a bad capacitor in my mainboard

[µT6]

after reading about the free licenses for windows 8 i decided to see if i could get one

i was preparing the pc to install it by unplugging my hard disk and put a old ide i have around to play with new os i get

while installing win 8 from a usb drive i heard a annoying noise coming from the fan taking air outside the case so decided to clean it, while i was removing the 4 screws i discovered this



i haven't had problems with the pc so i never knew it was failing, in fact you see the cpu fan spinning as normal

no idea when it happened but the mainboard was working a bit weird but nothing serious(maybe just a hunch), this mainboard is 6 years old now

i decided to replace it, i had a old motherboard doing nothing that died some years ago so it was the perfect candidate to donate a capacitor to replace the damaged one

it was very easy to remove it but something that worried me was the capacitor itself, it didn't had one with the exact same characteristics, the one exploded was 1800 µf at 6.3v but the other was 2200 µf at 6.3v

logic says that it shouldn't work but someone on another forum said that this trick can help to maintain stable a overclocked system, never heard of it so i did it anyway, it is a old system and i know that is close to reach his end of life

it was a problem to remove the damaged one, it was in a position hard to reach surrounded by many other components, after a fight it came out, broken, it seems that the tin was lead free making harder to melt it and remove the component

one of the terminals detached from the capacitor, to remove it from the mainboard it took me 30 minutes applying more tin and lots of flux

after all that put the other was a pain too, it was a bit bigger and the tin didn't melted well to make pass trough the capacitor terminals, lots of flux helped but it didn't went the way i wanted but it remained in place, it seems

i reconnected the mainboard and pressed the power button and it worked, i installed windows 8 just for the fun of doing it

[Just17]

something that worried me was the capacitor itself, it didn't had one with the exact same characteristics, the one exploded was 1800 µf at 6.3v but the other was 2200 µf at 6.3v

Values of capacitor around those you mention are for smoothing of the power supply rails usually.
So a slightly higher value of capacitor could be desirable and almost definitely not undesirable.

The voltage value, once it was the same or higher would also not be a concern.
Even if the voltage rating was 10V or 12V it would work well.

All you need to hope for now is that the replacement capacitor has not deteriorated while left idle in the failed motherboard 

[µT6]

yes, that can be a problem, it could blow up like the other one but if that is the case, i will have to change it again or go find one with the same value, i also need a tin remover, really useful

[Just17]

yes, that can be a problem, it could blow up like the other one but if that is the case, i will have to change it again or go find one with the same value, i also need a tin remover, really useful

The value of the one you used will not be a contributing factor IF it does fail.

[µT6]

i know, i said it because others will blow soon, especially ig that was caused by a rail on the psu not working properly

this one could fail for the reasons you gave, it is older than the one it replaced

water might not be in it anymore but mainboard is working so all is fine for the moment

[bnc75ohm]

As the others have stated, the difference in value shouldn't be a big deal.  But when replacing the failed cap be sure to get the polarity correct.

[µT6]

yes, have you place one wrong?

is so beautiful, try not to look at it when it blows up 

BANG!

[DeBaas]

All those capacitors in power cirquits have a problem with switching frequencies after a while.
When one is gone they should all (6?) be replaced.
Used in 24/7 on situations they are gone within 1 max 2 years.
Tolerance is sometimes 50 % so 1500 or 2200 is allright on this power positions.
The soldering is done with other stuff that need higher temperatures than the home soldering irons supply.
If you want to save your mobo take it to a good supplied/trusted repair facillity and ask them to replace all those capacitors for trustworty 115 degrees C long live versions. The Capacitors are not expensive, the tools to replace them............

Good luck,
Ed

[gandy]

I have an old VIA C3 mini ITX that I was trying to use as a media box. I knew that three of the caps were starting to go because they were bulging on top. One day, when I was using it, it went weeeeeeee and shutdown and wouldn't start up again.

I did the same as you described. I figured, nothing to lose even though I don't have much experience soldering on electronics. I was successful with two of them but the third, not so much. I hooked it up and, to my surprise, it posted. The USB ports on the rear are non-functional. They are near the third cap but there is a header on the board so I still have the capacity for two. I think it still works but I haven't used for awhile.

[ThirdOfSix]

I think that if you look at the traces under the board, you will find that the bad capacitor is in parallel with one or two of the others near it. Therefore a different value capacitor will have no effect on the circuit.

