IBM NeXtScale nx360 M4 Installation And Service Manual page 94

Power problems can be difficult to solve. For example, a short circuit can exist
anywhere on any of the power distribution buses. Usually, a short circuit will
cause the power subsystem to shut down because of an overcurrent condition. To
diagnose a power problem, use the following general procedure:
1. Turn off the server and disconnect all power cords.
2. Check for loose cables in the power subsystem. Also check for short circuits, for
3. Check the lit LEDs on the operator information panel (see Light path
4. If the check log LED on the light path diagnostics panel is lit, check the IMM
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IBM NeXtScale nx360 M4 Type 5455: Installation and Service Guide
example, if a loose screw is causing a short circuit on a circuit board.
diagnostics).
event log for faulty Pwr rail and complete the following steps. Table 5 identifies
the components that are associated with each Pwr rail and the order in which
to troubleshoot the components.
a. Disconnect the cables and power cords to all internal and external devices
(see "Internal cable routing and connectors" on page 180). Leave the
power-supply cords connected.
b. For Pwr rail A error, complete the following steps:
1) (Trained technician only) Replace the system board.
2) (Trained technician only) Replace the microprocessor.
c. For other rail errors (Pwr rail A error, see step 4b), remove each component
that is associated with the faulty Pwr rail, one at a time, in the sequence
indicated in Table 5, restarting the server each time, until the cause of the
overcurrent condition is identified.
Table 5. Components associated with power rail errors
Pwr rail error in the IMM event log Components
Pwr rail A error
Pwr rail B error
Pwr rail C error
Pwr rail D error
Pwr rail E error
Pwr rail F error
Pwr rail G error
v Microprocessor 1
v Microprocessor 2
v Adapter (if one is installed) in PCI riser-card
assembly 1
v PCI riser-card assembly 1
v Fan 1
v DIMMs 1 through 6
v Dual-port network adapter
v Fan 2
v DIMMs 7 through 12
v Hard disk drives
v DIMMs 13 through 18
v Adapter (if one is installed) in PCI riser-card
assembly 1
v PCI riser-card assembly 1
v Fan 4
v DIMMs 19 through 24
v PCI adaptor power cable (if one is present)
v Fan 3
v Hard disk drives
v Hard disk drive backplane assembly