Fluke Biomedical 956A-201-M2 - Manual (Page 80)

5-2
If a problem develops, verify that the voltages at connection point inputs and outputs are present and that
all wiring is secure, for both the detector and UDR. Refer to Appendix B and C for drawings and parts
lists. If a PROM requires replacement, specify the PROM part number, PROM revision letter, and unit
model number. The PROM part number and revision is marked on a label attached to the top surface of
the PROM. Refer to Section 4 for calibration and electronic adjustments.
Troubleshooting is required for the detector/preamplifier when the measured output of the test source
shows a marked change in the count rate observed at the UDR while high voltage remains constant, or
when an error code is displayed on the UDR. Check for visible signs of physical damage.
A fault that cannot be isolated to the detector/preamplifier must be in the wiring between the
detector/preamplifier and the UDR, or in the UDR itself.
If the fault has been isolated to the detector preamplifier, the unit should be returned to Cardinal Health,
Radiation Management Services for repair and recalibration on an NIST traceable calibration range. If
desired, the following procedure, along with the applicable drawings, may be used to identify the faulty
component. The high voltage power supply should be disconnected at this time. The UDR is to remain
connected to provide the low voltage power supply and proper termination of the preamplifier. If the fault
is isolated to the UDR, the UDR should be returned to Cardinal Health, Radiation Management Services
for repair. To troubleshoot the UDR, a test PROM and special test set, P/N 942TS-100, is required.
Refer to Appendix B and C for all applicable schematics, drawings, TP locations, and Bill of Materials.
Periodic Field Test
There is 120 VAC present at the low voltage DC power supply
and 600 Vdc at the high voltage power supply P.C. board. Use
extreme care when performing the following tests.
On the 956A-201-M2, 120 Vac is also present on the Alarm and
Fail relay contacts. Use care when working on these circuits.
The following tests may be performed on the UDR to check its operation. In addition to these tests, alarm
circuit and relay operation may be verified via use of a field test source, or the detector check source.
Resetting of the alarm trip points to a level before the expected response may be required to perform this
test.
Equipment Required
• Digital voltmeter
• Small flat blade screwdriver
• Signal generator
WARNING