Crate BX-220H problem

[rf7]

I'm trying to fix this amp, but I just hit a wall. I used this thread as guidance:

http://music-electronics-forum.com/s...ighlight=ampeg

I've replaced most of the semiconductors, and any open resistors after the op amp (IC1 pin 7), and got these test point voltages:

TP3=0.1V
TP4=5.6V
TP5=-5.4V
TP6=2.99V
TP7=-3V (I tweaked the bias pot to get 6 and 7 near +/-3V)
TP8=2.3mV

I hoped those were close enough, and stuck in 1 each of the Mosfet's (matched by Crate/Loud) and promptly blew a fuse. No load on amp. Both Mosfet's were shorted along with their 47 ohm gate resistors going open.

Is the offset at TP3 causing the slight imbalance in the test point voltages? Is that why I'm blowing the Mosfet's?

[rf7]

I think I know what happened. I ran the amp without the heatsink installed on the Mosfet's. Would that cause them to short out?

[Enzo]

Could.