F4 – Faults
Gem-5 User’s Manual 225
detector) does not have a valid calibration date, for example, it is using the factory
default value.
The control program checks for proper communications with the Carrier Board and
the Sensor Board and reports these boards as “OK” or “Fault”. If a board “Fault” is
indicated, check the connections on the ribbon cable at the Sensor Board and confirm
that the Carrier Board is properly seated in the computer box. The Carrier Board is
equipped with a temperature fault indicator (i.e. Board Marking 7078121, drawing
7078120 and SCN 7078120) then the temperature (fault status) is indicated as OK or
HOT. The current voltages on the +12 V, + 5 V, Serial Bus and 3.3V on the Carrier
Board along with Carrier Board temperature in °C are reported by the on-board ADC
chip (in essence a DVM).
All actions related to placement of detectors in Conditional Service are performed
using function keys F1 through F5. These actions are recorded in the Service Data
Log, if enabled (on page 162).
Note that detectors in conditional service are always shown in yellow.
Fault descriptions are shown in the colors in Table 12 on page 177. Note that the
Dosimeter Badge Reader type DOSICARD (when set to AUTO) uses special case
cyan color since only the DBR goes out of service, not the monitor).
Failure to Return to Service
General Information
If, after placing the monitor in service (F1 – Place In Service, from Service Menu),
the unit immediately goes out of service or hangs up on restart, showing many
detectors marked in red, this suggests the high voltage is missing or the
communications line is broken on the Detector Interface bus. In both cases, the
common element is the low voltage power supply in the computer box, which
provides +12 V, +5 V, and 3.3V. Common frequent (but not all) failure causes are:
• Detector Interface bus ribbon cable shorted (may be pinched or cut),
• Detector Interface bus ribbon cable connector not seated properly (check all
connections).
• Missing or incorrectly connected terminator Board,
• +12 V system overloaded (may be a short on a Detector Board).
To troubleshoot this problem, disconnect the ribbon cable at the first [red] detector
from the Carrier Board (in the computer box) and power up. If the boot-up is normal,
switch off power, connect one more detector, and power up. Repeat until the [red]
detectors show up again. This is where the cable problem or Detector Board short is
located. The cable is likely pinched or the connector is shorted. Replace the defective
cable, clean and/or reseat the connector, or replace/repair the Detector Board as
required.
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