Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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  #1   Report Post  
Al
 
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Default bulging top capacitors

In trying to figure out why this atx pc won't start, I carefully look ed
at the motherboard. Some of the blue 'can' capacitors are straight across
the top, with the X shape. But others are bulged up. Some have a smudge
of some yellow material on the bulged tops, and one has a smudge of
black. Is this normal, or a sign of failure? Thanks.
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Time for a new motherboard. There is a known problem with poor quality
capacitors from about 2 years ago on many brands of motherboards. Pull
the CPU now before it gets fried and buy a new mother board.

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James Sweet
 
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"Al" wrote in message
. ..
In trying to figure out why this atx pc won't start, I carefully look ed
at the motherboard. Some of the blue 'can' capacitors are straight across
the top, with the X shape. But others are bulged up. Some have a smudge
of some yellow material on the bulged tops, and one has a smudge of
black. Is this normal, or a sign of failure? Thanks.


You've got a board made during the bad electrolyte fiasco, replace all the
electrolytics on the board, the bulging ones are completely shot, the rest
of them WILL fail shortly. Be sure to clean up the electrolyte that leaked
out, it's corrosive.


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James Sweet
 
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wrote in message
ups.com...
Time for a new motherboard. There is a known problem with poor quality
capacitors from about 2 years ago on many brands of motherboards. Pull
the CPU now before it gets fried and buy a new mother board.


Why not repair it? I've fixed a whole pile of motherboards with this
problem, never cost me more than about 15 bucks. THey can be tricky to
desolder though, I had to use a 140W Weller on the ones with a large ground
or vcc plane.


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CJT
 
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Al wrote:
In trying to figure out why this atx pc won't start, I carefully look ed
at the motherboard. Some of the blue 'can' capacitors are straight across
the top, with the X shape. But others are bulged up. Some have a smudge
of some yellow material on the bulged tops, and one has a smudge of
black. Is this normal, or a sign of failure? Thanks.


See:
http://www.spectrum.ieee.org/WEBONLY...eb03/ncap.html

I've repaired some such boards, and had one repaired by the manufacturer
at reasonable cost; whether doing so is worthwhile in your particular
case depends on factors (like cost and the hassle of switching machines)
that only you can decide.

--
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minimize spam. Our true address is of the form .


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www.badcaps.com

....says it all

regards, Ben

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Harvey
 
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"James Sweet" wrote in message
news:gelId.13643$IP6.13358@trnddc05...

wrote in message
ups.com...
Time for a new motherboard. There is a known problem with poor quality
capacitors from about 2 years ago on many brands of motherboards. Pull
the CPU now before it gets fried and buy a new mother board.


Why not repair it? I've fixed a whole pile of motherboards with this
problem, never cost me more than about 15 bucks. THey can be tricky to
desolder though, I had to use a 140W Weller on the ones with a large
ground
or vcc plane.

Probably because you can buy a new motherboard cheaper than a set of new
capacitors for the older one.

And then there's the added issue of the faulty capacitors over-stressing the
regulators making them go thermally intermittent too, resulting in hours of
wasted time spent changing the capacitors only to find the mobo is no better
or even worse than it was before you started.

More info about bad mobo caps here http://badcaps.net/




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Why not fix it? The replacement cost of a motherboard that will take a
cpu and memory from a couple of years ago is what, $45 for a good one
and it will be upgradeable to the newer and faster cpu come upgrade
time.

Then there is the opportunity cost of the time involved. If it takes
one hour to replace all the capacitors on the board, and the board does
wind up being good, how much was that one hour worth?

  #9   Report Post  
CJT
 
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Harvey wrote:
"James Sweet" wrote in message
news:gelId.13643$IP6.13358@trnddc05...

wrote in message
roups.com...

Time for a new motherboard. There is a known problem with poor quality
capacitors from about 2 years ago on many brands of motherboards. Pull
the CPU now before it gets fried and buy a new mother board.


Why not repair it? I've fixed a whole pile of motherboards with this
problem, never cost me more than about 15 bucks. THey can be tricky to
desolder though, I had to use a 140W Weller on the ones with a large
ground
or vcc plane.


Probably because you can buy a new motherboard cheaper than a set of new
capacitors for the older one.

And then there's the added issue of the faulty capacitors over-stressing the
regulators making them go thermally intermittent too, resulting in hours of
wasted time spent changing the capacitors only to find the mobo is no better
or even worse than it was before you started.

