Bulging capacitors on motherboard - Fix?

[SZR48207]

I seem to recall that some folks here are very knowledgeable about the bulging/bad caps that affected a lot of computers back in the early 2000s. I have an older AMD motherboard with this issue, BUT the system seems to run fine most of the time. The caps are definitely bulging, but have not leaked yet.

I have some identical spec Nichion capacitors and decent soldering skills. Should I replace the bad caps? This is a 10+ year old motherboard that I use on a spare computer.. so no major loss if I screw up the job.

 

[VeryNoisyPoet]

Replace them before it gives up at an inconvenient time. I've even brought boards back from the dead by doing that.

 

[redhat]

Yes, absolutely replace them.

 

[vwmaniaman]

I hope you have good soldering skills. The computer boards are multilayer and have copper traces between the board layers. Sometimes it is best to just get the cap off and leave the leads sticking out of the board and wrap the new caps legs on the leftover leads and solder that.

 

[Virtus_Probi]

Originally Posted By: vwmaniaman
I hope you have good soldering skills. The computer boards are multilayer and have copper traces between the board layers. Sometimes it is best to just get the cap off and leave the leads sticking out of the board and wrap the new caps legs on the leftover leads and solder that.

To be honest, I would try something like this.
I was good at soldering for a couple of years, but my skills have faded from lack of use...even at my best, though, I would have tried hard to mess with the board as little as possible and make use of the old leads. Or maybe just solder a more modern surface mount ceramic cap across the leads, although that might be risky as the ESR of the electrolytics may have been contributing a zero that actually improved the stability of the nodes they were sitting on.

 

[PandaBear]

I wouldn't solder a surface mount cap with the big Nichion in parallel, they are not for the same purposes and may end up popping instead.

 

[i_hate_autofraud]

Those caps are usually "low ESR" caps meaning "low effective series resistance" there's a lot of current
going in and out of these, any cap not a low ESR will get hot right away can can blow in 1 year or in 1 minute!

Those caps are part of a switching power supply right on the motherboard.

Be aware that the holes for a caps are "plated thru", since the board is a multilayer board,
self heat-sinking of the board will effect removal.

Use a good hot iron, a solder sucker tool to pull out the most of the solder in the joint,
then start removing the cap, rocking it side to side as you 'walk out' the leads one at a time
with the iron on each lead alternately.
Technique is an issue for sure.

 

[28oz]

I replaced dozens of those in the early 2000's.....................and one the other day, in fact. I'm by no means an expert with a soldering iron, but I've never screwed one up. I'd definitely replace them. Just go slow and pay attention to what the iron's tip is touching.

 

[Lubener]

I have recapped a few motherboards but they were not as old as yours. I wouldn't recap a ten year old motherboard. Run it till it is unreliable and upgrade then.

 

[sleddriver]

Be warned that lead-free solder may have been used thus a cheap hobby iron won't get hot enough. Chip-Quik works fine here. So does upgrading to an adjustable temp. iron.

I had to completely disassemble a 17" PPC iMac to do this operation. While not all AEC's were bulging, all 17 or 18 were replaced as I only wanted to do this once.

Only use low-ESR, computer-grade AEC's.

 

[Colt45ws]

I would give it a shot. I was able to do a few mobos back in the day, no problem.

 

[Virtus_Probi]

Originally Posted By: Virtus_Probi
Originally Posted By: vwmaniaman
I hope you have good soldering skills. The computer boards are multilayer and have copper traces between the board layers. Sometimes it is best to just get the cap off and leave the leads sticking out of the board and wrap the new caps legs on the leftover leads and solder that.

To be honest, I would try something like this.
I was good at soldering for a couple of years, but my skills have faded from lack of use...even at my best, though, I would have tried hard to mess with the board as little as possible and make use of the old leads. Or maybe just solder a more modern surface mount ceramic cap across the leads, although that might be risky as the ESR of the electrolytics may have been contributing a zero that actually improved the stability of the nodes they were sitting on.

I thought about this a little more and trying a modern low ESR ceramic is probably a bad idea here.
It would probably be fine for looking at something in a lab like I would be doing, but not for something you want to work flawlessly for years. I would be happy if a board I used in the lab would stand up to a few months of abuse, and anything that wasn't soldered down on the board was almost disposable (I went through many dozens of LEDs when I was evaluating one my parts, couldn't easily get ones rated for the max output current of the part so I massively overdrove smaller ones and they tended to melt!).

Stick with using caps of the same value and type as the old ones!!