My CTC-16XL Project.

[old_tv_nut]

Duh.. I think I'm awake today... If you use a coupling cap and remove L9, you will need to add a grid bias resistor (say, 100k) from G1 to ground.

[Yamamaya42]

Now I'm going to go out on a limb here, I assume the only real reason that they said use a color bar input for the color AFC setup is that they wanted a stable non-moving color picture input to work with, and back then, the color bars were the best choice?
So that in this age, it can be also done with a DVD input on pause?

[old_tv_nut]

Originally Posted by Yamamaya42

Now I'm going to go out on a limb here, I assume the only real reason that they said use a color bar input for the color AFC setup is that they wanted a stable non-moving color picture input to work with, and back then, the color bars were the best choice?
So that in this age, it can be also done with a DVD input on pause?

Correct. Even a DVD on play. But it's easier to see what you're doing when the screen is full of bright color.

[Yamamaya42]

Originally Posted by old_tv_nut

Correct. Even a DVD on play. But it's easier to see what you're doing when the screen is full of bright color.

This is why i made the " Lost In Space" DVD, cause season had the extremely loud color in the outfits

[Yamamaya42]

getting closer

https://imgur.com/Tvyc044
not quite there yet
following the setup did not get me anywhere after a couple tries, so I tried what most say NEVER to do, and that was eyeballing it.

Now that is this close, I will try to run through the setup instructions again and see what happens.

[Yamamaya42]

Still not able to get clean color w/o barber-poling, will try the color AFC setup later, in a few weeks once back from recovery from surgery ( Ugh! ), but I'm not holding my breath, as I mentioned earlier in the thread, I see evidence that L24 & L25 have been replaced, and they even look new, so chances are the chroma bandpass is messed up also, and I'm not aware of a way to align it w/o a sweep marker generator. Unless there is some way that I don't know of.

[old_tv_nut]

Your picture looks like you're getting enough chroma amplitude. If that's correct, you should also be getting enough burst to lock up the phase detector. In that case, you should not try re-aligning the bandpass first but should look for a problem in the burst gate, burst phase detector, or reactance circuit first.

[old_tv_nut]

Good luck with your surgery!

[Yamamaya42]

ODD, I went and got a cheap DVM that had a freq meter built in and hooked it up to l33, and it reads 34.8 meg hz at that point. Now the meter can be way off, ( unlikely ) or the ref osc is not at the freq that it needs to be, I have not checked the caps around the area yet to see if they are correct, new. Old or replaced with wrong parts, the crystal is the orig, from what I have seen, and I'm not sure what one to replace it with, it that is what is needed, 3.58 vs 3.579545Mhz ( you can get either ) and not sure what capacitance rating for the CTC-16xl :/

It being off freq might be the source of my problem with not being able to do the AFC setup.
I have a list of caps to get , but I won't be able to do it for about 2 weeks or so.

[Electronic M]

Originally Posted by Yamamaya42

ODD, I went and got a cheap DVM that had a freq meter built in and hooked it up to l33, and it reads 34.8 meg hz at that point. Now the meter can be way off, ( unlikely ) or the ref osc is not at the freq that it needs to be, I have not checked the caps around the area yet to see if they are correct, new. Old or replaced with wrong parts, the crystal is the orig, from what I have seen, and I'm not sure what one to replace it with, it that is what is needed, 3.58 vs 3.579545Mhz ( you can get either ) and not sure what capacitance rating for the CTC-16xl :/

It being off freq might be the source of my problem with not being able to do the AFC setup.
I have a list of caps to get , but I won't be able to do it for about 2 weeks or so.

Given the barberpoling pictures I've seen you post I'm fairly certain your meter is giving you an incorrect reading. If the waveform is not a linear sine wave it is easy for a digital counter to register some multiple of the true freq.

If you have an oscilloscope I'd use that to check the freq if I got a reading that out there.

[Yamamaya42]

Originally Posted by Electronic M

Given the barberpoling pictures I've seen you post I'm fairly certain your meter is giving you an incorrect reading. If the waveform is not a linear sine wave it is easy for a digital counter to register some multiple of the true freq.

