I got an old Sony Trinitron Crt tv and decided to repair it. Firstly, when it is powered, the standby light turns on and after triggering the power button, the standby light turns off and within few seconds it comes back again to standby mode.(the standby light turns on again). B+ voltage = 115V and 15V output from the chopper transformer. I found that the 33v zenor diode is defective and repalced it. Also, all the suspicious capacitors including mylar capacitors are replaced. I found that the high frequency diode at H- Out transistor is short and replaced it. Then I powered the Tv and suddenly i heard high voltages at flyback are turned on and in a few seconds tv turns off and again turned on automatically with a sound of turning on high voltages of flyback transformer and again turns off. This happened repeatedly and i turned off the tv. Then i checked the new diode i replaced at H-out and i found that that diode is short as the old one was. I tried with few diodes but all of them became defective when i try to turn on the tv.
- H-out transistor is OK.
- I replaced flyback transformer but the problem is the same.