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Leaky Capacitors and Computer Instability

Some time back I did an article here about leaky capacitors and linked to some really great photos of a “healthy” mainboard capacitor and “bulging” capacitors. The long-story short version is this… Once upon a time there was some corporate espionage among capacitor manufacturers. Someone had a really good electrolyte formula (the goo inside a capacitor) and the other companies wanted it. Well, what they wound up getting was not the real formula, but a fake. So… any capacitors made with the false formula will be more likely to fail. In fact, it’s as though over time the electrolyte expands causing the capacitors to bulge and in some cases leak. Why is this computer related? Because if you crack the cover of a pc and look there are dozens of electrolytic capacitors on the mainboard.


I’ve seen some active failures (smoke) and I’ve seen some that are just “bulging”. So… when I see a system that is acting unusual. Strange and seemingly random freezes and the hard drive doesn’t seem to be the problem, the next thing I start suspecting is that the system board has problems. The most recent one that I saw had a row of capacitors next to the CPU and all had bulged and a tiny bit of crusted electrolyte had leaked out on each.

The symptoms the system gave were as follows: to start out with the power supply was dead – not sure if this could be caused by the capacitor issue on the mainboard – (fluctuating power demands?) but upon replacing the power supply the system failed to post – it gave a long beep followed by two short ones. This is when I inspected the board and found the crusty/leaky capacitors.

So, I made sure video/cpu and memory were firmly seated and tried to boot again. This time it started up and made it partway up to a scandisk. In fact it was at 52% when it just stopped, frozen. I waited a little while, but the system had really hung. So, I powered down again and doublechecked all on board connections. Tried a third time, again long post beep… again… start to boot and make it through the scandisk to the desktop and it freezes while accessing the old tape backup. Reboot… long post beep – long post beep… then finally successful boot to the desktop and a seemingly stable system.

At this point I put the cover back on and set it up right and tried to make sure that everything was working… it was. So, I held my breath, shut it down and started up again and all seemed well.

The moral of the story is…. after things warmed up the system seemed fine. However, it’s in the process of failing due to the leaky capacitors and I advised the owner to make plans to replace it. In this case it was fine after it warmed up but considering the nature of failing capacitors it’s impossible to say that’s always the behavior you’ll see…. it may be that they do fine cold and when it warms up it starts going “loopy”. So… if you’re having unexplained flakey behavior it could just be that your the victim of a 10-15 year old case of corporate espionage gone bad.

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Posted by on July 7, 2008.

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Categories: Computers, Hardware

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