Vernon Paul wrote:

I have a phillips 29 inch tv(model PT4423) which lost power suddenly.

After replacing a shorted chopper transistor in the switching
circuit and two open resistors the TV came back to live with another
problem.

When ever a picture is pumped into the TV's AV sockets the picture
shrinks vertically before shutting down. Further attempts to on the tv
after that is not possible, unless the power is recycled. I've replace
the main filter capacitor, main bridge rectifier, output regulator,
PWM ic and a few zener diodes but the problem is still there. Next I
plan to replace the opto-coupler.

What do you think is the problem? Could there be a problem with the
deflection circuit?

Thanks-a-million.
You say chopper transistor? Is this a Thyristor, Mosfet or a bipolar
transistor?

In any case, it almost sounds like you have insufficient power being
generated.

Did you use exact replacement parts or SUBS like NTE ?

Also, is the circuit board brown from over heat in that area?

Jamie