R1, R44 burning up- ax-100

[audiodan]

Help

Ive just changed the position of the output fets( grouped them correctly) on the heatsink and restarted.

Now output resistors are smoking (R1, R44)

This aleph-x was working fine and no other changes were made except for position of the irfp240s.

Anyone enlighten me what could have gone wrong.?
my guess is broken fet but a quick measure reads correct on multimeter.

 

[Nelson Pass]

Could be disconnected Gates.

 

[Blues]

Could be shorted Drain(s) to heatsink...

 

[audiodan]

Thanks for the quick response Nelson and Blues!

But... Ive just checked both the gates to board which are good and also Drain to heatsink which is also good.

Ive just swapped the other board in there and getting same problem, so its either fet or power supply.

this might keep me working late into the night, lucky Im off for the weekend, long weekend, just hope I dont try to solve it to much in my head over the next few days.

Or it could be incorrect connection to board.

mmmmmmmm

 

[audiodan]

Well Ive found the problem

Lets hope its the only one.

Somehow I destroyed 3 of 4 of my lovely balanced IRF9610.

weekend break was what I needed.

 

[audiodan]

In fact all the rest of my batch of IRF9610 are toast except one, these little guys must be very sensitive, good lesson to learn, I was very blarsay with handling them.