View Full Version : My "new" 1954 CTC2B 21CT55 21" roundie


walterbeers
05-29-2015, 03:15 PM
Yes, I acquired a CTC2B, which I consider is probably the second most coveted 21 inch roundie among collectors. The model is 21CT55, and it is in really great shape considering it's well over 60 years old. The set was listed on Craigslist and was located in Iowa about 25 miles from me. I was told it originally came from Las Vegas from an estate. My friend Jamie from VK (jstout) found the listing as he new I was interested in trying to restore a very early color set. The seller even agreed to deliver it, so with the help of Jamie and the seller, they brought it over to my house while I was at work. I came home to find quite the surprise. Best of all the set is in really good shape, and I believe it doesn't even have that many hours of use on it. Yes, the top of the cabinet needs to be refinished, but the sides (although scratched) could be touched up and refinished if necessary. Best of all the chassis is mint, almost like it has seen very light use. The CRT was replace about three years after it was new, so probably around 1957. I hooked up my Beltron, and guess what, not only is the CRT under vacuum, it tests .9 on all three guns, although the blue and green are kind of slow warming up. I lowered the filament voltage to 5 volts and for the most part it stayed right at the top of the meter for emission, and has no short indications. Next I looked at the flyback and can't see any burn't spots, so I am hoping that it is good and usable as well. The CRT is a 21AXP22 dated 35-57. (1957). Chassis looks really good, except some rust on the small tube shields and the ballast resistor. The yoke cover of course like most of them is crumbling, but that is to be expected. Metal back and knobs are all there, along with the cord, front bezel and logos, and the wiring inside looks really good, and doesn't seem to be brittle. Right now I'm in "seventh heaven" however it will probably be put on the back burner for a bit until I finish some other projects that I have going on. The problem that I have right now is where to start with this project. Do I bring it up slowly on a variac, or do I pull the chassis and start changing caps, testing tubes, looking for defective parts, and give it a good cleaning up. (60+ years of dust and oxidation). I did find that one of the HV rectifier tubes was cracked, (3A2) but that's no big deal. There is some dirt built up between the safety glass and the mask, but honest, it's just dirty and can be cleaned up. I don't see any signs of infestation, (rodents, bugs, etc). Any input and suggestions from anyone who has worked on and has experience with these old CTC2s, is appreciated. Apparently this model chassis is similar to the sets that used the 15GP22, and was modified to accept the larger 21 inch tube. It's going to be a long project for me, (maybe years), but I hope to see a nice color picture on it someday.

DaveWM
05-29-2015, 03:25 PM
Nice!

rca2000
05-29-2015, 03:27 PM
You STOLE that set Walter !! $100 for a 21-ct-55 WITH a good TUBE ?

walterbeers
05-29-2015, 03:36 PM
If it had not been for him searching the web, I probably would not have found this set. He has helped me out with many situations, finding retro electronics, and doing repairs and restorations on several of his units. He is on VideoKarma as jstout. When I need a hand lifting or moving a heavy piece of equipment he is always there to help out.

Also many thanks to my friend Rick, (titan1A also on VK) a friend for over 30 years, who is also a collector of retro stereos, hi-fi, old radios, computers, and other electronics. He is the one I restored an old 1938 Zenith console radio for, and he did a lot of the leg work searching for parts and information for it. When I have a computer problem that I get stuck on, he's always there to offer advice.

I also thank the people who keep this website going. Everyone on here is due thanks for all of the info and advice that I find interesting, useful and informative.

walterbeers
05-29-2015, 03:40 PM
You STOLE that set Walter !! WITH a good TUBE ?

I did give the seller an additional $20 for gas money and time for hauling the set to my place.

Username1
05-29-2015, 04:24 PM
Yah - you stole that ! ! Good deal and a good tube too ! !
I would rather have that set over a ct100...... All that cabinet
and a bigger screen ! Fire it up, post some pictures ! !


.

jr_tech
05-29-2015, 04:42 PM
Yes, I acquired a CTC2B, which I consider is probably the second most coveted 21 inch roundie among collectors. The model is 21CT55, and it is in really great shape considering it's well over 60 years old. Best of all I got it for only $100.


WOW! What a find! But what 21" roundie would you consider to be more coveted among collectors? Seems to me that the Very rare 21CT55 is at the very top of the 21" list!

jr

Electronic M
05-29-2015, 04:44 PM
Dang! I wish I had the kinda luck and friends you've got.

In your shoes I'd pull the deflection output tubes, put a meter the high B+ rail, and variac it up till that B+ rail reaches spec, or signs of trouble appear. If it goes good scope the Horizontal osc. If that is good reinstall the sweep tubes, and power it up while monitoring cathode current of the H out tube (the schematic should be on the ETF's site and should give you the safe max cathode current spec).

I don't know of a more desirable 21" color set. The 21CT55 was the first of them....Built in response to other companies coming out with 19" CRT loosely based on the 15GP, but containing many new innovations the 15G lacked....That and when a customer shells out what one of those cost they want the biggest screen they can get.

rca2000
05-29-2015, 04:50 PM
I have seen these sets with UNKOWN tubes go for OVER 1K..and one with a GOOD tube got over 2K IIRC at the ETF some years back...

hi_volt
05-29-2015, 04:55 PM
Wow! Super nice find! :drool:

etype2
05-29-2015, 05:00 PM
Congratulations, really nice.

MRX37
05-29-2015, 05:26 PM
You lucky SOB...

I really want to see this set restored and playing.

http://www.videokarma.org/attachment.php?attachmentid=186929&d=1432930075

Scratch that, you ridiculously lucky SOB!!

Seriously, i hope you can get it running, and provide lots of pics to show off its colors.

Steve D.
05-29-2015, 05:51 PM
Walter,

I was in touch w/Jamie earlier today before he turned the 21-CT-55 over to you. I had sent him a link to the SAMS. Here it is just in case you didn't get it.
http://www.earlytelevision.org/pdf/RCA_21-CT-55-Sams-300-8.pdf. Best w/ this project. Be very careful powering it up. Don't want to damage any unobtainable parts. Also, this is the only ad for your set I have ever come across: http://www.earlytelevision.org/pdf/rca_21ct55_ad.pdf

-Steve D.

Sandy G
05-29-2015, 06:18 PM
Ahh HATE Yew...-Y. Sam, Philosopher Extraordinaire... Seriously, you oughta go buy a BUNCH of lotto tickets w/THAT kind of luck... And I think I can say w/o fear of contradiction that-1) We're ALL tickled pink for you, & 2) WE wanna see it restored to "Glorious Lollipop Color" ASAP...(grin)

Tom S
05-29-2015, 06:21 PM
Congrats man. great looking set. I'd say bring it up slow and go for it. My CTC10 is playing fantastic. I just recapped it in January. All the litics. Plays like a dream with a great tube to. I've had it 3 yrs now. I'd clean all the controls first then put the power up on it.

Kamakiri
05-29-2015, 06:56 PM
If it had not been for him searching the web, I probably would not have found this set. He has helped me out with many situations, finding retro electronics, and doing repairs and restorations on several of his units. He is on VideoKarma as jstout. When I need a hand lifting or moving a heavy piece of equipment he is always there to help out.

I actually posted it on his Facebook wall like hours after it was listed ;)

Of course, I can't take 100% credit for that one....he might have seen it before I did.

Zenith6S321
05-29-2015, 07:08 PM
Any input and suggestions from anyone who has worked on and has experience with these old CTC2s, is appreciated.

Here is a link to my 21CT55 restoration thread:
http://videokarma.org/showthread.php?t=257587&highlight=21ct55

I found it a real challenge, but very pleased with the result.

Dave

Steve McVoy
05-29-2015, 08:25 PM
Please post the chassis and cabinet serial numbers so we can add the set to our database.

walterbeers
05-29-2015, 08:49 PM
Good thread about your restoration, Zenith 6S321! Problem is that I don't have all the nice equipment that you do. I do have of course have a digital VOM, and a 20 MHZ scope, HV probe, color bar generator, a variable isolation transformer, variac etc, but I don't have things like a B&K analyst, or sweep and marker generator. Another thing that I don't have is a test picture tube jig, and I'm not even sure that would work with a CTC2. Usually, I change all the electrolytic caps, the old wax capacitors, and any out of tolerance or burn't resistors, but alignment is not one of my specialties, except maybe adjusting the sound detector, 4.5 trap, or 3.58 osc. coil to get the color to lock in. I have never re-stuffed the cans, as I usually just find room underneath the chassis. Maybe it's time I try my hand at re-stuffing them. If the selenium rectifiers have not already been replaced with diodes, I plan to do so, putting in appropriate dropping resistors. I used to have an old Eico sweep and marker, but it was so unstable, that is was useless, and got rid of it many years ago. This project is going to turn into quite a challenge, and possibly buying some new old stock or good used test equipment. (E-bay is my friend!) It would be nice to have or make up some cables so I can hook up the CRT while the chassis is on the bench. That would make servicing it so much easier. (Clip leads are great, but not in this instance). I do have a couple of yoke adapters though. I have repaired TVs since 1972, but I have never taken on one as old and involved as this. Wish me good luck. Walterbeers

walterbeers
05-29-2015, 09:11 PM
Please post the chassis and cabinet serial numbers so we can add the set to our database.

Steve: I am not sure these are the numbers you are looking for, but here goes. Stamped on the wooden cabinet is 1921 and also 539.
The serial number of the set is B8802697 Also on the chassis is RVB274 Also on the label is 506L. Stamped into the back bottom of the metal chassis is
11 03 207-1 SUB10 Hope these numbers help you identify the set.

Phil Nelson
05-29-2015, 09:30 PM
Wow, what an amazing find -- and with a good CRT to boot!

I look forward to hearing about its restoration. My thinking with a set like this is, you may never find another one, so take your time, do it right, and enjoy the process.

