best guess: I worked for sony and saw this same problem and same part fail. we called it a money maker. it was used on many models. its called an HVR block. (high voltage resistor) looking at the back on the right side, attached to the CRT shield you'll see a red rectangle shaped block with a knob sticking out the center. this is for adjust convergence. still with me??? you will have to remove this block, turn it upside down an examine for a crack. if present this is your problem. the bad news is its almost for sure, not available anymore. the sony part number is on the block itself. probably starts with 1-228 or 226. go to sony.com. click support > parts>contact us. shutdown varied. from a few secs to many hours. luck.

It is a white block like resistor in inside the back of the tv. Probably cracked or broken. You can buy this for about 75 cents in the US and sawder it in yourself. If you use the wrong one, you may have trouble tuning the set off. It will turn off and then back on when you press power. Good luck!