CTC 21 Console Aquisition
I grabbed it from the thrift store today, they were happy to take $20 for it. and it weighs a ton.
Aside from convergence, the picture is pretty good. sometimes the color goes, but is brougt back by messing with the fine tuning. Signal is being fed by a BT agile modulator on channel 8. And the bars in the picture are from my camera. The convergence seems impossible to improve, the pots are real scratchy and I cant figure out how to clean 'em...... https://farm1.staticflickr.com/832/2...43a3b134_c.jpg https://farm1.staticflickr.com/823/4...99272d3e_c.jpg https://farm1.staticflickr.com/910/4...5d638e8a_c.jpg https://farm1.staticflickr.com/981/4...e4134f86_c.jpg |
Holy smokes! You lucked out big time! These CTC-21's are great sets, I've been trying to find one for nearly three years. The thrift stores here would never have something like this. Enjoy it!
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Spray some de-ox-id under the edge that faces the board to clean the pots.
Protip: the diode packages on most deltagun sets even into the 70's was selenium, and can go bad. Replace with a few 1n4007s and convergence may improve, on the convergence board the caps may be worth replacing and the resistors are worth checking. The position of neck hardware can also screw with the range of the dynamic convergence. |
Great $ave! RCA's finest tube-rectangular work IMHO.
I had the guts to one of those models, shop I was working for retrofitted and RCA 25" monitor and reconnected those speakers. The customer was thrilled, RCA no longer offered a cabinet that matched t heir furniture. I got to remove the leftovers:D It worked right away when I put it in another early American maple cabinet and it was OUR college apartment set. Used it the whole summer of '82 to watch HBO-CINEMAX repeat movies, enjoyed in lots of company and everyone was amazed it was 15 yrs old. I miss it terribly, as fine an example of RCA's last good tube chassis as any made. The color and video were just perfect. I sold it for rent money in fall semester, got a 69" Zenith again when I got another TV shop job. |
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Is that funky thing towards the top left corner (of the convergence board) a selenium diode pack? I also figured out the static convergence last night so I got a much better picture. I'm just learning about delta gun CRT setup. There's something about the color on these old sets, It's almost like Kodachrome............ |
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Very strong CRT. The conv problem is mostly center conv. When you
get the center good the edges will follow. All the controls on the conv PCB are wire wound so they feel "scratchy" compared to to regular carbon pots. For the color first turn off AFT or AFC if it has it then put back on after fine tuning. You can also turn the color killer control all the way off. The set uses a bunch of 6GH8 tubes so pick up some of those NOS, they are nothin but trouble. The 6GH8 & there sockets were the biggest fault of these sets ! You are off to an excellent start with this one, nice buy ! 73 Zeno:smoke: LFOD ! |
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Is a 6GH8 and 6GH8A the same? |
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It still good practice to have a few extras on hand. :thmbsp: |
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The CTC38 (and several before it) were consummate 6GH8-eaters:thumbsdn: |
Yeah I only found one 6GH8A in the set, which tests good, I'm gonna check the solder joints at that socket and a few other places.
Now when I set up the purity, do I just feed the set a "blank" signal? I don't have a crosshatch/colorbar generator, Ive just been using the picture viewing feature on my DVD player, with various patterns of course. In the mean time enjoy some badly converged Star Trek :D https://farm1.staticflickr.com/952/4...609cd8b0_c.jpg |
If this set has a service/raster switch you can put it in "raster" mode, and turn the blue and green screens down until you get a full red raster. Degauss the set, then pull the yoke back and adjust the purity rings until the red blob is in the center of the screen. Push the yoke back and adjust greyscale with the switch in "service" mode, and you should be good to go.
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And if you buy some 6GH8 tubes, look for NOS Sylvania. RCA manufactured tubes did not hold up. For that matter, toward the end, RCA bought the 6GH8 from Sylvania and rebranded it RCA because they were better.
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With 21" roundies, it's about 1/4" to 3/8" shy for best red purity. |
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