CT-100 color sync issue?

[Phil Nelson]

Originally Posted by yagosaga

Is there a chance to tune or detune the reactance control until the color bars are in sync?

You can access the top of the reactance transformer, 2T124 in the RCA manual ( http://antiqueradio.org/RCACT-100Tel...Service_Manual ). Is this what you're referring to? That adjuster is named A40 in step 37 of the Sams alignment instructions, http://antiqueradio.org/art/temp/RCA...structions.jpg .

Turning that control while watching the screen, I can change the number of bars but not eliminate them.



I wonder if the frequency is too far off to bring into locking range by that means . . . .

Phil

[old_coot88]

Originally Posted by Phil Nelson

You can access the top of the reactance transformer, 2T124.... Is this what you're referring to?

Phil, that adjustment should bring the osc. into sync. See if it will lock in solid, or if it still has 'weak' sync. Bill(oc)

[Phil Nelson]

I'm not entirely sure what you mean by weak sync, but I can get it to lock on a set of horizontal color bands. They don't roll vertically. Moving that adjuster in one direction makes more bands. Moving it in the other direction makes fewer bands. In between the stable points, the bands roll. Continuing in the fewer-bands direction, the adjuster runs out of travel before you reach the Good Place.

Maybe something fishy upstream . . . ?

Phil

[old_coot88]

Phil, what does it do with the original crystal in place?

[Phil Nelson]

Bill, do you have ESP? About 20 seconds ago, I just finished uploading this fresh picture of the TV with original crystal back in place.



Colors aren't perfect, but we're back in the game.

I'm not sure what possessed me to try the original crystal, since I was so convinced it was bad. Couldn't think of anything else to try, maybe.

I should quit tormenting this poor old thing and just watch a movie for a change

Phil

[jr_tech]

In the first post on this thread the color bars from the generator looked fine but the DVD exhibited off-frequency color frequency of perhaps 120 Hz... Is Dorothy looking good now?
jr

[Phil Nelson]

Dorothy's back, too.



Other issues remain, but color sync isn't one of 'em.

The most recent set of color bars were from the test pattern DVD. I just tried the generator again, and with its stronger signal it's easier to get better color bars -- including magenta, for instance, and a deep blue.

I'm playing the TV for a few hours -- Gone With the Wind, for a change -- to see whether this improvement sticks. Then I'll pull the chassis back out and take another look at the color circuts while dealing with some other stuff. I'm inclined to set the generator aside and use the test pattern DVD from here on out. The ultimate goal is to watch movies and TV, not generator patterns.

Thanks,

Phil

[old_coot88]

Originally Posted by Phil Nelson

Bill, do you have ESP? About 20 seconds ago, I just finished uploading this fresh picture of the TV with original crystal back in place.

No ESP. Darndest thing though, i don't remember ever seeing the xtal cause loss of sync. Of course that's been nearly 50 years ago, and xtals might go bad over time. Evidently yours didn't.
A couple of little tips worth bookmarking.. the reactance coil is the primary 'color sync' adjustment. To tell if the color osc. tube is weak (even if it shows "Good" on a tester), have the set running with a normal in-sync color picture. Shut the set off for maybe 5 to 10 seconds, and turn it back on. It should come on in sync. If it comes on with color bars and takes a while to lock in, the tube is weak.
The same test can show a weak horizontal osc tube too. Bill(oc)