My CTC-16XL Project.

[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...

[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.

[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]

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.

[dtvmcdonald]

Peaking value coils are never critical. In fact, its sort of silly worrying
much about just the value, unless you can get a for certain absolutely exactly original
factory model coil.

You see, these thing have capacitance across them and thus are parallel tuned circuits. Whether they are used in series with the signal or as a plate load, that resonant frequency matters.

And the "standard replacements" listed are often, while close in low frequency
inductance, way pff in parallel resonance. That can make for a bad picture.

I have an RCA CT-100 color TV with lots of peaking coils that are potted in something white that corrodes them. In fact though some of mine were bad, none were
so bad I was unable to unwind a few turns and get measurements of inductance and resonance. I had to experiment to get the waveforms to look right. I bought
two or three coils for each replacement. The best inductance value varied
up to 35% from spec. Most were noncritical but a couple were critical.

Putting coils in series thus generally simply won't better than just getting close.

[Yamamaya42]

on the "to do " list next time the chassis is out.

Replace R70 (out of tol) , & C31,R71 just to be sure, they are most likely OK , but new parts won't hurt, hopefully this can cure the retrace problem.

Inspect delay line VERY closely, checking for any damage at the grounding point, and see if repair/ replace needed, re-connect ground to OEM position, similar to as seen in GE chassis. Replace L13 that had been slightly damaged with NOS RCA part. Replace R64 with new 2% part, it's most likely OK, but while I have it out, why not, inspect L15/L15, they are on the topside of the PCB, and unlikely to be bad.

Check remaining original orange drop caps for leakiness.
Replace focus resistor & cap.
Fix the damn loose connection on the heater pin on the socket of the HOT.

I did manage to view the entire DVD , Watchmen Director's Cut, this weekend with it, and I saw no macrovision problems whatsoever, I'm not sure if it was because of the player used, or the DVD, or because I was using direct A/V input, but it was very stable, no problems at all.

[Yamamaya42]

Damn, L13 will be arriving surprisingly fast, It was shipped from within Texas, only 10 hours from here, It will be here Thursday.

The focus resistor, however, is coming from REEDLEY, CA, that will take a wile

does the 130 PF cap in the focus circuit really wear out that much and need replacing?

[Yamamaya42]

new L13 has arrived, no other parts yet, it does not look like the old one, but that is not unexpected,

https://i.imgur.com/pVTY6tn.jpg

found an old pic of the underside with the delay line and coil
https://i.imgur.com/1XZjvKL.jpg
you can see how I grounded it, and L13. (but not the damage to it )

waiting for the other parts

[Yamamaya42]

Well, USPS, “says” that the 66meg focus resistor is in the mailbox, but I won't fall for that again after the thermistor fiasco, I won't believe it until it's in my hands.

FEDEX says that the replacement for the 130pf cap in the focus circuit will come Friday, now there seems to be some flexibility on the value of a usable replacement, CTC 10-16 SAMs list no sub for it other than the RCA part# @130pf, but in the CTC 20, a 120pf is listed as a replacement, however, in the GE CTC 15 & 1/5 clone, it lists a 150pf as one, which I have used successfully, and since the focus circuits are all identical for the most part in all of them, I got another 150pf / 15kv for CTC-16XL.


Meaning that now, I should have have all the parts needed to do all the minor updated to my RCA that I had been wanting to do, including removing that black wire I have grounding the delay line, and grounding to the nearest gnd point via a heavy lead from a power resistor, the thicker, the better.

But, I'm still debating on to try it this weekend or to try and get the GE clone downstairs, setup and converged.
It's still too heavy for me to move on my own, so I'd have to bribe someone to help, or take it apart, IE remove the CRT from the cabinet and take them down separately, ( which I really don't want to do ).

The specs say a 21FJP22 is 43lbs, the cabinet rough guess is 20lbs? Separately, easy enough for one person to move, even with a shoulder that's healing fro surgery, together,, NOT... the chassis is very light compared to the CTC-16XL, and even the FADA rca 630ts clone, I was surprised at how light it was, like someone pointed out, GE= Good Enough.

Still not sure which way I'll go this weekend.