Do I have a dead power supply?


J

John Gordon

I'm having trouble with my PC hardware, and I'm hoping someone can offer
some advice.

Two nights ago, I came home from work as usual and turned on my PC to do
some web browsing. After just a minute or two, the PC suddenly shut itself
off.

I waited a minute and turned it back on. Everything came back okay, and
I launched World of Warcraft. I had barely gotten logged in to a character
and again the PC shut itself off.

So I unplugged it and took it out to the porch to blow out the dust.
There was some (we have three cats), but not an excessive amount. I put
the side panels back on and plugged everything back in then turned it on.

Nothing happened. The fans did not spin, no humming noise, nothing.
Well, actually one small LED on the case top did come on. I think it's
the hard drive activity light.

And -- here's the bad part -- after ten seconds or so there was a
noticeable burning smell, so I quickly shut everything off and unplugged
it.

I don't know specifically where the burning smell was coming from, but
the fact that the fans did not spin up leads me to think it's the power
supply, and I might be able to put things right with a new one.

Am I right in thinking it's probably the power supply?

My PC is old enough that it may be time for a new one, but it worked just
fine (until the burning smell of course) and if I can get it running again
for the cost of only a new power supply I'd love to do that. I don't look
forward to spending $800 or so on a new PC.

Any advice?
 
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D

Don Phillipson

John Gordon said:
I'm having trouble with my PC hardware, and I'm hoping someone can offer
some advice.

Two nights ago, I came home from work as usual and turned on my PC to do
some web browsing. After just a minute or two, the PC suddenly shut
itself
off.

I waited a minute and turned it back on. Everything came back okay, and
I launched World of Warcraft. I had barely gotten logged in to a
character
and again the PC shut itself off.

Yes, this and other faults suggest a dead or dying Power Supply
Unit. None lasts for ever and they last anything from two to 10
years. I have had three die during use in 28 years.

PSUs are cheap ($30) and rapidly installed. Family PC stores usually
test without charge and instal a new PSU without charge.
 
L

Loren Pechtel

I don't know specifically where the burning smell was coming from, but
the fact that the fans did not spin up leads me to think it's the power
supply, and I might be able to put things right with a new one.

Am I right in thinking it's probably the power supply?

What does your nose say is the problem?

Also, when the smoke escapes it generally leaves a mark. See the
mark?
 
J

Jan Alter

--
John Gordon said:
I'm having trouble with my PC hardware, and I'm hoping someone can offer
some advice.

Two nights ago, I came home from work as usual and turned on my PC to do
some web browsing. After just a minute or two, the PC suddenly shut
itself
off.

I waited a minute and turned it back on. Everything came back okay, and
I launched World of Warcraft. I had barely gotten logged in to a
character
and again the PC shut itself off.

So I unplugged it and took it out to the porch to blow out the dust.
There was some (we have three cats), but not an excessive amount. I put
the side panels back on and plugged everything back in then turned it on.

Nothing happened. The fans did not spin, no humming noise, nothing.
Well, actually one small LED on the case top did come on. I think it's
the hard drive activity light.

And -- here's the bad part -- after ten seconds or so there was a
noticeable burning smell, so I quickly shut everything off and unplugged
it.

I don't know specifically where the burning smell was coming from, but
the fact that the fans did not spin up leads me to think it's the power
supply, and I might be able to put things right with a new one.

Am I right in thinking it's probably the power supply?

My PC is old enough that it may be time for a new one, but it worked just
fine (until the burning smell of course) and if I can get it running again
for the cost of only a new power supply I'd love to do that. I don't look
forward to spending $800 or so on a new PC.

Any advice?


Hi,

Well on the surface the PS going bad sounds like a good bet and it's
certainly worth substituting a good one if you can. On the other hand
there's the possiblity that even if it is a bad PS that it could have done
damage to the motherboard, and the hard drive as it went out.. In any case
I'd try another PS if one is easily available and it meets the wattage
requirements to boot your system.
Below is a video which gives a simplified option to check out the PS.
The person doing this is using a paper clip as a jumper to get the PS
powering a small fan from the computer. I'd use a spare hard drive for a
heavier load. Don't test the P.S. without a load.

