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I was using my computer in the morning then later in the afternoon I noticed some bad smell coming from the power supply. As I checked in, I noticed that one of the big capacitors was leaking and dry. The black wraping on it had peeeled out and some black matter was pasted on the sides.My machine has been doing great since, but today it caused trouble. what could have caused this and how do I fix it?

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> what could have caused this? Capacitor plague? > how do I fix it? New PSU? – Synetech Jul 27 '12 at 16:07

That capacitor has blown, probably it's suffering from the dreaded capacitor plague. What you're smelling and seeing is the electrolyte that's leaked out.

Depending on what the capacitor in question is actually doing, you may not see an immediate impact (as you noticed), but things will degrade, and what's worse is that the other capacitors are likely to start failing shortly. You could solder in replacements, but it's probably just best to replace the power supply entirely.

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Many things can cause a capacitor to fail. Manufacturing defects, low quality components, and adverse environmental conditions can shorten the life of the capacitor. Once you see it bulging or leaking, you should consider the device failed and stop using it or you risk damaging any equipment connected to it.

If the capacitor is connected to an accessible board and you're comfortable soldering, you can purchase a replacement capacitor of the same type and rating and very likely repair the device. For a power supply, however, I would very strongly recommend against servicing it yourself unless you absolutely know what you're doing. Power supplies use capacitors to transform voltages, and as a result can store very dangerous levels of electricity. Personally, I would never service a power supply, as the potential risk is too high compared to the cost of a replacement power supply.

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