jl audio 1000.1 amp prblem

[ampjunkielikeme]

the gate resistors traces on one side of the power supply run to the outside leg of 2 small transistors . 4403 , 4401

and it has the same parts for the other gate resistors on the other side
pins 9 and 10 run to the middle legs of each set of transistors..

 

[Perry Babin]

The 4401/03 should be able to drive the 3205s. Replace the 100 ohm gate resistors with 47 ohm resistors.

 

[ampjunkielikeme]

ok, perry

ive replaced the gate resistors to 47ohms, put the irf3205's in. ive also tested all the 4403's/4401 and they tested good out of the board.

the amp was fine hooking up the hot and ground, but it blew one of the irf3205's as soon as i hooked the remote wire up to it..... and the amp put my 20 amp power supply in protect...

i clipped the bad irf3205 off the board. i havent tried to power it back up again.....
could it be that the 4403/4401's cant drive the irf3205's?
the torrids are not shorted ., and the rectifiers seem to be ok...

 

[Perry Babin]

When you checked the driver transistors, did you confirm that you had two readings of ~0.6 and all terminal/probe combinations were open, or did you simply check for shorted transistors?

The 4401s would not have caused this if they were in good working order.

Measure the resistance from the gate leg/pad of the blown FET to the gate leg of an adjacent FET (one on the same gate drive circuit), do you read ~100 ohms?

 

[ampjunkielikeme]

i went back and tested the 4403/4401's and i dont get 2 readings of 0.622 on one of the 4403's . i get 0.6 one way, but 1.632 the other ..just so happens that the one bad 4403 is hooked to the side where it popped my new 3205...

what part number will replace the 4403/4401 ?

i found a few on mouser, but dont know which one will work correctly...
like: 2N4403G and 2N4401G . both are 600ma 60v . will these work?...thanks perry