Acquired a CTC-15 from a VK member here. It's in great shape and produces a nice color image.

Two questions:

1. After about 3 hours of operation, the color fades out to near nothing with a green tint. This does not happen gradually, it will be fine and then just loose the color all at once. Cannot bring back the color by switching the channel selector, fine tuning etc. After maybe 5 or 6 hours, if I turn on the set, it will be fine with great color image again. What should I check first?

2. The set is 100% original, so only plan to show it to guests that visit and watch vintage TV shows on DVD. What is best, leave the set plugged in or unplugged? Is there a trickle current in the set when plugged in?

Well--the first thing I would check is to see if the 3.58MHZ osc. is running--when you lose color. It most DEFINITELY sounds like either the crystal itself, or maybe a cap or such in it's ckt. I also would get a voltage reading on the plate and grids of the burst tube--and any in the ckt. with the crystal--when you DO have color--and THEN again--after it goes away. You might find a big discrepancy, between the 2 conditions.

As for "trickle current" in this set--the answer is NO..this set did NOT have any sort of instant on ckty--so there should NOT be any current drawn by it--when switched off. If there IS--then SOMETHING is not right--such as a leaky line-isolation cap-- and MUST be looked into.

burst amp tube, color osc tube, band pass amp, check color killer setting.

If you turn the color down (while its working) is the green tint there (grey scale setting).

No. Good grey scale. When it looses color, barely there mostly green, like a tint with severe mute of color. Sometimes after the condition sets in, intermetent color pulses.

When the 3.58 craps out on most tube RCA's it gives you a
pink & green pix. Not sure if this applies to the -15. Its distinctive
when you see it. Dont remember the layout but its best
to get at least one known good 6GH8 & sub it once at a time.
Do not move them around it will cause confusion. 'GH8's
will work fine in one place but not in another...... Lots of
folk would bring in all the tubes for testing & when they put
them back in had different symptoms.:scratch2:

Not this but also watch for a short jumper wire at the
demod tubes that carried the filament voltage. Very common.
Its brown & dries up badly.

73 Zeno

99.99% confident it's the 3.58 section. Saw a lot of them in the shop.
Phil

You all mentioned the 3.58 section. Thanks for the lead, will update later.

A few screen shots of the CTC-15 when working properly.

http://www.visions4.net/journal/wp-content/uploads/RCA-CTC-15-SS-2-full-WP.jpg

http://www.visions4.net/journal/wp-content/uploads/RCA-CTC-15-SS-3-full-WP.jpg

Could you post some shots of when it's not working properly. That might help verify it's condition.

I could do that. When the color go's about 3 hours after it's turned on, it looks like black and white with just a hint of color. When the scenes shift, I can see the color trying to come back a bit but very faded out. Best description I can come up with.

Sometimes the 3.58 osc. just needs a tweak one of my roundys would take ~1/2 hour to have it's color synch, work for a few hours then flake out again. Tweaking the osc. slug while messed up cured the issue.

That set sure produces a great color picture, when it's in sync, Yowza!! :-)

until the color problem rears it's ugly head. Then perform a complete AFPC circuit alignment.

This will either fix the set, or reveal which circuit is malfunctioning.

always go for the easy fix 1st, wiggle tubes, esp the color osc.

Thanks guys.

One of the biggest problems I had fixing these sets years ago with color problems like that was coils opening up. Most were easy fixes as you would open up the can and pull out the coil and re-solder the terminals on it. Check the voltages on the plate of the adjacent 6GH8's or other tube in the color circuit. The fact that they are getting older doesn't help as they developed these kinds of problems 50 years ago.

I am a little curious here. The trouble symptoms and solutions are basically the same, but did RCA actually use the CTC15 chassis in 1963? I have a 63 RCA using the same control layout, but mine is definetely a CTC12 chassis. When did they release the CTC15, and what about the CTC13 and 14 chassis? I don't remember any 13 or 14 sets anyway.

Well the guy I got it from said it was a 1963. He has a ton of roundies and is a member here. If he sees this post, maybe he could elaborate.

Officially I believe this is a 1964 according to a Chicago Tribune article. It is called the "Canton". I do know that typically you could buy a new model year from RCA as early as August of the previous year. Maybe why he called it a 1963?

