Hi all,

I'm starting a thread for the restoration of the RCA CTC-11D that I picked up last week. Thanks to Phil Nelson, I have the SAMS info for it. I pulled the chassis and gave it the once-over. For the most part, it's clean and unmolested (aside from missing six tubes).
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/CTC-11Resto1003_zpsbde855e9.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/CTC-11Resto1003_zpsbde855e9.jpg.html)
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/CTC-11Resto1004_zps35a6e708.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/CTC-11Resto1004_zps35a6e708.jpg.html)

When I went to check the condition of the thermistor, it fell right off its leads. I'm starting to think that these failing thermistors were a good thing because they got people to just push these sets aside decades ago.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/CTC-11Resto1006_zps4ae13ab4.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/CTC-11Resto1006_zps4ae13ab4.jpg.html)

I opened the HV compartment and found that the 6BK4 regulator tube had separated from its base. When I tried to remove it, it broke. I think it had already gone to air.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/CTC-11Resto1007_zpsc422761e.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/CTC-11Resto1007_zpsc422761e.jpg.html)

I removed the HV cage to investigate and there is evidence that the 6BK4 got seriously hot-- hot enough to melt the HV cup. Fortunately, the flyback looks OK.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/CTC-11Resto1008_zpsf8f0ffd0.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/CTC-11Resto1008_zpsf8f0ffd0.jpg.html)
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/CTC-11Resto1011_zps7d6b54f6.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/CTC-11Resto1011_zps7d6b54f6.jpg.html)

Is the HV cup usable like this? Could I try to heat it up and bend it back? What would cause the regulator tube to get so seriously overheated?

This restoration will probably take a while because I have so many other irons in the fire right now.

-Clark

seen that before, don't think its a problem. I would not worry about it, just leave it be.

Thanks, Dave. That's what I was hoping to hear. I'll leave it be, at least for the initial power up.

you will know if the shunt tube is working by checking the current thru it with the screen darkened. IIRC they want it to be about 1.4ma. With that much you will see the tube glowing pretty brightly figure its disapating nearly 30 watts. Of course the real test is does the HV hold constant regards of scene brightness.

I have a CTC 10 and 11. Both great performers. I have my 10 in my living room. Use it on a regular basis. Love to watch the old early color shows on it. I also have Schematics too. Let's see a pic on the set soon.

I have the chassis all cleaned up and the missing tubes replaced. I just got my order from Mouser, so now I just need to find the time to change out the electrolytics. After that, I'll do a first power-up to see what else I'll need to do. I got a CL-90 thermistor to install, but I think it's underrated at 2 Amps. I'll use it for initial testing. I will definitely measure the shunt regulator current (along with the HOT cathode current). They make it easy with a little jumper to remove.

I got a CL-90 thermistor to install, but I think it's underrated at 2 Amps. I'll use it for initial testing.Yes, a CL-60 (5-amp rating) might be a better choice. I used CL-90s in a couple of TVs because I happened to have them on hand for radio projects. They have held up under occasional use, but since this is a known weak point of the set, there's no reason to skimp.

Phil Nelson

Keep in mind the cold resistance for a CL-60 is only 10 ohms while a CL-90 is 120 ohms. So the CL-60 doesn't provide much of a soft start.

I have used the CL-90 on 60's era tube color sets with no problems.

I had the day off work yesterday, and it was drizzly and cool so it was a perfect day to work on vintage TV's! I recapped the power supply and the EC on the vertical output board. I also installed a new CL-90 thermistor. It took quite a while just to remove the cardboard cover on C1: No wonder, I've never seen so much tar used just to hold on the cardboard!
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/Tarrycap_zps21729465.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/Tarrycap_zps21729465.jpg.html)

The new caps are so much smaller, I could fit them all in the cans.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/Newcaps_zpsf1bce92f.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/Newcaps_zpsf1bce92f.jpg.html)
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/Newcapsinstalled_zpse3fe2f69.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/Newcapsinstalled_zpse3fe2f69.jpg.html)

I triple checked all my work, and powered up the set with a metered variac. All the filaments lit, but the set was drawing only 1 Amp and there were no other signs of life. A quick checked confirmed no B plus. Although I had checked it, I suspected the circuit breaker. Sure enough, that was the issue. On next power up, I had B plus and the set was drawing about 2.5 Amps. I got a raster and a wild blue light show from the chassis which tuned out to be a defective NOS 12BY7A video output tube. After replacing that, I was able to get stable horizontal and vertical lock and a decent color image.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/Screenshot1_zps854fcdea.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/Screenshot1_zps854fcdea.jpg.html)

After a very quick set up, things looked considerably better.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/Screenshot2_zps2ad7bdb3.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/Screenshot2_zps2ad7bdb3.jpg.html)

There is clearly a vertical issue and the focus control seemed to have little effect. The set is still full of leaky brown drops and even a couple of paper caps, including one across the AC line :thumbsdn: After about 30 minutes I shut it down. The HV cage was much warmer than I would have expected. I think there is still an issue with the HV. Next time I power it up, I'll measure and adjust the HV. Then I'll recap the horizontal and vertical boards and reassess.

