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Amp won't power up,anymore! Even with new parts installed,removed

Rockford Fosgate 100a2 car amp Replaced BUZ power supply transistors then powered it up,Power LED went Dim,powered back down immediately.Removed left channel outputs (IRF540 & IRF9540 I believe)then powered it up and play the right channel all day!
Re installed left channel output transisters,powered up and now it has a shorted power supply.Measures 5 volts at power terminals of amp.I think I possibly swapped the Output transitors(IRF540 & IRF9540) positions in the board and smoked one of the BUZ transister.Also removed the U1620 & U1620R rectifiers,tested them OK and in my hast ,Don't remember their positions on the board either.
Picture of board would help.That would tell me if I reversed positions on those output transistors
Did I reverse positions on output transistors or should I check some transistors farther back in that right channel?
Any advice would be greatly appreciated!

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Hiya, dont have a diag either what you will have to try and is compare the left channel with the right. There will be 2 driver transistors (also likely on heatsink) close to the outputs. Check which driver drives which output on the left, then match it on the right. Those same drivers could very well also be a problem on the right as they often go with the outputs. There is a possibilty they have smoked again. See here to test FETS
http://www.4qdtec.com/mostest.html

Basically the left will match the right but not similar locations but definitely by track joins.

Also check the power resistors at the output. Often also go.

Hope that helps

Posted on Jul 16, 2009

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