Possibly the auto-degauss thermistor trying to take a (*bleep*). Those going open was a very common problem. Usually doesn't fix itself though.

If it does it again, don't let it run like that for any length of time. If it is the thermistor going open, it will quickly burn up its paired varistor (the big black disc thingy that sits next to it).

old_coot88, thanks for the information.

Could also be a main lytic failure. If any of the cans are getting warmer than the surrounding chassis metal after ~15-45 minutes run time the offending can(s) should get changed.

I forgot to mention that this chassis is almost 100% original, and I'd like to keep it that way as long as possible. When I was looking it over, I only saw one new capacitor and a few new solid state diodes on the convergence board. All the rest is 1966.

Here is the flyback in the RCA CTC-25. I measured the temperature after an hour with my infrared-thermometer, and the highest number I saw was 133 degrees F. This is the original flyback for this TV, and it is on its third CRT. Your collective thoughts? I want to avoid melting wax, arcing, and smoking. This TV is my daily watcher for no more than two hours a day. 5-6 days a week.

Break the cathode ground connection on the H output tube, connect an ANALOG current meter set to the 0-250mA or 0-500mA scale, and adjust the H. linearity/efficiency coil with a PLASTIC diddle stick for minimum current current reading possible. That reading will likely be in the 185-225mA range. Sam's manual should have typical value in the schematic and max listed under the H adjustment procedure. As long as it is below max by at least 10mA you should be good long range. Adding a 1/4A fuse between the cathode and ground while doing the measurement is a good idea, and if mounted topside will facilitate future current checks. Report back the number and record the number so you have a referance if it changes in the future.

Two things to beware of on CTC-16 and later chassis with that style of flyback tire are 1.) some HV rect tubes are too short so the glass of the top does not fully seat against the fly causing damaging arcing, 2.) if the brown part of the tire starts to turn black (what I see in your pic looks fine) between the HV tube top cap and fly core then the tire is becoming conductive and allowing damaging arcing....If that occurs peel the brown rubber off (best done when the fly is warm from running if it can still safely run and produce HV) any skin colored silicone in the blackened area any char on the windings (be careful not to go too deep), and re-coat the HV winding with silicone. Check both the front AND back rubber for blackening as it does not always get both sides at once.

Sensor safe or electronics safe silicone, or the acid will eat up the copper windings.

Take a good sniff of the fly for any sign of scorched odor. From the old servicing adage, "the nose knows". :smoke:
On the H out. cathode current, we strove for 200 ma. or less, with 210 ma. the absolute max for any degree of longevity.
And with an analog meter to be sure.

One thing that tubed color RCA's lack that contributed to shortened flyback life is lack of ventilation openings in the cage.
If you look at a Zenith, GE, Motorola or Philco of the same era, they all had louvers. Not sure about Admiral and Sylvania but Magnavox lacked them and a few burnt up also.

That digital screen shot does not show how GREAT that picture really is. A CTC25, 28, 30 and 35 blew away the lower-priced CTC24, 31 and 38 chassis sets on many points, sets which all outwardly looked similar :thmbsp:

I have a Sylvania Saratoga, it has louvers as does my TV-123. If I had another later RCA I would definitely have the cage punched out for ventilation, or at least position a fan through that round door like usual. Kills me how they left the fly in there with those hot tubes and no airflow, it's a wonder any of them survived.

I scored big time at an estate sale today. I picked up an RCA tube caddy with a bunch of tubes. It's not exactly full, but it's not bad for $24. I also got a NOS CTC-38 flyback 119834. The sale had a bunch more tubes, but I didn't have any more money to get any. I'll go back Sunday when it's half off and get as many as I can.

When those RCA color sets were first uncrated, the first thing we did was change the primary tap for 'high' line voltage. That dropped the H.out cathode current several milliamps. To change the tap, you have to turn the set up on end and slip the chassis back just enuff to access the terminal strip where the two taps connect. Your set may (or may not) have had this done by the original dealer.

I really need the tube tube lineup for this TV. I might to back to that estate sale tomorrow, but I don't have time to go through and document every single tube. I want to to get some spares.

I'm an idiot. I totally forgot that I have the tube lineup on the flyback cage.

I went back to the sale today with the intention of buying tubes, but somebody had bought the whole table for $175. I did manage to get four Sylvania triplers, a Zenith flyback, and a NOS brightener.

Gojo Hand Crème isn't just for radios anymore! I tried it on my CTC-25 Winslow, and the finish magically popped before my eyes! I could not believe the results just from slobbering Gojo on this set. I just used an old rag to rub it all around and toilet paper to wipe it off. In the picture, top is before and bottom is after. That really is how it turned out!

Wow that looks great.

Thanks. Yeah, I didn't expect this kind of result - escpecially for it requiring almost no effort!

My CTC-25 is working super awesome, except that I have noticed a slight defect in the picture. On the far left side of the screen, there are a few thin vertical bars. It's not too noticeable unless you look really hard. Sorry about the picture being rotated - the bottom is really the side.

any vintage tv collectors in my area
 

R there any vintage tv collectors in my area I'm in the st Lucie county area between vero beach west palm breach area of florida please let me know always looking to buy more sets or even trade thank u tom.

I think users TVcollector and Swizzyman are in Florida.

I tried to bring that Colorama back to life using my B&K 470 and 445. I clean and balanced the tube twice, then rejuvenated it twice. After that didn't work, I tried to dynamically intensify the non existent green with the 445. It helped a little. That tube is history. The picture is after using the 470 four times.

Monochrome sets often can still make a decent picture like that, but colors depend on the guns having relatively similar emission, and often don't focus well as they die.

Changed the picture tube in the Winslow today. Took out the super strong - almost brand new 1972 Zenith 23VBAP22 black matrix tube, and put in a 60's RCA tube that was rebuilt in 1980 by an Atlanta company called Video Display. I want to save the Zenith Chromacolor tube for a deserving Zenith 23" set, if I ever get one. I want the set to be as good as the tube though. Mint condition, remote, and a cabinet I really like.

Here you can see why I prize that Zenith CRT so much. The last picture is how it tests at 6.3 volts. I have never seen any other CRT test so good.

vdc was one of the best of the crt rebuilders.back in the mid to lates 70s,we used there tubes almost exclusively and never had a complaint.i have a ctc 15 with a vdc rebuilt 21 round and the picture rivals any newer crt.also have a 25vdmp22 in my e 48 superset.it was a sad day when they no longer rebuild crts