The HV was a bit low at 22KV and it was easily adjusted to the specified 24KV. I got the first look at it playing in daylight, and the image was certainly bright enough. I was able to adjust the focus, too. Here it is playing a few minutes ago:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/Screenshot3_zps8eeb7377.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/Screenshot3_zps8eeb7377.jpg.html)

I'm pretty happy with how this is turning out!

Great work!

looking good. those chassis really are easy to work on. :thmbsp:

Did you have a Bad breaker? if so I have a couple of n,o.s ones you can come and get

Great looking pictures! I really like my two CTC-11 sets, they are easy to work on, and can provide nice looking video, especially with a good CRT. Good job on your restoration, enjoy seeing your progress in pictures!

Thanks guys! And thanks for the offer of a circuit breaker. It's seems to be working OK now, but I'll let you know if that changes.

I hope to recap the vertical and horizontal boards by next weekend.

Found the time yesterday to recap the horizontal and vertical boards, plus several around the HOT, damper and HV regulator. There are several oddball values that I didn't have on hand that I'll order and replace on the next round.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/P1030652_zps3b63799a.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/P1030652_zps3b63799a.jpg.html)
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/P1030651_zps64ceacba.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/P1030651_zps64ceacba.jpg.html)

The recapping improved things significantly, and I was easily able to get good screen geometry (the vertical linearity had been quite bad).
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/P1030656_zps33b2b391.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/P1030656_zps33b2b391.jpg.html)

I also decided to measure the 6DQ5 cathode current and double check the HV. The cathode current measured almost 230 ma:eek: And when I tried to adjust the coil, the core wouldn't budge. I feared that the slug had been cracked previously, but close inspection revealed that was intact. I applied gentle heat with a hair drier and I was very relieved that the core began to turn freely, yay!

I was able to get a nice sharp dip at about 192 ma. Not as low as I'd like, but a lot better than it was and below the specified 200 ma maximum.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/P1030654_zpsd73554f2.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/P1030654_zpsd73554f2.jpg.html)
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/P1030655_zps79cb102f.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/P1030655_zps79cb102f.jpg.html)

Now I feel like I can watch the set without fear of it self-destructing. The picture looks quite good now.
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/P1030657_zps027d88a0.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/P1030657_zps027d88a0.jpg.html)
http://i1216.photobucket.com/albums/dd366/IsthmusTV/RCA%20CTC-11/P1030661_zps3698df9e.jpg (http://s1216.photobucket.com/user/IsthmusTV/media/RCA%20CTC-11/P1030661_zps3698df9e.jpg.html)

It will probably be a while until I do more work on the chassis. I plan to do some work cleaning up the faux wood grain finish.

Thanks for the help and encouragement!

one thing to consider is the line voltage as well, I found that adj to 117vac got me to under 180ma IIRC. Even at that it still gets warmer than I like, but guess that is just the way it is. Pic looks great :thmbsp:

Thanks Dave, that's a good suggestion. My line voltage has been running about 122V. I always use an "RCA Color Volt" constant voltage transformer with my CTC-7 which keeps it at 117V and I do think it runs cooler.

I think you will prob see about a 10ma drop in cathode current going from 122 down to 117, just a SWAG.

Thanks Dave, that's a good suggestion. My line voltage has been running about 122V. I always use an "RCA Color Volt" constant voltage transformer with my CTC-7 which keeps it at 117V and I do think it runs cooler.

A google search for "RCA Color Volt" turns up surprisingly few results. Can I side-track you into a small information post on it?

I imagine its a classic "Magnetic Conditioner" like was used on computer and medical equip in the 70s and into the 80s, but with a name like "Color Volt" I wouldn't bet on anything, honestly.

I'll have to post a picture of the Color Volt (I forget if they spelled it as one word or two). I think it was made for RCA by the Sola Corporation which sold their own line of Sola Volt CVT's (constant voltage transformers). Here's a link to a used one forsale: http://www.radio-mart.net/Sola-Constant-Voltage-Transformer.html
If you Google CVT you can read all about how they work. Since they intentionally drive the transformer core into saturation, they tend to be quite noisy (loud hum) and generate quite a bit of heat. I keep mine behind the set so the noise isn't too much of an issue.

-Clark

Wow, that TV is really shaping up. A CTC-11 makes an awfully nice picture when it's working right.

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

Looking great, Clark. :thmbsp:

RE: Sola transformer - I believe that is called a saturation transformer.

That looks Great! makes me want to drop everything and work on my CTC11A

Thanks for the nice comments! This one turned out to be pretty easy to resurrect. I wish they were all this easy! (Or maybe not, since trouble shooting is half the fun :D) Since I took the photos, I degaussed the CRT which cleared up a minor purity issue. I haven't touched the convergence and I'm inclined not to since it's really pretty good. I am now running it on a variac set to 117V which is the input voltage specified by RCA.

-Clark

I have one of those Sola Constant Voltage Transformers and they are Very Noisy ,but no so bad in a room that has a Carpeted Floor

I haven't touched the convergence and I'm inclined not to since it's really pretty good.It does look good, even in far edges like the lower right, where I see little or no color fringing in the TV station logo. I wish all of my color roundies had such good border convergence.

Phil Nelson