Regards,

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

Radiotronman
05-29-2015, 10:36 PM
Awesome find. A pretty rare set to find with a very lucky to find working crt!!! That looks like the maple version of my rca ctc-9 Caulfield in the background also. Great sets.

walterbeers
05-30-2015, 06:19 AM
I actually posted it on his Facebook wall like hours after it was listed ;)

Of course, I can't take 100% credit for that one....he might have seen it before I did.

I didn't realize that is was posted on jstout's facebook page, so to whom ever found it first, I really super appreciate it. I also appreciate Kamakiri keeping track of posts, as we really need to keep saving and restoring these rare and retro TVs from the scrap piles.

I once mentioned to a co-worker that when I was kid we only had B&W TV. The response was "black and white"???? "I don't think I've ever seen one!!!" and probably not, as he was only around 16 or 17 years old.

jstout66
05-30-2015, 07:07 AM
The Story.....
We totally lucked out having something this rare pop up in our backyards. The set was located in Glenwood, Iowa. I am an insomniac, and check facebook and craigslist whenever I am up. I saw the posting and literally 2 seconds later Tim posted it on my FB wall. ( Tim.. THANK YOU!! I think it was the shock of seeing it on CL and the "push" from Tim that made me immediately contact the seller) I debated for a hot minute to purchase it for myself, but my good friend Walter had been looking for a CTC-4 for ages, and he is better equipped to repair something this old and rare. I knew if I kept it, he'd have to do most of the work anyway, and funds are tight on my end as I just had to pay $2700.00 to have a dead tree removed. Anyway.. obviously this is older than a CTC-4 ( neither of us thought we'd ever find anything older ) I had a CTC-4 that I sold to Mark Mason some years back, as I knew he'd appreciate it more than I. Just like I knew Walter would love this set. I called the seller, and I felt like I was on a job interview. I think what clinched the deal was I said I would send him a video if we got it working. I made arrangements to have it delivered, and he texted me about 3 hours before he hit Omaha. I called Walters wife Kathy, and met him at Walters house and had it dropped off while he was at work. Let me state that I forgot how HEAVY these 50's color sets are.... haha.
Anyway, we'll appreciate any tips on this set thru VK or my tv friends on facebook.

IsthmusTV
05-30-2015, 09:08 AM
Wow, simply incredible! It's nice to know that sets like this can still be found in the wild. Congratulations :tresbon:

I also advise you to proceed slowly and don't try powering it up until you've thoroughly checked out the power supply and sweep circuits.

Looking forward to the restoration thread. Best of luck.

-Clark

walterbeers
05-30-2015, 02:01 PM
I haven't done anything yet with this set except check the CRT and open up the HV cage, finding a cracked rectifier tube. I intend to take it slowly. First I'll check out the power supply, and sweep circuits, and of course bring it up slowly, monitoring the B+, with the horizontal output tube removed. If I get some audio noise, that will be a good sign, then maybe hook up the horizontal, bring it up slow again, as I monitor the horizontal osc waveform and high voltage. I am hopeful the flyback is ok, runs cool, and doesn't smoke or anything. Time will tell, and I will keep everyone posted as to it's progress.

rca2000
05-30-2015, 03:43 PM
I THINK...a 3A3 will work in place of that 3B2 ..in case you do not have the original.

BigDavesTV
05-30-2015, 04:19 PM
A really amazing find! Congratulations and best wishes for a successful restoration! Looking forward to the end result!

Zenith6S321
05-30-2015, 06:02 PM
Walter, you may want to check for shorted HV caps in the HV cage. The largest one in my set was shorted. With rare sets like this I think it is best to proceed cautiously. Burning up a flyback would really ruin your day.

Dave

walterbeers
05-30-2015, 06:19 PM
Well, some good news, (well sort of anyway), I removed the horizontal output tube and brought the AC voltage slowly up to 75 volts, and I got noise from the speaker, and had about 250 volts at the top cap connector for the 6CB5. So I hooked up a converter box to the antenna terminals, went to channel 4, and I did have sound. The selenium rectifiers are still in circuit, and one of the fuses had been bypassed with a clip on fuse, which was actually broken. So, for now I just clipped in a 3 amp pigtail temporally. Just getting sound raised my enthusiasm. I did find out that the fine tuning knob is broken, so if someone has one that would work as a replacement let me know. I'm not going to do any more with it today, as I have other stuff to do, and I'm getting really tired. Been up since 5AM, my usual wake up time. A 3A3 won't work, the 3B2 is a small 9 pin tube with a top cap.

rca2000
05-30-2015, 06:57 PM
[QUOTE=walterbeers;3134977]Well, some good news, (well sort of anyway), I removed the horizontal output tube and brought the AC voltage slowly up to 75 volts, and I got noise from the speaker, and had about 250 volts at the top cap connector for the 6CB5. So I hooked up a converter box to the antenna terminals, went to channel 4, and I did have sound. The selenium rectifiers are still in circuit, and one of the fuses had been bypassed with a clip on fuse, which was actually broken. So, for now I just clipped in a 3 amp pigtail temporally. Just getting sound raised my enthusiasm. I did find out that the fine tuning knob is broken, so if someone has one that would work as a replacement let me know. I'm not going to do any more with it today, as I have other stuff to do, and I'm getting really tired. Been up since 5AM, my usual wake up time. A 3A3 won't work, the 3B2 is a small 9 pin tube with a top cap.[/QUOTE

You are thinking of the 3A2...and it IS a 9 pin tube. No sub that I know of for it. The 3B2 is a large octal tube.

walterbeers
05-31-2015, 12:10 PM
Yes, It uses a 3A2. My bad. Yes, It is a 9 pin tube, not an octal. I don't know what happened. I must have transposed the number either in my mind or on the keyboard. Looks similar to a 1X2, but has a 3 volt filament. I will also check for shorted the high voltage caps.

walterbeers
06-01-2015, 06:48 PM
Well, I put in a 1V2 in temporarily for the 3A2 and I"m getting high voltage although low, I do have some light and video on the screen although not really a picture. Sound is there, everything needs cleaned, recapped and check out, but preliminary testing shows that the CRT is usable and it thrills me that the main stages, flyback, yoke, HV, and sound, IF, tuner, etc at least are somewhat working. I know a 1V2 will not last in place of a 3A2 but this was for maybe 5 minutes just to find out what works and what doesn't. Obvious it needs filter caps, and vertical isn't full. What I really need is connectors that I can put the cabinet on the bench with the chassis removed, so I can work on the chassis, leaving the CRT in the cabinet. As of right now, I prefer not to take the CRT out of the cabinet, I feel it's just too risky with that old of a set, since the CRT appears good, and usable. I will be ordering several 3A2s, and probably other tubes as well as I test them out.

Zenith6S321
06-01-2015, 07:29 PM
If you lay the set on its side (make sure the chassis is bolted down) you can get to a good deal of the underside of the chassis. Long cables might cause odd problems, but then again maybe it would be ok.

Dave

Titan1a
06-01-2015, 10:00 PM
I wouldn't expect problems with temporary extension cables. Just be slow and careful.

walterbeers
06-02-2015, 03:52 PM
Does anyone know of extension cables for the set, that is a yoke connector (Octal), convergence connector (A 9 pin, looks like an octal), and a CRT connector (for the base of the tube). I'm sure I could rig up some high voltage wire for the anode though. Or was, or is there any type of test jigs that were made that would work with the set? Or, is it best to lay the set on it's side and remove the bottom metal plate? How has other restorers of CTC2s, 21CT55s, done it. There is a fellow on here that has a CRT test jig he want to sell, but I doubt it was made to work with a set this old. Even with all the adapter cables, I doubt if there is a way to connect up the convergence unit. I guess right now, I'm thinking of lying it on it's side, when I get a couple of strong guys over here to help with it.

Electronic M
06-02-2015, 04:14 PM
I wouldn't expect problems with temporary extension cables. Just be slow and careful.

Some who have worked on later roundys with extender cables have had phantom video ringing and ghosting caused by the extender cables....It is not guaranteed to happen, but something to be weary of.

DavGoodlin
06-02-2015, 04:39 PM
Some who have worked on later roundys with extender cables have had phantom video ringing and ghosting caused by the extender cables....It is not guaranteed to happen, but something to be weary of.

We used to have this problem with all extender cables. Making them shorter helps. One factory item on my RCA CTC11 set is a cardboard disc that keeps the three G1wires to the CRT socket separated.

Many Congratulations Walter - you just grabbed the headlines:thmbsp:

Username1
06-02-2015, 05:12 PM
The size, and wavy sides indicate bad power supply capacitors, you should not
run it again until you replace the electrolytics in the power supply at minimum....

.

Gregb
06-02-2015, 05:23 PM
I came across a set of the extender cables and I use them all them time. They are great for testing purposes but nothing more as they introduce interference. No settings can be done until the crt is back in the cabinet but like I said they work great for rough testing, making sure there is a raster, approx. width and height and such.
The ones I have are 4 feet long and they came with a test crt I bought on ebay. There's one for the crt, two for the yoke, one with that octal plug and the other has alligator clips, and an extender for the high voltage lead.

Gregb

ChrisW6ATV
06-03-2015, 01:12 AM
was, or is there any type of test jigs that were made that would work with the set?
My Sylvania CK3000 test jig (which also works with the RCA jig adapter cables) was only made to work with CTC-7 and later chassis, but I made a (yoke) adapter cable that works with the CTC-5, CTC-4, and CTC-2/CT-100. If I remember right, I also checked the schematics and it should work with a CTC-2B/21-CT-55 as well. There is one wire that gets either connected or disconnected among those different chassis.

