Re: Freeze-ups. Is power supply the only remaining possibility?
- From: Paul <nospam@xxxxxxxxxx>
- Date: Wed, 26 Sep 2007 21:55:45 -0400
Not Here wrote:
On Wed, 26 Sep 2007 04:03:24 -0400, Paul <nospam@xxxxxxxxxx> wrote:
Not Here wrote:I'm experiencing persistent freezes--screen freeze, mouse and keyboardIf things were that simple, there wouldn't be any repair shops around :-)
not responding.
I've tried installing XP Pro several times and never make it through
without a lockup.
I was able to run Windows 98 for several hours, but eventually it
froze too. I was also able to run Mini-PE Boot from CD for some time and didn't
have a problem. Also ran Memtest 86 for 2 hours plus, no problems
found. I've switched hard drives among 2 IDE's and one SATA on a PCI to SATA
controller card.
I've used the onboard video and an AGP Video card and the freezes
continue.
The computer is about 3 years old and was working until recently. The
original owner didn't want to deal with this problem so they gave it
to me.
Is the power supply the only remaining possibility? It's the first
thing I thought of but have to buy a new one and I won't be able to
return it if that's not the problem.
Thanks
AsRock 266A Motherboard
Celeron 2.4
512 MB DDR
I'd take a look at the condition of the capacitors on the motherboard.
The board in the picture here, has a two phase Vcore regulator in the
upper right of the picture. The tops of the black cylinders should be flat.
There are about seven of them in the upper right of the photo.
(Four upper right, three middle right.) If there is a brown stain on the
PCB underneath the capacitors, or if the tops of the caps are bad (bulging),
then the capacitors would need to be replaced. Some third parties would
"re-cap" a board for about $50, but since the motherboard is only worth
about that much when new, that is hardly cost effective.
http://www.asrock.com/mb/photo/M266A(Enlarge).jpg
You can verify some things about a power supply, using a multimeter.
But that won't tell you everything you'd need to know. Someone working
in a shop, would have a small amount of test equipment, and a bunch
of stuff dedicated to swapping in and out, for debugging purposes.
For a person at home to become their own "repair shop", could cost
a few bucks, so don't expect the process to be a cheap or easy one.
If you plan to work on computers regularly, you should already
possess a spare supply. It is handy to keep your current machine
running. If you want to keep a spare on hand, make sure you purchase
something of quality, that can be reused in a new build. If you
buy a $20 supply, you'll never know whether your spare supply is
bad, or the system you're working on is bad.
And if you need to know what products to avoid, look at the hundreds
of products on Newegg. There are customer reviews. If you find a
reviewer mentioning they are on their fourth RMA for one of the
cheap power supplies, that should tell you everything you need to
know.
Paul
Thanks so much to all for your replies.
Paul:
The upper two capacitors at middle right next to the CPU are bulging
and have a brown deposit on them.
What would have caused that?
Electrolytic capacitors have a basic life rating. It will be so many
thousand hours at X degrees C. The Arrhenius equation (from chemistry)
predicts that the life rating will double, for every 7C cooler operation
you can manage. So when these parts are rated at 85C, and your
computer case runs at 35C, the 50C improvement means a roughly 2**7 increase
in life, or a factor of 128 times longer. If they were rated for 3000 hours
at 85C, then in your computer, they'd last roughly 3000*128 = 384000 hours.
Obviously, there are limits to the accuracy of an extrapolation like that.
http://en.wikipedia.org/wiki/Arrhenius_equation
For good capacitors, you might predict an average 10 year life before there
is trouble. There were some batches of bad capacitors (billions of bad ones
in fact) that have half the life or less, than expected. The formulation of
the chemicals was stolen by industrial espionage, and they didn't steal
all the info needed to make good electrolyte. The results was several
years of defective merchandise - basically capacitors failing before
their time. Some motherboard makers were affected more than others,
based on who they were buying their capacitors from.
If you know someone who is handy with a soldering iron, you could try
replacing the caps with new ones.
Good caps are hard to find (i.e. lots of hours at a high temp rating).
Stocks in North America would likely consist of crap that would not make
it worth your while to buy them. (Lots of Radio Shack grade parts.) But
some people do spend the time to find the good ones, and you might get
some here that are decent. Based on the "series" information, you could
look them up to see what kind of life rating they have. That is what I'd do.
http://www.badcaps.net/pages.php?vid=22
Caps can be hard to remove from a circuit board. At my old employer, they
used to use extra large holes for the legs of the electrolytics, which made
it a pleasure to replace them (the legs came out real easy). But a lot of
motherboards use a tiny hole, just barely big enough for the component to fit.
You can easily damage the motherboard, trying to deal with that. Doing a good
job, without collateral damage, isn't easy. Even snipping the cap, and
pulling on the legs while the solder is molten, is not a guarantee of
success. You'd want someone who has practiced removing them on a
dead motherboard first, to do the work.
If you cannot repair the caps, and you continue to use the board, eventually
you'll have a MOSFET failure (black plastic, three leads, in the Vcore area).
So once the caps start to leak, the life of the motherboard will be limited,
unless it can be repaired before other parts get damaged. Finding replacement
parts for the other stuff that can get damaged, is a lot harder. Caps are
the easy ones to find.
Paul
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