Faulty Motherboard

[M.Joshi]

Hi,

A few days ago, our computer suddenly started to emit black smoke an
stopped working.

Upon further inspection, the power supply had a large hole blow
through the case which seemed as though something had exploded and
black 'gunky' substance leaking from it.

We replaced the power supply and tried testing the motherboard but onl
the fans power up. I have checked that both power connectors ar
connected and also tried removing all peripherals and cards.

Nothing appears on the screen and the motherboard does not even get a
far as the P.O.S.T?

Looking at the electrolytic capacitors near the P4 power connector,
few of them seem 'puffed up' at the top, with a powder substanc
leaking from the top.

I tested the capacitors with the continuity setting on a multi-mete
and two of them showed as a short circuit. I know testing in circui
will not give a conclusive reading so I will de-solder just to mak
sure first.

I am wondering whether the short-circuited capacitor(s) on th
motherboard near the P4 connector caused the power supply to becom
damaged?

Does the P4 power supply affect the motherboard's startup routine?

I thought the BIOS would be powered from the main power connector an
that the P4 power supply is just for the processor?

The motherboard is a Gigabyte P4 Socket 478 GA-8IRML.

I remember reading about Gigabyte having a problem with faulty powe
supply decoupling capacitors a few years back

 

[Dave D]

Hi,

A few days ago, our computer suddenly started to emit black smoke and
stopped working.

Upon further inspection, the power supply had a large hole blown
through the case which seemed as though something had exploded and a
black 'gunky' substance leaking from it.

We replaced the power supply and tried testing the motherboard but only
the fans power up. I have checked that both power connectors are
connected and also tried removing all peripherals and cards.

Nothing appears on the screen and the motherboard does not even get as
far as the P.O.S.T?

The capacitors in the power supply exploded, forcing the motherboard
capacitors to handle unsmoothed DC.

Looking at the electrolytic capacitors near the P4 power connector, a
few of them seem 'puffed up' at the top, with a powder substance
leaking from the top.

Yep, they're toast.

I tested the capacitors with the continuity setting on a multi-meter
and two of them showed as a short circuit. I know testing in circuit
will not give a conclusive reading so I will de-solder just to make
sure first.

They'll all have to be replaced, forget about testing them. There should be
a few capacitors in parallel to give an overall large value. If one in the
'row' has burst or domed on top then you'll have to change all of the
paralleled caps. There's no guarantee this will fix the motherboard though,
there may have been overvoltage which may have destroyed a lot of
components, possibly including the CPU.

Good luck getting those capacitors out- it isn't easy without really good
tools like a very hot temperature controlled iron!

Incidentally, reading a short could be normal- the motherboard draws a *lot*
of current and the supply rail will have a very low impednace.

I am wondering whether the short-circuited capacitor(s) on the
motherboard near the P4 connector caused the power supply to become
damaged?

More likely the other way round. It's possible though that there was a
catastrophic failure on the motherboard, eg a shorted CPU, which caused the
power supply to blow.

Does the P4 power supply affect the motherboard's startup routine?

I thought the BIOS would be powered from the main power connector and
that the P4 power supply is just for the processor?

P4 power supply? You lost me. If you mean the extra connectors and not the
main ATX power connector. They're all tied together in the power supply unit
itself, they don't come from a seperate.circuit IIRC.

The motherboard is a Gigabyte P4 Socket 478 GA-8IRML.

I remember reading about Gigabyte having a problem with faulty power
supply decoupling capacitors a few years back?

And others as well. It wouldn't likely cause your power supply to blow up
though, it would just cause very erratic performance and crashing.

Dave

 

[James Sweet]

Hi,

A few days ago, our computer suddenly started to emit black smoke and
stopped working.

Upon further inspection, the power supply had a large hole blown
through the case which seemed as though something had exploded and a
black 'gunky' substance leaking from it.

We replaced the power supply and tried testing the motherboard but only
the fans power up. I have checked that both power connectors are
connected and also tried removing all peripherals and cards.

Nothing appears on the screen and the motherboard does not even get as
far as the P.O.S.T?

Looking at the electrolytic capacitors near the P4 power connector, a
few of them seem 'puffed up' at the top, with a powder substance
leaking from the top.

