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High output
voltage and
Fan voltage
failure
CURRENT
This circuitry senses and indicates if the load on the mainframe power supply
is too high. Upon sensing an over-current condition, the power supply is shut
down and latched. It will not attempt to restart until ac line power is cycled.
If a CURRENT fault indicator is on, check for a faulty module before
attempting to repair the mainframe. The following steps will help isolate the
problem.
1. Turn the mainframe o .
2. Remove all the modules from the mainframe.
3. Cycle the power. Is the CURRENT indicator still on?
NO
YES If the CURRENT indicator is still on when all of the modules have
This cycling will continue until the input thermistors warm up
to a point where the sensed voltage is within tolerance. At
this point the fault indicator stops
ashing, the mainframe is
operational.
If the condition does not go away after several minutes, check
the input line voltage under load or change the ambient
operating temperature.
These two conditions will also cause the the VOLT/TEMP fault
indicator to come on and the instrument will latch in a fault
condition. The mainframe is in need of internal repair or
adjustment. It will shut down and not attempt to restart until
ac line power is cycled.
Turn o the mainframe and one by one replace the modules (cycling
power each time) until the faulty module is identi ed. Refer to the
repair procedures in the installation and veri cation manual for the
system master or the service manual related to the faulty module for
repair alternatives.
been removed from the mainframe, the mainframe probably has an
internal problem. Check to ensure that the grounding springs on the
50 pin module connectors are not shorting the 40 KHz to ground.
Refer to the HP 70001A Service Manual for additional troubleshooting
information.
Troubleshooting 5-3
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