I recently revisited my car after a few weeks out of my hands, and seconds after turning the key and the unit powering up, the sound of popping and shrapnel in the amp was heard and the smell of smoke escaping, before it quit being an amplifier. I opened it up to see a little cluster of four 47uF capacitors had all exploded. I removed and replaced each one and powered the unit up again with a glass shield over them. They exploded again almost immediately. Nothing else in the unit seems damaged/corroded/damp etc., in fact it all looks very clean and new. What is going on?

What has probably happened is a short somewhere in the amplifier. Here are some possible scenarios:

1. When the new capacitors were installed, make sure that no solder shorted any pads on the circuit board to anywhere else.

2. There is probably a resistor upstream of the capacitors that has shorted but still appears to be fine. Look at the circuit board & follow the traces that connect to the 2 terminals of each capacitor and follow them to other components. Examine them very carefully. Pull on the wire terminals of upstream & downstream components to ensure they are solid. Check each side of the component with an ohm meter. If a zero resistance is given, or no (open) resistance is given the component could be in question. To properly check it out, one side of the resistor must be pulled up from the board, then check the resistance again. If out of spec, it would need replaced & then it would properly voltage limit the capacitors, keeping them from going up in smoke.

3. This can be a very tricky problem without a schematic. See if you can get your hands on one, it makes circuit tracing much much easier