Bad electrolytic capacitor teardown


Teardown and analysis of a bad electrolytic capacitor from Electronupdate:

So, there sitting in a dumpster is what looks like a perfectly good monitor… some of the protective plastic on the base was never even peeled off.
A quick power up showed why it was tossed: it simply did not turn on.
I had been reading about the most likely failure mode was the electrolytic capacitors, especially in the power section. A quick disassembly quickly pointed out the likely culprit:
The bulging top is the give away. After replacing it with a capacitor from my parts bin the monitor powered right up looking really good. A fix that only cost me a few pennies.

More details at Electronupdate blog.

Check out the video after the break.

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  1. You can repair some motherboards the same way. Computer power supplies also fail like this. My Toshiba TV set was recovered after my GF found a site where several people had posted the same failure, and one of them listed the PCB designation of the cap that caused it.

    1. I had one of my PC power supplies go out of spec due to two bulging low ESR caps. Changed them and the thing worked fine. I would say in my case the cap was good but it wore out. Cap was close to heat sinks and air flow impeded by other parts, coupled with high dust levels and no air cond, it will definitely reduce expected lifetimes of caps.
      As for motherboards, I think bad caps are less of a problem unless with older boards. I hope most folks don’t own boards with bad caps anymore, and it pays to check the clock battery voltage…

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