Bazooka and exploding fet caper ?

[romeoklr]

Hi all

I need a little help, I have several Bazooka RSA75.2HC amps. They all have the same problem, blown fets... replaced the fets, tested the rectifiers, removed the outputs. trying to isolate the problem. Amp turns on and pegs the amp needle, tested gate resistors .. What gives ? Can I have a B/O tl 494. I do not have access to a O scope at the moment, is there anyway to test the IC w/o an Oscope ? Any input will be greatly appreciated.

Thanks Guys !

 

[Perry Babin]

Unsolder and resolder the connection on the ends of R42 on both sides of the board. Do the same on D6.

Check the driver transistors Q7 and Q8.

All connections like those on R42, D6 and R6? (can't read the second digit) need to be unsoldered and resoldered on both sides of the boards. This is a significant problem with this type of design.

 

[swordfish689]

Yes they have very bad soldering. I had 2 of these amps and i had the worst time trying to figure out why the power supply fets were always shorting. And my probelms were the driver transistors. I had to resolder them and it worked great.