6. TROUBLESHOOTING page
27
Model PRM-470B
It is recommended that the voltage divider be changed first.
Do not go onto step 6.2.4. until the pulses are present.
6.2.4. Amplifier:
Re-attach the signal wire and place a small
137
Cs source near the detector. Place an oscilloscope
probe on TP1 on the PRCB-001. The pulses should be positive and approximately 3.2 volts in
amplitude. If these pulses are present the input to the amplifier section of the computer board
is working.
At this point there are correct pulses coming into the computer board from the detector assembly.
Go through the Electronic Calibration Procedure (section 5.2.)
If any of the steps fail, then the computer board must be replaced.
6.2.5. Switches:
To test the front panel switches, remove the PRCB-001 board and test the switches using an
ohmmeter. They should be normally open and less than 20 ohms to common when held down.
The switches are an integral part of the front panel overlay and can not be replaced individually.
Disconnect J5 from the PRCB-001 board and test the
switches at the pigtail.
The switches that adjust sigma and cps/µsievert may be
tested by changing the setting and turning the unit on.
The settings are displayed on power-up.
If the above steps do not isolate the problem and effect repair, contact TSA Systems Ltd. for
engineering assistance.
FRONT PANEL SWITCHES
J5 pin
Switch
1 Mode
2 Light
3 Power
4
common