I tested the capacitors with the continuity setting on a multi-meter
and two of them showed as a short circuit. I know testing in circuit
will not give a conclusive reading so I will de-solder just to make
sure first.

I am wondering whether the short-circuited capacitor(s) on the
motherboard near the P4 connector caused the power supply to become
damaged?

Does the P4 power supply affect the motherboard's startup routine?

I thought the BIOS would be powered from the main power connector and
that the P4 power supply is just for the processor?

The motherboard is a Gigabyte P4 Socket 478 GA-8IRML.

I remember reading about Gigabyte having a problem with faulty power
supply decoupling capacitors a few years back?

The capacitors being shorted will definitely prevent the board from
working, you could try replacing them but the only boards I've seen
which have had the power supply blow up like that were toast, they had
other bad components.

 

[mistermaniac]

Hi,

A few days ago, our computer suddenly started to emit black smoke an
stopped working.

Upon further inspection, the power supply had a large hole blow
through the case which seemed as though something had exploded and
black 'gunky' substance leaking from it.

We replaced the power supply and tried testing the motherboard but onl
the fans power up. I have checked that both power connectors ar
connected and also tried removing all peripherals and cards.

Nothing appears on the screen and the motherboard does not even get a
far as the P.O.S.T?

Looking at the electrolytic capacitors near the P4 power connector,
few of them seem 'puffed up' at the top, with a powder substanc
leaking from the top.

I tested the capacitors with the continuity setting on a multi-mete
and two of them showed as a short circuit. I know testing in circui
will not give a conclusive reading so I will de-solder just to mak
sure first.

I am wondering whether the short-circuited capacitor(s) on th
motherboard near the P4 connector caused the power supply to becom
damaged?

Does the P4 power supply affect the motherboard's startup routine?

I thought the BIOS would be powered from the main power connector an
that the P4 power supply is just for the processor?

The motherboard is a Gigabyte P4 Socket 478 GA-8IRML.

I remember reading about Gigabyte having a problem with faulty powe
supply decoupling capacitors a few years back?

Just replace the caps that are blown or have "Rubycon" written on it

 

[M.Joshi]

Hi,

Thanks for all your useful suggestions.

All the parts including the CPU have been tested separately o
different computers and they all seem to work.

I did try to de-solder one of the capacitors (GSC brand) that wa
puffed up but it was really difficult using an Antex soldering iron an
doing so seemed to damage the tiny PCB tracks.

Incidently, the capacitors that were puffed up were around the P4 powe
connector (Additional power for the processor).

I figured that maybe a short on the motherboard caused the power suppl
to overheat and one of the capacitors to blow hence delivering a hig
ripple voltage to the motherboard and possibly damaging variou
components?

I think we will just purchase another P4 Skt. 478 motherboard - the
are fairly cheap on Ebay!

Any brands/models to avoid?

Thanks

 

[Wayne]

Hi,

A few days ago, our computer suddenly started to emit black smoke and
stopped working.

Upon further inspection, the power supply had a large hole blown
through the case which seemed as though something had exploded and a
black 'gunky' substance leaking from it.

We replaced the power supply and tried testing the motherboard but only
the fans power up. I have checked that both power connectors are
connected and also tried removing all peripherals and cards.

Nothing appears on the screen and the motherboard does not even get as
far as the P.O.S.T?

Looking at the electrolytic capacitors near the P4 power connector, a
few of them seem 'puffed up' at the top, with a powder substance
leaking from the top.

I tested the capacitors with the continuity setting on a multi-meter
and two of them showed as a short circuit. I know testing in circuit
will not give a conclusive reading so I will de-solder just to make
sure first.

I am wondering whether the short-circuited capacitor(s) on the
motherboard near the P4 connector caused the power supply to become
damaged?

Does the P4 power supply affect the motherboard's startup routine?

I thought the BIOS would be powered from the main power connector and
that the P4 power supply is just for the processor?

The motherboard is a Gigabyte P4 Socket 478 GA-8IRML.

I remember reading about Gigabyte having a problem with faulty power
supply decoupling capacitors a few years back?

