So one day while working on a Waveshield project a couple weeks ago, we had a big wind storm here, and the power went out. When it came back on, I discovered that two amplifiers have been fried, with both the same symptoms. One in my stereo, and one in a nice studio monitor powered speaker. They both do the same thing: blast incredibly loud 60Hz hum to the speakers, regardless of what goes into them (or what the volume’s set at). The powered speaker has a fuse that blows after a short duration of this, while the stereo fries two little transistors which go up in smoke and explode after a short time. After either of these happen, the noise to the speakers stops; replacing them repeats the process.
I was wondering if anyone’s debugged something like this before? The symptoms are very similar between the two, and other aspects of both keep working (the digital parts of the stereo appear fine: cd player, digital tuner, etc all look like they work; and the indicator lights on the monitor speaker all keep working when that fuse blows). It seems like a similar component or components blew in both cases (and indeed, the amplifier circuits look similar: two big audio amplifier chips on huge heatsinks, big rectifier bridge chip, big filter capacitors, toroidal transformer, etc.). Any ideas where to start?
Thanks for any suggestions anyone might have!