Another successful repair


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).


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.


It lives!

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