I've been blessed!

[old_tv_nut]

The guy who took the pics tried something called "liquid wire", but foudn it's not so conductive - the burned segment should be 25 ohms, but he ended up with a few hundred ohms. The total is supposed to be 100 ohms. I suspect this low resistance and the high currents involved (compared to a video or audio signal) are pushing the carbon pot technology beyond its limits. I suspect high contact resistance could develop and then there would be local heating. Don't know why they didn't use wirewound pots for this function. The circuit I came up with using two pots has a wirewound 25 ohm in it, mainly because that's what I could find. There is no problem with coarseness of adjustment for this application.

[jshorva65]

I'm also looking for info on how to fabricate the correct mounting brackets for retrofitting a glass 21FBP22 (actually a delaminated 21FJP22) in place of an (aired) metal 21AXP22 to restore a Sylvania model 31C304M, hopefully without hacking up the shroud used with the 21AXP22, thus making the retrofit reversible in case a fix for leaker 21AXP22's becomes available.

Another question I hope someone here can help answer is whether anyone has data on feasibility of making an adaptor for use in bench testing an early 21" color chassis with a test rig.

I have the GTE/Sylvania CK-3000 test rig and know someone with a TeleMatic rig. For both units, the earliest color chassis supported directly by its adaptor complement was the RCA CTC-7. If a correct set of Yoke Program, Convergence Ballast, and Yoke Cable characteristics could be determined, then the use of test rigs would help simplify these early sets' restorations greatly. It would seem that the correct yoke wiring harness could be as easy to create as making an adaptor to mate the leads of the existing "roundie" yoke harness to the correct plug for the older chassis. That would leave only the correct Yoke Program and Convergence Ballast values and pinouts to be determined, since the CRT cable should be directly compatible with all 21" color tube applications.

[ChrisW6ATV]

Originally Posted by jshorva65

I have the GTE/Sylvania CK-3000 test rig and know someone with a TeleMatic rig. For both units, the earliest color chassis supported directly by its adaptor complement was the RCA CTC-7. If a correct set of Yoke Program, Convergence Ballast, and Yoke Cable characteristics could be determined, then the use of test rigs would help simplify these early sets' restorations greatly. It would seem that the correct yoke wiring harness could be as easy to create as making an adaptor to mate the leads of the existing "roundie" yoke harness to the correct plug for the older chassis. That would leave only the correct Yoke Program and Convergence Ballast values and pinouts to be determined, since the CRT cable should be directly compatible with all 21" color tube applications.

Maybe you could get ideas for the correct adapter needs by comparing schematics of the CTC-7 (and -9, -11 etc.) with the older RCAs to see what major differences there might be. With very early color sets, there may not be too many differences from one brand to another, except the connector types.