  
the switch printed circuit board (effectively also the panel), and the other terminal of the green lamp is  
connected directly to +14 V. Consequently, a low input to pin H on the relay driver board puts 14 V on  
both terminals of the lamp and goes out.  
5.14 Provision of Inputs to Terminals M and P on the Power  
Supply Board  
Operation of the green lamp is the same for manual and automatic reset functions. The closing of the  
ECS switch causes a sharp negative pulse to be generated by the differentiating circuit R217-C205. The  
differentiated pulse is passed to the anti-initiate circuit whose purpose is to prevent malfunction in case  
the ECS button is inadvertently pressed twice. The circuit consists of two sections of U208 (pins 3, 4, 5, 6,  
and 7). It has two outputs:  
1. From pin 5 a pulse is sent to U206, another pulse generator that provides a more powerful pulse or  
the initiation of the low voltage ramp, 0 to 6.2 V.  
5-9  
Victoreen 875  
Operators Manual  
2. An auxiliary pulse from pin 3 of U208 to the automatic pulse generating circuits resets them so that  
an automatically generated pulse will be present 17.1 minutes later if the ECS Test is not  
conducted manually during that time. The purpose of this pulse is to insure continued operation of  
automatic testing.  
5.15 Outputs of U206 Pulse Generator on the ECS Board  
We have noted that U206 can be triggered by pressing the ECS button. Its main output is a power pulse  
to the ramp generator. However, it also initiates a pulse from U203 (pin 10) to pin 5 of U207A, the muting  
multivibrator. The muting multivibrator also has two outputs:  
1. One output to U203 that ultimately causes a muting pulse six seconds wide at terminal 9. This is  
coupled to the power supply board on pin M. It also returns to the circuit so that jitters will be  
eliminated on manual ECS.  
2. A second output to U207 is a one-shot multivibrator that provides an enabling pulse to the latch  
circuit (which also contains a flip-flop). The latch circuit consists of four NOR gate sections of U202  
(pins 1 through 6 and 8 through 13), and also inverter U208 (pins 9 and 10). The latch circuit output  
is taken from terminal 8, and will be either 6.2 V or 14 V. The operation is explained below.  
5.16 Operation of the Latch Circuit  
The latch circuit has two inputs and one output:  
Input 1 - Enters on pin 6 (U202) and pin 10 (U208), which are connected. This is the monitoring input.  
Its value is the result of the ECS Test. It enables the circuit to change state only after the conditions  
brought about by the ECS Test have stabilized.  
Input 2 - Enters pin 1 (U202) and pin 5 of U202 which are connected. The output is taken from pin 10  
and pin 2 of U202, which are connected.  
Output - The output may be either 0 V, which is a pass indication, or +14 VDC, which is a fail indication.  
The two NOR gates (pins 8, 9, 10, and pins 11, 12, 13) are effectively a flip-flop circuit which will  
change its state only when a certain combination of the two inputs is present. The presence of CR201  
and a pull-up circuit on the power supply printed circuit board permits pin 10 to be 0 while terminal 8 is  
6.2 V.  
Input 1 has a normal resting voltage of +15 V. However, during the ECS Test it takes on a voltage  
determined by the steady detector current that exists during the ECS Test. This current generates a  
voltage of about 2.57 V (0.33 scale) in the panel meter, at which time pin 6 of U202 is at approximately 0  
V. If, at this instant, the enabling voltage (input 2) arrives, it will cause the flip-flop to switch states.  
Input 2 is initiated by pressing the ECS button, but its actual occurrence in time is delayed so that it  
occurs during the flat portion of the current cycle generated by the ECS ramp.  
Assume that the green light is ON at the beginning of the ECS Test. Actually this is probable because:  
If the green light were off, troubleshooting would not begin with the ECS Test. With this assumption we  
can work backwards in the truth table (Table 5-1) from the output (which must be low) to the possible  
inputs.  
In Figure 5-2, the initial output is assumed low (circuit condition did not show fail prior to ECS Test).  
