Sony KPS4112 Rear Projection Dead !!

[New memeber]

The chopper transistor (BUZ91A) in the power supply board failed short circuit. The main's fuse also blows. Has anyone got any ideas what to look for next? I have replaced R613 which was found to be open circuit, at the same time I replaced TDA4605-3 and the opto-coupler. However, the transistor BUZ91A still fails even after replacing all the above mentioned components. I have no circuit to work to, so please help if anyone got any idea what to look for next.

Regards,

[New Member]

I have a copy of the circuit diagram and will work on it and will update anyone interested with similar fault(s).

Regards,

[jgdas]

Defently you have an open or sort at the primary of psu
unsolder all the diodes and the resistor of the primary of the psu and measure them outside of the ckt,and the small resistor.
This problem is at the most of the case produse by lighting or over voltage
but there is and another one place you must check.
at the progector check if is oil run from the tube to the high voltage transformer,this oil produse s/c at high voltage trafo.