Jan Alter
(e-mail address removed)
 
J

John Gordon

What does your nose say is the problem?
Also, when the smoke escapes it generally leaves a mark. See the
mark?

I haven't opened up the case to visually and olfactorily (?) inspect
each component. Will do so later tonight.
 
J

John Gordon

Well on the surface the PS going bad sounds like a good bet and it's
certainly worth substituting a good one if you can. On the other hand

I picked up a new PSU over lunch and I'll try it out tonight. Thanks
for the link!
 
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J

John Gordon

In said:
Yes, this and other faults suggest a dead or dying Power Supply
Unit. None lasts for ever and they last anything from two to 10
years. I have had three die during use in 28 years.

Thanks Don! I got a new PSU over lunch and I'll try installing it
tonight.
 
P

Paul

John said:
I'm having trouble with my PC hardware, and I'm hoping someone can offer
some advice.

Two nights ago, I came home from work as usual and turned on my PC to do
some web browsing. After just a minute or two, the PC suddenly shut itself
off.

I waited a minute and turned it back on. Everything came back okay, and
I launched World of Warcraft. I had barely gotten logged in to a character
and again the PC shut itself off.

So I unplugged it and took it out to the porch to blow out the dust.
There was some (we have three cats), but not an excessive amount. I put
the side panels back on and plugged everything back in then turned it on.

Nothing happened. The fans did not spin, no humming noise, nothing.
Well, actually one small LED on the case top did come on. I think it's
the hard drive activity light.

And -- here's the bad part -- after ten seconds or so there was a
noticeable burning smell, so I quickly shut everything off and unplugged
it.

I don't know specifically where the burning smell was coming from, but
the fact that the fans did not spin up leads me to think it's the power
supply, and I might be able to put things right with a new one.

Am I right in thinking it's probably the power supply?

My PC is old enough that it may be time for a new one, but it worked just
fine (until the burning smell of course) and if I can get it running again
for the cost of only a new power supply I'd love to do that. I don't look
forward to spending $800 or so on a new PC.

Any advice?

No one has mentioned the topic of collateral damage yet.

There are some power supplies, that when they die, they damage
stuff in the computer. There is a Bestec brand supply that does that.
When it dies, it's something like the 5V rail that goes above its normal
voltage. Directly connected components (motherboard, hard drive, CDROM, keyboard,
mouse perhaps) are at risk, while memory and CPU may survive and be reusable
in a new motherboard.

I'd say chances are good it won't affect you, but take a look at the
label on the power supply and see what brand it is.

*******

If you're new to changing supplies, it helps to take notes of where the wires
go, and where "pin 1" is. For example, the rule I remember, is the yellow wire
goes on the outside, for the hard drive and optical drive. Just write
down what you see, on a sheet of paper.

A trouble maker, is the floppy connector. It wobbles up and down a bit,
and needs to be wobbled before it can be retracted. Also make note of the
wire colors. I think it's keyed so it only fits one way, but it never hurts
to be sure of your wire color.

Many of the connectors are keyed, and have unique shapes in the connector shell.

The IDE drives, they may have a keying pin, but you won't find the keying pin on
all of the cable assemblies you own. Look for a red mark on the ribbon cable itself,
as this marks pin 1 for you. And then, put the ribbon cable back the way you found it
later.

*******

There are at least three different ATX power supply specs. This one is for
a supply with a 20 pin main connector, and no -5V on the connector. Page 30
here, has a pinout. Connecting PS_ON# to COM (pin 14 to pin 13), will start
the power supply fan running and energize the main rails. Of course, there
is no need to do that, because your supply is already dead (we have already
given up hope). All that remains, is an optional post mortem if you're
interested.

http://www.formfactors.org/developer/specs/atx/ATX12V_1_3dg.pdf

I had a power supply go, that looked like this inside. My power supply
had four capacitors with the orangy/rust colored goo on the top of the
capacitor. Mine let out a little puff of smoke as well.

http://upload.wikimedia.org/wikipedia/commons/8/84/PSU_Caps.jpg

If you take the lid off, you're allowed to look, but don't touch anything.
The main capacitor can be charged to 300VDC. It has a bleeder resistor
across it, to make it safe after a minute or two. But if the bleeder
resistor had failed for any reason, there is nothing to make it safe
any more. And thus the advice to not touch anything in there. Once you're
finished looking, you can discard it. Put the lid back on, before tossing it.
And *don't* attempt to discharge the main cap with a screwdriver. If there
was any energy stored in there, there would be a huge noise that could
deafen you. While folklore is to stick a screwdriver across the
terminals, you don't do that when the "total joules" is too big.
It's equivalent to making your own lightning bolt.