The CTC-15 IS a 64 model--but I THINK it came out early in the model year. So--a lot of them have 1963 date codes that are a LOT older than would normally be for a 64 model.

I am a little curious here. The trouble symptoms and solutions are basically the same, but did RCA actually use the CTC15 chassis in 1963? I have a 63 RCA using the same control layout, but mine is definetely a CTC12 chassis. When did they release the CTC15, and what about the CTC13 and 14 chassis? I don't remember any 13 or 14 sets anyway.

My CTC12 is marked in paint on the back the back of the chassis CTC12W

The CTC13 was an RCA experimental set using a CTC12 chassis. CTC14 wasn't marketed.

http://www.earlytelevision.org/Deksnis/CTC13.html

http://www.earlytelevision.org/Deksnis/CTC14.html

My CTC12 is marked in paint on the back the back of the chassis CTC12W

The CTC13 was an RCA experimental set using a CTC12 chassis. CTC14 wasn't marketed.

http://www.earlytelevision.org/Deksnis/CTC13.html

http://www.earlytelevision.org/Deksnis/CTC14.html

And didn't it also use the "short neck" 90 degree tube--that did NOT make it to the market ?

Sometimes the 3.58 osc. just needs a tweak one of my roundys would take ~1/2 hour to have it's color synch, work for a few hours then flake out again. Tweaking the osc. slug while messed up cured the issue.

That was the problem. After operating the set for about 2 1/2 hours, the color faded out again, so while the set was in this condition, we removed two suspected tubes and let them cool down one at a time. After cooling down, we placed them back in the chassis and the color returned briefly and faded again. Next, we replaced the suspected 6GH8A OSC. tube with a new one and the problem persisted. Next, we adjusted the 3.58 Oscillator slug and saw a big improvement. Further tweaking and the color remained stable. We think we solved the problem and left the original 1963 coded 6GH8A installed and we still have a 100% original CTC-15.

Glad you got it sorted out. I've always liked control only repairs best form a cost/convenience/time stand point.

Sounds like good news, I agree with Electronic M, and here's hoping it continues to work well, that's a really nice picture and TV, congratulations! Dave.

Sounds like good news, I agree with Electronic M, and here's hoping it continues to work well, that's a really nice picture and TV, congratulations! Dave.

Thank you, it's my first roundie. You have some excellent sets in your collection.

Thanks all for your suggestions and comments. We had the the set on for 7 hours yesterday with no problems.

Now if we could get rid of that beginning stage cataract. The tube is original with low hours and tests near perfect, so don't want to replace. Watched the You Tube videos on removing cataracts and the water submersion method looks the safest. I have never done it before, does the safety glass just slide off after say three weeks or does it still need an assist?

What is the best way to reseal the safety glass? Does it really need a silicon seal?

From what I have read here, after days or weeks soaking face down in water, an RCA-type CRT (as opposed to a Zenith-type, on which the water trick does not work) will then need to have thin wooden shims put in the edges at multiple locations, and they will need to be GRADUALLY pushed in further over an additional period of time. I have seen mention of this shimming process being done with the CRT being put back into the water as well as with it being kept out. The big thing is to not push the shims in too far, too fast, since that is always what leads to a broken glass faceplate. The indication that the water-and-shim process is working seems to be when "fingers" of air start to appear between the faceplate and the PVA "goo" next to or near the shim ends. Others may be able to post better and more correct descriptions of the process.

On the one CRT that I did (using the heat-gun method, a few years ago), I only put thin pieces of double-stick tape around the edge of the CRT and did not try to "seal" the faceplate to the tube again.

From what I have read here, after days or weeks soaking face down in water, an RCA-type CRT (as opposed to a Zenith-type, on which the water trick does not work) will then need to have thin wooden shims put in the edges at multiple locations, and they will need to be GRADUALLY pushed in further over an additional period of time. I have seen mention of this shimming process being done with the CRT being put back into the water as well as with it being kept out. The big thing is to not push the shims in too far, too fast, since that is always what leads to a broken glass faceplate. The indication that the water-and-shim process is working seems to be when "fingers" of air start to appear between the faceplate and the PVA "goo" next to or near the shim ends. Others may be able to post better and more correct descriptions of the process.