When the enable pulse arrives in the two cases of the signal pulse [pass (L) or fail (H)] the following  
conditions exist:  
U202, pins 12, 10 L (Assumed as initial condition)  
5-10  
Maintenance, Calibration, and Troubleshooting  
5
Operation of Latch Circuit  
U202, pins 1, 5, L  
(Enable pulse active; i.e. low)  
From these conditions, the following must hold true.  
Pin  
4
Comment  
Depends on 6  
Depends on 2  
3
Further analysis is contained in the truth table (Table 5-2).  
Figure 5-2.Latch Circuit  
Table 5-1. Truth Table for Pass and Fail Conditions in The Latch Circuit  
(Circuit assumed initially in Pass Condition)  
Fail Condition  
Voltage  
State  
Pass Condition  
Pin  
Voltage Comments  
Pin  
State  
Comments  
4
L (low)  
Since 6 is H (high)  
Since 1 & 2 are Low  
Connected to 3  
Since 13 is H  
4
H
L
Because 6 is L (also 5)  
Because 2 is H  
3
H (high)  
3
13  
11  
9
H
L
L
8
H
L
Connected to 4  
Connected to 3  
Because 8 is H  
13  
10  
Connected to 11  
L
5-11  
Victoreen 875  
Operators Manual  
8
L
Connected to 4  
Since U202, (8, 9, 10) is  
NOR  
12  
11  
L
10  
H
H
Because 12 and 13 are L  
Result: Output switches  
from Low to High  
This is the original condition. No  
change takes place.  
12  
H
Notes:  
1) Enable pulse assumed present, so 1 and 5 are L.  
2) Initial condition assumes 12 and 10 L.  
The truth table shows that no change in the output can occur without the presence of the enable pulse,  
even though the monitoring signal indicates a fail condition. This is necessary because the ramp voltage  
starts from zero during the ECS Test.  
Table 5-2.  
Signal In Fail State (High Signal Input)  
Pin 1  
Voltage State  
Comments  
10, U208 and 6, U202  
9, U208 and 2, U202  
1,5, U202  
H
L
H
L
L
L
Fail state  
After inversion  
No enable input  
4, 8, U202  
Because of NOR action  
Because of NOR action  
Because of NOR action  
3, 13, U202  
10, 12, U202  
Thus the circuit does not react to a fail signal input unless pins 1 and 5 are low.  
NOTE  
If a problem cannot be resolved by applying the  
troubleshooting and maintenance procedures  
provided here, please contact Fluke Biomedical at  
440.248.9300 for assistance.  
5-12  
Appendix  
Calibration and Test Procedures  
A
Appendix A  
Calibration and Test Procedures  
A.1Calibration Procedures  
Document Number  
CAL877-1  
Description  
High Range Detector 877-1 Calibration  
Calibration of Model 877 to 3.0 MeV  
REPORT 877  
The calibration and data listed above is for reference only and need not be performed.  
A.2Test Procedures  
Document Number  
Description  
TP876A-1-108  
Monitor  
Test Procedure 876A-1-1 08, High Range Containment Area  
TP877-1-5  
Test Procedure for 877-1-5, HRCM Detector  
A-1  
Victoreen 875  
Operators Manual  
(Blank Page)  
Appendix  
Cable and Pull Box Procedures  
B
Appendix B  
Cable and Pull Box Procedures  
B.1Cable and Pull Box Procedures  
Document Number  
CABLE-877  
Description  
HRCM Cable Termination and Installation Procedure  
878-12-3  
High-Range Containment Monitor Pull Box Cover Installation  
Procedure  
B-1  
Victoreen 875  
Operators Manual  
(Blank page)  
Appendix  
C
Applicable Drawings and Bill of Materials  
Appendix C  
Applicable Drawings and Bill of Materials  
C.1Applicable Drawings  
Document Number  
GEL876-1-55  
GEL876A-1  
GEL875-1  
GEL-877-1  
876-1-114  
844-8-5  
Description  
Rack Chassis & Recommended Seismic Mtg.  
