Repairing Desktop PC Power Supply

spannerzone

Unless it was a decent PSU and cost some money, I would never bother personally, sure you can trace a faulty component probably, with time but you might end up finding it's some component you can't identify cause it's burnt out or not easily available. Meanwhile you could have got a £30 replacement fitted and got the PC running again.

I'm all for repairing things, what with working in an electronics workshop in the past and repairing other electronic devices in my current job but I'd rarely waste my time on a cheapo PC PSU.

Many are glued up inside and incredibly awkward to get apart let alone get plugged in while dismantled to check voltages etc.

skivenov

Yeah, the main purpose of jumping them out of the PC and testing the voltages with a meter on the plug was to give us a quick measure of whether the PSU was the fault or the problem lay elsewhere.

As far as internal faults went, if it wasn't the fuse or something massively obvious, in the bin it went!

googler

skivenov wrote: »

Sounds daft, but pull the mains lead out the back of the PC, leave it a while, then plug it in and give it a try. The LED might be running off some other latent voltage, so test your mains lead or try a known good one. Dafter things have happened.

Tried that; waited for the LED to die away, then plugged back in. Repeated this two or three times

If you're got a multimeter (or an LED), whip the PSU out (remember there a lot of electrostatically sensitive bits in the box).and test for the 5v standby voltage coming out of pin 9 (purple).

That's the kind of advice I was looking for....


In the good old days, I haven't worked in IT for years, we used to take the PSU out of the PC, plug it in on the bench and earth pin 9 (purple) to a black to simulate the power button being pressed. If you Google "ATX pin out" and you'll find loads of hits showing what wire should kick what out. Here's one http://www.pcguide.com/ref/power/sup/partsMotherboard-c.html

Also the useful fault-finding stuff I was after... thanks

googler

New PSU thru eBay; tested +5v standby on pin 9, and both old and new supplies registered +5v OK......

Tried the new one anyway in the PC (with the hard disk out of the way, in a caddy connected to another machine), and the fans kicked in and it went through the POST and BIOS sequence, stopping to tell me No Boot Disc Fitted (or similar msg).

So, the old one's giving out a standby voltage, but something else must have failed internally, and it's not powering the mobo or HDD.....

OH was already budgeting for a new PC, but a £9.99 purch from the Bay saved the day....

Thanks again to those that helped here.

macman

It may not be giving a stable enough voltage in order to satisfy the POST process, if so it will not boot beyond POST.

googler

macman wrote: »

It may not be giving a stable enough voltage in order to satisfy the POST process, if so it will not boot beyond POST.

I had a quick look inside, there's no obvious blown or fried components, so I think it may just go on eBay as spares/repair for another hobbyist to have a go at.

poppellerant

Can you post some internal pictures of the PSU?

I very much doubt anybody would want to buy a faulty PSU, unless the old one is something special or valuable. It would take time to find the fault, which could potentially be expensive to repair.

In a nutshell, bin it.

macman

The weight of a PSU makes it highly unlikely to be worth ebaying except for very local collection/delivery.
If its faulty, even more so.

googler

macman wrote: »

The weight of a PSU makes it highly unlikely to be worth ebaying except for very local collection/delivery.

I just bought my replacement through eBay and it got posted to me....

googler

poppellerant wrote: »

Can you post some internal pictures of the PSU?

I very much doubt anybody would want to buy a faulty PSU, unless the old one is something special or valuable. It would take time to find the fault, which could potentially be expensive to repair.

In a nutshell, bin it.

If you're of this opinion, why do you want photos of it....?