tda4605 application circuits
hello my friend
well , first of all check and replace C409,IC401 TDA4605 and T401 BUZ90 but before replacing them make sure to Discharge C410 and main filter capacitor otherwise u will have a defective TDA and BUZ again , so please make sure to Discharge C410 before Replacing them , also check and replace D406 1N4148 .
if this doesn't make any changes , check and replace R413,R414,R415
if u still have the same problem , try to connect a 15V or 18V Zener between the source and gate terminals of the mos fet BUZ 90 to prevent spikes from damaging the the mosfet again.
if u still suffering the problem again that means u have a shorted chopper transformer , try another one or ring it using ur scope .
here's the best service manual i could get for this chassis hope it'll help u .
Kind Regards