'63 GE B&W clarity troubles - Videokarma.org TV - Video

Thyratron · #1 03-17-2007, 12:11 AM

I've got a '63 GE 17" B&W (can't remember the model right now, but I can get it if need be), which has some trouble with picture clarity. Upon turning it on and within about the first 20-30 minutes, the picture is quite clear, considering the type of set. However, after the set has had a chance to really heat up, the picture begins to degrade and become very grainy, sometimes to the point that it will begin to roll vertically out of the range of control of the vertical hold knob. At times, it will become unwatchable and will need to be shut down. Anyone have any ideas as to what I might look for as a problem?

Tubejunke · #2 03-17-2007, 02:15 AM

Sounds like you have two seperate problems. I would check all of the components in the vertical output and oscillator sections. The problem with the picture is probably a bad component in the video circuitry based on the fact that you did not mention the sound being effected. As always first check your tubes. Start with the easiest and most likely points of failure, which will be the tubes.

Typically a very old TV will have more than bad tubes to be dealt with but not always. If you like the set and want to use it for more than a few minutes you need to consider replacing the capacitors and check resistor values for being out of spec by more than 20%. You need to have a schematic but it is not completely necessary. Just learn your resistor color code. Replace capacitors with equal or more working voltage and capacity. Pay close attention to polarity with electrolytic capacitors. I don't know what your experience is with electronic repair so I wont go into this too far but these are some basic rules of thumb. Then of course there is safety. You can get jolted pretty good with an unplugged set if you are not carefull. Discharge all capacitors that you come in contact with. Last the CRT is basically a very large capacitor with stored 2nd anode voltage. You DO NOT want to feel the result of becoming part of that circuit!!

Be careful, have fun, and I'm sure if you have any specific questions with your repair some of the folks with way more knowledge than I will be glad to assist, as will I if I know the answer....

jpdylon · #3 03-17-2007, 11:53 AM

I would look to the tuner section first if its becoming grainy and snowy. Sounds like an RF tube that's going bad after it heats up. Also check the IF and video strip as mentioned. i doubt that its related to the vertical section because the grainy picture leads to the rolling and instability. I would also look at the sync and AGC sections. You may have a faulty AGC delay line as well.

Thyratron · #4 03-22-2007, 12:38 AM

Thank you both for your help. I will hopefully get a chance soon to try some things. It seems worth it to get it back in good running shape again if for no other reason than it's one of the later VHF-only sets (correct me if I'm wrong), which gives it some historical value.