Lenovo System x3550 M4 Installation And Service Manual page 174

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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:

Turn off the server and disconnect all power cords.

Check for loose cables in the power subsystem. Also check for short circuits, for example, if a

loose screw is causing a short circuit on a circuit board.

Check the lit LEDs on the light path diagnostics panel (see "Light path diagnostics LEDs" on page

If the check log LED on the light path diagnostics panel is lit, check the IMM event log for faulty Pwr

rail and complete the following steps. Table 17 "Components associated with power rail errors" on

page 160 identifies the components that are associated with each Pwr rail and the order in which to

troubleshoot the components.

Disconnect the cables and power cords to all internal and external devices (see "Internal cable

routing and connectors" on page 185). Leave the power-supply cords connected.

For Pwr rail 1 error, complete the following steps:

1. (Trained technician only) Replace the system board.

2. (Trained technician only) Replace the microprocessor.

For other rail errors (Pwr rail 1 error, see Step b), remove each component that is associated

with the faulty Pwr rail, one at a time, in the sequence indicated in Table 17 "Components

associated with power rail errors" on page 160, restarting the server each time, until the cause

of the overcurrent condition is identified.

Table 17. Components associated with power rail errors

Pwr rail error in the IMM event log

Pwr rail 1 error

Pwr rail 2 error

Pwr rail 3 error

Pwr rail 4 error

Lenovo System x3550 M4 Installation and Service Guide

• Microprocessor 1

• Microprocessor 2

• Optional adapter (if one is installed) in PCI riser-card

• PCI riser-card assembly 1

• ServeRAID SAS/SATA adapter

• DIMMs 1 through 6

• PCI adapter power cable (if one is installed)

• Hard disk drives

• DIMMs 7 through 12

Troubleshooting