View Full Version : CTC 11 Static Convergence


Kevin Kuehn
04-04-2017, 10:58 PM
I've been practicing setting up the convergence on my 11 and I have a question for you color roundie gurus: What does it indicate when the center is fairly well converged but you get a red and green dot on opposing sides of the vertical white line? When I have dots displayed on the screen the red and green dots disappear( they only show when I display a crosshatch). :scratch2:

http://i452.photobucket.com/albums/qq245/Kuehn/VK%20Pictures/Convergence%20004_zpsr8g2p00s.jpg

Kevin Kuehn
04-04-2017, 11:25 PM
On closer examination they appear to follow the vertical retrace, I guess? And there are blue dots in there too.

http://i452.photobucket.com/albums/qq245/Kuehn/VK%20Pictures/Convergence%20007_zpsjijg8vg4.jpg

Kevin Kuehn
04-04-2017, 11:35 PM
A closer look.

http://i452.photobucket.com/albums/qq245/Kuehn/VK%20Pictures/Convergence%20010_zpsayhslbjr.jpg

TUD1
04-04-2017, 11:41 PM
A very interesting phenomenon. Might try slightly turning down the G2's. Looks like retrace lines trying to form. None of my TV's have ever done this, so I really don't know. Here's my CTC-11 after as thorough a convergence job as I coukd muster.

IsthmusTV
04-05-2017, 11:43 AM
Hi Kevin,

I observed the same phenomenon on my solid state CTC-59X chassis. At the time I attributed it to the test pattern generator, but now I'm not so sure:

http://i1216.photobucket.com/albums/dd366/IsthmusTV/XL100crosshatch_zps186gwrp7.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/XL100crosshatch_zps186gwrp7.jpg.html)

-Clark

Zenith26kc20
04-05-2017, 11:48 AM
I've seen a number of test generators do that problem. I guess it's digital noise from the synthesizer circuitry bleeding into the output.

Kamakiri
04-05-2017, 12:19 PM
Kevin, if you want to try a test pattern DVD I can send you a copy.....let me know.

Kevin Kuehn
04-05-2017, 01:14 PM
I have one, thanks!

reeferman
04-07-2017, 10:41 PM
Kevin,
Those things were usually a bear to converge back in the 60's. They don't get any better with age. So don't feel too bad.
Looking at the first picture I’d say adjust the blue lateral. But after looking at the next picture that wouldn’t help much. The dynamic convergence is off.
Check the rectifiers and other components on the board. You might try rotating the assembly. It might make a marginal difference. Maybe
Just be aware that converging sets is a lesson in compromise. Some think that near perfect convergence can be obtained on those sets. Never have and never will. Adjust for the best overall convergence.
My advice is to enjoy the picture. It's amazing how fast you lose track of the convergence.
Good luck and have fun.
Phil

sampson159
04-07-2017, 11:16 PM
listen to reeferman.perfect convergence is a myth.rarely seen.get it as close as you can and stop.my main job back in the shop was to rebuild tuners and setup the convergence.i learned very quickly that close was best.the older the set,the harder to set up.

old_tv_nut
04-07-2017, 11:45 PM
It's definitely video pulses during vert retrace. During retrace, the dynamic convergence waveforms can be wildly different, and it is meaningless because there is not supposed to be any video there! Blame it on the generator, not the TV, and don't worry about it if there are no retrace lines on real video.

Kevin Kuehn
04-08-2017, 02:10 AM
Thanks for the replies. It does appear to be generator related, because I don't see it with my DVD crosshatch pattern. I thought possibly the color killer threshold would have some influence, but that didn't help at all. Anyhow I have the dynamic pretty well dialed in now other than one small area on the far upper right edge. There's simply no way to adjust for an unruly small area without messing up the overall bigger picture. But once you start watching a movie you pretty much forget about the outer edges. I'll post some more pictures when I get a chance.

Penthode
04-08-2017, 06:49 PM
The dots are simply the generator cross hatch extending into the vertical blanking interval. The red, blue and green dots do not converge during retrace.

Try looking at the vertical blanking interval on a scope and you will see what I mean.