My phillips TV went out (no raster no sound) and when I try to turn it back on the power botton just flashes on and off after a minute or two it turns off. while the power botton is flashing an oscilating sound is heard coming from the inside of the TV. I had let days go by and try to turn it back on and it stll does the same thing. Thanks for any help on that, the model #50p8342
That unit is a PTV916 chassis. The oscilating sound you hear is probably a feedback pulse on the secondary transformer. That would first make me suspect that the HOT (Q802 / 2SD1556)(horizontal output transistor) has shorted. You need to check for any short between the base and emitter pins of that component. If that's the problem properly replacing it should restore normal operation. If that wasn't it, you would next check for failer of the SSB located on the left side of the unit next to the tuner, mounted vertical. That board has been a problem in many of the PTV9xx series chassis. It can be rebuilt, but will take some extensive knowledge and equipment to test. If any of this sounds too complicated I strongly suggest a qualified shop do the testing and repairs. If you have any difficulty locating a reputable shop try contacting NESDA (National Electronic Service Dealer's Assn.) for a listing of shops in your area. It is worth repairing. Good Luck Bill
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Thanks for that input. Preliminary testing of the Horizontal out put Transistor shows that it might be ok, but I probably need to take it out for proper check and I don't know if it has a damper diod built in.
Yes the oscillating sound comes from the transformer.
Thanks again for your support and I will check those two things you suggested in the nest two days.
I replace the H. output transistor, turned it on and I'm still having almost the same problem no sound no raster, however the power button stays on and does not flash on and off and there is no oscillating sound coming from the transformer as before.
However, I am now confused as to what connector goes to the 1082 plug on the foor board. Of course if I find out where this one goes it will solve where the other one goes.
Last step before I order teh service manual.
Thanks again for your input, much appreciated.
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