On the one CRT that I did (using the heat-gun method, a few years ago), I only put thin pieces of double-stick tape around the edge of the CRT and did not try to "seal" the faceplate to the tube again.

Thanks for that. As you know, it gets super hot in the Phoenix area in Summer. If I just put the CRT upright in the sun, that alone might be enough to get things going for the spacers! Just kidding, don't want to risk the CRT.

Read through another thread about cat's here. Why are form spacers needed under the safety glass prior to reseal? Isn't the safety glass bonded to the CRT directly? Can't you just place the cleaned up safety glass directly on the CRT and reseal? I would prefer to use tape like you did, just seems easier and less messy.

On mine I just use single side sticky foam tape around the perimeter of the LENS not the CRT its about 1/4 wide and about 1/8 thick. Then you just place the lens on the CRT, since its not sticky you can take your time and position it carefully. once you are happy with the position, get some wide packing tape and secure it on the top and bottom where the mask hides the CRT. The foam all around the lens prevents any dust or other garbage from getting between the lens and CRT face. this makes it very easy to remove the lens if ever needed, but I think the main thing is if you get a piece of dust in you can just lift of the lens get it clean and put back on, examine if all good tape and done.

The foam tape is a spacer to keep the safety glass from touching the CRT directly (duplicating the spacing the removed PVA used to provide). That way if something slams in to the installed tube hard enough to break/crack the safety glass there is at least a fighting chance the face of the CRT is still undamaged.

http://i1095.photobucket.com/albums/i469/ElectronicMemory/CRT%20cateract%20removal%20pictoral%20journal/DSCN1085.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/CRT%20cateract%20removal%20pictoral%20journal/DSCN1085.jpg.html)

http://i1095.photobucket.com/albums/i469/ElectronicMemory/CRT%20cateract%20removal%20pictoral%20journal/DSCN1091.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/CRT%20cateract%20removal%20pictoral%20journal/DSCN1091.jpg.html)

I like to clean the glass ABSOLUTELY SPOTLESS add four small foam spacers at the edges and caulk the edge. It will stay spotless indefinitely (probably longer than the PVA lasted) if you achieved a good seal (versus potentially having to open it up every few years with tape). You can always slice through the caulk with a razor and dissolve the residue with chemicals (like 'goof off') later on if you somehow need to clean it or (in my case) discover the (spare) CRT is gassy years after cataracting it and cut thru the caulk holding the safety glass to steal the glass for another tube that needed a new safety glass...

As you know, it gets super hot in the Phoenix area in Summer. If I just put the CRT upright in the sun, that alone might be enough to get things going for the spacers! Just kidding, don't want to risk the CRT.

Why are form spacers needed under the safety glass prior to reseal?
With the CRT that I used the heat gun on, I did first put it face-down on a blanket in my back yard for a while (on a sunny summer day), then I also left it face-up in the metal can in the sun for a short while before I started the heat-gun process. If a person is going to use the heat-gun method, it probably is better for the CRT if its whole envelope is warm, not just the face.

On my CRT, the curve of the safety glass was a bit shallower than the curve of the CRT's face itself, so the foam tape around the edge held the glass away from the CRT slightly, even in the center.

Guys, thanks for the information. This is my first roundie and inexperienced in repair. The caterract is not to bad, but just seeing it bothers me and considering the condition of the set, I want to fix it.

http://www.visions4.net/journal/wp-content/uploads/RCA-CTC-15_2-full-WP.jpg

http://www.visions4.net/journal/wp-content/uploads/RCA-CTC-15_-3-Closed-full-WP.jpg

Hope to find a CTC-5 next.

Very very nice, a cabinet style never seen in these parts.

A difference I noticed between a CTC15 and a CTC12 is that the CTC12 has VHF fine tuning as a pull-to-adjust concentric knob behind the on-off volume (the 12's power-volume is same as the brightness/tint/color knobs), at least my '12 has it this way.

That's a really nice Oriental style cabinet, it really shines! A great set to hang on to!

I generally don't go for black furniture, but that cabinet is gorgeous.