I have a Rockford Punch p400-4 that was given to me, had to idea whether it worked or not so I hooked it up to the car and to my surprise I got smoke 
The first thing I noticed was with the car off, connecting the B+ resulted in the remote wire having a current, enough to power a small led that I have so I know when the amp is on next to the hu. This seemed strange to me so I opened it up and discovered what I believe to be the power supply transistors burnt.
With Barry's help I ordered the correct power transistors. I am now having trouble figuring out how to test the gate resistors, which I believe are the surface mounted components next to the gate on the fets, and the drive transistors. If anyone has the schematics for this amplifier or the gate resistor values I'd really appreciate it, and any other help with trying to fix this amp. Thanks
The first thing I noticed was with the car off, connecting the B+ resulted in the remote wire having a current, enough to power a small led that I have so I know when the amp is on next to the hu. This seemed strange to me so I opened it up and discovered what I believe to be the power supply transistors burnt. With Barry's help I ordered the correct power transistors. I am now having trouble figuring out how to test the gate resistors, which I believe are the surface mounted components next to the gate on the fets, and the drive transistors. If anyone has the schematics for this amplifier or the gate resistor values I'd really appreciate it, and any other help with trying to fix this amp. Thanks
The pictures weren't attached to the first post and I'm unable to edit it so I'll post them here. Also since I didn't clear this up the amp does not power on, if I connect the ground them the power transistors smoke.
Amp Overview: http://i40.tinypic.com/29e5hec.jpg
What I believe to be the driver transistors: http://i44.tinypic.com/5y7pzl.jpg
What I believe to be the gate resistors: http://i43.tinypic.com/xgftq1.jpg
Output transistors: http://i39.tinypic.com/s3onx1.jpg
Where the 4 power transistors were: http://i42.tinypic.com/uvxhd.jpg
Amp Overview: http://i40.tinypic.com/29e5hec.jpg
What I believe to be the driver transistors: http://i44.tinypic.com/5y7pzl.jpg
What I believe to be the gate resistors: http://i43.tinypic.com/xgftq1.jpg
Output transistors: http://i39.tinypic.com/s3onx1.jpg
Where the 4 power transistors were: http://i42.tinypic.com/uvxhd.jpg
The power supply fets are likely HUF75344G3's the gate resistors are connected to the gate leg of the power supply fet. That would be leg number 1 all the way to the left. Just follow the trace from the gate pad where the gate leg of the fet would solder to the board and you will run right into it. You can test them with a digital multimeter touch the black probe on one end and the red probe on the other end and see what resistance in ohms you read.
The gate resistors will have the value printed right on them if you are not sure how to decipher the value post what the number is and I can tell you what it is. Its hard to tell Rockford used alot of different values in different amps. They are likely 60.4 or 22.1 which are a metric size I believe are 0805 size or 2012 metric.
The driver transistors Will be marked 1AM and 2A and are near the power supply fets or near the PWM chip the TL494C not 100% on this amp without a schematic.
You can e-mail or call Rockford and they will send you a schematic in PDF form via e-mail, they are really good about that.
The gate resistors will have the value printed right on them if you are not sure how to decipher the value post what the number is and I can tell you what it is. Its hard to tell Rockford used alot of different values in different amps. They are likely 60.4 or 22.1 which are a metric size I believe are 0805 size or 2012 metric.
The driver transistors Will be marked 1AM and 2A and are near the power supply fets or near the PWM chip the TL494C not 100% on this amp without a schematic.
You can e-mail or call Rockford and they will send you a schematic in PDF form via e-mail, they are really good about that.
I found the driver transistors, and the TL494C. Looks like the gate resistors are right by the gate pad, I posted a picture but it has yet to be approved. How would I test the drive transistors? The resistors have the top burned out so I can't make out the numbers on them.
This isn't the exact model, but like most RF amps not much changed from year to year.
https://sites.google.com/site/brandescm/home/projects/P4004_E.pdf?attredirects=0&d=1
https://sites.google.com/site/brandescm/home/projects/P4004_E.pdf?attredirects=0&d=1
A little update, I replaced the output fets as well as the power supply fets. The amp turned on, blue light, but it was turning on without the remote wire even being in. So I replaced the gate resistors but it seems I didn't solder one on correctly and it cause a small fire So again I replaced the resistors with 51.1ohm resistors suggested by perry since the originals were too burnt to read, ensuring they're all on there correctly now. I also replace the power supply fets once again. Now it turns on but only the protect orange led, which is very dim. Anyone have any ideas what it could be? The output fets are good, could it be the driver transistors? I have yet to replace those.
So again I replaced the resistors with 51.1ohm resistors suggested by perry since the originals were too burnt to read, ensuring they're all on there correctly now. I also replace the power supply fets once again. Now it turns on but only the protect orange led, which is very dim. Anyone have any ideas what it could be? The output fets are good, could it be the driver transistors? I have yet to replace those.
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