Chapter 6 Diagnostics/Maintenance
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If the replacement of the cable(s) does not solve the problem the Terminator Board may
be missing, not plugged in correctly, or malfunctioning. The detectors at the beginning
of the serial bus may be visible and working correctly, but more distant detectors from
the computer would not work. Reseating or replacing the Terminator Board may solve
the problem in this case.
In the unlikely situation that a detector indicates “Fault” but the monitor seems to
be
functioning normally, try to clear the problem by completely switching off the computer.
Under certain conditions, this will fully reset the power supplies and Detector Boards that
have “glitched” for some reason. If this situation occurs frequently, contact Mirion
Technologies (Canberra CA) Ltd. for assistance in correcting the problem.
The Faults screens above indicate the fault status for individual detection zones.
Fault Status is hidden for items that do not apply to the selected zone, for example
Low, Excessive, and High Background Rates do not apply to sum zones. The
recognized failure conditions and probable causes are as follows:
Board Fault: Detector Board not responding when queried by Carrier Board.
Possible causes: Detector Board dipswitch (ID) set incorrectly, cable failure or
connector dislodged.
Not Calibrated: efficiency less than 1%.
Possible cause: Calibration source not placed in front of correct detector.
Low Bkg Rate: Background count rate less than the Low Background Rate
alarm setting.
Possible causes: Detector failure, Detector Board failure, photomultiplier tube
(PMT) failure.
Excessive Bkg Rate: Background count rate greater than the Excessive
Background Rate limit.
Possible causes: Damaged detector light seal (Gamma detector), noise in
photomultiplier tube or electronics, or background interference.
HV Out of Range: Greater than ±2% Full Scale (FS) between set and measured
detector high voltage.
Possible causes: Detector Board failure, PMT failure, static glitch.
Live Time Error: Live time is zero or less.
Possible cause: Computer or Detector Board failure or very high-count rate.
Detector Contaminated: Contaminated detector alarm.
Possible cause: Contamination on detector.
High Bkg Rate: Background count rate greater than the High Background Rate
limit.
Possible cause: Monitor located in excessively high background field, Maximum
Monitor Time set too low, background conditions changed (Krypton Mode).
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