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Old May 26th 07, 03:41 AM posted to alt.comp.hardware
PeeCee
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Posts: 61
Default Computer won't turn on, power supply squeals


"Ben" wrote in message
ups.com...
We have a PC that's a component of a much bigger system. The system
uses European-style power (it was made in France), so the computer's
power supply must be set to 230 volts. After some recent maintenance,
someone forgot to set the PC back to 230 when putting it back into the
system. The user turned it on, heard some loud pops, and unplugged it.
I was called in to help from there.

The power supply smelled like smoke, so I replaced it. When plugged
in, the power supply makes a very high-pitched noise and the computer
won't turn on at all. I tried replacing the processor, memory, video
card and unplugging everything else, but this did not fix the problem.
I replaced the motherboard, no dice. I have tried two other power
supplies, another processor, different memory, etc. Basically,
everything that's hooked up in the system is new, but the power supply
still whines and the system won't boot. The power supply only makes
the noise when the main power connector to the system board is
attached.

The system is a Dell XPS R450 with an Intel P2 processor (yes, it's
rather old). Some documentation:
http://support.dell.com/support/edocs/systems/dkhan/

I'd really appreciate any suggestions anyone might have.

Thank you,

Ben



Ben

Depending on your luck when a power supply is blown up like this, the down
stream effects can range from nothing (ie replace the supply and all is
well) to all manner of parts fried/spiked.

The whining sound usually indicates the power supply is trying to supply
current outside it's ratings and going into a shutdown restart cyle at the
'whining' frequency'
This overload current could well be caused by fried components in any one of
the parts of the PC or something as simple as a loose screw shorting
something out.

As Pen and Kony have pointed out that model Dell usually requires a 'Dell'
specific power supply.

If you used a suitable Dell replacement power supply then the symptoms you
described suggest there were more fried components in the original
motherboard/cpu/ram/hd/fdd/video card (etc) as a result of the overvoltage.
Subsequent connection of good parts to damaged parts may well have fried
some of the new good components.

If you replaced it with a standard ATX supply there is regretfully a good
chance you have simply complicated the situation.

May I suggest the most productive course of action would be to write the
Dell off and tell the owner/user to 'go get a new one'.
Then treat all the parts that have been installed in that PC as suspect and
auction them off as damaged goods.


Best
Paul.