The way the jig works on later chassis is, you plug in a "convergence load" to the chassis, that replaces the now-disconnected convergence control panel. However, on the CTC-5 and older models, only the convergence yoke is disconnected with the cable is unplugged from the chassis; the controls themselves are still attached, so no replacement "load" is needed when using the jig. (So, in this case, the CTC-3 chassis would still need to be connected to the CTC-2B chassis, but not the convergence yoke itself.)

If you do get that jig and you want the adapter information I have, let me know and I can probably copy it and post it here.

oldtvman
06-03-2015, 01:18 PM
Well, I put in a 1V2 in temporarily for the 3A2 and I"m getting high voltage although low, I do have some light and video on the screen although not really a picture. Sound is there, everything needs cleaned, recapped and check out, but preliminary testing shows that the CRT is usable and it thrills me that the main stages, flyback, yoke, HV, and sound, IF, tuner, etc at least are somewhat working. I know a 1V2 will not last in place of a 3A2 but this was for maybe 5 minutes just to find out what works and what doesn't. Obvious it needs filter caps, and vertical isn't full. What I really need is connectors that I can put the cabinet on the bench with the chassis removed, so I can work on the chassis, leaving the CRT in the cabinet. As of right now, I prefer not to take the CRT out of the cabinet, I feel it's just too risky with that old of a set, since the CRT appears good, and usable. I will be ordering several 3A2s, and probably other tubes as well as I test them out.

That looks like a low voltage power supply problem.

walterbeers
06-03-2015, 07:49 PM
I came across a set of the extender cables and I use them all them time. They are great for testing purposes but nothing more as they introduce interference. No settings can be done until the crt is back in the cabinet but like I said they work great for rough testing, making sure there is a raster, approx. width and height and such.
The ones I have are 4 feet long and they came with a test crt I bought on ebay. There's one for the crt, two for the yoke, one with that octal plug and the other has alligator clips, and an extender for the high voltage lead.

Gregb


Gregb: where did you ever come across the set of extender cables? Are they available in Canada, since I can't seem to find them on the web. Can one buy them, or find them on e-bay? I understand I can't set up the adjustments until it's back in the cabinet, but it would make for good rough testing as I recap and do repairs to the set. It would make it much easier for me (since I have back problems), instead of getting down on the floor to work on the set, as that is really hard for me. I'll first will tackle the power supply, electrolytic's, etc. The small raster (if you can call it that), indicates definitely that it needs new caps in the power supply and will also be replacing the selenium rectifiers with diodes. I don't intend to run it much more (probably not at all), until at least the power supply is taken care of.

Kamakiri
06-03-2015, 08:18 PM
I have a couple extra female sockets off a test jig that you're welcome to have if you can adapt them. They have different plug ends on them, but if you had the cap off a 21" color tube you could use them and make one easily.

walterbeers
06-03-2015, 08:52 PM
I have a couple extra female sockets off a test jig that you're welcome to have if you can adapt them. They have different plug ends on them, but if you had the cap off a 21" color tube you could use them and make one easily.


I'll send you info in your VK mail box.

Phil Nelson
06-03-2015, 09:13 PM
Is there any way to stand (or brace up) the chassis on its side behind the cabinet and connect up using the original cables?

http://antiqueradio.org/art/RCACTC-4LameSetup.jpg

I realize your chassis isn't designed to stand up that way, but if the connectors would reach, that might be a way to access the underside while it's powered up.

Just an idea . . . .

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

walterbeers
06-04-2015, 01:32 PM
Good suggestion Phil, and I even have a cooler just like that to sit it on. It just might work out for me. Maybe I could like tie a string, or something to brace the chassis to it stands up like yours, seems as it if would work. Thanks for the picture.

Phil Nelson
06-04-2015, 07:10 PM
During part of my CT-100 project, I stood the chassis sideways on a square of heavy plywood. I screwed one end of a diagonal brace (a wooden stick) to the plywood and lashed its top end to the upper part of the chassis. That allowed me to make measurements & adjustments with the underside of the chassis exposed.

Tube extenders let you make many voltage measurements from above, when the chassis is in the cabinet, but if I recall correctly, there were some tubes under the CRT without enough vertical room to take an extender.

I use a second cooler with a folded quilt to make a seat behind the chassis.

Phil Nelson

Steve McVoy
06-04-2015, 09:11 PM
It makes more sense to remove the yoke and put the chassis on the bench. You can then work your way through it, using a scope, to make sure everything is working. Then put the yoke and chassis back for final test.

walterbeers
06-04-2015, 09:18 PM
Both of you Phil and Steve have very good ideas. I sort of like to see whats on the screen as I work on it, but I also understand that it is much easier on the bench. I am concerned about the yoke only in the sense that the cover is crumbling, and I believe there was a post about how to make one using something common, such as a plastic lid, or something. Of course the crumbling yoke covers were common on all of the old sets, even B&Ws as well.

Zenith6S321
06-04-2015, 09:47 PM
Both of you Phil and Steve have very good ideas. I sort of like to see whats on the screen as I work on it, but I also understand that it is much easier on the bench. I am concerned about the yoke only in the sense that the cover is crumbling, and I believe there was a post about how to make one using something common, such as a plastic lid, or something. Of course the crumbling yoke covers were common on all of the old sets, even B&Ws as well.

I used a Home Depot paint can cover suggested by another VKer. Look at this thread post #27 to see a before and after picture of the yoke:
http://videokarma.org/showthread.php?t=257587&highlight=21ct55&page=2

The cover fit on the yoke nicely. I made three small holes to allow the rivets on the shield that mounts on the back of the cover to snap into the cover.

I did my initial powered testing on the bench with the yoke plugged in but no CRT connected. I made many quick powered checks with the HV loaded by a 40KV HV probe. Once all the voltages, currents, and waveforms looked right I put the chassis back into the cabinet laying it on its side to get at the bottom of the set.
Dave

dtvmcdonald
06-04-2015, 10:01 PM
It makes more sense to remove the yoke and put the chassis on the bench. You can then work your way through it, using a scope, to make sure everything is working. Then put the yoke and chassis back for final test.


That's a nightmare! No matter how carefully you mark a CT-100,
you will never ever get the yoke tilt the same, so you will have to
start convergence from scratch. Perfect convergence is possible
but the yoke position is critical to the millimeter, including the tilts.

I don't know if this applies to 21axp22 sets. I know I never got my
college roommate's CTC5 or 9 anywhere near as good convergence,
but they of course don't have tilts.

Steve McVoy
06-05-2015, 06:08 AM
Two other ways to work on the chassis:

Everything on the chassis except the AGC, sweep, and HV will work without the yoke. You need to put a jumper in the yoke socket to connect the B+, though. You will need a bias box to set the AGC voltage. That will allow you to get almost all the circuits working before putting it back in the cabinet.

Make a yoke extension cable and leave the yoke in the cabinet.

Popester
06-06-2015, 02:05 PM
What is the RCA in one of your pictures that is to the right of your find? Looks like a '58 or '59 model??

miniman82
06-07-2015, 11:05 AM
Or do what I did and break apart any octal tube to harvest the socket, and use that as your B+ jumper. All you need to do is connect the appropriate pins, and you'll have power to all the circuits. Just make sure you NEED power to all the circuits! It works on all the early CTC chassis.

walterbeers
06-07-2015, 11:58 AM
What is the RCA in one of your pictures that is to the right of your find? Looks like a '58 or '59 model??


The other roundie is a CTC9, model 210CK924. It looks pretty good, but still needs some work. Set has low hours and has the original 21CYP22 CRT. Right now (as of yet) it is running with the original filter cans, which I still intend to replace with modern caps, although they do run fairly cool. It still has a problem with the vertical and horizontal sync at times, and the vertical height has a tendency to collapse. (I believe there is a broken ground somewhere on the vertical/horiz circuit board) Cabinet is in perfect shape, no scratches, back and everything is complete and the set when I got it was super clean inside for it's age. I obtained this on Craigslist from Blair NE. I have another post on here somewhere about the set.

walterbeers
06-20-2015, 06:37 PM
Some progress on this set, the CTC2B, 21CT55, from 1954. I removed the chassis, yoke, and convergence assembly. The set looks to be in really good shape, and it looks to be a low hours set. Yes, there is some rust on the tube shields, but other than that, it's clean, even the flyback looks really good, just a small amount of wax drippings. Here are some pictures of the chassis before recapping, and cleaning. Even the resistors don't seem to be discolored with heat and age. Next for me is the tedious task of recapping, checking tubes, cleaning, and replacing several peaking coils that are open.

walterbeers
07-04-2015, 04:04 PM
Just to let you guys know why there hasn't been any more progress of restoring this 21CT55, CTC2 1954 color. I hurt my back moving a heavy piece of equipment about a month and a half ago, and I've been sort of laid up as far as getting things done. I herniated (sliped disc) in my back and it causes me a lot of back pain, and also burning pain down my legs. I have been taking pain pills and steroids for it, and also got shots of cortisone into my spine, which have helped, and also doing certain exercises to get my back into shape again. The spine doctor seems to think everything can get me back to near normal without doing risky surgery. Also have been seeing a Chiropractor. I do have the chassis removed and cleaned up, tested the tubes, (4 bad), and ohmed out the convergence transformer which has continuity on all of the windings, which is a good thing. It seems as if nearly all the white coated peaking coils are open so have to find the values and order them. Next is ordering the necessary caps, and other parts, as I am getting back into action. I sure hope I can get a good picture on this set when everything gets done. I believe it will be an on going (probably a 2 year) project.

Tom9589
07-04-2015, 05:27 PM
I herniated disc in 2007 after a marathon auto repair procedure. I went to a Physical Therapist and followed her recommendations religiously. I didn't have to have surgery. I still don't lift heavy loads, but otherwise I'm back to normal.

Best of luck with your recuperation. and restoration.

