Check Procedures  33
Start
This is the entry point for all check procedures. The 
check procedures use failure symptoms, Power-On 
Self Test (POST) error codes, or beeps to help 
determine the defective field replaceable unit (FRU). 
Follow the suggested check procedures or use the 
diagnostics diskette to determine the problem FRU.
IMPORTANT: 
 Replace FRUs ONLY when it is 
determined that the error is not a result of 
software, loose contacts, or dirty component 
surfaces. Any FRU change should be verified 
by running a complete test (“Diagnostics - All 
Tests” in PC-Doctor diagnostics program).
This book comes with a diagnostic program diskette. 
This diskette should be used ONLY with 
2284 
Service Level A (SL-A)
 IBM Personal Computers. 
Do not use this diskette on other models.
POST error codes and error messages are displayed 
on the screen after the IBM logo. Meanwhile, error 
beeps could be issued to help diagnose syste
problem. Please refer to “Index of Symptoms, 
Messages, Error Codes, or Beeps” on page 38 for 
additional help.
All voltages in the check procedures are positive 
unless otherwise indicated. Use frame ground for all 
voltage checks unless otherwise specified.
IMPORTANT: 
 There is a Power Override switch 
located at the back of the machine, just above 
the connector for the power cable. If the 
system does not power on after pressing the 
power button situated on the front of the 
machine, please check the power cable and 
the Power Override switch. If the Power 
Override switch is switched on, no power is 
supplied to the system.
NOTE: 
If the check procedures instruct you to replace 
a FRU and the error message persists, an 
option adapter card might be causing the 
failure. Remove all option adapter cards, one 
at a time, until the error changes or the 
problem is no longer apparent. Replace the 
last option adapter card removed.