Computer Power Loss

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Baiting Guru Joined: 03 Mar 2006 Posts: 7103 Location: Yes

I humbly request the advice of any hardware-savvy members here who might have some clues as to why my PC has suddenly gone belly up and refuses to turn on.

I have an off-label PC, about 4 years old -- AMD Athlon 1.9, with 512 ram, 40GB. Has worked like a charm these past years, and while it's getting long in the tooth for some things, overall it's just fine.

I go to turn it on yesterday and nothing -- not a whimper. I take apart the case and do a once-over for any obviously loose wires and I don't see anything. I tried a different power cord, different outlet, even unplugged the fan to see if perhaps less load would make it easier to get started. My kids were playing upstairs with a friend the other day and it's very possible they jarred the thing -- but they never turned it on.

The only thing that comes to mind is the power source supply having gone bad, which I suppose I could replace, but any other ideas? Many thanks in advance.

Posted: Mon Mar 26, 2007 1:23 pm

Does the fan of the PSU start, when you turn the machine on? Or has it gone totally quiet? No beep, no nothing? If so, yes, I would also guess the the PSU is gone....

Posted: Mon Mar 26, 2007 1:27 pm

Some pc's do have an internal fuse, or one that screws into the back.
User : My PC is dead.
Op : can you turn it on?
User : no
Op : can you tell me the serial number ?
User : no
Op why not?
User : can't see the number
Op :why not?
User : its too dark
Op : why not turn the lights on?
User : can't
Op : why not?
User : we've had a power cut.

Posted: Mon Mar 26, 2007 2:26 pm

My guess is power supply as you have tried other things - if you dont hear any beeps or the fan doesnt kick on - a new case may be in order..

Are you good with a multi-meter?

Posted: Mon Mar 26, 2007 2:54 pm

Sounds like you already know what's going on. At this point the thing would be to simply change it. The PSUs are not expensive. If you do want to make sure for some reason, you can take it out and pull off the cover plate. You should be able to smell a fried bridge rectifier block or see a cooked component. Do not replace the component. Just remove and replace the PSU. There are wattage ratings on the unit. No reason to go higher but make sure that the replacement is rated for your processor. Really old PS's were not.

Baiting Guru Joined: 03 Mar 2006 Posts: 7103 Location: Yes

Okay, thanks guys. I will give it a go. If that doesn't work, then it may be new computer time for me -- aww shucks. Wink

Posted: Mon Mar 26, 2007 3:05 pm

One other thing that I have had on some pc's from time to time which can cause this...

Believe it or not depending on which peripherals you have plugged into it can stop it coming on. What you can try is to unplug everything except the power lead and see if that gets you anywhere.

A fairly simple if not exactly high tech way of finding out whether the psu is knackered or not is to put your ear very close to it while plugging in the power lead, if you cannot hear anything (there should at least be a little click type noise) then its most probably gone bye bye.

Baiting Guru Joined: 03 Mar 2006 Posts: 7103 Location: Yes

Yeah -- I had everything unplugged and up on my kitchen table -- nada. Crying or Very sad

Western Union · Posted: Mon Mar 26, 2007 3:09 pm

I would strongly advise you to be careful poking about inside your PSU. The capacitor inside can retain a fatal charge long after you have disconnected it.

Posted: Mon Mar 26, 2007 3:10 pm

hmmm, its bu88ered then!

Baiting Guru Joined: 04 Jan 2006 Posts: 3193

First thing to do: check any fuses you can find.

Most probably the power supply, but may be the motherboard. Certainly not the entire PC.

You need a friendly neighborhood PC shop to do some swapping for you. Note that if the motherboard has gone very bad they have been known to blow power supplies. So it's as well to have someone running the tests who has the equipment to take things carefully.

Baiting Guru Joined: 03 Mar 2006 Posts: 7103 Location: Yes

@Mr. Fishe -- I wasn't planning on opening the PSU, just removing it, intact. If that by itself is dangerous, then please advise -- I'd not heard of that fact.

@Thud -- I hear you, but I'm trying to avoid taking it in. I don't like others poking around in my computer if I can avoid it -- meaning my HD. And no, there's no goat porn or threats against the President, but I am loathe to have financial and other personal data available to a "well-intentioned" computer techie. My worst-case is if replacing the PSU doesn't do it, to see if a store can fix it without having to access the HD contents.

Posted: Mon Mar 26, 2007 3:45 pm

^^

Just take your pc in without the hdd, any tech shop worth its salt will have one lying around and wont complain.

