mainboard capacitor repair problem

Forum Forums General Hardware mainboard capacitor repair problem

  • This topic has 5 replies, 4 voices, and was last updated Jan 3-1:56 pm by Anonymous.
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      I came by a Supermicro dual slot 1 mainboard with onboard SCSI that was unused and still boxed, but with most of the capacitors bulging up and bursting due to bad quality electrolyte. As I have 2 100mhz slot 1 cpu’s and the required RIMM I decided to repair the board with new caps. I have been unable to get a decent looking solder joint on 2 of the caps no matter what I do, having tried extra flux, more cleaning and tinning of the cap wires, &tc, and the small prints on the board surface have now vanished, they were hardly larger than the 0.8mm cap wires themselves. Has anybody been this way, and can offer suggestions for a workable repair. I thought of digging for the print. Is it worth the effort or should I scrap the board? Snapshots show a reasonable looking row of joints then the unsatisfactory 4 from 2 caps.

      One should take note of the poor quality components used on this board. I have other boards years older than this one that have shown no signs of cap failure and still run well.

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        Looks like a shoddy previous repair was attempted.

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          Hey roland,

          What I would do is to clean all of the extra flux off of the board where you are trying to solder.

          If the traces are gone than you can take a small piece of wire and follow to where the trace runs to and solder it there.

          When soldering take a wet sponge and clean the tip of you soldering iron before soldering on the board.

          Also make certain that you are using the electronics solder / rosin core solder and also try and not overheat what you are trying to solder so as to not burn up the traces.


            Thanks for that, I’ll give your suggestions a try. Should I clip off the cap wires short before soldering.? Should I bend them over like I have done or leave them straight up? I have several irons, bought a 100w pointed one after reading some advice on the www suggesting that will help to get quick joints. maybe I will do better with a smaller one? I tried ordinary multicore with lead, then mulitcore lead-free for electronics use, can’t see much difference between them. When I removed the old caps there was hardly any print on the board to solder to in those places. I’ve had mainboards with bulging caps after only 2 or 3 years, it’s shameful.


              Hey roland,

              A 100 watt iron is way to much heat and all you need is a 30 watt pencil tip iron with small gauge rosin core electronics solder and keep the tip clean.

              When replacing the capacitors spread the capacitor leads wide and insert then with leads sticking straight up solder them and then clip off excess lead although not to short.


                For MB soldering, you should use a 30 Watt iron (no more), clean the surface and wipe it with alcohol (90% preferred), use a small diameter solder wire, and use a very thin solder tip. Using extra flux to coat the area before soldering helps. Be sure to clean the tip on a wet sponge often. Apply solder to the tips of the cap wires carefully just to tin them. Most people say apply heat for the count of 3 then apply solder for a count of 3. (You may have to vary the time depending on the thickness of the wire.) And that should do it.

                I purchased thin solder tips on ebay that work good with my iron. Don’t buy junk $5 USD irons. Get good ones like Weller that will last for years. Mine is close to 45 years old. I just change the tips as needed and the electrical connecting cord as needed.

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