Computer Power Failure

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I removed the case from my PC today to check the make of my sound card.
I didn't touch anything inside, although there was a lot of dust and
fluff flying around.
After replacing the cover, I tried to turn the power back on but
nothing happens - no fan, no lit LED, nothing. I know power is getting
to the cable because I can route it through the speakers and they work.
(I have also tried it without the speakers.)
Every time I remove the power cable from the PC there is a slight
whistling noise a few seconds later.
Have I fried the PC by accidentally touching something, or disturbing
some fluff? Any other suggestions?



Re: Computer Power Failure

   Did you remove power cord from wall before making any
hardware changes?  Did you make efforts to eliminate static
electricity - ie static wrist strap, room humidity above 40%,

 Test system without sound card installed.  Inspect everything
that human skin may have touched or brushed. Do not try to fix
anything that is not broke.  ie. don't try to complicate a
problem by cleaning out dust.  And carefully record (or
remember) what you did.  IOW don't wildly just change things
on wild speculation that 'this or that' might fix things.

  Next step is to discover what is and is not working in but
two minutes with a 3.5 digit multimeter.  In your case, first
numbers to report are voltages on purple wire (from power
supply to motherboard) while computer is off but connected to
wall receptacle.  Then green and gray wires before and when
power switch is pressed.  And then finally what happens on
orange, yellow, and red wire as power switch is pressed.
Numbers that will make responses here useful.

  Above to determine a problem on (for example) power supply
controller or power switch connection to that controller,
verses something related to power supply.

  Your power cable reconnect says a protective feature of the
power supply controller was reset - and it was not a
solution.  This paragraph just so that you learn about one
feature of the power supply 'system'. wrote:
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Re: Computer Power Failure

Try holding the power button in for 10 seconds; then release it. wrote:
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Re: Computer Power Failure

On 26 Dec 2005 16:17:45 -0800,

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So how old is this system?  It might be that battery is
dead, check it's voltage with a multimeter.  Go ahead and
unplug AC to PSU, pull battery out and leave it out for 10
minutes.  That will clear the CMOS, and while battery is
out, check the voltage if possible.

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It is always good to begin a post in a computer hardware
group by describing the hardware, for example make and model
of whole system (if OEM) or at least the major individual
parts like motherboard make/model, power supply, CPU, etc...
and links to manufacturer product pages on any seemingly
relevant parts.

Is it possible you have an OEM system with a chassis
intrusion switch that is not now being depressed by the
cover now that it's reinstalled?  In a perfect world one
would expect that replacing the cover so it seems installed
properly would be enough, and yet it would be good to check
for this potential as overlooking it could make a lot of
other things a wasted effort.

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Not significant, some power supplies do that for a moment
while the power is drained down.

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I thought you didn't touch anything?  It begs the question
though, if you had opened it to check the sound card, did
you not touch things to do that?

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Clearing CMOS by removing battery and measuring it (or if
all else fails, buy a new battery) is the first step.  If
it's the typical coin-battery must systems use, it's a
CR2032 (20 mm diameter X 3.2mm thick) and very common,
available at most places that sell coin batteries like

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