IBM RS/6000 SP, Service Manual

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5. Look for an SRN indicating a clock problem, such as “External clock” being listed as one of the failing
components.
6. Do the “css0” diagnostics fail with indication of a clock problem?
v
If yes:
a. Problem is the clock selection in this SP Switch.
b. Return to “Step 0620-035” on page 1-33.
v
If no, go to “Step 0620-039”.
Step 0620-039
The “css0” diagnostics did not fail. This indicates that the problem is not in this SP Switch.
1. Return all cables to their original positions.
2. Return to “Step 0620-034” on page 1-33.
Step 0620-040
The clock settings on the problem switch appear to be okay and the problem switch is mounted in a frame
that also contains processor nodes. The ground straps appeared to be okay so you set up a test
processor node and went through the “css0” advanced diagnostics. The diagnostics passed on the first run
through so you disconnected the switch data cable and ran the diagnostics a second time. On the second
run, the diagnostics failed. This indicated that the problem was not in the SP Switch.
1. Make certain that you replaced the switch data cable corresponding to the selected clock at both SP
Switches.
2. Run advanced diagnostics on “css0” on the “test” processor node and its associated switch port.
v
Do not perform cable wrap test.
v
Refer to
″
Running diagnostics in a processor node
″
in
RS/6000 SP: System Service Guide
.
3. Look for an SRN indicating a clock problem, such as “External clock” being listed as one of the failing
components.
4. Do the “css0” diagnostics fail with indication of a clock problem?
v
If yes, go to “Step 0620-041”.
– Replace the “master-clock” SP Switch.
v
If no:
a. Interframe clock problem resolved.
b. Go to “Step 0620-043” on page 1-36 to verify fix.
Step 0620-041
You have determined that there is a problem in the SP Switch and that you need to replace the switch
assembly.
1. Put the SP Switch’s circuit breaker into the Off (‘0’) position.
2. Disconnect all switch data cables (also clock cables and data cable interposers, if present) from the
bulkhead of the switch assembly.
3. Replace the switch inner chassis.
4. Replace the switch planar.
5. Reinstall all cables inside the switch assembly.
6. Reinstall the top cover.
7. Reinstall the switch assembly.
8. Go to “Step 0620-042”.
Step 0620-042
You have replaced switch components and need to complete a final check before verifying the fix.
1. Be careful to reconnect all cables according to the appropriate wiring chart or labels, and put wrap
plugs on any unused data ports (S00-BH-J3 through S00-BH-J34).
SP Switch function (MAP 0620)
Chapter 1. Maintenance Analysis Procedures (MAPs)
1-35