Tom9589
07-04-2015, 05:32 PM
In the pictures in Post #57, I noticed the name Glaser Steers Corporation on the convergence coil assembly. I remember Glaser Steers as the name of a high end record changer company. Most notable was the fact this record changer stopped the turntable when the next record was dropped. Quite a sight to watch in operation.

walterbeers
07-08-2015, 04:11 PM
I am seeking some answers about replacing the selenium rectifiers with silicon diodes. I plan to leave the old ones in place for the nostalgic effect, but I do have a question for you guys. Since the selenium's drop voltage (maybe 10 to 25 volts), has anyone had any experience of what value and wattage resistor(s) to put into series with the diodes to limit excessive voltage to the power supply and the rest of the set. I obviously plan to replace all of the electrolytic's in the set (most with higher voltage ratings), but I still don't want to "cook" the set with too much B+ voltage. I have searched the web and this site and found all kinds of different answers, including putting in no resistors at all. The set is my "new" 21CT55, CTC2B, 1954 color. Of course the answer may just be taking a variac and substituting different values until the find the correct voltage (400 volts) at 120 volt line voltage as published in the Sams schematic. The line voltage at my house usually runs around 125 volts just for your information.

miniman82
07-08-2015, 05:56 PM
If I were in your shoes (I am actually, fellow 21CT55 owner), I'd always run my sets on a variac and monitor input AC voltage to make sure it's receiving the rated 117 VAC stated in the schematic. Higher voltages tend to cook irreplaceable parts, and I don't fancy trying to locate a flyback for any of my sets. I'm a big stickler on horizontal/HV circuit adjustments too, and it's served me well in collecting TV's.

I tried to find a resistor/diode substitution that worked well on my CTC-4, and in the end wound up with one of those adjustable high wattage resistors so I could home in on the perfect value without spending too much cash. Something in the 100-ohm range that is adjustable usually works, that way you can slide it around from 0-100 to see what the set likes. Just remember: if you do this while running the AC input at 117 VAC, you must always use a variac or B+ will still be too high if you forget. Most simply plug the set directly into the wall, then set the series resistance to whatever it needs to be for proper B+ readings. The tube filaments won't care about a couple extra AC volts on the line, but the effect is dramatic when looking at horizontal output cathode currect. A few input volts ends up spiking it higher than you'd expect, so monitor things and zero in on the best set of variables for it.

Zenith6S321
07-08-2015, 06:07 PM
I ended up with a 40 Watt 4 Ohm resistor in series with the 4.5 Amp fuse to get my voltage down. I used two 20W 8 ohm resistors in parallel. You will probably need to experiment to find the right value.

Dave

old_coot88
07-08-2015, 07:46 PM
Sometimes it's handy to use the 6.3VAC heater rail as a proxy.
If it's over the nominal 6.3V, a little droppage on the primary side is in order to get it back down.
And then get the appropriate droppers on the replacement B+ silicons.

walterbeers
07-09-2015, 06:16 PM
It seems as if a 100 ohm adjustable resistor would be kind of high in value. I agree that an adjustable resistor is the way to go, that way I can get the exact B+ voltage by setting the resistor so that I get the required 400 volt by adjusting it. I am thinking more in the 10-25 ohm range with adjusting it to the close end would be 0 ohms and maybe like 10-25 ohms at the far end. If Zenith 6S621 achieved the proper voltage using just 4 ohms, a 100 ohms resistor would be adjusted all the way to the end. I found out that I can re-stuff at least the main filter cans, so I'm going to give it a try.

Steve McVoy
07-09-2015, 06:36 PM
I think you are splitting hairs. These sets were designed to operate over a wide range of line voltages, and differences in components in individual sets will result in quite a variation in DC voltages.

I wouldn't worry about getting the DC just right. Even if you got the 380 v line right, the others won't match what you read on the schematic. Put a small resistor in series with the diodes and you will be fine. In fact, I don't think you'd have a problem with not using a resistor. You might end up with 20 or so volts more on the DC, which won't be a problem.

walterbeers
07-09-2015, 07:04 PM
I think your right Steve, I know most all older electronics ran a tolerance of at least 10% or more. Sometimes I don't know why I'm such a perfectionist. I'll probably slap a 4 ohm resistor in series with the B+ and check the voltage. If it's within 10 volts or so, I'll call it good. Also I found a bunch of peaking coils open. Those little round white ones, mostly in the video circuits. Thanks to the internet, I'm sure I can find most of the correct (or close) values online. One of them is located in the center of the attached picture.

Steve McVoy
07-09-2015, 07:49 PM
In my experience all the white, powdery inductors should be replaced. The yellow ones seem to hold up well. I got mine for a recent CT-100 restoration from Newark, like these:

http://www.newark.com/bourns-jw-miller/70f271af-rc/choke-270mh-36ma-5-62khz/dp/63K3982?categoryId=800000016501

miniman82
07-09-2015, 10:29 PM
I think you are splitting hairs. These sets were designed to operate over a wide range of line voltages, and differences in components in individual sets will result in quite a variation in DC voltages.

But let's not forget: his line voltages are in the 125 range, and when you combine that with the 20 or more extra volts the silicon is likely to add it can get too high fast. I personally don't like risking unobtainium like CTC-2B flybacks, so I do what I can to keep things in check.

Only way to know if you're safe is checking horizontal output tube cathode current, if it's too high you risk a meltdown. Check the Sams on the set, it should have the values you need.

Findm-Keepm
07-10-2015, 12:21 AM
As to replacing the selenium, some guidance, first from International Rectifier, as found on the back of their 1965 "Universal Silicon Replacement Rectifier" rated 600V at 1 Ampere.

The second photo is guidance from Sarkes Tarzian, a maker of both Selenium Rectifiers and later, Silicon replacements. This was an enclosure with their M150 "Silicon TV Replacement Rectifier" from the late 60s. It is only rated at 360V, 150mA, obviously aimed at Black and White sets, but it too recommends adding a dropping resistor.

Others here have some great advice as well.

old_coot88
07-10-2015, 12:23 AM
But let's not forget: his line voltages are in the 125 range, and when you combine that with the 20 or more extra volts the silicon is likely to add it can get too high fast. I personally don't like risking unobtainium like CTC-2B flybacks, so I do what I can to keep things in check.

Indeed! And remember, wattage (and heat) don't increase linearly with voltage, but by the square of volts times amps.
That's why the earlier suggestion of using the 6.3 VAC heater supply as 'standard marker' when line voltage supply is over spec.

Steve McVoy
07-10-2015, 06:49 AM
I think it makes sense to install a small resistor in series with the diodes, but beyond that I think no other precautions are needed. I install fuses in the cathode of the horizontal output tube on restorations I've done to protect against excessive current. Horizontal output tube current can be controlled by the horizontal drive control.

walterbeers
07-10-2015, 02:38 PM
I will definitely be checking the horizontal output current as I adjust and experiment with different resistors in the rectifier/power supply circuit. Also will be following the Sams as far as adjusting and getting the 6CB5 horizontal output current as low possible keeping the width and HV within acceptable limits. Thanks for all the advice, I'm first going to start with an 8 ohm dropping resistor and bringing it up on a variac and make adjustments as necessary. I sure don't need to "cook" the flyback. Things can't go wrong, I've got my cat, Lala, as my helper. (just a bit of humor).

ohohyodafarted
07-10-2015, 03:31 PM
Indeed! And remember, wattage (and heat) don't increase linearly with voltage, but by the square of volts times amps.


I think you mean
P= I * E
or P= (I squared) * R
or P = (E squared) / R

DaveWM
07-14-2015, 09:51 AM
Pie R round Cornbread R square.

walterbeers
07-21-2015, 08:39 PM
Well, here is the latest. I replaced the electrolytic caps in the power supply, however haven't yet replaced all of the electrolytic caps that are in the sets circuitry. I have the chassis on the bench, so hooked up the deflection yoke, convergence assembly, and of course the speaker, without the CRT connected, and of course with the horizontal output tube pulled. Applied power with my variac, (actually a switchable isolation transformer "pictured"). At about 50 volts AC I got about 200 volts (of the rated 400 volts) from the power supply, which I suspected. Then raised it to 75 volts AC, and got 300 volts out of the power supply, so gradually raised it to 100 volts AC, and got the rated 400 volts, so left it there for a bit. All tubes lit up, so I hooked up my converter box to the antenna terminals, and got audio. It became promising, so installed the 6BQ4 horizontal output tube. I began to get 20KV high voltage, but heard some arcing, smelled ozone and something getting hot. Then the 1/2 amp fuse in the horizontal output B+ popped, before I could disconnect the set. At least it wasn't the flyback, but I found a bad focus control, arcing internally running too hot to touch. Disconnected the lead providing the focus voltage to the pot, powered it up again, and WOOO!, almost 30 KV, and pop (just a loud arc) so pulled the power cord immediately. Looked at the schematic and I noticed that the regulator 6BD4/6BK4 derives it's bias off of the down side of the focus control, so that explains the excessive HV. Also before hand, I had replaced all of the peaking coils that were bad, (those tan round balls), which nearly all of them were open. (A common problem I have run into with several other sets). Oh yea, by the way, the selenium rectifiers have been replaced with silicon diodes. Also I intend to cover the small new power supply capacitors with cardboard insulator covers to make them look like the originals for appearance sake. Another thing I noticed was that the 6AN8 tube V11 (AGC and Sync Seperator started to glow bright blue, hopefully just a bad tube). So my next move is to find a suitable replacement for the 5 meg ohm focus control. Control is quite large but is only rated, according to the Sams at 1/2 watt, 5 meg ohm. RCA part number 79028. I know workman used to make some of these style controls and focus resistors, so hope I can find something that will work.

