CTC-4 Director 21

[old_coot88]

3.58 is simply the rounded-off figure. "Three fifty-eight crystal" or 'color crystal' is all the same thing.

[old_tv_nut]

If the oscillator uses the crystal alone as a series resonant element, the crystal is tuned to be series resonant (a short circuit) at 3579545 Hz. However, nearly all chroma oscillators use a crystal in a "parallel resonant" mode. I put "parallel resonant" in quotes because the crystal is not tuned to be parallel resonant in itself, but to be inductive, so it can be either series resonant or parallel resonant when combined with a small amount of capacitance (consisting of both strays and discrete separate parts). In this mode, the crystal acts as a very large inductor resonating with a small capacitance, and the combination is resonant at 3579545 Hz. The crystal series resonance in itself is then a few hundred Hz different from the correct frequency. Common values for the total tuning capacitance would be in the range of 20-30 picofarads. The value of capacitance for which the crystal is tuned is specified in a manufacturer's part drawing, but not in service literature. Generally, crystals made for different values of capacitance can be substituted because in most cases the oscillator center frequency can still be tuned to the correct value; however, the pull-in range and hence the temperature drift will be different than intended.

[SwizzyMan]

Might have to replace the crystal. It rattles when barely tapped. And as I was recapping I accidentally hit it with my pliers.

[Phil Nelson]

I would suspend judgement on the 3.58-Mhz crystal until you finish recapping and try the TV again. If the crystal is bad, the telltale signs should be pretty obvious, as I observed when working (and working and working) on my poor old CTC-4. It will be easier to diagnose that after you eliminate bad caps from the color circuits.

If you do eventually find that your crystal is bad, I can send you a spare from my stash.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[SwizzyMan]

Good Idea Phil. Better to narrow it down first. It was working last time I powered it up since the color oscillator was in fact running at the correct frequency. I really appreciate your offer to send me a crystal if the need may arise. Thanks!

[SwizzyMan]

Only have about 7 more paper caps to replace. Some values Im going to have to order. Going to do a power up later this week. Found one of those El-shitco caps that the ceramic case had cracked and the inside was almost hollow... wow.

[SwizzyMan]

Fixed the previous issue. I have a few more paper caps to replace which are values I didn't have on hand. Did a power to see where I'm at. Still pretty much the same when the old caps were still here. Didn't expect recapping to do much since that's not how it usually works.

[SwizzyMan]

Here is what I got. As you can see I have a nice black and white picture. But the color is a different story. There seems to be an absence of yellow and any purple colors. Rotating the Hue didnt do much and this was the best I could get it. I also have to turn up the color control about 3/4 of the way up to really get any color. And you can see i have that slow horizontal bending that almost looks like bad filters (all were replaced)when straight lines show up on the screen. I almost suspect that the crystal oscillator is actually bad.

[Electronic M]

Have you checked the tubes recently for Heater-Cathode/Heater-anything shorts...That could be introducing your hum bar.

On my set I had to adjust one of the transformers in the color demodulator....The one that controls the phase angles that the 2 demods operate on....It has an above chassis and a below chassis adjustment on it's can...You have to adjust both at once with color bars on screen, and you have to use 2 plastic flat edge alignment tools (metal screw drivers will make your adjustments shift as soon as you remove the drivers from the can)....I had to make my 'alignment tools' out of ruined mechanical pencils. I wish I could tell you which can it is, but it has been ~4 years since I did that work.
http://videokarma.org/showthread.php...Seville&page=4

[old_tv_nut]

You appear to have horizontal sync problems. Since this could affect color burst gating, you should probably fix the sync first. Those wigglies could come from poor sync separation, a problem with the horizontal AFC, or even a bad signal level due to AGC problems or wrong AGC setting - suggest you hunt down the horizontal trouble, and check the burst gating before tackling color. The color oscillator is probably OK, since you have stable (but wrong) colors.

To clarify: I would try the simplest things first - try adjusting the AGC to see if it makes any improvement.

[Phil Nelson]

Amen to Wayne's advice to look at simpler causes before you mess with color circuits/adjustments. To quote various old manuals, make sure you have a perfect (well, darned good and stable) black and white picture before you tackle color stuff.

If your 3.58-Mhz oscillator wasn't working, you'd more likely have rolling "rainbow" bands of color, not stable bars, as I learned in struggling with my sad old CTC-4.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[SwizzyMan]

Now that I think about it. I had this problem with my pensbury. A 68k resistor went off value and caused the horizontal sway. Hopefully its just an AGC adjustment on this set.

[SwizzyMan]

Finished recapping (finally). I have to say some spots were very hard to work at, the convergence module being the most difficult. Overall recapping this set was relatively stressful to the fact I was working around fragile coils and try not to drip any solder on anything. I also made sure to check all my connections with my Ohmeter. I decided to give it the shrink wrap treatment since this set is a hard to find set and neatness is a must. I have yet to fire it up and quite frankly im a bit scared to do so since Im worried I might have accidentally broken a coil or a coil in the convergence module, while I don't recall messing up too bad anywhere (with the exception of 2 or 3 solder dropping mishaps) I'm still scared out of my mind about powering it up since this set is relatively rare. I hope the power up goes well!

[SwizzyMan]

Did a power up and all went smoothly thank God! Still have the same problem, superior black and white picture but piss poor color. Still got that pesky interference. Adjusting the AGC control helped a little with the interference. It is also becoming increasing evident that the red gun is pretty weak, and its impossible to do a color temperature set up according to the service manual. What really puzzles me is the absence of all other colors pretty much except for blue and red on the color bars. I adjusting the hue coil (T125) for about half a turn and realized that wasnt it so I returned it back to its original position. adjusting the hue control really doesnt make much difference. The red and blue bars stay there until about a full turn ccw when they shift to maybe a purple color. Also i must not I have to turn the color control to pretty much the max color setting to really get any sort of a chroma signal. This further backs up the statement that replacing capacitors on antique tv or radio doesnt always magically fix everything. Any ideas on what is wrong here and any possible adjustments i can do?

[Electronic M]

One thing you should do is degauss it and perform a purity adjustment.

A note the coil that changes the hue and relative demodulation of the different bars has 2 slugs one bottom and one top (should be flat edge blade adjustments)...On that coil you want to adjust both simultaneously with plastic adjustment tools (metal ones will skew the adjustment once removed).