Another successful repair

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This is the board from a friend’s cable modem. It stopped working, so he opened it up, suspecting bad capacitors, which were the biggest cause of electronics failure between 1999 and 2006 (just my estimate).

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Hard to see from this angle, but that is a bad capacitor. The top is swollen and there is electrolyte leaking out. The rest actually look good, but they are all the same brand and thus also vulnerable.

So I looked in my parts bin to see what I had that matches. I had almost all, with equal or greater voltage ratings. Even got to get rid of some 6.3V ones! The only thing was that instead of a 330uF, I only had a 470uF. I decided not to replace that one,  though I could have. Wait, you say! That was the wrong value, how could you replace it anyway? Well, this is not commonly known, but you can replace a capacitor with another of same or greater voltage rating and UP TO 10x capacitance (or 1/10th), if you have to. The reason is that most capacitors are used for decoupling and filtering and will still perform well. In a cable modem, any critical timing will be accomplished by crystals and smt capacitors.

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It lives!

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