Oh yea, speaking of PI, well PIE, the kind you eat (from the post above), the best pies you can buy in the Omaha and Midwest area are frozen ones that are home made from the Village Pie Maker. They can be found in the HY-Vee stores, Bag and Save, and other locations. They are made in Nebraska, from a small company that several local women got together and decided to make a business of it. They use fresh fruit, (not frozen), and have Rhubarb, Cherry, Apple, Mix Berry, Peach and others. Look them up, just type in a search for the Village Pie Maker. Maybe they are even available in your area.

Steve McVoy
07-22-2015, 12:15 AM
If you can't find a 5 meg pot of the original style, another option is to use a standard 2 meg one. The voltage differential across it will be small enough to prevent arcing. You will have to experiment with resistors on either side of it to total 5 megs and have good focus at the midpoint of the pot.

walterbeers
07-26-2015, 12:13 PM
I am also going to have to find something to make and use for a yoke cover as the old one was crumbled beyond use. The yoke is slightly over 6 1/2 inches round and also I am wondering if a cover from another roundie yoke cover would fit. I know someone on here manufactured his own, and also heard of someone using a plastic paint can lid. Suggestions?

dtvmcdonald
07-26-2015, 12:32 PM
Plastic top from some sort of food pail, for example, ice cream. May cost money,
but at least you can eat it.

For my CT-100 I just cut two pieces of cardboard into two overlapping
halfs, slipped them on the already assembled CRT neck, and taped them
together. You could do that with plastic sheet.

miniman82
07-26-2015, 07:51 PM
coffee can top is what some have done.

walterbeers
07-27-2015, 12:26 PM
I'll give the can lid/top a try. I might get some strange looks measuring can tops at the grocery store, but if I can find one 6 1/2 inches it might just work. Thing is though it has to be heavy enough to hold the copper ring along with the heavy (lead)? circular piece in place between the yoke and the convergence assembly. Are those pieces even really necessary? I have never seen them on any other roundie set, and also wonder what they are for. The heavy ring is held by the three stand offs with rubber pieces between. The stand offs go through the copper plate which was riveted on to the back side of the yoke cover. The heavy ring is not a magnet, as far as I can tell. It doesn't seem to be magnetic at all. Just a heavy ring. I wonder if I really need them. Oh, by the way there is a ground wire running to the copper ring.

walterbeers
09-23-2015, 05:44 PM
Well, progress has been slow, but going in the right direction. I was able to find a 3 meg 3 watt pot for the focus control, and using a combination of 14 meg from one side of it to ground and 4.2 meg from the plate of the 3A2 V23 I was able to achieve around 4 KV, adjustable about a half a KV either way. That may be close enough, maybe not. Will have to experiment. Set powers up on the bench without the CRT attached, and have about 22KV at the second anode. The Sams, calls for 25 KV, but I don't remember any roundie running more than 22 to 24KV on the second anode. I will say that the dropping resistor I have in the power supply is only running the B+ at 375 volt, so I probably can get more high voltage if I go up to the full 400 volt rating. I have replaced all the electrolytic capacitors, leaving the cans intact, but most of the cans are disconnected and wired underneath. The power supply caps were taken out, and replaced on top, in which I intend to mount the cans over them making it look original. I'm now onto replacing all the paper wax capacitors, but I just ordered all of them today, so that is a major soldering task ahead for the next step. I was able to fashion a yoke cover from a Tupperware lid, and mounting the copper ring to it. I have no idea how things will turn out, and if the set will ever produce a good picture, if any? Once I get all the rest of the capacitors replaced I am going to power it up connected up to the CRT and see what happens. I have high hopes though. As I said, this is going be an on going 2 or more year project.

pendulum
09-23-2015, 06:05 PM
Keep up the good work! Thanks for all the updates and the nice photos. I love the high voltage setups in these early color sets. They always look like a crazy science experiment.

Titan1a
09-23-2015, 07:10 PM
Keeping in touch. Don't give up!

Electronic M
09-23-2015, 08:39 PM
Don't forget the white video peaking coils under chassis....If those are open (which they tend to be) you will have video problems.

jstout66
09-24-2015, 06:13 AM
Walter checked and changed all the peaking coils already. (I think only 2 were good)
We got to experience the joys of bad peaking coils on my 56 Motorola.

Alastair E
09-25-2015, 03:41 PM
That heavy grey ring--Looks like its made of ferrite.

Could be to magnetically screen the scan-coils from the convergence-yoke--or vice-versa....

Not seen one like that on any UK Delta gun convergence-assembly....

walterbeers
09-26-2015, 06:07 AM
I believe it is ferrite. A magnet will stick to it, but it's not magnetic itself and quite heavy. I also believe the it's to screen out the magnetic field between the yoke and the convergence coils. The copper ring, well, it has a ground wire running to it. I also wondered if it is was used to reduce X-radiation, however I think it would have to have lead in it then. I had never seen one of those ring setups on any roundie I had ever worked on till till I got this one. Does a CT100 model (the 15 inch set) use the same type of set up with the rings?

walterbeers
10-08-2015, 04:29 PM
Here is the latest on the restoration of the 21CT55, CTC2B Oct 7, 2015 All wax caps have been changed out, except those mentioned below.

Well, I powered it up again on the bench, although it still needs a few more caps, 6 in total, 2 are already ordered from MCM. I have sound, vertical, high voltage, and video waveform (on my scope at all three CRT grid connections), and voltages are within range at the CRT socket proving that the set should produce some kind of picture or at least a raster, when I get it hooked up to the CRT. When I first powered it up, there was a buzz and a wisp of smoke somewhere in the audio section. After trying it again, and not being able to locate what got hot, sound came on just fine. I can get plenty of high voltage, although if I push any more than about 22kv, it sometimes arcs and snaps like a firecracker. Not sure where it is arcing. Flyback runs pretty warm, almost hot, after being on for 15 minutes or more in the center part of the flyback. Current being drawn by the horizontal output tube is normal, even a little on the lower side, 185ma, so that shouldn't be the cause of the warm flyback. I also still need a couple more tubes that check bad, a 12BH7, and a 6LN8. None of the tubes or capacitors that are still needed should affect the flyback. Power supply runs right at the rated 400 volts with 115 volt AC line. I want to get the other caps and tubes in there before I figure out how to hook it up to the CRT and still be able to service the chassis. I can either sit in on top, or on top of something right behind the set. I also still need to order a much longer piece of high voltage wire to hook up the set outside of the cabinet. Sams indicates that the high voltage should be at 25kv. I still wonder if that is higher than it needs to be. My biggest concern is that the flyback will be OK. If it goes up in smoke, well, finding one is almost impossible. I still have high hopes for the old 1954 set, as I have lots of time and $$ into it.

Today's update: Oct 08, 2015. Powered it up again, no snapping of HV at 24KV, so may just be moisture or dirt. Found the problem with the buzz and smoke up by the audio section. It was just a pinched wire, which runs upfront by the service adjustments. I don't think any damage was done. Flyback will get quite warm, even though the Horizontal output tube current is within the normal range. However the waveform at the grid of the horizontal output, (the sawtooth waveform) is flattening on the top. Picture attached. I noticed there are adjustments for wave shape, etc in the Sams, so I'm assuming that will take care of it. The waveform may be what is causing the flyback to get warm, mainly in the center of it close to the core of the transformer. The large ring for the high voltage winding remains cool. Yoke, convergence yoke, and magnets are ready to go back into the set. I have the possibility of getting a CRT test jig. An RCA. I'm not sure if I can use it with this set or not, but could also use it on my CTC9, and others. I am encouraged, I'm just taking it a little at a time.

ohohyodafarted
10-09-2015, 05:11 PM
This chassis has a very large HV door knob cap mounted to the back side of the HV cage. On my set that door knob was bad, probably leaking. I purchased a 40KV replacement on ebay. I needed to modify some of the mounting hardware, but it works fine.

I would suggest that you check the big 30KV door knob to see if it is getting warm which would indicate leaking. If yours is leaking, I would replace it before it wipes out your flyback.

I also installed a small cooling fan in the side of my HV cage to keep my flyback temp nice and cool.

When I restored my CT55, I placed the cabinet next to my workbench and made extension cables to connect the chassis to the crt and other components in the cabinet.. That worked very well.

You may find this link to the page on my web site of some use.
http://antiquetvguy.com/WebPages/TheRestorations/1954RCA21CT55/1954-RCA-21CT55.html

miniman82
10-09-2015, 06:20 PM
Ditto on the mega doorknob, mine got hot and leaked a bunch of wax but thankfully didn't take out the flyback. I shut it off and let it cool down and it never happened again, but I don't trust it. Gotta get a new one at some point.

walterbeers
10-09-2015, 06:38 PM
I know which doorknob cap your talking about, and I felt it, and it seemed to be cool, at least after 15 minutes or so, and ran my HV probe around the back side of it, and no arcs between the metal frame and back side of the capacitor. Although, I still wonder if it could be leaky causing the problems. I have a CRT booster in which I can make extension cables out of it, and also an octal socket for the yoke, provided it handles the higher horizontal voltages going to the yoke. Convergence with the sub chassis removed should give me enough room to hook it up. My problem right now is finding a long enough HV wire with connectors in order to hook up the CRT with insulated plugs or sockets that won't arc to something close, or produce corona. I found HV lead wire on e-bay, but I need something to insulate the connections. The one end I can stick in a wire, in tape it and it probably would be fine. The other has to plug onto an exposed pin coming off the wire that goes straight to the CRT. I need to find something in which I can solder a terminal onto and plug into the wire going to the CRT, and have some kind of a sleeve to go over it that will insulate the connection. I also have the possibility of getting a color test jig in a couple of weeks. Doubt if it will work on the CTC2B, but maybe it will have some HV, or yoke connectors that I can use. Even if I could hook up the high voltage and yoke to it, at least it should give me an image, (although not converged) I could work with it to start with..

