Reverse polarity on Power inputs

If it was properly fused, there may be no damage.

If it was not properly fused, it may have blown the reverse protection diode (if it had one), the PS FETs and the power supply driver IC. If there were op-amps on the primary side (used in the protection circuits), they may have failed also. It could also have open traces.

Generally, if this happens, the damage isn't expensive to repair unless it's a large amp.
 

jol50

Member
2007-11-08 2:14 am
I have an amp right here that had a smoked ground to the case, then I see the ground is blown near the power terminal also thus killing the amp. Do not see any shorts on the outer case but they could have hooked it up wrong. Have not fixed yet so don't know if it did other damage, but most things test good in there; diodes/PS/outputs. It burned the solder right off two jumpers to the case ground screw. Its about 1000w. Only so many reasons it would do that. However the bottom cover is worn in a spot where it rubbed on metal possibly. I still go old school and never mount amps on metal.

I've seen a bunch of amps that did not work, they were cheap and had a burn spot on the case....blew the ground trace every time in that amp. Or they put the 12v on the ground terminal with it touching metal. A few had other issues. They came with boxes I was buying but I did end up fixing most of them and selling them for $20 each....for fun I guess.
 

jol50

Member
2007-11-08 2:14 am
It has been a long time, but back when I installed we were not even allowed to mount an amp touching metal. Maybe it was noise issue or some strange amp they sold there I can't remember now (mostly LP, pioneer, kenwood...maybe for GM120s). There is rarely a good place to mount an amp on metal in a car anyway....but yes the ones I have looked at the case is grounded.

That amp worked BTW, it was just a blown ground. The PS had power but the driver did not.