Hope this is not a repeat of another post - have a look at this site -
lots of info on how to remove and install, identify bad caps, etc.
http://www.badcaps.net/

Wayne

 

[Dave D]

Hi,

Thanks for all your useful suggestions.

All the parts including the CPU have been tested separately on
different computers and they all seem to work.

I did try to de-solder one of the capacitors (GSC brand) that was
puffed up but it was really difficult using an Antex soldering iron and
doing so seemed to damage the tiny PCB tracks.

I use a 50W temp controlled station and even that doesn't make the job easy.
If you've damaged tracks forget about repairing it.

Incidently, the capacitors that were puffed up were around the P4 power
connector (Additional power for the processor).

I figured that maybe a short on the motherboard caused the power supply
to overheat and one of the capacitors to blow hence delivering a high
ripple voltage to the motherboard and possibly damaging various
components?

I think we will just purchase another P4 Skt. 478 motherboard - they
are fairly cheap on Ebay!

A wise move. You'll likely have no luck with your old one.

Any brands/models to avoid?

Not really, even the very cheap ones have given me good results. If you see
one you like, try and find some reviews before buying.

Dave

 

[Asimov]

"M.Joshi" bravely wrote to "All" (19 Feb 06 23:05:10)
--- on the heady topic of "Re: Faulty Motherboard"

M.> From: M.Joshi <[email protected]>
M.> Xref: core-easynews sci.electronics.repair:358750

M.> Hi,

M.> Thanks for all your useful suggestions.

M.> All the parts including the CPU have been tested separately on
M.> different computers and they all seem to work.

M.> I did try to de-solder one of the capacitors (GSC brand) that was
M.> puffed up but it was really difficult using an Antex soldering iron
M.> and doing so seemed to damage the tiny PCB tracks.

M.> Incidently, the capacitors that were puffed up were around the P4
M.> power connector (Additional power for the processor).

M.> I figured that maybe a short on the motherboard caused the power
M.> supply to overheat and one of the capacitors to blow hence delivering a
M.> high ripple voltage to the motherboard and possibly damaging various
M.> components?

M.> I think we will just purchase another P4 Skt. 478 motherboard - they
M.> are fairly cheap on Ebay!

M.> Any brands/models to avoid?

M.> Thanks.


M.Joshi,

The proper technique for removing electrolytic caps from a multi-layer
PCboard is to snip the cap body itself close to the base, pull off the
remainder, and then desolder the remaining pins 1 at a time. Trying to
unsolder the cap all at once is likely to cause track damage, as you
may have already noticed.

A*s*i*m*o*v

.... That was a fascinating period of time for electronics

 

[AZ Nomad]

The proper technique for removing electrolytic caps from a multi-layer
PCboard is to snip the cap body itself close to the base, pull off the
remainder, and then desolder the remaining pins 1 at a time. Trying to
unsolder the cap all at once is likely to cause track damage, as you
may have already noticed.

I once tried to removed bad caps from a motherboard and couldn't desolder
the pins. It was as if the leaked electrolyte had chemically welded
the pins to the motherboard.

 

[James Sweet]

The proper technique for removing electrolytic caps from a multi-layer
PCboard is to snip the cap body itself close to the base, pull off the
remainder, and then desolder the remaining pins 1 at a time. Trying to
unsolder the cap all at once is likely to cause track damage, as you
may have already noticed.

I've had reasonable luck heating the pins one at a time while rocking
the cap side to side to free them. YMMV of course, but that worked for me.

 

[James Sweet]

I once tried to removed bad caps from a motherboard and couldn't desolder
the pins. It was as if the leaked electrolyte had chemically welded
the pins to the motherboard.

It may very well have corroded them together. I suspect what happens is
the electrolyte corrodes the solder and changes its properties,
increasing the melting point, I've noticed similar behavior with battery
leakage on circuit boards.

 

[M.Joshi]

"M.Joshi" bravely wrote to "All" (19 Feb 06 23:05:10)
--- on the heady topic of " Faulty Motherboard"

M. From: M.Joshi [email protected]
M. Xref: core-easynews sci.electronics.repair:358750

M. Hi,

M. Thanks for all your useful suggestions.

M. All the parts including the CPU have been tested separately on
M. different computers and they all seem to work.

M. I did try to de-solder one of the capacitors (GSC brand) that was
M. puffed up but it was really difficult using an Antex soldering iron
M. and doing so seemed to damage the tiny PCB tracks.

