Ct-100

[Tom Albrecht]

Thanks for the tips on possible modification of the vertical deflection power supply. I'll keep an eye out for the type of image squeeze you describe, and fix it if it looks like it's a problem. So far I don't see it, so perhaps that happens more with the larger screen sizes of later sets as you describe.

My shunt regulator is working fine, so I won't need to change resistors there. On the other hand, man did this set need a lot of work to get this far. If I was looking for a trial-by-fire set to learn about color TV, this set ended up giving it to me and more. Particularly in the area of alignment it needed many hours of work. And of course all the stuff with the flyback and voltage tripler ended up giving me more education than I necessarily had intended to sign up for!

After making some minor modifications to the adjustment ranges of the various color drive, screen, and background control ranges, I gave the convergence some more attention. I was able to get it much better after figuring out that the position and orientation of the yoke has a pretty big impact on convergence (as well as purity, raster scan linearity, and probably a few more things!). After some careful adjustment of yoke position and observing the interaction with the convergence adjustments, I got it looking reasonably decent:



No problematic areas left in any part of the screen, although there is just a touch of misconvergence on the left. Mainly I wanted to fix the poor convergence I previously had on the bottom, because that is where text banners often appear, and poor convergence really messes up the fine print.

I also found I was able to get the vertical linearity better at the bottom of the screen by replacing the vertical osc/output tube.

I think I *might* actually be "mostly done" with electronic restoration. Color fidelity is by no means outstanding, although I'm not sure how good these sets can really be. I know my CRT red gun is a little weak, and that is certainly making it difficult to get good color tracking from black to white. Also, certain colors like orange are never quite right. Nonetheless, it's quite a lot of fun to watch now. I'm probably overdoing it here, but here are a bunch of screen shots off live over-the-air TV this evening:











With all the work that has gone into aligning, adjusting, etc., I simply can't imagine that the typical TV sales shop was capable of really doing justice to one of these sets when installing in a customer's home. In New York City or Philadelphia, maybe some RCA factory hot shot set up the sets for customers, but in other places I imagine the skill level of the installation techs was mixed at best.

I remember as a kid in the late 60s and early 70s seeing color sets at neighbors' homes that were wildly out of adjustment, and those were sets a lot newer that this that weren't nearly so difficult to adjust. I can only imagine how some of these CT-100s looked in customers' homes in the mid 1950s! Maybe some of you remember those times and can tell me I'm wrong...