GE13PF6504 no picture but green splotches

[technoman9]

SUCCESS!

Tonight I installed the new regulator, a new diode in D805's slot, and replaced four capacitors that had opened up. I plugged it directly into line voltage and well-lah! She produced a picture for the first time in ten years.

The picture itself it decent, though I had to turn the brightness and contrast up quite a bit to show well. The color controls are touchy (meaning small changes result in large shifts of color), the middle if the screen is slightly brighter than the upper and lower areas, and the right side is bowed toward the center a bit. I presume some of this is due to the low-end nature of this set and quite a bit due to it's age (I have no idea how many hours are on it).

If anyone has any suggestions on what to check out for these quirks, I'm all ears. Otherwise, thank you for educating me about B+ voltage checks and regulator testing. Another feather in my repairman's cap!

@damen: Yes I did check that mica insulator. The new regulator did not come with one but the old one was in excellent shape when I examined it. I put a thin layer of silicone grease on the new regulator before installing.

[JohnCT]

Originally Posted by technoman9

SUCCESS!

The picture itself it decent, though I had to turn the brightness and contrast up quite a bit to show well. The color controls are touchy (meaning small changes result in large shifts of color), the middle if the screen is slightly brighter than the upper and lower areas, and the right side is bowed toward the center a bit. I presume some of this is due to the low-end nature of this set and quite a bit due to it's age (I have no idea how many hours are on it).

There is no geometry correction in these, but even so, it looks fairly straight to me.

Not sure about that brightness issue but that might be normal. Hard to tell from a still pic.

The *old* GE Portacolors would do this even when new, and the dark area was usually different in color than the lighter areas, but those were different animals.

John

[old_tv_nut]

Geometry is probably within spec. As to the picture being brighter in the center: hook up a DVD payer (which will run at the standard 59.94 fields per second instead of 60.0 of some test gear and sources). If the bright area slowly moves vertically, it indicates some kind of 60 Hz hum is present - probably a bad cap somewhere in a power supply section.
If the bright area remains in the middle, you can chalk it up to a design limitation, or look for some way that the vertical sweep may be producing hum in the video section power supply.

[technoman9]

I did as you suggested and tried a DVD player through a VCR into the TV as well as a Homeworx converter box. Both methods showed the same lighter area in the middle of the screen which did not move. This issue is not very noticeable when regular programming is being viewed and actually has a good picture. I'm going to chalk up this lighter-area issue to the age of the set and target low-value market design.

Thanks again to all of your input. I now have a working GE TV set with a decent picture and learned something about 1980s low-voltage regulator circuits.