PS/2 FAQ, App D

Appendix D     Error Codes

Micro Channel Adapter Errors
     I/O Channel check 
     DMA timeout 

   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. 

POST Errors 
         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 interrogates them) 

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, display, etc. 
      3.    Plug in, power on and listen for a beep. The beep indicates POST has run. Multiple beeps may occur. 
      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. 85/90/95/500 PS 
      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.

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