Evaluating Startup Problems

There are many problems that can plague the PC, but perhaps the most troubling problems occur during startup-when computer fails to start at all or does not start completely. Startup problems make it most impossible to use diagnostics or other utilities that we depend on to help isolate problems. With the advent of windows 95, there are even more difficulties that can develop. This part of the chapter offers you a series of possible explanations for full and partial system failures.

When a system doesn't start at all

1. If there is no power light, and you cannot hear any cooling fan:

• Check the ac voltage. Use a voltmeter and confirm that there is adequate ac voltage at the wall outlet.
• Check the ac cord. The ac cord may be loose or disconnected.
• Check the power supply fuse(s). The main fuse may have opened. Replace any failed fuse.  

1           1   Orange     Pwr Good
             2   Red          +5
             3   Yellow       +12
             4   Blue          -12
             5   Black        Gnd
 6          6   Black        Gnd

                                                                   Motherboard power connector
1           1   Black        Gnd
             2   Black        Gnd
             3   White        -5
             4   Red          +5
             5   Red          +5
6           6   Red          +5

NOTE: If you replace a main fuse and the fuse continues to fail, you may have a serious fault in the power supply. Try replacing the power supply.