My CTC-16XL Project.

[old_tv_nut]

My philosphy is "fix the obvious things first." In your case, the obvious is what you have mentioned about things being untweaked or madly mis-tweaked. The delay line is basically working, so that becomes a second priority to check. Plus, as I said, sets are never perfect when properly aligned anyway, due to component tolerances.

[Yamamaya42]

Well, I know it can do better, but I'm basically stuck in a position that I can do little about it due to lack of exp/ equipment.
Unless there is someone in the general area who has the equipment and knows how to align it, it will have to stay like it is.

I do plan to pull the chassis sometime to replace the 6meg focus resistor and 130pf cap, not that they are really failing now, but I'm sure that they are worn and could use replacing.
I have always wanted to look into to a retrace line problem this set has, where as all resistors on the color PBC have been replaced, the ones on the sweep PCB have not been, there is a 100k resistor on the sweep PCB that is old that I suspect to be out of tol, it's tied directly to the plate of the vert output tube and transformer, and thus being hit by very large vert pulses, it then goes to a .01 ceramic disc cap, (not suspect) , then a 68k resistor (new) , then to the plate of the video output tube, thus the source of vert blanking, I overlooked this last time I had it apart, and was looking mostly at horz blanking.

Step by step, I'll try to make this set work the best I can.
It has come a long way from a set that was in pieces, with it's non working color PCB hanging out by it's wires, cover to the IF section removed and lost, and most original screws gone then stuck in storage for many years!

[Yamamaya42]

yup, I was right!
https://i.imgur.com/i7CqJ42.png

Added to the to-do list,
it checked at 120k almost.
was easy enough to check, pull the vert tube, VOM at pin 6, and point 52 is right at the back of the color PCB at the back of the chassis, easy to reach.
I will most likely replace C31 while I'm at it, even though it prob OK, and hopefully the retrace lines will be all gone after that, and at least THAT annoyance will be addressed,

[Yamamaya42]

I would still like to try bypassing the delay line, but the question is, how to go about doing it w/o disturbing anything, been thinking about this for a few days now.
I don't want to A) remove the chassis yet, or B) remove the cover of the IF section where the 1st/2nd video amp tube is, and this is what I'm thinking of doing, and I want to make sure it sounds right before I try it, IE, I don't want to let any magic blue smoke out.

https://imgur.com/fnlu7ZN

re-using old pic, ignore red circles.

Remove V4, wrap kapton tape around metal shield on tube, leaving space on bottom for ground tab, wire wrap piece of magnet wire to pin 3 of V4, secure magnet wire with kapton for safety, connect magnet wire to junction of of C25 & R66, bypass complete.
This also leaves out L13, 72uh coil, I could add in one of the extra coils I have laying around, but I'm not sure if it's really needed.
I'm pretty sure that doing this won't blow anything up, but I'm not %100 sure.

[old_tv_nut]

This should work, as the delay line and L13 are essentially a DC short. Don't bother trying to replace L13, it's purpose is to improve the transient response of the delay line, which you are bypassing anyway.

The dangerous part is connecting to V4 pin 3 carefully so as not to short to adjacent pins.

If the cover is not soldered in place, I would try doing this with the cover removed first, see what you get, then decide if you really need to do this with the cover in place.

Did you try the fine tuning yet to see if the transients move or are stationary? If they move, then you know it's an IF alignment issue and not the delay line.

[Yamamaya42]

Originally Posted by old_tv_nut

This should work, as the delay line and L13 are essentially a DC short. Don't bother trying to replace L13, it's purpose is to improve the transient response of the delay line, which you are bypassing anyway.

The dangerous part is connecting to V4 pin 3 carefully so as not to short to adjacent pins.

If the cover is not soldered in place, I would try doing this with the cover removed first, see what you get, then decide if you really need to do this with the cover in place.

Did you try the fine tuning yet to see if the transients move or are stationary? If they move, then you know it's an IF alignment issue and not the delay line.

That's sort of two fold, in RF input mode, there is shadows that move with fine tuning, but are mostly seen in the color, if color is turned down, no shadow movement is seen, but there is a shadow also seen in the luminescence that does not move. This is also seen in direct A/V input.

I have known about the set having IF problems that had an effect on the color ( mostly red ) thus set the auto bypass circuit in it via a signal relay at TP1 Point B, direct input does look much cleaner, but still has the same shadow to the right as IF input, if I ever can get the IF aligned correctly someday I can remove the mod.

Shorting it won't be an issue really,
I essentially have an exact copy tube in the GE CTC-15ish clone, that I can take to work and rig up under microscope and make sure it's OK before I put it in.

[old_tv_nut]

Originally Posted by Yamamaya42

...if color is turned down, no shadow movement is seen, but there is a shadow also seen in the luminescence that does not move. This is also seen in direct A/V input...

OK - definitely in the video section then.

