Troubleshooting Without Diagnostics

Solving Power Supply Problems (Continued)

Problem

Cause

Solution

 

 

 

 

Power LED flashes Red, four

Power failure (power

1.

Check that the voltage selector

times, once every second,

supply is overloaded).

 

(some models), is set to the

followed by a two second

 

 

appropriate voltage. Proper

pause, and the computer

 

 

voltage depends on the region.

beeps four times. Beeps

 

2.

Open the hood and ensure the

continue for five iterations

 

 

 

4- or 6-wire power supply cable

after which the LED flashes

 

 

 

 

is seated into the connector on

will continue until the

 

 

 

 

the system board.

problem is resolved.

 

 

 

3.

Check if a device is causing the

 

 

 

 

 

problem by removing ALL

 

 

 

attached devices (such as hard,

 

 

 

diskette or optical drives, and

 

 

 

expansion cards). Power on the

 

 

 

system. If the system enters the

 

 

 

POST, then power off and

 

 

 

replace one device at a time

 

 

 

and repeat this procedure until

 

 

 

failure occurs. Replace the

 

 

 

device causing the failure.

 

 

 

Continue adding devices one at

 

 

 

a time to ensure all devices are

 

 

 

functioning properly.

 

 

4.

Replace the power supply.

 

 

5.

Replace the system board.

 

 

 

 

 

D–6

433612-001

Service Reference Guide, dc7700