Quote:
Originally Posted by ohohyodafarted
Nice Job Walter,
RE: your issue with contrast and brightness. My CT55 does the same thing. I have never been able to figure out what causes this issue. Someone told me that the HV section is probably just not capable of supplying enough current when you drive the tube real hard. My set has a NOS flyback so I know that the flyback is not the issue.
I would bet that if you look at the HV level when you drive the tube real hard to the point where the picture pulls in, you will see the HV droping. I can drive mine so hard that I can cause the picture to almost fade away. My 21AX was rebuilt by Hawkey before they closed so it has very strong emission from the guns which easily can overwhelm the HV section.
I also have another issue that I never was able to track down. It takes about 15 minutes for the convergence to stabilize. I thought the problem was a leaky capacitor in the convergence chassis, but after rebuilding it, I still had the issue. I can speed up the stabilization by turning the brightness up real far and forcing the picture to shrink in and go out of focus. I don't understand the relationship between these issues, but after the set warms up it has a great picture.
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The RCA service manual purity adjustment step 5 states that the repair man should set the contrast fully counterclockwise and set the brightness control for maximum brightness with out blooming. This would tell you that it normal that the set can bloom with the brightness turned up to high. Also when you do convergence on any tube color set, It is best to run the set for twenty minutes before you start the convergence procedure. So really, Your set's are working fine. I have a ctc 16 that has to be on for a few minutes before the convergence stabilizes. I changed the convergence board with a known good one And it still has to warm up, So it must be the CRT. Walter beers. That is a really good picture on your set.
