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  #31  
Old 07-20-2016, 09:17 PM
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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)
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  #32  
Old 07-20-2016, 11:26 PM
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Quote:
Originally Posted by jr_tech View Post
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.
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  #33  
Old 07-21-2016, 08:21 AM
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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
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  #34  
Old 07-21-2016, 09:31 AM
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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.
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  #35  
Old 07-21-2016, 09:53 AM
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Originally Posted by DaveWM View Post
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.
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  #36  
Old 07-21-2016, 10:00 AM
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Alignment doesn't just go off by itself, so I would start looking for some kind of component failure. Verify any work you did on the sets since it last worked better. It's easy to make a mistake. 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.
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  #37  
Old 07-21-2016, 10:07 AM
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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.
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  #38  
Old 07-21-2016, 10:12 AM
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baluns, terminations, OTA on that channel, connections, etc...
I had one with an intermittent balun in the tuner that gave me issues once.
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  #39  
Old 07-21-2016, 11:11 AM
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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.
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  #40  
Old 07-21-2016, 12:43 PM
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I'll switch to channel 4 and sub the 3rd IF 6AN8. Don't see why 8 months would totally mess this thing up.
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  #41  
Old 07-21-2016, 02:10 PM
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was nothing done to it in those 8 months?
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  #42  
Old 07-21-2016, 02:45 PM
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Quote:
Originally Posted by andy View Post
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.
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  #43  
Old 07-21-2016, 04:44 PM
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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.
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  #44  
Old 07-21-2016, 05:13 PM
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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.
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  #45  
Old 07-21-2016, 05:52 PM
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Quote:
Originally Posted by SwizzyMan View Post
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.

That's interesting, the CTC4 I'm restoring also has a huge amount of chroma noise, but produces a decent B&W picture. So far, I've recapped it, and changed a lot of off value resistors. I've done a few of the simpler adjustments, but not a full alignment.
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