M. Incidently, the capacitors that were puffed up were around the P4
M. power connector (Additional power for the processor).

M. I figured that maybe a short on the motherboard caused the power
M. supply to overheat and one of the capacitors to blow henc
delivering a
M. high ripple voltage to the motherboard and possibly damagin
various
M. components?

M. I think we will just purchase another P4 Skt. 478 motherboard
they
M. are fairly cheap on Ebay!

M. Any brands/models to avoid?

M. Thanks.


M.Joshi,

The proper technique for removing electrolytic caps from a multi-layer
PCboard is to snip the cap body itself close to the base, pull off the
remainder, and then desolder the remaining pins 1 at a time. Trying to
unsolder the cap all at once is likely to cause track damage, as you
may have already noticed.

A*s*i*m*o*v

.... That was a fascinating period of time for electronics

Most of the time the capacitors are soldered really close to the PCB s
you cannot reach just under the can to cut the pins

 

[AZ Nomad]

It may very well have corroded them together. I suspect what happens is
the electrolyte corrodes the solder and changes its properties,
increasing the melting point, I've noticed similar behavior with battery
leakage on circuit boards.

Now that I think about it, I also had trouble getting solder to flow into the
connections. It was as if I was using solder without any flux. The solder
just beaded off.

 

[Daniel Rudy]

At about the time of 2/19/2006 5:28 AM, M.Joshi stated the following:

Hi,

A few days ago, our computer suddenly started to emit black smoke and
stopped working.

Upon further inspection, the power supply had a large hole blown
through the case which seemed as though something had exploded and a
black 'gunky' substance leaking from it.

Through the sheet metal case?

Yikes.

We replaced the power supply and tried testing the motherboard but only
the fans power up. I have checked that both power connectors are
connected and also tried removing all peripherals and cards.

Nothing appears on the screen and the motherboard does not even get as
far as the P.O.S.T?

Dead board. Better to replace it and HOPE the CPU didn't fry.

Looking at the electrolytic capacitors near the P4 power connector, a
few of them seem 'puffed up' at the top, with a powder substance
leaking from the top.

How old is this computer?

I tested the capacitors with the continuity setting on a multi-meter
and two of them showed as a short circuit. I know testing in circuit
will not give a conclusive reading so I will de-solder just to make
sure first.

I am wondering whether the short-circuited capacitor(s) on the
motherboard near the P4 connector caused the power supply to become
damaged?

Does the P4 power supply affect the motherboard's startup routine?

Uh..Yeah... The P4 power supply powers the CPU.

I thought the BIOS would be powered from the main power connector and
that the P4 power supply is just for the processor?

You are wrong. The BIOS is a ROM chip that has the computer's bootstrap
code in it. It is executed by the CPU. If any *ONE* of these (Power,
CPU, CPU Support, Clock, Chipset, Bus, BIOS, etc...) is blown out or not
functioning, then your computer will not boot.

For example: I have a computer motherboard where the USB controller
marked it's passing with a whole lotta smoke. Scorched the board in
fact. Because I don't use the USB on that machine, it continues to
function because it is not a critical part. IOW, the computer can
function without it.

The motherboard is a Gigabyte P4 Socket 478 GA-8IRML.

I remember reading about Gigabyte having a problem with faulty power
supply decoupling capacitors a few years back?

As the story goes...

A few years ago, a couple of people from some manufacturer in China left
the company and took with them the formula for a water based electrolyte
for the capacitors. They then turned around and sold the formula to
various other parts manufacturing companies in China, Tiwain, Hong Kong,
South Korea, etc... The problem is that they only got part of the
formula. As a result, the electrolyte was unstable and would degrade
rapidly at elevated temperatures before the caps blew out. You would
get something like 250-500 hours or so out of it before you had a
problem. Because MY computer uses a motherboard from that era, I check
mine periodically. There is a website that details all this.



Unless you are good with a soldering iron, It's best to replace the
board. They are not that expensive these days.

