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My PC does not turn on

Last response: in Motherboards
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November 8, 2011 1:55:51 PM

Hi all,
Today my PC went dead!
When I say dead, I mean it: no PSU fan, no CPU fan, no case fan; no Beeps, no leds.

The only led that is on is on the back of the case close to the PSU, and it has always been on should the power cord be connected.

So I tried:
- Checked the cables (24 pin + 4 pin): they were OK
- Removed everything except RAM: did not change anything
- PSU: worked fine in another PC
- power button: works fine
- BIOS reset: did not change anything
- CMOS battery: 3.2V: OK

BUT, if I:
- disconnect the 24 pin connector from the motherboard
- short out the green wire to any black (earth) wire with a paper clip
- and then reconnect the 24 pin in the MB
then the PC turns ON magically and boots normally!

Only this sequence allows to turn on the PC: for example, if I short the green wire and the black wire when the connector is in the MB, then the PC does not start.

If this matters, one thing that I noted is that the back panel LED is brighter when the 24 pin connector is disconnected, while it gets weaker when I connect the connector in the MB.
(Does it makes sense?)


What could it be?

My PC: HP Pavillion T3000

More about : turn

a c 121 V Motherboard
November 8, 2011 2:00:20 PM

Looks like you have a short either in your MB or PSU that is drawing current. It could be either component, but I would lean towards MB. Do you have a different PSU you could try to see if that is the issue?
November 8, 2011 2:29:11 PM

I found the problem: it looks it is the PSU.
The 1st PSU in a 2nd computer generates the same behaviour as the 1st computer (=not starting).
The 2nd PSU in the 1st PC worked perfectly fine.

Considering that if I start the 1st PC and the 1st PSU with the method I described earlier everything works fine, I assume that the PSU can be repaired, right?

Is there a guide on how to repair a PSU?

thanks

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a c 121 V Motherboard
November 8, 2011 2:38:51 PM

anything *can* be repaired... but generally you are going to want to stay away from trying to repair PSU's...

They are a lot of high voltage capacitors and sensitive components in there. Generally if a PSU goes out it is best to get a new one as they are relatively cheap...
November 8, 2011 2:41:37 PM

You are right.
thanks a lot for pointing me in the right direction.

a c 121 V Motherboard
November 8, 2011 2:42:46 PM

no problem. Good luck!
!