For my garage workbench, I am working on putting an old computer in the same chassis as a salvaged integrated amplifier. The computer is a microATX 360Mhz celeron (told you it was old) and the amplifier *used to be* a Sharp unit, with a biggish LCD display and lots of pretty buttons (now in a remote control panel), with TDA chips, 2x20 and 2x60ish, with a decent-sized linear unreg. supply. The CD player made bad noises mechanically and wouldn't play, and I didn't even want to try the tape deck, which didn't like to stay closed. Three large spiders died during the disassembly/cleaning process, along with a few small ones and a couple egg sacs. 
The computer suffered terminal flakiness due to a 70W constant 3.3V+5V rating power supply.
If you read all that, you are a glutton for punishment.
Anyhow, the thing is almost done. I put a full-size ATX power supply in there. I ran the mains leads for the amplifier into the ATX power supply case, and soldered to the input from the power socket. I had already dusted out (almost) all of the shavings from the metalwork required to mount everything for the computer, having already verified the tuner and amplifiers worked.
I wanted to be sure that the motherboard wasn't dead and that the power to the amplifier was ok after that job. I didn't look around inside the chassis before plugging in the mains plug.
Sparks
Flames
Rapid removal of the plug from the socket.
You know how it goes, you've been there.
anyhow, this actually SOLVED a minor problem with the amplifier. Hold the jokes until the story is over please. The first test of the amps once they were all screwed in place showed that they didn't work until the headphone socket-cable was plugged in. The headphone PCB was resting on a hot jumper on the power supply PCB
Well, now it works without the headphone socket plugged in. The sparks came from the exploding resistor on the heaphone socket PCB. The flames came from the corresponding resistors on the amplifier PCB. The motherboard got as far as figuring out there was nothing plugged into it and it beeped at me.
Well, at least the important parts still work.
The computer suffered terminal flakiness due to a 70W constant 3.3V+5V rating power supply.If you read all that, you are a glutton for punishment.
Anyhow, the thing is almost done. I put a full-size ATX power supply in there. I ran the mains leads for the amplifier into the ATX power supply case, and soldered to the input from the power socket. I had already dusted out (almost) all of the shavings from the metalwork required to mount everything for the computer, having already verified the tuner and amplifiers worked.
I wanted to be sure that the motherboard wasn't dead and that the power to the amplifier was ok after that job. I didn't look around inside the chassis before plugging in the mains plug.
Sparks
Flames
Rapid removal of the plug from the socket.
You know how it goes, you've been there.
anyhow, this actually SOLVED a minor problem with the amplifier. Hold the jokes until the story is over please. The first test of the amps once they were all screwed in place showed that they didn't work until the headphone socket-cable was plugged in. The headphone PCB was resting on a hot jumper on the power supply PCB
Well, now it works without the headphone socket plugged in. The sparks came from the exploding resistor on the heaphone socket PCB. The flames came from the corresponding resistors on the amplifier PCB. The motherboard got as far as figuring out there was nothing plugged into it and it beeped at me.
Well, at least the important parts still work.