--
Daniel Rudy

Email address has been base64 encoded to reduce spam
Decode email address using b64decode or uudecode -m

Why geeks like computers: look chat date touch grep make unzip
strip view finger mount fcsk more fcsk yes spray umount sleep

 

[Andy Cuffe]

I've had reasonable luck heating the pins one at a time while rocking
the cap side to side to free them. YMMV of course, but that worked for me.

That's what I do. Also, applying some fresh solder will help conduct
more heat to the connection. The thick power and ground traces to the
caps conduct the heat away very quickly. A temperature controlled
soldering iron is a must (the more powerful the better).

This motherboard sounds like a goner to me. They are rarely
repairable when they fail to post. I doubt the caps are shorted. If
they were shorted, the power supply would shut down. A very large
capacitance can look like a short to a DMM continuity test.
Andy Cuffe

[email protected]

 

[M.Joshi]

This motherboard sounds like a goner to me. They are rarely
repairable when they fail to post. I doubt the caps are shorted. If
they were shorted, the power supply would shut down. A very large
capacitance can look like a short to a DMM continuity test.
Andy Cuffe

[email protected]

When testing the capacitors with a DMM continuity test off the board
they did read as a short until they discharged and then the same wit
the opposite polarity i.e the probe leads switched.

We managed to test the other critical components in other computer
(CPU, Graphics card) and luckily they work fine, so it looks like a ne
motherboard!

Haven't been able to test the RAM though? Hopefully it should be O.K?

On a separate note, the existing RAM is of the 266 variety. Will thi
work on new boards with DDR400 RAM

 

[Asimov]

"M.Joshi" bravely wrote to "All" (20 Feb 06 18:37:07)
--- on the heady topic of "Re: Faulty Motherboard"

M.> From: M.Joshi <[email protected]>
M.> Xref: core-easynews sci.electronics.repair:358797

M.> Most of the time the capacitors are soldered really close to the PCB
M.> so you cannot reach just under the can to cut the pins?


M.Joshi,

Don't try to get under the can. Snip the can itself. It is cheaper,
faster to replace a cap than to try salvaging it, and risk damaging
the PCB. Caps cost what, $1? A PCB costs what, $50? Your time costs?

A*s*i*m*o*v

.... Who's got the Thermonuclear Welding Set? - ToddS

 

[mistermaniac]

As the story goes...

A few years ago, a couple of people from some manufacturer in Chin
left
the company and took with them the formula for a water base
electrolyte
for the capacitors. They then turned around and sold the formula to
various other parts manufacturing companies in China, Tiwain, Hon
Kong,
South Korea, etc... The problem is that they only got part of the
formula. As a result, the electrolyte was unstable and would degrade
rapidly at elevated temperatures before the caps blew out. You would
get something like 250-500 hours or so out of it before you had a
problem. Because MY computer uses a motherboard from that era,
check
mine periodically. There is a website that details all this.

A.K.A. Rubyco

 

[Daniel Rudy]

At about the time of 2/21/2006 7:05 AM, M.Joshi stated the following:

When testing the capacitors with a DMM continuity test off the board,
they did read as a short until they discharged and then the same with
the opposite polarity i.e the probe leads switched.

We managed to test the other critical components in other computers
(CPU, Graphics card) and luckily they work fine, so it looks like a new
motherboard!

Haven't been able to test the RAM though? Hopefully it should be O.K?

On a separate note, the existing RAM is of the 266 variety. Will this
work on new boards with DDR400 RAM?

Maybe. Unless the CPU has a 266 FSB, you will be better off buying the
400. It's not that expensive, and you will see a big performance
improvement over the 266 if you do alot of number crunching.

--
Daniel Rudy

Email address has been base64 encoded to reduce spam
Decode email address using b64decode or uudecode -m

Why geeks like computers: look chat date touch grep make unzip
strip view finger mount fcsk more fcsk yes spray umount sleep

 

[Dave D]

On a separate note, the existing RAM is of the 266 variety. Will this
work on new boards with DDR400 RAM?

Assuming you get a motherboard which supports your existing CPU then yes. If
you want a faster CPU with a faster bus speed then some motherboards will
support slower memory than the bus speed but with a big performance hit.
Basically, if you're re-using your old CPU then yes, your RAM should work
fine.

Dave