Rockford Fosgate T-15004

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I recieved this amp in for repair.

The left rear channels had DC voltage on the output terminals and the right rear channels had alot of distortion.

I found 6 output fets shorted and 6 source resistors burned to a crisp.

I replaced the 6 output fets and the 6 source resistors. I replaced 6 gate resistors. I found numorous smd resistors out of tolerance and replaced them. I replaced 3 pnp and 3 npn drivers the PZTA56 and PZTA06. I found two 22.1 ohm resistors out of tolerance which were linked to the drivers.

The right rear channels produce audio now but the left rear still has bad distortion. There are about four 5D smd diodes that are linked to the drivers as well. Just wondering if those should be replaced.

I am not familiar with these amps and unsure which are the protection transistors. Wanting to see if I could remove something to get rid of the distortion.

Any clues as to where to look?
 
The area thats giving me problems is the 4 series area. I posted a pic the first pic is of the problem area.

The second pic is of the waveform on the left rear channel.

I can make a list for you of all the parts I have changed if it would be helpful in troubleshooting for you.

One thing I thought I would mention when the head unit is turned to half volume there is about 3.657 vdc on the channel, turning it any higher causes my meter to bounce between 3.657 and OL
 

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I replaced D4003, D4004, D4005 and the amp seems to be working. The audio is clean from what I can tell.

The bias control is now working too. I guess the problem was the protection circuit?

I didnt replace D4002 because I am unsure what it is. It has the marking JS but when I look it up it doesnt come back as sot-23 package.

I am not sure if it needs to be replaced or what a good sub would be or even the correct replacement would be.

Any thoughts on D4002?
 
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