The fault can be in the power supply or uPC section. This is a bit
sophisticated a problem to have a simple answer over an email. You
would have to track this down, starting from the power button to the
microcontroler, and then verify the clocking and data commands for it.

The very first thing to verify is the power supply performance. This is
most important that all the outputs are in spec and the noise
characteristics (filtering) is in proper specs.

You will need to buy the service manual, and have a scope and DVM to
fix this type of thing.

In my opinion, if the CRT is in good condition, I would suggest you
give the set out to an authorized Sony service center to have it
properly serviced. This would be more fasible than to fix it yourself.
Jerry G.
======