DS8000 Service Documentation Version 7.5

MAP2090 Primary power supply 208 VDC overcurrent

Use this procedure when the primary power supply (PPS) reports an overcurrent in the 208 VDC power boundary.

About this task

This can be caused by a PPS failure or a short in the distribution system.

DANGER

Hazardous voltage, current, or energy levels are present inside of a component to which this label is attached. (L001)

MAP2090 Section -1

Procedure

Determine the location of the PPS by using the location code listed in the problem FRU list.
Observe the LED on the PPS sequencer module labeled "S0" . shows the disable/enable switch.
Figure 1. PPS sequencer module and LED enable/disable switch
Find the condition that applies:
- LED is amber, go to the next step.
- LED is green, the failure is not occurring now so you will not be able to isolate the problem with this MAP. Exit this MAP and close the problem.
The LED is amber. Disconnect the cable from the PPS sequencer module to the 208 VDC bus bar. Reset the "S0" output by setting the enable/disable switch below the LED to disable (down) and then enable (up).
Figure 2. Disconnecting the cable from the PPS sequencer module to the 208VDC bus bar
1. Observe the LED on the PPS sequencer module labeled "S0". Find the condition that applies:
- LED is amber, the PPS is failing. Return to the repair screen to continue the repair and replace the PPS.
- LED is green, the failure is external to the PPS. Go to the next step.
There is an overcurrent in the bus bar distribution system.
Note: The power supplies connected to the output connectors of the secondary 208 VDC bus bar are protected by individual fuses as shown in Figure 3. Those fuses would blow before the PPS would detect an overcurrent.
The possible failing FRUs are:
- PPS to primary 208 VDC bus bar cable
- Primary 208 VDC bus bar
- Primary 208 VDC bus bar to secondary 208 VDC bus bar cable
- Secondary 208 VDC bus bar
Figure 3. Power supplies connected to output connectors of the 208VDC bus bar
Disconnect cable from connector C. Reset the "S0" output by setting the enable/disable switch below the LED to disable (down) and then enable (up).
1. Observe the LED on the PPS sequencer module labeled "S0". Find the condition that applies:
- LED is amber, the failing FRU is cable or bus bar. Go to the next step.
- LED is green, the failing FRU is cable or bus bar . Go to step 7.
Disconnect cable at connector B. Reset the "S0" output by setting the enable/disable switch below the LED to disable (down) and then enable (up). Observe the LED on the PPS sequencer module labeled "S0". Find the condition that applies:
- LED is amber, the failing FRU is cable or bus bar. Go to the step 8.
- LED is green, the failing FRU is bus bar . Go to step 8.
Connect cable to connector C.
1. Disconnect cable from connector D. Reset the "S0" output by setting the enable/disable switch below the LED to disable (down) and then enable (up). Observe the LED on the PPS sequencer module labeled "S0". Find the condition that applies:
- LED is amber, the failing FRU is cable . Go to the step 8.
- LED is green, the failing FRU is bus bar . Go to step 8.

Select the FRU to be replaced:

FRU to replace	Action
PPS to primary 208 VDC bus bar cable	Go to Cables to replace the FRU and then go to the next step.
Primary 208 VDC bus bar cable	Go Cables to replace the FRU then return to the next step.
Primary 208 VDC bus bar to secondary 208 VDC bus bar cable	Replace the FRU and then go to the next step.
Secondary 208 VDC bus bar	Go to Exchange the bus bar, 208VDC secondary to replace the FRU and then return to the next step.

Return to the service screen that sent you here and continue the repair by selecting the PPS in the FRU list. Do a pseudo repair of the PPS.
Note: A pseudo repair means that you use the normal PPS FRU replace procedures, but do not disconnect cables, or physically remove the FRU as guided. The pseudo repair ensures the error conditions are properly reset and all verification tests, including FRU power on self test, are correctly run.