My CTC-16XL Project.

[DavGoodlin]

That NOS FLY is money in the bank. If you ever sell the TV, don't include but sell that replacement fly separately.

Another VK member sold me a badly needed NOS Thordarson fly that he never used, for a similar price.

[Yamamaya42]

Originally Posted by DavGoodlin

That NOS FLY is money in the bank. If you ever sell the TV, don't include but sell that replacement fly separately.

Another VK member sold me a badly needed NOS Thordarson fly that he never used, for a similar price.

I don't ever plan on selling it :p
I did not hang on to it for so many years in order to ever let it out of my ownership!

I just wish I could go back in time and save the CTC-10A that my father wasted...

[Yamamaya42]

I thought WTH, i have mentioned this before, but never really SHOWN IT.

https://www.youtube.com/watch?v=Oaw7...ature=youtu.be
I do not consider this to be a real problem, just something rather endearing to this set, for it has always done this since I got it, and it does it not matter if there if no RF input of a good strong signal.

I do wonder sometimes WHY it does it, and if other RCA sets do it also.

Since the IF section on it was jacked up by who ever had it before me, I have put A/V bypass relays in the set, and the sound on this id bypassed right out of the detector 6HZ6 far side of C53, (point 30 ) for external audio by the flip of a switch, and I have noticed it does not do it with external audio.

It's odd, what ever it is! :p

[Yamamaya42]

I have noticed a slight ghosting problem with my CTC-16XL, very much like seen in this thread,
http://videokarma.org/showthread.php?t=265940

I can say right now however, this is NOT a tuner/if problem, because it is seen with both RF input and on bypass/ direct AV input, so I'm already suspecting the old delay line, I had already been wary because it looked rather raged and abused to star with (beat up, tape peeling off, etc ), but like other things, I deem this a minor annoyance, and will be looked into later.
This may or may not be related to the other minor problem of shadowing on the screen of bright text/ letters.

Things I intend to do to try to address this is replace both the 1st/2nd video amp ( 6lf8) and video output (12by7a ), they are a bit old, and I'm not sure how up to par they are, I'm sure that NOS tubes would help.
There are still a few film caps in the circuit that are original, they say they don't go bad, but who knows, they may have degraded a bit, so it won't hurt to replace.
And as mentioned before, all resistors on the color PCB were replaced before I got the set, and checked by me, so they are OK.

A delay line problem will be tricky to deal with I'm sure, ( repair/replace? )
It should be easy enough to bypass it from the top w/o removing the chassis, that will at least tell me if my guess is right, if it is then what to do...


One thing to try, but I'm not sure what effect it will have on the old delay line, will have to try and see, wrap with layer of kapton tape first, then copper tape over that, with ground wire soldered to both ends, and then another layer of kapton tape over that. And see how it behaves.
If it's still acting up, there is places to get a NOS one, but I'm not exactly sure which one to get if I have to resort to that.
https://www.vivatubes.com/nos-nib-mi...dio-amp-parts/
They have many to pick from, and I'm not sure which is right for my 16.
But at least, if it is the old delay line, there is a way to get a replacement.

But as i said, this will be looked into later.

[old_tv_nut]

Bypassing is a good first test.

Wrapping an additional layer of copper tape:
If the outer layer is a ground layer already, this will not help UNLESS the existing layer is bad somehow (or disconnected from ground).
If there is no outer ground layer on the original, adding one will mess things up, as it will lower the impedance (producing transients) and increase the delay. (UNLESS the underlying layer is bad or disconnected, in which case an added outer layer may fix it).

Regarding caps:
Film caps are generally too large in value to cause short video transients, unless they are meant to be bypasses and are open. Transients can be caused if smaller capacitors or peaking coils associated with the delay line are bad.

Regarding replacement delay lines:
Delay lines are designed for a specific impedance, obtained by the number of turns per inch, their diameter, and the capacitance per inch determined by the copper ground sheet or sheets (under and/or over the windings). So the best bet is to get one from the same TV chassis number. Second choice would be to look for one of similar dimensions, although this wouldn't guarantee the winding count.

[Yamamaya42]

Originally Posted by old_tv_nut

Bypassing is a good first test.

