RF Power T30001bd subwoofer amp from dead to comatose after first aid.

[LoupeGVD]

Hello all,
Could you help me figure out what can really be wrong with this Rockford Fosgate Power T30001bd subwoofer amplifier?

Possibly apart from the mosfet's themselves, as at least the visibly cracked ones I replaced. (Tricky operation with each pair joint together on a side board where both fet's backs are soldered on but got it all in place.)
It now only squeeks right into safety when powered up..

-So what to check first on this baby to see if there is hope on recovery and if it will be worth the trouble?
-Any known issues that could be the case here?
-Would there be an obvious reason for the mosfet's to physically blow in the first place?
-When I got it (with the blown fet's) the heavy connections in the middle between the two PCB's where disconnected............can that point somewhere?

Over all it looks in the best possible condition, no thermal discoloring or anything suspicious anywhere. It's a 2004 make.
I got the schematics thanks to RF.
I am no expert, hence my post, but I am fairly skilled and can pick up on directions.
Any of which will be much appreciated.
Still hoping not to have to ship her out for expensive repair and also miss out on this chance to learn and expand my skills.
Thanks.

[Perry Babin]

Which ones are cracked?

[LoupeGVD]

Hi Perry, well they were all IRFP260N like all in the end stage(?)
From the 16 pieces there are 4 on the left side and 12 along the back.
So facing like this we look at the output board that is the left half of the interior.
Now not counting the first 4 on the side, in the back row of 12 (6 pairs) the cracked ones were number 5, 6, 9 and 10.
(The 3rd and 5th pair) The machine is back at the workshop now and I am looking at the schematic here, which is as usual not set up in the actual board lay out so can not be completely sure about the TC numbers right now. I thought both pairs were TC7 and TC8.
I did allready manage to replace them with new ones so now the whole thing looks in fine condition to the naked eye.
By the way, at my attempts to power up it blew the 30 ampere fuse I put in..
Apart from that it only gives the sqeek that lands it into safety mode.
Hope this cal tell you a little more, thanks!

[Perry Babin]

Have you checked all of the driver transistors and the SMD diodes near the outputs?

The TC... numbers are meaningless. In the future, use the circuit board designations silkscreened on the board next to the transistor.

If the inductor was not firmly mounted to the board, you need to remove it and make sure that it didn't short to the circuit board.