Originally Posted by hlmiii
The first post made it clear that the amp was wired backwards. It is possible that this could have torched some part of the component circuitry from the inverted DC power. The subsequent spark situation - without evidence of a blown fuse - would support that possibility.
A fuse will break a circuit that is running too much current. It will not break a circuit running at nominal current with reversed polarity. (The caps, LED's, diodes and chips will do that. Unfortunately ...
Seriously? That is DEAD WRONG!
If he reverses the polarity, the fuse will blow. Why would it not blow? If a bare +12v wire touches ground, the fuse blows. Car audio 101...wire a fuse within 18" of the battery on your positive wire.
I've reversed wires before. It happens. But I've never fried anything because I fuse any positive leads which tie into the car's wiring.
A fuse won't blow from excessive current until it reaches about 200% of the fuse rating...doubt that happened.