CTC-4 Director 21 - Page 7 - Videokarma.org TV - Video

SwizzyMan · #1 09-20-2016, 06:32 PM

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 · #2 09-20-2016, 08:04 PM

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 · #3 09-20-2016, 08:38 PM

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 · #4 09-27-2016, 08:08 PM

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.

Electronic M · #5 10-04-2016, 04:18 PM

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 · #6 10-04-2016, 04:24 PM

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 · #7 10-04-2016, 05:53 PM

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 · #8 10-04-2016, 06:33 PM

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 · #9 11-16-2016, 05:29 PM

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 · #10 11-18-2016, 07:35 PM

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 · #11 11-18-2016, 09:53 PM

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).

SwizzyMan · #12 11-19-2016, 08:59 PM

Quote:

Originally Posted by 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).

Ill have to try both of those suggestions. Anyone else have any ideas? I almost feel the weak red gun may partly be at play here.

Phil Nelson · #13 11-20-2016, 02:52 AM

Instead of trying adjustments piecemeal, I would recommend working through the setup procedures described in the service manual. This article has a link to the 91-page RCA manual:

http://antiqueradio.org/RCACTC-4ColorTelevision.htm

Those procedures include purity, convergence, tracking, color AFC, etc. Follow the order given in the manual. First, as noted, make sure you have a good "black and white" picture. Then comes purity, and so on.

There's a reason why the factory doc describes this stuff in detail and in a particular order. The complete setup on an early color set is not something that the average consumer could "eyeball" by whipping out a screwdriver and turning random adjusters for a minute or two.

If you're patient and your TV is in good shape, the CTC-4 will reward you with a very nice color image.

Regards,

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

SwizzyMan · #14 11-20-2016, 06:36 AM

Quote:

Originally Posted by Phil Nelson

Instead of trying adjustments piecemeal, I would recommend working through the setup procedures described in the service manual. This article has a link to the 91-page RCA manual:

http://antiqueradio.org/RCACTC-4ColorTelevision.htm

Those procedures include purity, convergence, tracking, color AFC, etc. Follow the order given in the manual. First, as noted, make sure you have a good "black and white" picture. Then comes purity, and so on.

There's a reason why the factory doc describes this stuff in detail and in a particular order. The complete setup on an early color set is not something that the average consumer could "eyeball" by whipping out a screwdriver and turning random adjusters for a minute or two.

If you're patient and your TV is in good shape, the CTC-4 will reward you with a very nice color image.

Regards,

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

I'll go through a complete set up procedure today and report back with my findings. I probably could be a bit more patient with this set but I'm a bit behind schedule on my goal to have a decent picture by Christmas.

SwizzyMan · #15 11-20-2016, 10:42 AM

So I tried going through the setup as indicated by the manual and I couldnt even get past screen temp without an issue. I followed the instructions in the manual. I couldnt get the "barely visible red screen" and I think I know why. I went to measure the bias on the Red grid and cathode as i adjusted the brightness and the voltage was way too low. Im talking almost 200v below the intended 70v. I did have all controls adjusted correctly while checking the bias and adjusting the brightness for a dim red raster. I suspect a resistor downstream of the red screen control or downstream of the cathode and grid has drifted way too low or has even shorted. I guess ill have to do some investigation. This all seems odd since I at one point did have red in my color picture and things looked pretty watchable, but now its kinda taking a turn for the worse. I have one picture attached of what it used to look like before I really recapped any paper caps.