My CTC-16XL Project.

[Yamamaya42]

Originally Posted by Electronic M

I wonder if the door knob who worked on it before you used something like acid core plumbing solder?... You're never supposed to use that on electronics but some people did, infact if you go back to the 20s and 30s some electronics makers used it.

Not a clue , I just know that what is left behind is white scale, hard and crusty, and I can also see that the replaced resistors did not have the lead protrusion clipped off on the bottom but were broken off by stress, ( I can see the copper in the center ) , this is probably not a big deal in this case, but such a thing is a big no-no in my line of work, and violates iso standards in every way.

[old_tv_nut]

Originally Posted by Yamamaya42

Mouser has crystals @ both 20pf and 30pf.
I don't know for sure that the original is bad, but I don't know that it's good either.
I do know it's oscillating, but something seems to be off with the circuit.
If I understand things correctly, with point J grounded, I should be able to hook a frequency counter to L33 ( general area ) and be able to adjust L31 (A16) to get 3.579545 mhz, and as well as a respectable range above and below.

20 pf version should be fine.

The fact that it's oscillating and the frequency doesn't go all over the place as you adjust it would indicate that the crystal is working.

[Yamamaya42]

from a pic of the bottom I took when Rocket wanted to see how my switches were wired,
https://i.imgur.com/lF885FA.jpg
if you look very close, you can see the krud :/

[Yamamaya42]

So far, replacing caps has not helped
https://imgur.com/uodtlrG
almost all caps in the OSC circuit new, point J grounded, this is as close to 3.579545 i can get.
not sure what else to try other than replacing the carbon film-resistors that were put in there with 1% metal film.
The crystal IS OK. removed and tested in x-tal tester, it was on freq.
and got a really neat pic with crystal removed, all reds were green, there was color lock, so burst amp and related circuits are working. not sure what else to look at other than the resistors that were put in before i got it, I only checked visually they they were right value. 5% carbon film in there now.

[old_coot88]

Originally Posted by Yamamaya42

...got a really neat pic with crystal removed, all reds were green, there was color lock, so burst amp and related circuits are working.

Does the 'green' turn down when you turn the color control down? If so, the osc is not running. What you're seeing is the chroma amplitude without the 3.58 phase-reference signal.

[old_tv_nut]

Originally Posted by Yamamaya42

So far, replacing caps has not helped
https://imgur.com/uodtlrG
almost all caps in the OSC circuit new, point J grounded, this is as close to 3.579545 i can get.
not sure what else to try other than replacing the carbon film-resistors that were put in there with 1% metal film.
The crystal IS OK. removed and tested in x-tal tester, it was on freq.
and got a really neat pic with crystal removed, all reds were green, there was color lock, so burst amp and related circuits are working. not sure what else to look at other than the resistors that were put in before i got it, I only checked visually they they were right value. 5% carbon film in there now.

Hard to believe you're off that much with the crystal in place (800 KHz low!), especially since the crystal tests to be the right frequency on a crystal meter. I suspect your frequency meter is reading really off. If the frequency were this far off, you would have fine rainbow stripes that might not even be visible.

Also agree that the green without the crystal is an indication that the oscillator is not running.

More sleuthing needed. Dumb question, but do you have any scope probes, meters, jumper wires, or etc. attached when you are trying to tune the oscillator frequency? Which caps in the oscillator circuit are NOT new?

[Yamamaya42]

https://imgur.com/9HcgQcz

pic with crystal unhooked
when i took the readings with that meter, both times, there was nothing hooked to the set but the meter shown in the post hooked to L33.
right now c120 and 123 are not new, as they are under the can of L32 and i really did not want to remove it if i did not have to.

[old_tv_nut]

C120 and C123 should not affect oscillator frequency, so I think no worries there.

[old_tv_nut]

Does L31 measure 8 ohms, as the schematic says?

[old_tv_nut]

How far have you turned the core of L31 when you try to tune it? Do you think you could remove it completely without breaking it? (Trying to find out if you are always on the low side of 3.58 Mhz).

[Yamamaya42]

Originally Posted by old_tv_nut

How far have you turned the core of L31 when you try to tune it? Do you think you could remove it completely without breaking it? (Trying to find out if you are always on the low side of 3.58 Mhz).

That is the one thing I have not checked yet, The resistance check of L31, and I am able to tune the core all the way from as low as it will go to where i can sii it poking out the top, i did not go any higher, i could have, but saw very little change on the meter.
i will check the resistance of it when i replace the 5% resistors with 1% in the area, i got a huge box of them of most common values, so it wont be much of a problem to change them.

the larger ones, 1w are most likely OK anyway

[Yamamaya42]

OPEN COIL!!

it read 12 ohms
had to operate on it to get it to 8 ohms.
and then..
https://imgur.com/MNNx88t
https://imgur.com/CqMWDXJ

[Electronic M]

Looks good!

It is probably time to fix the cataract and adjust the greyscale to be less blue.

[Yamamaya42]

Originally Posted by Electronic M

Looks good!

It is probably time to fix the cataract and adjust the greyscale to be less blue.

color level is changing slightly perhaps I need to re tweak A15 & A17 now that I can get lock?

or could this be a symptom of the a symptom of the new coils in bandpass never being adjusted?

At this point, i don't even have the Convergence assembly on the neck, its plugged in but I made no attempt to set output levels , or adjust anything, spent all this time trying to get color, now on to next things, i guess!

[Electronic M]

If your color control is set too high that may be causing fluctuation. In tube sets, if you overdrive the chroma it will get noisy and flickery.