Service Guide

Undetermined Problems

Read this section if the diagnostic tests did not identify the failure, the devices list is incorrect, or the system is inoperative.

Note:

A corrupt CMOS can cause undetermined problems.

Check the LEDs on all the power supplies (see "AC and DC Power LEDs".) If the LEDs indicate the power supplies are working correctly, return here and go through the following steps:

1. Power off the computer.
2. Be sure that the system is cabled correctly.
3. Remove or disconnect the following devices and parts (one at a time) until you find the failure (power on the computer and reconfigure each time):
   1. Any external devices
   2. Surge suppressor device (on the computer)
   3. Modem, printer, or non-IBM devices
   4. Each adapter
   5. Drives
   6. Memory modules (Minimum requirement = 256 MB)

      Minimum operating requirements

      • Three power supplies
      • Power backplane
      • Processor/PCI board (with pins 2 and 3 on J-23 extension cable connected together to bypass the power switch; default is pins 1 and 2)
      • System Board (Verify that connection to Processor/PCI Board is secure.)
      • One Microprocessor and VRM
      • Memory module (with a minimum of 1 bank of 256-MB DIMMs)
4. Power-on the computer. If the problem remains, suspect the following parts in the order listed:
   1. Power Supply
   2. Power Backplane
   3. Processor/PCI Board
   4. System Board

Notes:

1. If the problem goes away when you remove an adapter from the system, and replacing that adapter does not correct the problem, suspect the Processor/PCI board, then the system board.

2. If you suspect a networking problem and all the system tests pass, it could be a network cabling problem external to the system.