Also, it used to be that electrolytic capacitor ratings were  the rated value  -0% to +50%. It may not be that way any more. I have been out out of the design side of things for quite a while.

The point is that, as others have said, using a higher rated part should not be a problem in most situations. In some circuitry like switch mode power supplies, substitutions are not advised. But as computer power supplies are discrete interchangeable units that are for all intents and purposes, unserviceable, this is a problem that should never come up. The one variable that should not be changed is the voltage rating. In an emergency, you can substitute one of higher voltage rating but never lower.

When using an old capacitor, to be on the safe side, it is best to reform  it by connecting it to a bench supply and slowly bringing the voltage up to rated voltage.

If you do not and you hit it with full voltage, it may cause holes to form  which will not be obvious since on some capacitors they are self healing to an extent but may result in failure in the future.

If there is a problem due to age, there is a good chance that the capacitor would heat up on applying power. After you make the repair and run the computer for a while, shut it down and touch the capacitors to see if any are getting hot.

As others have said, if you goof and put it in backwards, and if it is being used as a power supply filter, if will either explode or you will release the magic smoke from the underside of the motherboard at which time you throw away the smoked motherboard.

Good luck.

[µT6]

"All those capacitors in power cirquits have a problem with switching frequencies after a while.
When one is gone they should all (6?) be replaced."

i already mentioned that i kno that others will fail soon

"The soldering is done with other stuff that need higher temperatures than the home soldering irons supply."

it is only done with lead free tin on some recent mainboards, older mainboars didn't used lead free tin so any of the cheap soldiering iron tin will do the job

"If you want to save your mobo take it to a good supplied/trusted repair facillity and ask them to replace all those capacitors for trustworty 115 degrees C long live versions. The Capacitors are not expensive, the tools to replace them"

i know those tools and the procedure that should be done because i worked with those tools in the past so i know how to do it, i know how expensive is when you pay someone and since this is right now my backup pc, if it dies, it won't matter, it will probably become my soldiering toy, also i mentioned that it is a 6 year ld mainboard, not much will be lost if it dies

"I think that if you look at the traces under the board, you will find that the bad capacitor is in parallel with one or two of the others near it. Therefore a different value capacitor will have no effect on the circuit."

i didn't checked that but probably is the case, also explains why this happened yet the system kep working well, only made sudden restarts while playing some games in recent months

"If there is a problem due to age, there is a good chance that the capacitor would heat up on applying power. After you make the repair and run the computer for a while, shut it down and touch the capacitors to see if any are getting hot."

i did that and it is as hot as the rest of the capacitors, none overheated so all is fine for the moment

[ThirdOfSix]

For future reference, if you get some of the original politically incorrect solder such as .025 inch diameter rosin core solder, and tin your old or too small iron with it and then apply it to the joint done with the politically correct solder, it will change the alloy such that it will melt easily with your old tools. You can then use solder wick or a round tooth pick and careful blowing to clear the holes of the old solder.

Then solder the new part in with the evil lead alloy solder and it will work easily.

This way, you will avoid destroying the traces and the motherboard trying to get that new *$%*&#@ solder to melt using old tools.

And if you are worried about lead poisoning, don't eat any of the solder and don't lick your soldering iron to clean it.

[µT6]

"And if you are worried about lead poisoning, don't eat any of the solder and don't lick your soldering iron to clean it."

 

the fear of lead on the tin comes from breathing the smoke coming from the soldiering process for long periods of time, years doing this many times per day, also manipulating the tin alot, something that when you are learning to use the tin soldier is common

it can be dangerous but i'm sure that i have been exposed to lead in greater quantities from other sources for longer periods of time without even noticing it

[ZX80Man]

This reminds me of a story I herd, some time ago.  They say: All electronic devices are packed with smoke from the factory.
The problems start when it begins to leak out!

[JALU]

"And if you are worried about lead poisoning, don't eat any of the solder and don't lick your soldering iron to clean it."

 

the fear of lead on the tin comes from breathing the smoke coming from the soldiering process for long periods of time, years doing this many times per day, also manipulating the tin alot, something that when you are learning to use the tin soldier is common

it can be dangerous but i'm sure that i have been exposed to lead in greater quantities from other sources for longer periods of time without even noticing it

I've been soldering components for decades and it hasn't it hasn't affected it hasn't affected me a bit it hasn't... 
BTW Those long life caps mentioned should be the low ESR type that handle higher ripple current.
Cages.