Electronic M
10-09-2015, 08:09 PM
I'd just stick the plug end of the HV in a glass jar.....It is what I did when I needed to make a HV extension when working on my CTC-4.

walterbeers
11-03-2015, 07:23 PM
Well, here is the latest as of Tuesday Nov. 3rd, 2015. I actually have a picture, color, sound and everything one would expect. Yes, I have had several problems getting there and still have problems to work out. All capacitors have been changed with caps from Capacitor World, with correct values. I did not re-stuff the cans, however I left the cans in there for appearance, and since most of the capacitors are so much smaller, there was plenty of room to mount them underneath. The big filter cans, I mounted smaller size ones on top, and I intend to put insulating sleeves over them to make it look close to original. I had to replace the horizontal output tube 6CD5 as it was weak, the vertical output tube as it showed weak on my checker, and when I got it one of the 3A2 Rectifiers was broken, so I changed all 3. Also one of the 12BH7's showed a short on my checker, so it was also changed with a NOS. I added a 5.1 ohm 25 watt resistor in series with the B+, and at my line voltage I have 405 volts, as the Sams calls for 400 volts, so I figure it's pretty close. I changed all of the white peaking coils, with values as close as possible, (most were right on), as half of them were open. I also had to change the big 2500pf 30KV doorknob capacitor as the one that was in there would arc and go off like a fire cracker. (oh yes, when it arced one time, it shorted the video detector diode 1N60 which I had to change). I now have 24KV at the second anode although the Sams says to set it at 25KV. HV won't adjust any higher. I was able to hook it up with a long piece of HV anode wire, an octal yoke extension, and used a booster as an extender for the CRT, although I patched the filament in directly eliminating the boost, as I didn't was to increase the filament voltage to the CRT. After powering it up on the bench without the CRT connected, I set the chassis on top of the cabinet, hooking everything up, even a speaker. I monitored the horizontal output current and it is running around 205ma. I had a raster, way off purity, but no big deal. I then hooked up a converter box to the antenna terminals and put the set on channel 4. I had a picture, not good, way off convergence, purity etc, but I was so happy, I actually had a picture. Of course I had to adjust the purity and center convergence. But then the next hurdle, I had no color. Checked with my scope for 3.58 osc. waveform and there was none. Started checking voltages, and the ones around the oscillator seemed to be within range, except for the color killer. I then concluded that probably the crystal was bad. Ordered a NOS crystal, soldered it in underneath, and I had 3.58 MHz waveform, but still no color. Got checking further, and found R211 12.5K 10 watt resistor open. Replaced it, and presto I had color, although sometimes the color was out of lock. I found that the crystal though needed to have it's case grounded like the original, so found a way to ground it, and now I have full tint range, and reasonable color. CRT looks good, and shows good emission on my Beltron checker. The next hurdle was that the picture was snowy, like watching a distant analog station. Found the 3.3 meg resistor on top of the tuner that supplies the RF agc was also open. Replaced it. Well, No snow! Oh yes, earlier in the restoration, I had to change the focus control and associated resistors. I had to compromise a bit on some of the values, but the focus looks good, and is adjusted to the center of the control. The next hurdle I haven't figured out quite yet. When I increase the contrast and or brightness the picture goes out of focus and pulls in from the sides, mainly the left side of the picture. I am still wondering if I could still have a bad horizontal output, damper, regulator, or horiz oscillator tube. It seems as if the beam current really pulls down the HV at higher brightness, causing the picture to narrow. That is where I'm at right now. Of course the cabinet needs to be touched up and or refinished, and I have decided I will not pull the 21AXP22 out, as I don't want to risk either breaking it, or it going to air. The top is the worst and it can be sanded and refinished with no problem as it comes off. I know of a guy that does woodworking and I might have him figure out what would be best to do, and do some work on it. Of course the trim, glass, pencil door, etc. all have to be cleaned up and polished. Here are some more pictures and screen shots. Oh yes, I was able to make a yoke cover out of a fairly solid Tupperware lid, cutting a hole through the center, and mounting the rings on it, gluing it all in place with silicon seal.

Phil Nelson
11-03-2015, 11:14 PM
I actually have a picture, color, sound and everything one would expect.Wahoo! I hope you did a little victory dance around the workshop when you saw the first color picture.

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

Electronic M
11-03-2015, 11:16 PM
Nice work!

Titan1a
11-04-2015, 02:57 AM
Good show! Kudos!

Username1
11-04-2015, 06:31 AM
Pretty cool ! ! Nice work !

.

kvflyer
11-04-2015, 11:31 AM
That looks excellent! I would bet it would never have come out of a service shop with it working that well.

Congratulations are in order!

Steve D.
11-04-2015, 12:16 PM
Walter,

Congratulations on a first rate job.:thmbsp:

-Steve D.

walterbeers
11-04-2015, 05:31 PM
Well, there still is a lot of work to do. I still have the width problem when brightness and contrast is increased, and my 25 watt 5.1ohm resistor that I am using in the B+ to drop the excess voltage, (since I used silicon rectifiers to replace the selenium's), gets so hot that it actually smells a bit. I may have to go to 2 separate resistors as I am afraid that the excess heat will cause it to open up. Then there is taking out the glass and cleaning up the cabinet, pencil box, and making it look "new" again. However I still want it to look original as possible. Hope I can get the cabinet looking nice, but had to get the set operating first. I may order a new damper, HV regulator, another horizontal output tube, and horiz oscillator tubes to see if that takes care of the width/ focus problem at higher brightness. Of course once I get the chassis mounted back into the cabinet, then I will try to set the purity and convergence as close as possible. There is a metal plate that the chassis sits on top of, and I hope to maybe mount it underneath somehow so if I need to work on the circuits from the underside that I don't have to pull the entire chassis. Any old retro TVs are an on going project, always hoping to improve upon it.

ohohyodafarted
11-07-2015, 11:13 AM
Nice Job Walter,

RE: your issue with contrast and brightness. My CT55 does the same thing. I have never been able to figure out what causes this issue. Someone told me that the HV section is probably just not capable of supplying enough current when you drive the tube real hard. My set has a NOS flyback so I know that the flyback is not the issue.

I would bet that if you look at the HV level when you drive the tube real hard to the point where the picture pulls in, you will see the HV droping. I can drive mine so hard that I can cause the picture to almost fade away. My 21AX was rebuilt by Hawkey before they closed so it has very strong emission from the guns which easily can overwhelm the HV section.

I also have another issue that I never was able to track down. It takes about 15 minutes for the convergence to stabilize. I thought the problem was a leaky capacitor in the convergence chassis, but after rebuilding it, I still had the issue. I can speed up the stabilization by turning the brightness up real far and forcing the picture to shrink in and go out of focus. I don't understand the relationship between these issues, but after the set warms up it has a great picture.

MRX37
11-07-2015, 01:02 PM
That is looking awesome, Walter.

Glad to see it up and running. :)

BigDavesTV
11-08-2015, 04:13 PM
Looks great, congratulations! So nice to see one of these old classics displaying a nice picture again.

technicolor
11-08-2015, 09:01 PM
Well, here is the latest as of Tuesday Nov. 3rd, 2015. I actually have a picture, color, sound and everything one would expect. Yes, I have had several problems getting there and still have problems to work out. All capacitors have been changed with caps from Capacitor World, with correct values. I did not re-stuff the cans, however I left the cans in there for appearance, and since most of the capacitors are so much smaller, there was plenty of room to mount them underneath. The big filter cans, I mounted smaller size ones on top, and I intend to put insulating sleeves over them to make it look close to original. I had to replace the horizontal output tube 6CD5 as it was weak, the vertical output tube as it showed weak on my checker, and when I got it one of the 3A2 Rectifiers was broken, so I changed all 3. Also one of the 12BH7's showed a short on my checker, so it was also changed with a NOS. I added a 5.1 ohm 25 watt resistor in series with the B+, and at my line voltage I have 405 volts, as the Sams calls for 400 volts, so I figure it's pretty close. I changed all of the white peaking coils, with values as close as possible, (most were right on), as half of them were open. I also had to change the big 2500pf 30KV doorknob capacitor as the one that was in there would arc and go off like a fire cracker. (oh yes, when it arced one time, it shorted the video detector diode 1N60 which I had to change). I now have 24KV at the second anode although the Sams says to set it at 25KV. HV won't adjust any higher. I was able to hook it up with a long piece of HV anode wire, an octal yoke extension, and used a booster as an extender for the CRT, although I patched the filament in directly eliminating the boost, as I didn't was to increase the filament voltage to the CRT. After powering it up on the bench without the CRT connected, I set the chassis on top of the cabinet, hooking everything up, even a speaker. I monitored the horizontal output current and it is running around 205ma. I had a raster, way off purity, but no big deal. I then hooked up a converter box to the antenna terminals and put the set on channel 4. I had a picture, not good, way off convergence, purity etc, but I was so happy, I actually had a picture. Of course I had to adjust the purity and center convergence. But then the next hurdle, I had no color. Checked with my scope for 3.58 osc. waveform and there was none. Started checking voltages, and the ones around the oscillator seemed to be within range, except for the color killer. I then concluded that probably the crystal was bad. Ordered a NOS crystal, soldered it in underneath, and I had 3.58 MHz waveform, but still no color. Got checking further, and found R211 12.5K 10 watt resistor open. Replaced it, and presto I had color, although sometimes the color was out of lock. I found that the crystal though needed to have it's case grounded like the original, so found a way to ground it, and now I have full tint range, and reasonable color. CRT looks good, and shows good emission on my Beltron checker. The next hurdle was that the picture was snowy, like watching a distant analog station. Found the 3.3 meg resistor on top of the tuner that supplies the RF agc was also open. Replaced it. Well, No snow! Oh yes, earlier in the restoration, I had to change the focus control and associated resistors. I had to compromise a bit on some of the values, but the focus looks good, and is adjusted to the center of the control. The next hurdle I haven't figured out quite yet. When I increase the contrast and or brightness the picture goes out of focus and pulls in from the sides, mainly the left side of the picture. I am still wondering if I could still have a bad horizontal output, damper, regulator, or horiz oscillator tube. It seems as if the beam current really pulls down the HV at higher brightness, causing the picture to narrow. That is where I'm at right now. Of course the cabinet needs to be touched up and or refinished, and I have decided I will not pull the 21AXP22 out, as I don't want to risk either breaking it, or it going to air. The top is the worst and it can be sanded and refinished with no problem as it comes off. I know of a guy that does woodworking and I might have him figure out what would be best to do, and do some work on it. Of course the trim, glass, pencil door, etc. all have to be cleaned up and polished. Here are some more pictures and screen shots. Oh yes, I was able to make a yoke cover out of a fairly solid Tupperware lid, cutting a hole through the center, and mounting the rings on it, gluing it all in place with silicon seal.






