Quote:
Originally Posted by Chris K
My pattern generator has adjustable RF output gain. If I lower that will it help? I don't think my contrast pot is working anymore. It was making a slight grinding sound. Now it's really not doing anything.
The issue now is I can't get a picture that's stable. Twitches...momentary brightness and focus changes...great picture if I wiggle no specific control for a second...then back to twitchy crap...tap on the focus coil, picture looks good for a second then goes to crap etc. There's just a general instability I can't track down. It's not the CRT...same thing on 2 different 10BP4s (and on my 5" tech CRT). It's not the pattern generator...I've used 3 different ones...same thing. Maybe I should try a broadcast signal? I don't think that's going to cure the symptom. It seems to be an issue at a much more basic level. Tuner has been cleaned...tube sockets have been cleaned...very frustrating.
I wish there was some way to post a video of how it's behaving. It's a lot easier to display than it is to describe.
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You need to learn and understand how it is supposed to work. There are many books on basic TV theory. I would suggest and old copy of the books by Grob and Kiver.
The contrast control simply varies the grid bias to the video IF and tuner stages. Have you measured it?
Do you have a smartphone? Can you take a few snapshots and post them?