CTC-4 Director 21

[old_tv_nut]

What size cap across the crystal? It's probably too big if it pulls it 545 Hz too low. It needs to free run close to correct so the reactance tube and coil can pull it either way.

[old_tv_nut]

I don't have the alignment procedure, but I imagine at some point you are instructed to tune the reactance coil for zero beat. If you can't make free-running frequency correct, the reactance circuit has little chance to pull it in.

[SwizzyMan]

Originally Posted by old_tv_nut

What size cap across the crystal? It's probably too big if it pulls it 545 Hz too low. It needs to free run close to correct so the reactance tube and coil can pull it either way.

I seem to be mixing up my results here. What I get with the crystal across the cap is 3.5760. The target is 3.57545. I am not putting the right results here. Let me start over now. The closest I can get the oscillator to run at is 3.5766 without a cap across crystal. With a cap across the crystal I pull about 3.5762 or thereabouts. the capacitor across the crystal does not pull down the frequency much at all. I would venture to guess the cap was maybe 5pf.

[old_tv_nut]

Are you getting tired? You seem to be missing a 9 this time. I think this time the numbers you meant to type were something like:
crystal across cap: 3.57960
target: 3.579545
without a cap: 3.57966

If that's right, the cap is pulling it 60 Hz, which is a nice amount of pull, so it seems something else is wrong. Which capacitors in the reactance tube section and the 3.58 MHz oscillator have you NOT replaced? Do you know for sure the reactance tube is good? Is the plate voltage 5 volts lower than the B+ supply as the schematic says? Time to look for anything that is not right.

[old_tv_nut]

By the way, too much capacitance across the crystal will lessen the effect of the reactance tube, so, since you see the frequency being pulled a good amount by the added cap, it may be better to remove it while looking for other causes.

I'm going to bed now, will check in tomorrow to read the latest. Good luck!

[SwizzyMan]

Originally Posted by old_tv_nut

Are you getting tired? You seem to be missing a 9 this time. I think this time the numbers you meant to type were something like:
crystal across cap: 3.57960
target: 3.579545
without a cap: 3.57966

If that's right, the cap is pulling it 60 Hz, which is a nice amount of pull, so it seems something else is wrong. Which capacitors in the reactance tube section and the 3.58 MHz oscillator have you NOT replaced? Do you know for sure the reactance tube is good? Is the plate voltage 5 volts lower than the B+ supply as the schematic says? Time to look for anything that is not right.

Yeah I was up a bit later than usual last night.. Sorry about that. Your numbers are right just know that the lowest frequency is a bit rounded. To be exact I get about 3.579620 which is a bit higher than 3.579600 but it shouldnt really make much difference. The 6AN8 reactance tube is confirmed good. I'll check the voltage on the plate of the pentode of the 6AN8 next.

[SwizzyMan]

There must have been some intermittent connection in the socket of the reactance tube because now the color is solidly locked!! Frequency is on the dot! But I do have the wrong colors for sure and the hue/tint control changes the colors but doesnt give me all the right colors. I do know that I can do a touch up by adjusting the coil that is controlled in a way by the hue control (the control seems to act like a variable inductor?). But i think I should do a color temperature setup first. Your thoughts?

[Electronic M]

You may need to adjust L86 (sams). It sets the relative phase angles of the demodulators...If it is off you will be able to get the red bar red and the blue bar blue but not both at once (and similar problems)... IIRC you have to adjust a slug on top of chassis and a slug under chassis simultaneously with plastic* straight edge alignment screwdrivers (had to do this on my CTC-4). *Metal screw drivers will act like an extension of the slug and your freshly tuned adjustments will de-tune as the metal driver is withdrawn from the transformer can (spoken from experience ).

If the color temp is right with the set operating in B&W mode then it is right, and does not need messing with....If turning on the color circuits throws the greyscale color temp off then there are problems in the color circuits causing that.

EDIT: BTW congrats on getting sync! It seems these sets like to get dirty intermittent tube sockets.

[SwizzyMan]

Originally Posted by Electronic M

You may need to adjust L86 (sams). It sets the relative phase angles of the demodulators...If it is off you will be able to get the red bar red and the blue bar blue but not both at once (and similar problems)... IIRC you have to adjust a slug on top of chassis and a slug under chassis simultaneously with plastic straight edge alignment screwdrivers (had to do this on my CTC-4).

If the color temp is right with the set operating in B&W mode then it is right, and does not need messing with....If turning on the color circuits throws the greyscale color temp off then there are problems in the color circuits causing that.

EDIT: BTW congrats on getting sync! It seems these sets like to get dirty intermittent tube sockets.

Glad it was just a matter of intermittent connection then that of a bad part! I'll give your suggestion a try.

[SwizzyMan]

Either im not adjusting L86 properly or we have a different problem here. After turning both shafts one turn CCW the screen develops a yellowish green tint. And after a turn clockwise it does the same thing. If i turn the slugs individually the top part of the coil seems to have a bigger effect than the bottom portion. What could I be doing wrong?

[Electronic M]

IIRC (it's been ~4 years since I was working on mine) There maybe some interplay with the tint control. I think there may have been some tinting of gray scale when adjusting those slugs on mine. Also on color sets if the color lock is lost with saturated bars the bars will tend to all turn one color.

Put 86 back how it was, adjust the tint so as many of the bars are as close to the correct color as possible, then try 86 together with the tint control and see if you can get it better.

Also you may have the color level up too high. The first bar should be white IIRC. If you overdrive the color level on some (otherwise perfect) sets the tint of some colors will shift abnormally. Reduce color level till the bars are pastel/faintly colored and readjust.

[SwizzyMan]

Originally Posted by Electronic M

IIRC (it's been ~4 years since I was working on mine) There maybe some interplay with the tint control. I think there may have been some tinting of gray scale when adjusting those slugs on mine. Also on color sets if the color lock is lost with saturated bars the bars will tend to all turn one color.

Put 86 back how it was, adjust the tint so as many of the bars are as close to the correct color as possible, then try 86 together with the tint control and see if you can get it better.

Also you may have the color level up too high. The first bar should be white IIRC. If you overdrive the color level on some (otherwise perfect) sets the tint of some colors will shift abnormally. Reduce color level till the bars are pastel/faintly colored and readjust.

I did have the color turned all the way up. But i did adjust the tint for the best match. The only color that is correct seems to be the red bar which is in the right spot.

[Electronic M]

What I mean is if you turn the color all the way up one or more bars may independently change tint in the opposite direction of another bar such that there is no setting where all the bars are right....I've seen it before where once color is over driven there is no longer a setting where all bars are right since one or more have wandered off of correct relation to the others.

[SwizzyMan]

Originally Posted by Electronic M

What I mean is if you turn the color all the way up one or more bars may independently change tint in the opposite direction of another bar such that there is no setting where all the bars are right....I've seen it before where once color is over driven there is no longer a setting where all bars are right since one or more have wandered off of correct relation to the others.

Got it. Ill lower it then try adjusting L86

[SwizzyMan]

After turning down the color a bit and adjusting L86 I finally have pretty much the correct colors! But as you can see there is heavy interference in the picture. What I think Ill do next is inject a video signal from a dvd player directly to the grid of the Audio amp tube and see if that clears up interference so I can narrow down whats causing it. Any thoughts on what could be the cause of the interference? The camera makes the picture look a bit more clear, but in person the interference is heavy.