Fluke Biomedical 943-35 - Manual (Page 19)

Maintenance, Calibration, and Troubleshooting
Troubleshooting
4
4-5
Personnel performing the following procedure must
be familiar with the operation of the monitoring
system and the location of each piece of equipment
used in the system.
Troubleshooting is indicated for the detector when the measured output of the check source or other
gamma source shows a marked increase or decrease in the number of counts observed at the readout
while high voltage has remained constant. Check for any visible signs of malfunction. To troubleshoot the
system, refer to the applicable drawings located in Appendix A. Insure that all electrical connections are
correct. If necessary, refer to the wiring diagrams for electrical connections.
Verify ± 15 VDC and detector high voltage are present at the detector cable termination point. If the
above voltages are present, and no output pulse exists, a failure in the detector preamplifier or
photomultiplier tube is suspected. Any fault that cannot be isolated to the detector must be in the wiring to
the readout or the readout itself. Consult the readout manual for troubleshooting procedures pertaining to
the readout.
Refer to cable connector pin outputs below for pin and function:
Pin Function
A High Voltage
B High Voltage Shield
C Signal (negative pulses)
D Signal Shield
E +15 VDC Supply
F -15 VDC Supply
G Power ± 15 VDC Ground
If the detector is determined to be at fault, it must be sent back to Fluke Biomedical for repair or repaired
by a technician qualified to ANSI 45.2.6, 1978, Skill Level 2.
If a problem cannot be resolved by applying the
calibration or troubleshooting procedures described
above, contact Fluke Biomedical at 440.248.9300
for assistance.
Dynode Test Measurement
The photomultiplier tube must be removed from the
detector tube socket during this test.
1. Turn off channel power at the readout device.
2. Disassemble the detector according to the instructions provided in "Detector Disassembly".
CAUTION
NOTE
NOTE