I lost my hearing in one ear for ten minutes, thanks to a capacitor.
The capacitor was in a microwave oven, an oven that was used at work
for popping microwave popcorn. Too much butter and salt collected
around the main capacitor terminals, leading to a very loud arc-over.
My right ear was facing the machine when I hit the Start button, and
the noise was so loud, I couldn't hear anything in that ear for ten
minutes. The cap in the ATX supply similarly has its share of joules
of energy stored inside. And I don't *ever* intend to test with a screwdriver,
to see how loud the ATX capacitor is :-( The microwave oven was enough
of a valuable experience, and I wasn't even playing with that one, just
trying to use it when it "went off". By the way, the capacitor in a microwave
oven is even more dangerous, and is charged to 5000 volts.

Paul
 
D

dawgs

Yes, this and other faults suggest a dead or dying Power Supply
Unit.  None lasts for ever and they last anything from two to 10
years.   I have had three die during use in 28 years.

PSUs are cheap ($30) and rapidly installed.  Family PC stores usually
test without charge and instal a new PSU without charge.
 --
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)

If your machine is shutting down, it's for a reason. The Bios is kind
of a fuse or circuit breaker too. If your current HD is fine and is
still operational, I would get a bare bones PC and install your HD in
the new machine, assuming that you're OS is also located there. And
yes, it could also be the PS, a stuck or broken fan or another
component. If your case is hotter than normal, that would also be a
clue.
 
G

GMAN

No one has mentioned the topic of collateral damage yet.

There are some power supplies, that when they die, they damage
stuff in the computer. There is a Bestec brand supply that does that.
When it dies, it's something like the 5V rail that goes above its normal
voltage. Directly connected components (motherboard, hard drive, CDROM,
keyboard,
mouse perhaps) are at risk, while memory and CPU may survive and be reusable
in a new motherboard.

I'd say chances are good it won't affect you, but take a look at the
label on the power supply and see what brand it is.


Paul,

You left out the possibility that its a bulged or blown capacitor or two,
or three etc.....
 
P

Paul

GMAN said:
Paul,

You left out the possibility that its a bulged or blown capacitor or two,
or three etc.....

It could even be a failure which is invisible to a quick inspection.
Capacitor failures, due to the capacitor plague era, are a popular
reason for failure. Bulging or leaking are good bets in that case.
But sometimes, a cap can be out of spec, and still look reasonably
good when you're staring at it.

In this case, the only reason for wanting to do a post mortem, is
to see whether it's just more classic bad capacitors or not. I
don't think there is much chance of repairing it, and I'm not
encouraging a repair attempt, as it just isn't worth the time.
There are people who repair them for fun, as a hobby, but that's
not me :) Finding good quality caps is part of the problem,
and even if I was going through the parts bins at work, I doubt
I could dig up enough of the right values, to re-cap a power supply.
Let alone stock the caps here at home.

And virtually any caps I can see for sale locally, are crap, so
they're not an option.

One of the problems, is the size of the caps. Bad caps tend to be
one case size smaller than good quality ones. You might buy a
good quality one, only to find it doesn't fit on the PCB where
the old one was. If the board density left room for a good one,
then repair would again be a worthwhile option. But I've run into
cases in the past, where I couldn't fit the replacements I'd got,
and leaving them "flying by their leads" isn't very professional.
So the practical side of repair is... frustrating. And we're not
even talking about the problems while soldering (trouble getting
the caps off the board).

Paul
 
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J

John Gordon

In said:
And -- here's the bad part -- after ten seconds or so there was a
noticeable burning smell, so I quickly shut everything off and unplugged
it.

The problem indeed turned out to be a bad power supply. I picked up
a Corsair 600W PSU over lunch and installed it that evening, and the PC
has been working fine since.

Thanks everyone for your advice!
 

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