Readout Module Dimensional Outline  
Interconnection Diagram High-Range Containment Monitor  
High-Range Detector & Bracket Dimensional Outline  
Support Strap  
Blank Panel Assembly  
876-1-55  
Rack Chassis  
876A-1-108  
876A-1-86  
876-1-100  
876A-1-3E  
876A-1-92  
876A-1-3D  
876-1-89  
High Range Containment Monitor Readout Assembly  
Preamp/Meter PC Board Assembly  
Preamp Shield Assembly  
Schematic Preamp Meter PC Board  
High-Range CAM ECS PC Board Assembly  
Schematic ECS PC Board  
Power Supply PC Board Assembly  
Schematic Power Supply PC Board Assembly  
Voltage Regulator PC Board Assembly  
Schematic, Regulator PC Board Assembly  
Relay Driver PC Board Assembly  
Schematic Relay Driver PC Board  
Switch PC Board Assembly  
876-1-3C  
876-1-89A  
876-1-93A  
876A-1-75A  
876A-1-3B  
876-1-104  
876-1-3J  
Schematic PC Switch Board  
876-1- 78  
Mother PC Board Assembly  
876-1-3A  
Schematic Mother PC Board  
Document Number  
876-1-107  
Description  
Rear Panel Assembly  
Rear Panel Assembly  
876-1-85  
C-1  
Victoreen 875  
Operators Manual  
876-1-3G  
876A-1-40  
876A-1-41  
876A-1-3H  
92-9015-A  
877-1-5  
Schematic, PC Board  
Front Panel Assembly  
Meter Assembly  
Schematic (Block Diagram.) Final Assembly  
AC Line Filter  
Detector Assembly  
877-1-81  
Containment Area Detector Assembly  
Detector Mounting Flange Assembly  
Wall Mounting Bracket  
877 -1-80  
877-1-17  
878-1-5  
Detector Cable Assembly  
Cable Termination Kit  
878-1-15  
878-1-9-TAB  
50-103-TAB  
878-12-5  
Detector Cable - In Containment  
Detector Cable - Out of Containment  
Cable Pull Box Assembly  
Flexible Metal Hose Assembly  
878-12-30 (TAB)  
C-2  
Appendix  
Applicable Bill of Materials  
C
C.2Applicable Bill of Materials  
Document Number  
875-1  
Description  
876A-1 Readout with 877-1 Detector  
High-Range Containment Monitor Readout  
Rack Chassis  
876A-1  
876-1-55  
876A-1-108  
876A-1-Kit  
876A-1-86  
876-1-100  
876A-1-92  
876-1-89  
876-1-89A  
876A-1-75A  
876-1-104  
876-1-78  
876-1-107  
876-1-85  
877-1  
High-Range Containment Monitor Readout Assembly  
Mating Connector Kit for 876A-1-108  
Preamp Meter PC Board Assembly  
Preamp Shield Assembly  
High-Range CAM ECS PC Board Assembly  
Power Supply PC Board Assembly  
Voltage Regulator PC Board Assembly  
Relay Driver PC Board Assembly  
Switch PC Board Assembly  
Mother PC Board Assembly  
Rear Panel Assembly  
Rear Panel Assembly  
High Range Detector  
877-1-5  
Detector Assembly  
877-1-81  
877-1-80  
878-1-5  
Containment Area Detector Assembly  
Detector Mounting Flange Assembly  
Detector Cable Assembly  
878-1-15  
878-12-5  
844-8-5  
Cable Termination Kit  
Cable Pull Box Assembly  
Blank Panel Assembly  
C-3  
Fluke Biomedical  
Radiation Management Services  
6045 Cochran Road  
Cleveland, Ohio 44139  
440.498.2564  
120 Andrews Road  
Hicksville, New York 11801  
516.870.0100  
C-4  

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