More info about bad mobo caps here http://badcaps.net/




The flip side is that the price of the motherboard can be irrelevant
compared to the cost of new memory (since current motherboards often
use a different sort) and the time to reinstall software and get
everything working as before. And capacitors are pretty cheap; you
ought to be able to replace them all for under 30 bucks +/-.

It's not an easy call, but I've done a couple of replacements, and
they've worked well for me.

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Art
 
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IMHO, after the period of time it has taken for these caps to fail, and
probably contribute to other damage, would it not be apparent that one
should consider upgrading to a faster CPU, more memory, and new motherboard
that has the USB2 feature,etc built in. I have done many computers this way
for less than $200 USD and have a fine, faster, more reliable piece of
equipment afterwards.
"Just my 2 cents worth", of course,being a technician I have resoldered IDE
connectors, SMD regulators and components, replaced caps, etc just to get a
unit operational. Then, after a period of time find out that other devices
indeed were stressed, inclusive of the power supplies.

"CJT" wrote in message
...
wrote:
Why not fix it? The replacement cost of a motherboard that will take a
cpu and memory from a couple of years ago is what, $45 for a good one
and it will be upgradeable to the newer and faster cpu come upgrade
time.

Then there is the opportunity cost of the time involved. If it takes
one hour to replace all the capacitors on the board, and the board does
wind up being good, how much was that one hour worth?

In my experience, finding and installing a suitable replacement
motherboard will take about as long or longer. That it's "upgradeable
to the newer and faster cpu" probably means it uses a different chipset,
which means the OS may need reinstallation, too.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .



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CJT
 
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Art wrote:
IMHO, after the period of time it has taken for these caps to fail, and
probably contribute to other damage, would it not be apparent that one
should consider upgrading to a faster CPU, more memory, and new motherboard
that has the USB2 feature,etc built in. I have done many computers this way
for less than $200 USD and have a fine, faster, more reliable piece of
equipment afterwards.


Sure -- been there, done that. But I've also been in the situation
where I've done what seemed like a simple upgrade and found that key
pieces of software could no longer be made to run due to differences
in the BIOS, etc.

Each case must be evaluated on its own merits.


"Just my 2 cents worth", of course,being a technician I have resoldered IDE
connectors, SMD regulators and components, replaced caps, etc just to get a
unit operational. Then, after a period of time find out that other devices
indeed were stressed, inclusive of the power supplies.


"CJT" wrote in message
...

wrote:

Why not fix it? The replacement cost of a motherboard that will take a
cpu and memory from a couple of years ago is what, $45 for a good one
and it will be upgradeable to the newer and faster cpu come upgrade
time.

Then there is the opportunity cost of the time involved. If it takes
one hour to replace all the capacitors on the board, and the board does
wind up being good, how much was that one hour worth?


In my experience, finding and installing a suitable replacement
motherboard will take about as long or longer. That it's "upgradeable
to the newer and faster cpu" probably means it uses a different chipset,
which means the OS may need reinstallation, too.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .






--
The e-mail address in our reply-to line is reversed in an attempt to
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James Sweet
 
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"Harvey" wrote in message
...

"James Sweet" wrote in message
news:gelId.13643$IP6.13358@trnddc05...

wrote in message
ups.com...
Time for a new motherboard. There is a known problem with poor quality
capacitors from about 2 years ago on many brands of motherboards. Pull
the CPU now before it gets fried and buy a new mother board.


Why not repair it? I've fixed a whole pile of motherboards with this
problem, never cost me more than about 15 bucks. THey can be tricky to
desolder though, I had to use a 140W Weller on the ones with a large
ground
or vcc plane.

Probably because you can buy a new motherboard cheaper than a set of new
capacitors for the older one.


Where can you buy a new motherboard for less than $15?


And then there's the added issue of the faulty capacitors over-stressing

the
regulators making them go thermally intermittent too, resulting in hours

of
wasted time spent changing the capacitors only to find the mobo is no

better
or even worse than it was before you started.


I've *never* run into a board that was intermittant after replacing the
caps, I suppose it could happen but it's rare. I say either repair the board
and keep it out of the landfill, or get a new board, CPU, RAM, etc to
upgrade to a newer generation.


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James Sweet
 
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"Art" wrote in message
...
IMHO, after the period of time it has taken for these caps to fail, and
probably contribute to other damage, would it not be apparent that one
should consider upgrading to a faster CPU, more memory, and new

motherboard
that has the USB2 feature,etc built in. I have done many computers this

way
for less than $200 USD and have a fine, faster, more reliable piece of
equipment afterwards.



