Repairing PC Power Supply?

[Valalvax]

So, my computer has been running fine for ages, but the other morning it cut off, I thought maybe a power outage, turned it back on, and it starts booting, then cuts off while Windows is loading, I try a couple more times then go to work, come home, try a few more times, then unplug the video card, it boots up fine

So, my thinking is that the power supply is unable to provide enough current to power the video card anymore, wondering what component failures could possibly cause that? Anyone have any experience with PC power supplies (or just enough knowledge of general electronics to know what kind of circuit is in play)

[AWOL]

Usually caps that go first in switch mode PSUs, but I've never bothered to repair one.

[Coding Badly]

Warning: Every power supply failure I've had has been followed by a hard drive failure.  This would be a very good time to make a backup.

[Valalvax]

Yea, I was thinking that it might be a cap (that's the one component I hear most about in computers going bad)


Good tip about the harddrive, luckily the only thing I really need to backup on that machine are game saves, 80% of the harddrive is games, probably 2% saves, and the rest is TV shows

[Valalvax]

So, tried turning it on again before disassembling power supply and it worked fine, I'm going to assume that the graphics card needed reseating, or something... >.> <.< *boggle*

Oh well, no use worrying about it (well, until it happens again DUN DUN DUUUN)

[cr0sh]

I've seen weird things happen with computers, that in many cases I thought was a power supply issue, when it turned out to be some completely different other component. One time, I saw a computer that wouldn't boot until disconnected the power from the CD-ROM drive, but left the IDE cable connected (it would fail to boot if you removed the cable!); on that one, it turned out to be a faulty network card (don't ask me how - that's just the way it turned out).

In order to really figure out a problem like this, you need to have on hand known-good components, and swap out one at a time while observing the results. The only problem with this scheme is if something is smoking parts - you might plug in a know-good component, only to have it turn into a dead component.

TBH, from your description, it sounds like it is likely a bad (or going bad) video card; have you noticed any other video related issues (things you thought may be due to the monitor - and not the video card)? Things like fuzzy graphics, noisy output, changes in color or brightness at random times? In many cases, you'll find these issues are due to bad caps on the video card.

Regardless, it isn't worth replacing caps anywhere on a computer system - it isn't worth the trouble, time, or money - unless you have absolutely no choice in the matter, of course. It is far easier and ultimately less expensive to just purchase something to replace the part and move on (throw the old device in your junk pile).

[NiHaoMike]

Regardless, it isn't worth replacing caps anywhere on a computer system - it isn't worth the trouble, time, or money - unless you have absolutely no choice in the matter, of course. It is far easier and ultimately less expensive to just purchase something to replace the part and move on

It takes only a few minutes or less to replace a few caps on an expensive board. Although it is true that hardware old enough to have those problems are due for an upgrade soon, a quick fix can keep an aging machine running long enough to postpone an upgrade for some time.

I do not recommend variable speed fans for most applications. All the ones I have seen let the components run hotter than necessary and cause them to fail earlier.

[Ran Talbott]

It takes only a few minutes or less to replace a few caps on an expensive board.

True, but a PC power supply isn't "an expensive board" these days, the cheap ones are notoriously under-engineered, and a failure has the potential to destroy some boards that are "expensive".

If a cap has blown in a switching PSU, there's a substantial risk that it's (near-)terminally stressed some other components in the process.

Even a cheapskate like me, who's been known to repartition hard drives around multi-cylinder bad spots to wring an extra year or two out of them, balks at the idea of trying to fix a PC PSU: the risk that it could literally set your PC on fire just isn't worth it.