If you have an oscilloscope I'd use that to check the freq if I got a reading that out there.

https://imgur.com/SZOb74Z
https://imgur.com/DQml4WL
the sign wave is very stable, it's here that I wish i had the digital o-scope that I use at work, which has Freq readings.
I know ( have read how to find freq on an analog scope) , but I am very bad with numbers...
i really cant tell with any detail what freq that is :/

edit.
I can't SEE any drift of the sign wave via the scope, it does not mean there is none, my scope is not been calibrated since i got it, but its a very good one, so i trust it. I nearly wet myself when I looked up the value. (Tektronix 7934 Mainframe only − 2019 value: $29,370)
I guess Like I mentioned, I will start with the caps, but I have heard from sources that the crystal can be suspect, but I don't know to what degree.

[old_tv_nut]

Originally Posted by Yamamaya42

ODD, I went and got a cheap DVM that had a freq meter built in and hooked it up to l33, and it reads 34.8 meg hz at that point. Now the meter can be way off, ( unlikely ) or the ref osc is not at the freq that it needs to be, I have not checked the caps around the area yet to see if they are correct, new. Old or replaced with wrong parts, the crystal is the orig, from what I have seen, and I'm not sure what one to replace it with, it that is what is needed, 3.58 vs 3.579545Mhz ( you can get either ) and not sure what capacitance rating for the CTC-16xl :/

It being off freq might be the source of my problem with not being able to do the AFC setup.
I have a list of caps to get , but I won't be able to do it for about 2 weeks or so.

1) From the picture, you are only off by 3 or 4 cycles per 60 Hz, or 180 to 240 Hz. You should be able to adjust L31 (A16) to go through zero beat and be off either way, from a few hundred Hz too low to a few hundred Hz too high. Can that be done? If so, the system should pull in when you get close to zero beat. If it doesn't, the problem is in the phase detector or reactance tube circuit, not the oscillator. If you cannot go THROUGH zero beat to be off either way, there is a problem in the oscilator circuit.

2) I hope you meant your meter reads 3.48 MHz, not 34.8 Mhz, but even that is very wrong and does not correspond with the number of rainbow bands you are seeing. Forget the meter.

3) A 3.58 MHz crystal and a 3.579545 are the same thing, just stamped with fewer digits. The one you wouldn't want would be 3.56 or 3.59, which would be used in a gated rainbow generator, not a TV.

[Yamamaya42]

Originally Posted by old_tv_nut

1) From the picture, you are only off by 3 or 4 cycles per 60 Hz, or 180 to 240 Hz. You should be able to adjust L31 (A16) to go through zero beat and be off either way, from a few hundred Hz too low to a few hundred Hz too high. Can that be done? If so, the system should pull in when you get close to zero beat. If it doesn't, the problem is in the phase detector or reactance tube circuit, not the oscillator. If you cannot go THROUGH zero beat to be off either way, there is a problem in the oscilator circuit.

2) I hope you meant your meter reads 3.48 MHz, not 34.8 Mhz, but even that is very wrong and does not correspond with the number of rainbow bands you are seeing. Forget the meter.

3) A 3.58 MHz crystal and a 3.579545 are the same thing, just stamped with fewer digits. The one you wouldn't want would be 3.56 or 3.59, which would be used in a gated rainbow generator, not a TV.

correct, it WAS 3.48 MHz that the meter displayed :p oops
and i did try adjusting L31 (A16) and it did not seem to have any effect that I could see on the scope.
I will try again once I go over all the caps. i have already checked all resistors, found 2 wrong.

[old_tv_nut]

Originally Posted by Yamamaya42

correct, it WAS 3.48 MHz that the meter displayed :p oops
and i did try adjusting L31 (A16) and it did not seem to have any effect that I could see on the scope.
I will try again once I go over all the caps. i have already checked all resistors, found 2 wrong.

You will not see any effect on the scope - a few hundred Hz is not a visible percent of 3.58 Mhz. Determine if you are having an effect by looking at the picture and the number of rainbow stripes you see.

[Yamamaya42]

Originally Posted by old_tv_nut

You will not see any effect on the scope - a few hundred Hz is not a visible percent of 3.58 Mhz. Determine if you are having an effect by looking at the picture and the number of rainbow stripes you see.

That it did,

just to clear things,

I understand " phase detector " v23 and related, bur I'm not sure what is meant by "reactance tube circuit"