Diagnosing And Solving Problems; Problems And Solutions - NEC POWERMATE 4100M Service Manual

4-6 Maintenance and Troubleshooting

Diagnosing and Solving Problems

One beep indicates that the computer has completed its power-on self-test. If intermittent
beeping occurs, power off the computer and try again. If the beeping persists, see
Table Section 4-4.
Table Section 4-3 summarizes problems that may develop during computer operation and
lists (in sequential order) suggested corrective actions.
Problem Symptom
No power Power lamp on computer status
panel will not light.
Power supply Any one or more of the following
malfunction conditions could occur:
Front panel lamps out, diskette
and/or hard drives do not spin,
monitor blank, interface ports not
working, and keyboard lamp out
and/or cannot input from keyboard.
Table Section 4-3 Problems and Solutions
Solution
1. Check that the power cord is
plugged into the AC connector on
the computer.
Check that the other end of the
cord is plugged into a live properly
grounded AC power outlet.
2. Check cable connections
between power supply and system
board.
3. Systematically eliminate possibly
shorted PCBs by removing cables
and expansion boards.
4. Check the +5 and +12 power
supply voltages (see Appendix A,
Connector Pin Assignments).
Measure voltages with the system
board installed.
5. Replace power supply.
6. Replace system board.
1. Perform steps 1 through 4 listed
in this table under No Power.
2. Check power supply voltages.
Voltages should be measured with
a load on them (system board
plugged in). See Appendix A for
connector pin assignments and
Appendix B for the power supply
specifications.
4. Replace power supply.