Glad our caps worked out for you Walter and thanks again for your repeat business. Awesome job on that set.

walterbeers
11-09-2015, 06:15 PM
I've used capacitors from Capacitor World for several different sets, and never had a problem with them. Once in a while when replacing large long wax caps, the leads don't reach so I have to solder some extra lead wire onto it, but that is to be expected since the capacitors today are so much smaller in size. I'm sure I will be ordering more from them as I continue to restore old retro, unique, and antique TVs, and radios.

etype2
11-09-2015, 06:32 PM
Congratulations on bringing the RCA 21-CT-55 back to life.

roundscreen
11-09-2015, 08:43 PM
Nice Job Walter,

RE: your issue with contrast and brightness. My CT55 does the same thing. I have never been able to figure out what causes this issue. Someone told me that the HV section is probably just not capable of supplying enough current when you drive the tube real hard. My set has a NOS flyback so I know that the flyback is not the issue.

I would bet that if you look at the HV level when you drive the tube real hard to the point where the picture pulls in, you will see the HV droping. I can drive mine so hard that I can cause the picture to almost fade away. My 21AX was rebuilt by Hawkey before they closed so it has very strong emission from the guns which easily can overwhelm the HV section.

I also have another issue that I never was able to track down. It takes about 15 minutes for the convergence to stabilize. I thought the problem was a leaky capacitor in the convergence chassis, but after rebuilding it, I still had the issue. I can speed up the stabilization by turning the brightness up real far and forcing the picture to shrink in and go out of focus. I don't understand the relationship between these issues, but after the set warms up it has a great picture.

The RCA service manual purity adjustment step 5 states that the repair man should set the contrast fully counterclockwise and set the brightness control for maximum brightness with out blooming. This would tell you that it normal that the set can bloom with the brightness turned up to high. Also when you do convergence on any tube color set, It is best to run the set for twenty minutes before you start the convergence procedure. So really, Your set's are working fine. I have a ctc 16 that has to be on for a few minutes before the convergence stabilizes. I changed the convergence board with a known good one And it still has to warm up, So it must be the CRT. Walter beers. That is a really good picture on your set.:thmbsp:

walterbeers
11-10-2015, 04:19 PM
Thanks for the compliment "round screen". Well I got another NOS Horizontal output and a NOS damper tube, and the set hardly pulls in at all unless I crank up the brightness way too high. Cathode current of the 6CB5 I think is a little high, 223 ma or so, and I tried adjusting the horizontal efficiency (linearity) coil and that is the minimum current I can get it adjusted to. Picture even looks a little better with the tubes in there. High voltage is running around 22 to 23KV, but it will not adjust up to 25KV as per the Sams. I'm not sure though if my probe though is completely accurate. Actually I haven't even touched the dynamic convergence yet, and it looks fairly close. I just did the center convergence and purity, and purity is still off a bit, but will make final and closer adjustments when I get the cabinet touched up or refinished, and the chassis back into the set.

walterbeers
11-13-2015, 05:15 PM
I still have the chassis on top of the cabinet, and attempted a rough dynamic convergence. I also replaced the 6SN7 tube, had to readjust the horizontal frequency coil to get the picture to lock and now I have the cathode current down to around 208 ma. Apparently the 6SN7 was a bit weak although the tube tested good. Here is a picture of my rough dynamic convergence attempt. It's not perfect, but close.

Steve D.
11-13-2015, 06:13 PM
Walter,

I'd say that's pretty good convergence. I wouldn't knock myself out doing much more set up until the chassis is back in the cabinet and the set is sitting close to its final resting place in your home. Of course, after convergence, purity and screen adjustments would be about the last items on the list imo.

-Steve D.

walterbeers
12-27-2015, 09:01 AM
Here is the latest, as of Dec. 27th, 2015. I have been working on refinishing the cabinet, and have it looking pretty good. (I am definitely a novice as a cabinet re finisher). I used a Minwax mahogany gel stain after a hefty rubdown with lacquer thinner on the sides and front of the cabinet. For the top I used a varnish/paint remover to get all of the old finish off down to the bare wood, sanded it with a power finish sander, then applied the gel stain. Then I gave it 2 coats of Minwax semi-gloss fast drying polyurethane. It has a few (feel-able) dust speckles in it as I had to do it in my finished basement shop area, since I don't have a dust controlled environment. I took the escutcheon off that holds the safety glass in, and cleaned off the black goo that was between the glass and the mask around the CRT. I don't really know what the goo was from, as I didn't see any kind of gasket or glue substance. The clips that held the escutcheon in were a challenge to get to, as I chose not to remove the CRT. I tried about everything to polish the escutcheon, but nothing worked, so I ended up spraying it with a brass colored spray paint. It may not be perfect or exactly original, but I gave it my best attempt. Here are some pictures of the cabinet. The chassis is set back into the cabinet, but it's not re-connected yet, and final adjustments have not been made.

PS: FOR THOSE INTERESTED, I am NOT intending to sell this set (or my CTC9) as I intend to cherish and keep it for all of the hard work I have put into it.

Electronic M
12-27-2015, 01:13 PM
From owning a CTC-4 with the same CRT mask assembly I can tell you the following: The black goo was once a rubber gasket. They degrade differently with each sets' unique storage conditions (mine was partially melted partially intact/rotted dry/gummy). That brass bezel is best polished with Brasso and an old (not going to be used on you again) toothbrush....Vigorously brushing while the Brasso is wet. Afterwords you will need to run steel wool or scotch-brite up and down the length of the strip to restore the "brushed" finish to the metal....The brass on my CTC-4 was nearly black.

ohohyodafarted
12-27-2015, 05:26 PM
I am not a fan of Minwax Gel Stain. It has a tendency to cover the character of the natural grain. It can be put on too heavily and become more like paint than a true stain. I only used the Minwax gel stain once and I deplored the results so much so, that I stripped it off and started over. Apparently it is a combination of some sort of varnish and stain.

I prefer any brand of liquid OIL stain directly against the bare wood which has already been grain filled.

For finish coat, I have been using Sherwood Pre-catalized lacquer from Sherwin Williams. It is a true commercial/industrial type coating. It's available in 4 levels of sheen from gloss to a dull mat. Comes in Gallons and 5 gallon sizes. Link below will take you to a SW Pdf of the product.

http://www.paintdocs.com/docs/webPDF.jsp?SITEID=SWOEM&lang=E&doctype=PDS&prodno=T77C35

I no longer use "varnish" for anything except when I re-finish hardwood floors.

You will need compressed air spray equipment to spray the Pre-cat. Since I started using the Sherwood Pre-cat, I have completely abandoned all other finishing lacquers and varnishes. And I very rarely use shellac any more because it spoils and always has to be made up fresh. The Sherwood Pre-cat also has a shelf life of only 6 months after the catalyst is added. However, you can ask the people at the Sherwin Williams store to give you the UN-catylized components and mix small batches when you are ready to do some spraying. That way you add catalyst to only enough to do the job at hand, and keep the UN-catalized material on the shelf for future use.

The Sherwood Pre-cat lacquer sets up in about 15 minutes. It is very easy to spray, more so than even conventional nitro-cellulose, or acrylic lacquer. Even an amateur like me can get professional results that look as good as if it came from a professional furniture factory.

I start by wiping down the cabinet with lacquer thinner. If the old finish is not too terrible, and I think it can be salvaged without an entire striping, I proceed as follows. After the wipe down with lacquer thinner, I locate any scratches that need touching up with stain. After staining the defects (where necessary) I take come Sherwood Pre-cat, and using an appropriate artists brush I paint on several coats of lacquer on the scratches to seal the wood where the old lacquer was scratched off. 24 hours later I wet sand with 220 to level the lacquer in the areas where I did the touch up. Then I lightly power sand the entire cabinet with 180 to scuff up the surface for good adhesion of the new finish. Wipe down the cabinet after sanding with an automotive type "pre-cleaner" to make sure all the old wax and silicone's are removed so you don't get "fish eyes' when you spray.

Then I spray 2 coats of Sherwood Pre-cat. 24 hours later I wet sand again to flatten out any dust particles that landed in the wet lacquer. And finally I give it one last coat of Sherwood Pre-cat. The results will look like it just came from the factory.

Kevin Kuehn
12-27-2015, 09:17 PM
Is that SW Pre-cat lacquer still dissoluble by lacquer thinner once it's fully cured, so you can blend in repairs like traditional nitrocellulose? I'm thinking not, but I've never used the stuff. However we may not have many choices in the near future, other than to use some non dissoluble finish.

Titan1a
12-27-2015, 11:21 PM
Walter, it looks great. Now for the picture! You do good work.

ohohyodafarted
12-28-2015, 04:13 AM
Is that SW Pre-cat lacquer still dissoluble by lacquer thinner once it's fully cured, so you can blend in repairs like traditional nitrocellulose? I'm thinking not, but I've never used the stuff. However we may not have many choices in the near future, other than to use some non dissoluble finish.

