pc power supply short circuit mishap

Hi everyone,

I'm sorry for my low level knowledge about electronics. I hope this group can help me. I use a compaq Tower PC from 1998.

It still functioned admirably, but I had connected a fan to one of the 4 cable (red black black yellow) plugs which also go into hard disk and cdrom drives, using wires I put loosely inserted into the plug.

Unfortunately, I caused in this plug a short circuit by pulling the loose wires which connected this fan to the plug and had the red and black ones touch each other for a second.

However stupid this may be, I first thought no damage was done to the power supply. However, the ATX motherboard power switch did not start the computer no more. I thought the motherboard was gone as well by then.

I bought a new power supply, and the problem is over, for now.

I still hope I can fix the first, older power supply, because the new power supply stated on the box that there was protection against short circuits.

Is it possible that only the small fuse in the old power supply has blown, or that I can repair the power supply ? The short circuit i caused only lasted for a second maybe.

MTIA,

peter

Reply to
<n
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Yes, this is possible that all that is wrong is an internally blown fuse.

Reply to
Bob Shuman

Try replacing the fuse. But if it blows again, then it's not worth fixing the power supply, especially given your level of experience.

WARNING: LETHAL VOLTAGES INSIDE WHICH CAN REMAIN AFTER UNPLUGGING! Take care.

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Reply to
Sam Goldwasser

Hello,

"Sam Goldwasser" schreef >

fuse.

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Hello,

Thanks for the feedback. I would not know where to find a replacement fuse, given I'm living far away from shops where they sell them. I bought a second power supply and will try to find a fuse later on.

This Compaq power supply was from 1998, I hope back then it was also designed to cope with short circuits like the new one I bought now. I suspect the red-black wires transport 12V supply, and the yellow one 5V (?).

Thanks again,

Peter

Reply to
<n

In my experience, any fuse(s) located inside the SMPS RARELY if EVER protect the circuit from a short condition... there's pretty much always something else fried in the unit. Switch-mode power supplies are amazingly cheap for what they provide, which is very well regulated, efficient DC power. They are also very very time consuming to diagnose and repair. As such, the general concensus in the repair industry is to throw it out and buy another one. I believe you made the right choice. As another poster has suggested, try replacing the fuse, if there is one, then throw it in the bin.

Dave

Reply to
Dave

You got 10 years out of it, that's a pretty good run. I wouldn't bother fixing it myself, you can salvage some interesting parts from them if you're into that.

Reply to
James Sweet

"Dave" schreef in bericht news:cyAZj.3685$Yp.3016@edtnps92...

protect

for

another

suggested,

Hi Dave, and thanks.

I must say, thinking of what could go wrong now, I fear - knowing nothing about power supplies or their electronics - that if I replace the fuze and something else in de unit is also damaged, it may well be that the actual voltage produced by the damaged power supply would maybe exceed what the motherboard of my pc could cope with. I would maybe be happy replacing just the fuze, but the unit could cause more damage. I think I will stay with the new power supply unit.

Thanks again to all,

Peter

Reply to
<n

If you know nothing about power supplies, then stay out of it, as others have mentioned, a switchmode PSU is no place for a beginner. Even as an experienced tech, I loath working on PC power supplies, I've failed on many more than I've succeeded in repairing.

Reply to
James Sweet

"Dave" schreef in bericht news:cyAZj.3685$Yp.3016@edtnps92...

protect

for

another

suggested,

Hi Dave, and thanks.

I must say, thinking of what could go wrong now, I fear - knowing nothing about power supplies or their electronics - that if I replace the fuze and something else in de unit is also damaged, it may well be that the actual voltage produced by the damaged power supply would maybe exceed what the motherboard of my pc could cope with. I would maybe be happy replacing just the fuze, but the unit could cause more damage. I think I will stay with the new power supply unit.

Thanks again to all,

Peter

Reply to
<n

Hi!

Most every computer power supply I've seen has used an AGC (glass) type fuse. It looks like a tube with glass in the center and metal at the ends. The rating and voltage will be printed (stamped) on one of the metal ends.

Normally a computer power supply will simply "crowbar" its outputs and shut down without damage when a short circuit comes up. That's assuming that the power supply is in otherwise good health with no components that are starting to fail or change characteristics.

The red wire is +5 volts. The yellow wire is +12 volts. Each black wire is a ground.

William

Reply to
William R. Walsh

Opposite. Red 5V, yellow 12V, black ground.

Reply to
Norm De Plume

On Fri, 23 May 2008 14:54:32 +0200, put finger to keyboard and composed:

A normal AT/ATX PSU has +12V on the yellow and +5V on the red. Be aware that certain 3rd party PC manufacturers (eg Apricot) intentionally wired these the other way around in an attempt to force the user to buy replacement parts from them.

- Franc Zabkar

--
Please remove one \'i\' from my address when replying by email.
Reply to
Franc Zabkar

On 23 mayo, 19:23, wrote: . I would maybe be happy replacing just

I'd just like to echo what other posters like Dave and James have pointed out - repairing a 10 year old power supply is not worth the trouble, especially for a beginner.

even if repair were feasible, the parts would exceed the cost /value of the whole thing! I suggest going to your local dump or fleamarket, those places are full of this stuff for next to nothing or free. you could probably pick up a better PC than your 1998 model while you're there!

oh yeah, and your local freecycle list is anpther good place for free stuff like this if you want machines to 'practise' on.

-B

Reply to
b

How many lawsuits did they have? :)

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Reply to
Sam Goldwasser

On 26 May 2008 19:14:12 -0400, Sam Goldwasser put finger to keyboard and composed:

I recently offered my old Apricot PSUs to an Apricot enthusiast for free. He hasn't yet responded to my email. Maybe that's a bad sign.

- Franc Zabkar

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Please remove one \'i\' from my address when replying by email.
Reply to
Franc Zabkar

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