DS8000 Service Documentation Version 7.5

MAP21E0 UEPO Loop Good LED should be on

The primary power supply (PPS) UEPO Loop Good LED should be lit when the UEPO switch on the rack operator panel is in the on (normal) position.

About this task

The UEPO switch has two sets of contacts, one set of contacts for each PPS. Each set of contacts has a two wire cable that goes to the PPS sequencer module J4 connector. When the UEPO switch is on (normal operation), the circuit is closed and the LED should be lit. When the UEPO switch is tripped off, the circuit is open and the LED should be off.
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How to start the service information center

MAP21E0 Section-1

Procedure

  1. Ensure the rack operator panel UEPO switch is in the on (normal) position.
  2. At the front of both PPS, observe the UEPO LOOP GOOD LED. Find the condition that applies:
    • the LED is off for both PPSs, go to step 3.
    • the LED is off for one PPS and lit on the other PPS, go to step 4.
    • the LED is lit for both PPSs, go to step 5.
  3. Each PPS has a separate UEPO loop so the only failure that would affect both PPS would be the UEPO switch not being fully on (normal). Do the following:
    1. Disassemble the operator panel as needed to fully inspect the mechanical operation of the switch
    2. Unplug the UEPO loop cable from the PPS sequencer module J4 connector cable. Use a volt/ohm meter to measure the continuity between the two pins of the cable. The cable should be closed (less than 1 ohm).
      • If the resistance is more then 1 ohm, replace the UEPO switch FRU while the storage facility power is off.
      • If the resistance is less than 1 ohm, the PPS UEPO LOOP GOOD LED should be lit. This indicates an internal PPS failure, but because both PPSs have the same failure, contact your next level of support.
  4. At the rear of the PPS with the UEPO LOOP GOOD LED that is off, unplug the UEPO loop cable from the PPS sequencer module J4 connector. Use a volt/ohm meter to measure the continuity between the two pins of the cable. The cable should be closed (less than 1 ohm).
    • If the resistance is less than 1 ohm, the PPS is failing and needs to be replaced.
    • If the resistance is greater than 1 ohm, the UEPO switch is failing and needs to be replaced. If the customer will allow the storage facility to be powered off, replace the UEPO switch FRU with the power off. If the customer cannot allow the storage facility to be powered off, see MAP2180 UEPO switch replacement (Models 94x, 95x, 96x).
  5. The failure is no longer occurring, return to the procedure that sent you here.