RCA P46921 PTK195 - so sound no picture?

Question

The above friends TV has no sound or picture. When plugged in it in it seems to draw power (plug sparks). I put an oscilloscope and VOM on the power board and it has 60 ~. I don't have a service schematic so I don't know where to go from there. I figure the board power is being shut off by a microprocessor.
The TV shut off and on a couple of times before it quit. He said it made a singing or ringing noise. He said no Ozone smell and there doesn't appear to be any HV crossover or burnt components. Any ideas on common causes?? Also where is a good parts source?

Answer 1

Hi k c , This is probably my last answer on here and I am doing it because I know that you have sufficient knowledge to tackle it.
Here goes then ! Multimeter on ohms range ( 10k will do ) You will have already checked the fuse in the set , if you can see the degauss thermistor, near where the degauss coils are plugged in ! feel at it ! is it warm to hot ? if yes then the on/off is ok and fuses before it. Now the multi meter --black lead to chassis and with red lead measure resistance to ground from collector of power supply regulator transistor ! it should measure over 10k ,.if that is ok then probably the transistor is ok, next go to the line amp transistor and measure fro collector to ground it should be high also. If that is ok and considering the high pitched noise before it died then the most likely suspect is the eht ( flyback ) transformer. These are only basic checks k c and it is difficult to guess further, Maybe if KC 2tv reads this he may have things to add ! Cheers Pete
PS. If you have drawn a blank so far then it might be worth just taking off the deflection yoke from the tube neck and have a look at the coil windings, it was common at one time for the line winding to start arcing and shut the set down !! The def yoke looks all innocent until you look underneath !