Wrapping an additional layer of copper tape:
If the outer layer is a ground layer already, this will not help UNLESS the existing layer is bad somehow (or disconnected from ground).
If there is no outer ground layer on the original, adding one will mess things up, as it will lower the impedance (producing transients) and increase the delay. (UNLESS the underlying layer is bad or disconnected, in which case an added outer layer may fix it).

Regarding caps:
Film caps are generally too large in value to cause short video transients, unless they are meant to be bypasses and are open. Transients can be caused if smaller capacitors or peaking coils associated with the delay line are bad.

Regarding replacement delay lines:
Delay lines are designed for a specific impedance, obtained by the number of turns per inch, their diameter, and the capacitance per inch determined by the copper ground sheet or sheets (under and/or over the windings). So the best bet is to get one from the same TV chassis number. Second choice would be to look for one of similar dimensions, although this wouldn't guarantee the winding count.

Most CTC-RCAa seem to have the same delay line 15/16/16XL have part #109837 and that site posted above most likely DOES have it, but I have been unable ( so far ) to find a cross reference to that # there HAS to be a Miller cross to RCA #109837, I just dot know how to find it

but as mentioned, I will try the tubes first I still am not allowed to lift above 15lbs yet, and I'm guessing its the line cause of how ugly it looked, and guessing I won't be able to fix it.
Who knows, I may be able to, the grounding may be lose on it, and may be able to be patched, but if not, I would like to know which new one to get.

As for the caps, i have mainly 2 in mind.
https://i.imgur.com/fnlu7ZN.jpg
C23 & C25

C23 is one of those elenco tube BOMB capacitors that has given me trouble in the IF section ( took it out once ) and C25 is an original orange drop, I have found them to be leaky in the set before, not many, but a few, mostly ones close to tubes.

Will just have too see how things go

[old_tv_nut]

C23 is small enough to cause video response effects, but C25 is large enough to carry all video frequencies and be essentially a short circuit at the frequencies involved in the transient. If it were open, you would have greatly reduced contrast.

[Yamamaya42]

yanked the back off yesterday to touch up convergence, it was off a bit.

https://i.imgur.com/ppZ7BnW.jpg
you can see the slight shadowing to the right, not TOO bad, but its there.

will most likely have to take a close look at the delay line grounding next time o take the set apart.

still can't find a cross ref number for it

https://i.imgur.com/d15IVcY.jpg

live video,, hard getting a good shot with this cellphone still :/

the brats got bored watching me play with the set. :O

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

[old_tv_nut]

Off-air pic is too blurry to see this kind of stuff.

Worth checking grounds, but it's likely the delay line and its grounds are OK, and you are seeing a combination of multiple effects that are normal

Possible contributors
1) using a crosshatch signal generator - signal spills all over the channel, has no phase compensation like a commercial transmitter, transient response varies with fine tuning
2) chroma trap ringing
3) delay line load impedance not perfectly matched, line has some phase distortion not perfectly compensated by the load coils
4) sound trap ringing, made worse by the bar generator splattering a lot of energy into the sound area
5) other IF response effects

(2), (3) and (4) may be within normal tolerance for this chassis, and may be less visible with a properly filtered commercial modulator. VCRs, DVD players and digital TV converters have no video phase slope pre-compensation as required by FCC rules for commercial transmitters. One would hope they had at least luma/chroma delay alignment to match the FCC requirement at chroma center frequency, but that was/is often not the case. (PAL did not use transmitter pre-compensation, intending for any chroma edge distortion to be cancelled by the PAL decoder.)

To separate video from IF issues, turn the fine tuning - if the rings move, it's IF, otherwise it's video (detector, 4.5 MHz trap/take-off, and following video circuits)

[Yamamaya42]

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

best pic i could get

Sometimes I'm surprised that the set works as well as it does, cause it WAS in the hands of a mad tweaker who made a mess of it before I got it.

And it took me forever to figure out why I was getting no color through the tuner but could with fed in video, and that was the 4.5mh trap was so far out of tune, it was blocking color.

IF needs alignment, because I know it was messed with, hell the entire set could use an end to end alignment but I don't have the equipment or know how to do it.

Example, I know for a fact that the color takeoff coil and bandpass coils were replaced and never adjusted , just left at the pre-set from RCA.

I will look at stuff next time I pull the chassis , but there may not be a lot I can do.

[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.