[Yamamaya42]

AHHHH! I just found something I missed before, even though the 1st/2nd video amp tube has the shield on it, it is NOT being grounded.

the tab must have broke, or bent and I missed it.
gonna have to fix it.
No telling what kinda mess it could be causing...

[DavGoodlin]

Originally Posted by Yamamaya42

AHHHH! I just found something I missed before, even though the 1st/2nd video amp tube has the shield on it, it is NOT being grounded.

the tab must have broke, or bent and I missed it.
gonna have to fix it.
No telling what kinda mess it could be causing...

I hope that improves it for you. I know what it is to go after issues one at a time and when you see little to no improvement with each one, but they do add up.

The 21" Zenith I restored was that way. Original trouble started with a shorted sync/sound detector diode (not before sending me on a journey through the Zenith-unique sync circuit) and extreme vertical and convergence issues, which I learned alot from.

At the beginning, I could not imagine it ever being Zenith-bright/sharp. After several weeks, looking back made me realize how easy one could give up before its working as it should. Its just physics!

[Yamamaya42]

Delay line bypass rig made, will try it this weekend.

https://imgur.com/IwoAhCB

grounding the shield did not make much of a difference.

[Yamamaya42]

Well, the bypass idea did NOT WORK!
fail BIG TIME!!

https://i.imgur.com/6P12EZj.jpg
caused an echo image, which was ironically at about the same place that I had be seeing the shadow image, so who knows, it may BE delay line related, I will have to wait till the next time I have the chassis out to know for sure, I still wish I i could find a NOS Miller cross reference chart someplace, as IF i have to replace it, I'm sure that site has one I'm just not sure WHICH one,

In the mean time, I'm gonna work on what I CAN do w/o pulling the chassis, as in getting the convergence as perfect as I can, I made a few mistakes in placing the parts on the, CRT neck, but it did not seem to matter much, I still cant get it the way I like it, I may never will, there are some original resistors on the convergence PCB that I intend to change next, that may help.

Aside from that, there is a moderate list of minor annoyances to hit next time I pull the chassis... heavy sigh!

[old_tv_nut]

D'oh. Now that I look again, this is to be expected because the delay line is not driven from a low impedance (cathode), but high impedance (plate). To do the check you wanted to try, both ends of the delay line should be disconnected and then the jumper put in its place. You are seeing multiple reflections in the delay line when it is still attached.

If the shadow image without the jumper is at the same spacing as the one you see with the jumper, that is the same triple transit effect. This circuit does not necessarily terminate the input of the delay line correctly. Therefore, if the output termination is not perfect (or the delay line impedance is not nominal at all frequencies), some energy may be reflected back to the input and will not be damped there and will reflect again and return back to the output ("triple transit").

This tells you that if none of the components are out-and-out defective, the set may be operating within factory tolerances, and they all were subject to a bit of triple transient effects.

At this point, the delay line is no longer very suspect. Instead some trial and error variation in the output load components may improve things. L13, L14, R63, R64, and maybe L15 can all have an effect. But don't be too surprised if you find that you can't make it much better, and mainly worse. The fact that R64 is the only 5% resistor in the area is a hint. You could try tuning the L's (to larger inductance only) by bringing a core or some iron on a stick next to them. If you had a stock of peaking coils, you could try various values.

[old_tv_nut]

more: You could try replacing the peaking coils even if none of them are open, in case they have shorted turns instead. But I don't know if that was ever a common failure mode.

[Yamamaya42]

I do know for a fact that the delay line was roughly handled when I got the set, I'm not sure if it was really damaged or not, but it was NOT treated well at all, left hanging loose with only the IF end connected, I wish I had pictures of it, it took me quite a while to work out where all the loose wires to the color PCB went.

however, L13 was damaged, ceramic broken on the leads, more than ½ way, but still had continuity, so I assumed it to be OK and suck silicone on it and put it back in.
This may be a source of a problem, no idea, but as luck would have it, I have just found an exact replacement for it, and will come who knows when :/

Another possible problem. however I doubt it, that when I put it together, I had no real visual reference on HOW to do it, unlike I do now.

example, how it's done in the GE RCA clone, https://i.imgur.com/FxjBWaj.jpg

you can clearly see the heavy wire going down that is grounding the delay line, in my CTC-16, that was GONE! all that was there was the grounding solder point on the DL, and since I was unsure where to ground it to, i used a piece of wire ( not as thick as seen in the pic ) that runs to a ground point to the ends on the color PCB.

I doubt that this is a problem, but who knows
Is the DL damaged , no way to tell w/o getting it out and looking at it under a scope :/
there has to be some way to find a cross for it, if it is.

As for the peaking coils, some of those oddball sizes will be hard to find. I got lucky with L13 (72 uh ) who knows, may get lucky again!

[old_tv_nut]

Grounding the delay line differently than originally could cause some trouble.

It would be reasonable to use series combinations of more readily available coil values to make a replacement for the odd peaking coil values. The specification of odd values is a hint that they may be critical, just like the 5% resistor.