Taking the power supply out intact wont do you a bit of harm, just dont go poking arond inside it.

Western Union · Posted: Mon Mar 26, 2007 3:59 pm

No problems taking it out and they�re fairly easy to replace yourself.

Baiting Guru Joined: 03 Mar 2006 Posts: 7103 Location: Yes

Thanks again to all.

And I should do all this standing in a pool of salted water, right?

Baiting Guru Joined: 08 Jul 2004 Posts: 11857 Location: UK

^^^^^ You don't need the salt Very Happy

My computer was like yours, I took out or unplugged anything that moved, cleaned fans and all the contact points of anything that unplugged, hoovered any crap out, put the bits back in, turned it on and it came back to life Shocked

Posted: Mon Mar 26, 2007 4:47 pm

Quote:

And I should do all this standing in a pool of salted water, right?

Naahh....you better check the power outlets of the PSU with your tongue to see if there is any current in it. Wink

(i guess I don�t need to tell you, that this is a joke Wink

)

on the other side: I really need to tell you that this was a joke since you are lawyer and would sue my ass Laughing

Posted: Mon Mar 26, 2007 5:35 pm

My PSU helpfully caught fire to tell me that it had had enough.

I unplugged it and blew the fire out, luckily there were no screws holding the case on, as I was always in and out of there.

Most computer parts shops sell a case with a PSU included. As long as you get one that is compatible, to install all your existing parts into a new case should be basic Meccanno technology, you only need a crosshead screwdriver.

The PSU should have standard connectors to plug into your mother board and drives.

Posted: Mon Mar 26, 2007 5:45 pm

If you're replacing the PSU, it's probably a good time to do a little cleaning in there. My old PC's PSU died - bought a new one (think it was about �30). Fitted it, everything OK. 2 weeks later, power on but no action - the heatsink on the CPU was completely clogged with dust. CPU had overheated & fried. Sad

Baiting Guru Joined: 03 Mar 2006 Posts: 7103 Location: Yes

Oh fun. Well, I'm going to try the PSU first, plus give the whole insides a once over. If that doesn't work, I'm going to consider a new computer (as I mentioned, it's getting old anyway).

Then I will need to figure out how to get my old HD contents onto my new HD...

Posted: Mon Mar 26, 2007 6:50 pm

Getting stuff off the HD should be easy, just get a HD case and plug it in via USB. The case should definitely not be too expensive, and you can always use the old HD as backup. Smile

Posted: Mon Mar 26, 2007 6:54 pm

The problem if you buy a new pc is that it will more than likely have a SATA hdd and your old one has an IDE hdd.

There is a device that converts an IDE hdd to use which you can then plug into the new pc and copy whatever you want, its just a bit of a waste as you'll only use it once.

If your new pc has IDE drives then its no problem as you can simply put your old one in as a secondary drive although if someone is selling you a new pc with IDE you should get it very cheap.

If you don't have that much data to copy off the old hdd then just zip it and put it on a flash drive, if that isnt enough then email it to yourself zipped at one of your gmail a/c's (I'm sure you have a few Wink

)

Baiting Guru Joined: 03 Mar 2006 Posts: 7103 Location: Yes

Down the rabbit hole go I....all i really need off the HD is some financial data, and ideally, some photos, and other misc data.

Luckily I figured out how to get my iPod songs off and on without iTunes getting in the way.... Wink

Posted: Tue Mar 27, 2007 4:17 am

Mr Fishe wrote:

I would strongly advise you to be careful poking about inside your PSU. The capacitor inside can retain a fatal charge long after you have disconnected it.

While I HAVE heard that about CRT monitors, I've never heard that about a power supply.

You have the computer on a batter backup, right? I've felt for several years now that it is FAR easier to replace a $100 battery backup than to fiddle with $1500 worth of stuff in my computer, hoping that most of it still works.

So far, I've had less hard drives fail, and general good luck.

Posted: Tue Mar 27, 2007 6:29 am

^^^ Certainly true for all switch mode regulated power supplies. The mains AC input is rectified and filtered before the regulator part of the circuit. The filter capacitors are a large value, typically from around 2200 uF to 5600 uF and during operation, charge up to about half the peak to peak input voltage (on a 120 VRMS circuit, to about 170 V; on a 240 VRMS system, to about 340 V). The input filter capacitors are very capable of dumping a fatal charge rapidly so take heed of Mr Fishe's warning.

@ IP: Oh, the joyous crackle of discharging a CRT before working on it. An accumulated charge of 20 to 26 kV potential certainly makes its presence known.