Routine Maintenance Procedures
555-233-123
5-10 Issue 4 May 2002
Troubleshooting power units
Use the following procedures to troubleshoot the power unit:
1. Check that the translation card is in its slot.
2. Type save translation and press
Enter to save translations.
3. Set the EMER XFER (Emergency Transfer) switch on the Processor circuit
pack in the PPN to ON. This locks the system in the Transfer Mode until the
trouble is cleared.
!
WARNING:
Electrostatic discharge can destroy or severely damage integrated
circuits or circuit packs. Always wear the electrostatic discharge
(ESD) wrist grounding strap when handling circuit packs. Connect the
wrist strap to one of the metal tabs located on the lower left or right
side of one of the carriers.
4. Unlatch both locking levers and unseat the power unit.
NOTE:
If the 1217A yellow power supply LED is not lit, the unit has likely
faulted due to overload conditions. However, the power supply
continues to provide other output voltages (±5V DC and -48 V DC) to
circuit packs and does not completely shut down as earlier power
supplies do if the +12V fan or the +12V DC tape drive outputs are
overloaded.
5. Unseat all the control circuit packs.
!
CAUTION:
Ensure that the customer administrator is aware that service is
interrupted during this step.
6. Reseat the power unit. If the yellow LED on the suspect power supply lights
immediately, the control circuit packs can be presumed to be healthy.
7. If the yellow LED on the suspect power supply does not light immediately,
reseat the control circuit packs one at a time while observing the LED on
the power supply.
a. If the yellow LED on the power supply lights when a specific circuit
pack is reseated, unseat and reseat the same circuit pack again to
rule out a transient problem.
b. If the yellow LED lights again, the problem is with the circuit pack,
and the power supply is functioning properly. Replace the defective
circuit pack (see ‘‘Replacing power supplies and fans’’).
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