Any info on FBT Promaxx14a?

[DINO_BS]

Hello.
I have a problem with the Mitus PU AMP repair.
According to the schemnatics diagram, the transistor Q20 IRFB5620PBF were damaged.
Along with him, U12 IRS2092S.
Q18, Q19 and Q21 look good.

After replacing U12 and pair Q18/Q20 I have the same problem.

Will somebody please help me?
Where can still be a mistake?
I don't have service documentation.
Well thank you.

Vladimir

[izzzzzz6]

TIP regarding a screw that grounds input board to main board on fbt promax 10a (if the screw with bronze spacer is missing or loose the protection will cut in, might be same on 14a).
Hi guys i am trying to repair an FBT promax 10a.
Not the input board or output transistors, psu is good.
I'm a bit stuck as the pre drive on the main board is smd stuff and i have no scope.
any other ideas appreciated.