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-   Early Color Television (http://www.videokarma.org/forumdisplay.php?f=36)
-   -   CTC-4 Director 21 (http://www.videokarma.org/showthread.php?t=267400)

old_tv_nut 07-20-2016 09:17 PM

The color bars have an obvious sound beat - so the sound trapping is definitely not right at this fine tuning setting. Does the interference dance to the audio? (hard to tell from a still shot)

miniman82 07-20-2016 11:26 PM

Quote:

Originally Posted by jr_tech (Post 3166798)
Interesting, I haver broken open a 21FBP22 so have not seen this lip... how far back does it go... far enough to cover the frit bead? Perhaps the frit bead is aluminized or dagged over to prevent charging and or secondary emission, or the lip perhaps covers it?

Been a while since I have looked at it, but on a guess probably 3/4" or a full 1"? Something like that. This particular mask and frame assembly was from an AXP that got turned into a picture frame, but I don't think they changed anything about its construction in later tubes. Don't remember where I read about it either, but I know that the lip in there is to prevent stray electrons from reaching the screen and lighting up any of the phosphor dots.

SwizzyMan 07-21-2016 08:21 AM

Here's a video of what it looked like back in December of 2015. I guess alignment can go that far off after sitting dormant for 8 months? https://www.youtube.com/watch?v=O15e4R8jr8k

DaveWM 07-21-2016 09:31 AM

alignment does not go off as far as the coils are concerned unless there has been screw driver drift. I would look somewhere else. Clearly the beat pattern is prob from miss tuning of the fine tune adjustment. the other is some kind of interference.

I assume you are using some kind of RF devise for the signal, is that the same as the early example? If RF try a different channel if that is an option. Assuming you have matching transformers and good quality cable for feeding the signal.

SwizzyMan 07-21-2016 09:53 AM

Quote:

Originally Posted by DaveWM (Post 3166833)
alignment does not go off as far as the coils are concerned unless there has been screw driver drift. I would look somewhere else. Clearly the beat pattern is prob from miss tuning of the fine tune adjustment. the other is some kind of interference.

I assume you are using some kind of RF devise for the signal, is that the same as the early example? If RF try a different channel if that is an option. Assuming you have matching transformers and good quality cable for feeding the signal.

I'm using a BT modulator. It has that horrible hum when the modulation is too high, but my other two roundies don't have the overmodulation hum in their speakers and for some reason only the 4 is humming. The fine tuning knob only turns about an eighth of a turn before I lose sync. It was originally hooked up to a dtv converter box.

andy 07-21-2016 10:00 AM

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old_tv_nut 07-21-2016 10:07 AM

Sometimes it is possible for the fine tuning to be so far off that the tuner is recieving while set on the next channel and/or tuned to the wrong sideband of a simple modulator.
If you are using channel 3 on the TV, try channel 4 or vice versa. If your modulator is versatile, try both one channel up and one channel down.

DaveWM 07-21-2016 10:12 AM

baluns, terminations, OTA on that channel, connections, etc...
I had one with an intermittent balun in the tuner that gave me issues once.

old_coot88 07-21-2016 11:11 AM

Just for the heck of it, try subbing the last IF tube. Ringing/smearing in the luma is a not-uncommon problem caused by the last IF tube, even tho the tube tests 'good' on a tester.

SwizzyMan 07-21-2016 12:43 PM

I'll switch to channel 4 and sub the 3rd IF 6AN8. Don't see why 8 months would totally mess this thing up.

DaveWM 07-21-2016 02:10 PM

was nothing done to it in those 8 months?

Electronic M 07-21-2016 02:45 PM

Quote:

Originally Posted by andy (Post 3166839)
Some things I've run into are accidental shorts in a tightly packed point to point chassis like this, or breaking one the the fine wires on a coil or transformer when it connects to the terminal.

CTC-4s have PCB IF, sound, and parts of other stages.

SwizzyMan 07-21-2016 04:44 PM

changed the channel to 4 and subbed the 3rd IF tube. Not much difference, but now I can get a pretty clear b&w picture, but when I turn on the color all the interference shows up. Once I get rid of all color the interference goes away. The fine tuning knob still has only an eighth of a turn before I lose sync, but about half way through the 1/8 turn clockwise the color starts to fade but does not disappear and the overmodulation hum gets louder.

SwizzyMan 07-21-2016 05:13 PM

I must also note that none of the tubes are shielded. I'm sure that isnt helping my interference problem anyways. And Dave, according to the previous owners the set hasn't been powered up since last December.

andy 07-21-2016 05:52 PM

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