Sears 9" Color TV Weird Problem
 

After the set has been on for a couple of hours, the red in the picture gets weak. Flesh tones get very pale. The greyscale changes a bit too. When first turned on, the picture is fantastic and the color is rich and vivid. I don't think it is the picture tube because weak tubes usually improve when warmed up but this gets worse. Also the red does not appear silvery as it would with low emission. It looks as though it gets turned down very slowly. This is a 1972 solid state set that appears to have never been serviced in its long life.

Any thoughts? Sorry I don't have the model or chasiss number handy but TV Beta Guy has the same set.

Model # 564.40050102

Not quite sure on the problem at the moment. Sounds like something is failing with temperature on the red drive? I don't have any schematics, so I'm not sure where to begin without taking mine apart.

check the CRT socket. There may be some corrosion on the pins. You may also want to de-oxit the screen controls (power off of course) I had a zenith that had a fading green. CRT was fine and after a good cleaning the problem went away.

I tried adjusting the greyscale and the controls did not appear scratchy. The Deoxit is a good idea. When I disassemblt the set for cleaning I'll Deoxit all the controls. Coult it be electrolytic caps drifting? It is a transistorized set and has all the original parts. A leaky transistor perhaps?

I don't want you to have to take anything apart. If I need to I'll get a Sams and measure voltages when the red goes down.

It may be a faulty transistor. Grab your freeze spray and spritz a little on the video driver transistors (particularly the red one) and see if your red comes back. If you are getting faded reds without the entire picture turning turquoise its most likely something related to the video driver.

Don't neglect poor solder joints either. Look carefully on the board for poor or loose connections.