Troubleshooting Without Diagnostics

Solving Power Supply Problems

Solving Power Supply Problems

Problem

Cause

Solution

Power supply shuts down

Voltage selector switch

intermittently.

on rear of computer

 

chassis (some models) is

 

not switched to correct

 

line voltage (115V or

 

230V).

Select the proper AC voltage using the selector switch.

Power supply will not

Replace the power supply.

turn on because of

 

internal power supply

 

fault.

 

Computer powered off automatically and the Power LED flashes Red two times, once every second, followed by a two second pause, and the computer beeps two times. Beeps continue for five iterations after which the LED flashes will continue until the problem is resolved.

Processor thermal protection activated:

A fan may be blocked or not turning.

OR

The heatsink/fan assembly is not properly attached to the processor.

1.Ensure that the computer air vents are not blocked and the cooling fan is running.

2.Open hood, press the power button, and see if the processor fan spins. If the processor fan is not spinning, make sure the fan's cable is plugged onto the system board header.

3.If the fan is pugged in and seated but not spinning, replace the processor fan.

 

Service Reference Guide, dc7700

433612-001

D–5