Appendix D Error Codes
Micro Channel Adapter Errors
I/O Channel check
On DMA timeout errors, note the arbitration level displayed
on the screen. Go to the "View configuration" screen and see which device
has that same arbitration level. Suspect that device is defective.
Refer to the General
and SCSI Error Codes below. If multiple errors occur during POST, resolve
them in the order that they are presented.
Always cold boot and
run Advanced Diagnostics (go into System Programs and at the main menu
do a Ctrl-A) before replacing components when trying to resolve software
problems. If diags don't fail, replacing components will probably not solve
the problem. Refer to the software vendor for possible patches. The software
may not be supported on the system.
Dead System (no POST, screen blank, no beep)
The most likely cause
is a device that is shorting out the power supply. An improperly inserted
memory module, a defective adapter or device can cause a short circuit.
To prevent damage to a power supply, the system board must present a "POWER
GOOD" signal to the power supply in 150 ms or less. If this does not occur,
then the power supply shuts down internally.
Known dufus tricks-
SIMM inserted backwards (with enough force ANYTHING is possible). adapter
not fully seated in expansion slot, power cord not plugged in, supported/defective
adapter (Non-IBM adapter, like ALR..), or with a heavily loaded system,
too many drives starting at once (overcurrent as the drives attempt to
spin up- leave motor start jumper open to start drives after the controller
Troubleshooting a Dead System
1. Verify power is available
(IS cord plugged in?). If the system has power, then go to #2
2. Remove all adapters,
options, extra memory, etc. Remove all external connections, KB, mouse,
3. Plug in, power
on and listen for a beep. The beep indicates POST has run. Multiple beeps
4A. If no beep is heard, verify continuity
through speaker. If OK, replace system board memory and retry # 3.
If still no beep, verify power supply voltages. If the voltages are correct,
replace system board. If voltages are incorrect, replace the power supply.
4B. If a beep occurs, reinstall
adapters one at a time and return to step 3. When something is added and
the beep is no longer heard, the last item plugged in is probably defective.
At this point, it is not necessary to reconfigure the system each time
an adapter or device is added because we are only expecting any beep.
Defective or weak
batteries can cause loss of all setup information. If only part of the
setup is lost, the battery is probably NOT the cause. Innacurate time is
usually caused by software.
POST Beep Codes and Error Codes
Determining failing memory module
For a chart how to determine a failing memory module on
Mod. 56/57, 76/77, 85 and 90/95 see HERE.