How hard is it to replace capacitors?

[emboss]

I've got a Soltek 75DRV5 that seems to have got bitten by the bad capacitors bug. Admittedly, it's probably got 20K+ power-on hours, so it may just be cheap capacitors failing :) All four of the 2200uF CPU VRM caps have leaked at the top, one of the two memory 2200uF caps is bulging at the top, and a 1000uF cap next to the AGP socket is also bulging at the top. None of them appear to lost anything out the bottom, though it is a bit hard to tell.

Amazingly, the system is still perfectly stable, and the MOSFETs and toroids are still quite cool. I'm guessing that the caps haven't failed completely yet ...

I've done some small electronics projects in my time (various kits, a few self-designed things) and am quite comfortable with soldering double-sided boards and SMT stuff. However, I've never touched anything as complex, or as layered, as a motherboard, nor have I done a lot of desoldering, so I really don't know what I'm in for. There's lots of horror stories about ripping up tracks and delaminating the boards, but there's also quite a few sites that say it's quite easy.

I'm having a bit of a look around for old/dead boards to practice on, but I'd be interested if anyone could help with a few questions ...
1) What sort of level of experience do you really need to pull this off?
2) Any good links to read ...
3) If I run the board till it gets unstable (ie: where I have nothing to lose by attempting repair), will this have damaged other components?
4) Good places to look for dead motherboards :)

[orionlion82]

http://www.ocforums.com/showthread.php?t=414664

maybe if you ask nicely... maybe via PM- this member can help?
no guarentee he'll be willing, but it seems hes been sucessful.

[four4875]

The worst thing ive done so far is replacing an onboard video connector, and it wasnt too terrible, just time consuming.

All you really have to do is heat the legs while rocking the cap so it pulls out the leg you're heating, till they're both out, then clean out the hole. might have to add al ittle solder and heat it and stick a needle through to get it opened all the way, or battle with a desoldering iron / bulb / solder sucker till its open, plop in the new cap, add solder and you're done. I havnt had any problems with delamination at all, using 30 to 40 watt irons. if you run the boad to the point of instability, you shouldnt have any problems with other hardware dyeing, it will just be choppy power to them to cause the instability. You should be fine on the other hardware aspect of it.

good luck in finding the answer to your problem :-)

[emboss]

Thanks for the replies :) One thing which I was thinking about doing was chopping the (dead) capacitors up so that I only have the legs remaining, then removing the legs one by one. I'll see if this is easier or harder once I find a couple of cadavers to test on.

[ThePCGuy]

http://www.ocforums.com/showthread.php?t=414664

maybe if you ask nicely... maybe via PM- this member can help?
no guarentee he'll be willing, but it seems hes been sucessful.

Well I'm flattered. :-D, that's the first time I've ever been recommended to someone on these forums, thanks. Anyways, I'll do my best to try to explain how I've replaced capacitors on my motherboards.

1: Get your tools ready, I typically use a 15/30 watt soldering iron from Radioshack. Also, make sure you have the correct solder for the job. People typically recommend a rosin cored solder. I've been using a .032 diameter 60/40 roll of solder from radioshack. It's the lightest/smallest that I've got and has been working find so far. Make a list of the capacitors that need to be replaced. You can find out the ratings of each capacitor by reading the side of the capacitor. Capacitors are measured in Capacitance and Volts. If there are 4 similar capacitors in a row and 3 of 4 are leaking, I would recommend replacing all 4 capacitors. I don't like to do my work twice. Order your capacitors, I personally have been using Nichion capacitors (some people don't like them, I do so far) from Mouser.com. If you have a few boards to fix, order all of your capacitors at once and save some money on shipping. A order I recently placed was $3.83 with $6.00 shipping. Next we'll move on to desoldering.

2: Make sure that the tip of the iron is clean and has a nice point on it. Tin the tip by touching a bit of solder to the tip. Next hold the soldering iron at a 45' angle to the board and lightly rest on the solder joint. While doing that (quickly, don't want to overheat the components) rock the capacitors leg out. So if you are heating the right leg, push to the left and the leg will pull out of the board. Next do the same to the oposite leg and remove the capacitor. I would recommend only removing similar capacitors (same ratings) at one time to reduce confusion as to what type of capacitor goes where.

3: In order to clean the hole in the board I've been using sewing straint pins. I lightly place the pin on the top side of the motherboard into the divet that's left in the solder. I then quickly place the tip of the soldering iron on the backside solder joint again and I rock the pin back and forth until it penetrates the solder joint. Be gentle, but be firm. After a few tries you should get the trick down. Do this to both holes for each capacitor.

4: After all your holes are clean you can start to replace the capacitors with your new capacitors. Make sure your polarity is right for the capacitor and gently rock the capacitor down into the board while making sure the legs are straight. Push the capacitor down until it's level on the board and flush against the board. At this point turn the board over and while maintaining pressure on the capacitor (to keep it from pushing away from the board) lightly heat the joint and apply a small amount of solder to the joint. This process should only take roughly 3 sec. max. (make sure your soldering tip is still clean). Do the same procedure to each leg for each capacitor and double check that the capacitors are still flush on the board. If not, simply push on the capacitor, then re-heat the joint and it will move and quickly cool into place. Once you are done with all of your capacitors snip the extra parts of the legs off (not too long or too short) and test it out. I've done 6 so far (first one wasn't pretty, check the link that was posted) and all work. I've gotten much better as I've done more. I've got 2 more coming now that I'm hoping to revive. I've got two really exciting ones that I did, my 2nd board I fixed was my 1st nForce board. I had used it for awhile (Epox 8rda+ rev 1.1) and loved it. Well an offer came up that I couldn't resist and I sold it. Well fast forward 3 years and the caps went bad. I liked the board too much to throw it away so I fixed it. It's running very well and paired with 512MB of PC3200 and a Athlon T-Bird 1.133 and a Radeon 9600xt it runs BF2 very nicely :). I also fixed a good friend 8kha+ that I had sold him (refurbed board, caps died on it about 2 years later). He is ecstatic to say the least. It runs like a champ again. I enjoy fixing stuff. Can you tell?

- Jim

[RJARRRPCGP]

http://badcaps.net