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mike49504 8th June 2010 06:02 PM

Rockford Fosgate P8004
I have this amp in for repair. Ive never seen an amp do this before.

The problem with this amp is when u hook it up it will play fine until u shut the car off and then turn it back on.

For example say your running this amp in your car everything is working like it should . Then you stop at a store shut the car off go in get what u need come back out start the car up And the amp will power up but will have no output.

The only way to get the amp back working again is to unplug the rca's shut the head unit off then turn the head unit back on and plug the rca's back in then the amp will work again til u shut the car off.

If this makes any sense.

Wondering what the problem might be and where to begin to check?

Perry Babin 8th June 2010 06:40 PM

Can you duplicate the problem on the bench?

mike49504 8th June 2010 06:51 PM

Yes i can get to do it it on the bench as well. I opened it up and found it had a defective output. Would this cause the problem or is ther something more possibly wrong?

Perry Babin 8th June 2010 07:29 PM

Unless the output was leaking (not completely shorted) or there was a fault in the protection circuit, I don't see how the output could cause it. Repair the channel to see if that solves your problem.

mike49504 10th June 2010 01:53 AM


Somemore checking into this amp i noticed some resistors and transistors that are badly burnt to the point i can read them. Wondering if you know what values i need?


Perry Babin 10th June 2010 02:20 AM

I don't have anything on that amp. Try to get the schematic diagram from Rockford.

speye 14th June 2010 03:24 AM

just had one of em amps opened this morning ...was checking it 4 a friend...wish i had seen this b4 ..could have hepled.

mike49504 28th June 2010 07:22 PM

Im working on this amp again. They are using 20 ohm resistors with 1% tolerance.

Closest thing i have right now is a 22 ohm resistor Wondering will the 22 ohm work?

Perry Babin 28th June 2010 08:19 PM

For the audio drivers?

They should work. You could use them for testing and if there are no other problems, you could order the correct ones.

mike49504 30th June 2010 04:49 PM

Im still repairing this amp. In one section of the amp the resistors and transistors burnt when they burnt they also took the some of the pads along with it. I can figure out where some of the traces went .

1 Side of R133 connects to Q105 in this amp I cannot tell where the other sides of R133 connects since the board is damaged.

Would the schematic tell me where it connects or not?

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