Computer won't turn on - Page 2

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Re: Computer won't turn on

On 9 Nov 2006 14:56:31 -0800,

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Sometimes help comes in different forms.  Today it was a
failed board, but a long term insight into PSU selection and
possible repercussions is helpful, too.

You should not be insulted by the term "ignorant", everyone
is ignorant of quite a few things... but not the SAME
things, hopefully.

Re: Computer won't turn on


I am ignorant about the qualifications of a good power supply.  I came
to this group looking for assistance which I was given
in every post other than w_toms.  Tom says   "It is possible that power
supply took out motherboard due to a computer assembler without basic
electrical knowledge.  Tom also said "IOW motherboard damage would be
directly traceable to human ignornace."  These attempts to insult me
didn't help resolve my problem.

You ask "Are you claiming to infallible knowledge abouteverything?"
Apparently you didn't read the whole post.  I said "I posted in
Google groups because I don't know everything there is to know about
failing components in a PC."  This statement alone proves that I don't
claim to have "infallible knowledge abouteverything.

Re: Computer won't turn on wrote
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Re: Computer won't turn on

I just fixed a friend's computer that seems to have had a similar
situation.  The motherboard was dead.  There was power getting to the
MB and the cpu fan would run but it wouldn't POST or do anything else.
I replaced the power supply and the motherboard and it booted up no
problem.  I used the old CPU and it still seems to be good.

Good Luck,

Re: Computer won't turn on

JamesG wrote:
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Okay maybe I forgot to mention that I also checked that it wasn't
solely the power supply by trying out a new power supply since the old
one was not good quality anyway.  The old, dead motherboard still did
nothing.  At this point I really didn't see the point in poking around
with a multimeter since it seemed obvious that the motherboard was dead.

Re: Computer won't turn on

A blown PSU may not have damaged the mobo, if you get a fault on the
feedback loop, usually a opto-coupler measuring some secondary supply
voltage... ka-pow it'll go big style and could quite easily damage the
mobo since regulation of the chopper device will turn on hard and
harder until destruction elevating the supply voltages....

More than likely the rattling you can hear is whats left of a
capacitor that has exploded, the rattling being caused by the outer
casing of it.  What happens is that its internal ESR rises this
creates heat which causes gassing.. if they are not vented... or the
vent cannot cope with the increased pressure.

I would be tempted to try by substitution... a test meter may read the
voltages correctly but it will not show any ripple on the supplies...
ripples produced by the switching frequency (around 18~22Khz) will
upset the applecart usually caused by deteriorating capacitors.

You may have removed the bios battery but is it any good, did you try
a new one..?


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