It's certainly an option if you need a faster machine, but in a lot of cases
$15 to get the computer back online vs $200 plus a bunch of time
reinstalling the OS and all the applications (or if you get really lucky, a
few tricks to reinstall the drivers), replacing the caps starts to look
appealing.


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JURB6006
 
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The other thing to consider is if it's running XP it uwill not/u migrate to
a new mobo. You must reinstall. Any apps that have significant registry entries
also will need to be reinstalled.

If you're running 98 and change the mobo you need to start in safe mode and
remove all references to the old mobo resources. If you don't you might get
nagged by a BSOD once in a while. XP won't even get into safe mode with such a
drastic hardware change. While the hardware change bothers 98, if you can
manage not to reinstall it your apps will run right. The exception might be
certain games if you wind up with a different vidcard.

Actually anyone who's still running 98 is doing so for a very good reason.

JURB


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On 23-Jan-2005, CJT wrote:


"Just my 2 cents worth", of course,being a technician I have resoldered
IDE
connectors, SMD regulators and components, replaced caps, etc just to
get a
unit operational. Then, after a period of time find out that other
devices
indeed were stressed, inclusive of the power supplies.


"CJT" wrote in message
...

wrote:

Why not fix it? The replacement cost of a motherboard that will take a
cpu and memory from a couple of years ago is what, $45 for a good one
and it will be upgradeable to the newer and faster cpu come upgrade
time.


It's no easy task to replace all the caps on a multi-layer board
with plated through holes. You are likely to end up with a dead board.
Try fault tracing on that one.
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Harvey wrote:
Probably because you can buy a new motherboard cheaper than a set of new
capacitors for the older one.


That's nonsense. A handfull capacitors will cost between 10 and 25
dollars, a motherboard will cost between 30 and 150 dollars.

And then there's the added issue of the faulty capacitors over-stressing the
regulators making them go thermally intermittent too, resulting in hours of
wasted time spent changing the capacitors only to find the mobo is no better
or even worse than it was before you started.


It happens, but reparing a motherboard does not take 'hours'. You put in
the electrolytics, if it does not work, take them out and throw the
board in the parts bin. Have you ever noticed the name of this
newsgroup?

---
Met vriendelijke groet,

Maarten Bakker.
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larry moe 'n curly
 
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Al wrote:

In trying to figure out why this atx pc won't start,
I carefully looked at the motherboard. Some of the
blue 'can' capacitors are straight across the top,
with the X shape. But others are bulged up.


It's a sign of impending doom, and if left unfixed may eventually cause
failure of the components connected to them, like the toroid coils and
MOSFETs. I had one MOSFET heat up enough to turn from black to light
tan, and after replacing the caps and installing a new MOSFET, it ran
at over 100C, even with a big copper heatsink, because the chip driving
it had been wrecked, too.

Probably the safest way to replace caps without using special equipment
is by cutting them off on top -- right through their cans, so that the
pins can be unsoldered individually. But I learned that multilayer
boards need a lot more soldering iron power than normal, and even 40W
may not melt the solder right away while 50W will. I used 2mm copper
desoldering braid to clean out the holes because I didn't have very
good luck with solder suckers.

I'd replace even the caps that still look normal because recently one
of my Antec PSUs had one cap bulge while the others were not only still
flat but also tested good with an ESR meter. Yet one of those "good"
caps bulged a week later and showed high ESR.

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James Sweet
 
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It's no easy task to replace all the caps on a multi-layer board
with plated through holes. You are likely to end up with a dead board.
Try fault tracing on that one.


I haven't found it to be particularly hard, just use a 140W Weller soldering
gun, you need a LOT of heat but if you have the right tools it's pretty
easy.




  #28   Report Post  
Lee
 
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JURB6006 wrote:
The other thing to consider is if it's running XP it uwill not/u migrate to
a new mobo.


Whilst it's not something I'd recommend, it most definitely *will*, and
I've done it countless times. Same method as 98, just remove the DM
tree, change the mobo and reboot.
I've had no issues doing this across different chipsets and different
CPUs, even across different HDDs.
Of course if the machine will not currently boot into XP, then it will
need a repair installation after changing the mobo.


Lee
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  #29   Report Post  
 
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CJT wrote:
I did, actually.


Maybe you miscalculated something. Btw, a chopper in a TV is _not_ a
motorcycle, allthough it does have something to do with dutycycles most
of the time.

---
Met vriendelijke groet,

Maarten Bakker.
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