Kevin,
I can tell you the pre-cat Sherwin Williams lacquer I use is Nitro-Cellulose based. They also make a pre-cat Acrylic lacquer for applications where you can not tollerate the fact that NC turns yellowish over the years. The acrylic pre-cat is useful for light blonde finishes that must not yellow over time.

The claim is that pre-cat is more durable than a conventional NC lacquer. I have read that if you re-coat during the time frame when the pre-cat is still not completely cured, the re-coat "melts" into the existing finish. I did read a thread where the poster spoke to SW tech support people and they assured the poster that regardless of how long the pre-cat had cured, re-coats would adhere into the existing finish.

I read another post by a furniture re-finisher who said he uses pre-cat lacquer all the time and it is easily "repaired" unlike polyurethane varnish.

Other sources say that pre-cat must be sanded prior to a repair job to make the new repair adhere mechanically. This infers that the cured pre-cat can not be dissolved by the new lacquer.

That said I can say that the Nitro Cellulose component of the pre-cat product should always be lacquer thinner soluble regardless of how old the pre-cat finish is. I just can't quantify for you how easily it will dissolve. I would suspect it would dissolve very much like 50 year old conventional NC lacquer that was applied to our tv sets back in the 60's

From what I understand, conventional NC lacquer dries when the thinner evaporates. Pre-cat has additional components that "cross-link" making the product more durable. Still the bulk of the product is nitro cellulose and should be soluble in lacquer thinner.

Varnish does not "dry" it "cures" through cross linking. That is why old varnish is notoriously difficult to soften and re-coat. Usually you have to sand varnish to re-coat to get mechanical adhesion. Or else you strip old varnish and refinish.

Post-catalyzed lacquers are a bit of a different story. You add the catalyst right before spraying. The cross-linking takes place very quickly. The terminology is post-cat finishes are very "HOT". The pot life can be as short as 15 minutes to 90 minutes. After that the product starts to gel and harden. The re-coat time on post-cat product is very short. If you miss the window, you have to wait until a full cure is obtained, sand and then re-coat.

Back in the 1970's I repainted a car. Back then base coat, clear coat was a new cutting edge process. I painted the car with a lacquer base coat (lime green), and then I use a post-cat urethane clear coat over the top of the lacquer. The pot life was about 90 minutes and after that, the left over clear coat product turned into a rubbery substance that could not be dissolved.

If you are concerned that a pre-cat lacquer is like IE: "2 part epoxy" or cured polyester resin after you added the methyl ethyl keytone peroxide, (which basically nothing on earth will dissolve after it sets up), I can assure you that pre-cat lacquer is nothing like that.

Unfortunately I can not give you a definitive answer on whether or not very old pre-cat will be repaired as easily as conventional NC or Acrylic lacquers.

But for me at least, the quality of the finish and ease of use is most important. I will let somebody else worry about how to fix the pre-cat finish on my antique TV sets after I am dead and the sets go to a new caretaker.

walterbeers
12-28-2015, 02:29 PM
I agree I'm not a pro furniture finisher, and I'm sure there are a lot better ways, stains and finishes to use. I think it looks fairly reasonable, not perfect, but acceptable, and it looks a lot better than it did. Maybe someone, will get the set in the future, can do a more professional job, (assuming the set will still be around). For now, I plan to keep the set, and I'm satisfied.

walterbeers
02-14-2016, 10:10 AM
Well, I have it done, at least for now. I'm sure maybe with more time I can improve upon it some more, but it does have good color, and is completely back together and working. Not bad for a color set produced at the end of 1954. I thought I would post some final pictures of this RCA CTC2B, 21CT55. Also in case someone is wondering about the set next to it in the one picture, it's my CTC9. They are 2 of my most prized possessions. Yes, lots of work has gone into it, but didn't really cost me a lot of money. Just the usual stuff, capacitors, some tubes, the color crystal, a doorknob capacitor, a few resistors, etc.

jr_tech
02-14-2016, 02:10 PM
A thing of beauty and a joy forever! - (Keats)

One of my favorite early color tvs... still has that great early tv upright packaging, has a tube that can be replaced, has I & Q demodulator system and enough tubes inside to heat a small room!

Good job!
jr

etype2
02-14-2016, 04:48 PM
Looking very good indeed.

Hagstar
02-14-2016, 07:22 PM
Cathode current of the 6CB5 I think is a little high, 223 ma or so, and I tried adjusting the horizontal efficiency (linearity) coil and that is the minimum current I can get it adjusted to. Picture even looks a little better with the tubes in there. High voltage is running around 22 to 23KV, but it will not adjust up to 25KV as per the Sams. .

NICE :tresbon:,

I want one of these for a next project sometime in the next few years, more than a CT100. And the figures and results you give above interestingly are the same as my CTC4.

John H.

Titan1a
02-14-2016, 10:04 PM
Righteous!

ChrisW6ATV
02-15-2016, 03:19 PM
Your 21-CT-55 looks fantastic, Walter. Very nice work.

bozey45
03-30-2016, 12:27 PM
My CTC11 is in the same blonde cabinet as your 9 I believe, very similar anyway.

joemama99
04-05-2016, 09:17 PM
Holy cow,Walter! Nice job...

Kevin Kuehn
04-05-2016, 09:41 PM
It turned out great! :thmbsp:

walterbeers
04-09-2016, 07:11 PM
Well, I have it done, at least for now. I'm sure maybe with more time I can improve upon it some more, but it does have good color, and is completely back together and working. Not bad for a color set produced at the end of 1954. I thought I would post some final pictures of this RCA CTC2B, 21CT55. Also in case someone is wondering about the set next to it in the one picture, it's my CTC9. They are 2 of my most prized possessions. Yes, lots of work has gone into it, but didn't really cost me a lot of money. Just the usual stuff, capacitors, some tubes, the color crystal, a doorknob capacitor, a few resistors, etc.

Well, the set is still operating, with good color. I turn it on every now and then just to make sure. Takes little time for the color to stabilize, (possibly a slow warming tube), but once on for a couple of minutes it looks great. My CTC9 still works as well, but needs a little more TLC. My helper (LaLa, my cat in the fourth picture) helps me relieve a lot my frustrations when things don't always go the way I think they should. Also a lot of thanks for my friend Rick (titan1A) for giving me the encouragement to keep at it and not become discouraged. Also many thanks to Jamie (jstout) for helping me get this set. Also thanks for all the advice and posts from the different members of VK.

MRX37
04-09-2016, 07:30 PM
How is its color reproduction compared to your CTC 9?

Steve D.
04-10-2016, 11:04 AM
Outstanding restoration Walter. You should take great pride in your work.

-Steve D.

walterbeers
04-10-2016, 03:03 PM
The comparison of the CTC2B (21CT55) and my CTC9. MRX37s post above got me interested in which was better. Obviously the CRT in the CTC2B is better than the CTC9 but in person, when not comparing the 2 together they both seem to have pretty good color balance. I paused the title page of a DVD so I had the same image on both sets and I must say as of right now, the old 1954 21CT55 wins, (at least in my estimation). Here are some photos. (After looking at the pictures, I see I didn't have the tint (hue) controls set exactly the same.)

MRX37
04-10-2016, 06:03 PM
Thanks for doing that. I asked because I've gathered that the CT-100 and the 21CT55 have better color reproduction then everything that came later, so I asked because you own a now working 21CT55 and a later CTC set.

Would love to see it compared to, oh say a Trinitron or some other more modern high end CRT set.

etype2
04-10-2016, 07:18 PM
Thanks for doing that. I asked because I've gathered that the CT-100 and the 21CT55 have better color reproduction then everything that came later, so I asked because you own a now working 21CT55 and a later CTC set.

Would love to see it compared to, oh say a Trinitron or some other more modern high end CRT set.

I could not resist the invitation although I don't think it's a fair comparison. A screenshot from a Sony KD-34XBR960.

The attached thumbnail looks compressed and blured so this link is not compressed of the same image.

http://www.visions4.net/journal/wp-content/uploads/Sony-KD-34XBR960-SS-11-Voice-2560-WP.jpg

dtvmcdonald
04-10-2016, 07:21 PM
I've not compared my CT-100 with a Trinitron CRT, but have
compared it with a medium end Sony 55 inch LCE set and a very top end,
Adobe-RGB gamut capable monitor, on the same set of still images
all made with a high end camera set to Adobe RGB wide gamut.

The CT-100 is not perfect, but has always been very close. I have posted comparison
images in my CT-100 thread. Recently I have even gotten my CT-100 gray
scale better, and they are not even closer. Except in scenes
with very bright, very pure yellows or mid-scale magentas they
are identical.

At low saturations they are almost perfectly the same. As one
increases saturation, magentas on the CT-100 start turning violet
at normal contrast. At low contrast this does not happen.

On those picture you posted, look at the upper left where a spire shaped magenta
building appears: on the other set there is no color discriminatiopn for it.

P.S.: my avatar does appear essentially identical on the CT100 and the monitor,
color wise.

Steve D.
04-10-2016, 07:25 PM
Walter,

In comparing the 2 set's images, I'm seeing more screen information on the 21CT55 then on the CTC-9. Interesting because the masking on the CTC-9 and it's 21CY tube offered 260 sq. inches of picture. The 21CT55 w/the 21AX. 254 sq. inches.

-Steve D.

walterbeers
08-01-2016, 08:48 PM
It was bound to happen, I had it on, when my friend Jamie "jstout" was over here, had an ok picture, ran it a while, looked back and all it had was a dim blur on the screen. Got back into it, and luckily the problem was minor. R173 a 1 watt 4.5 Meg resistor coming off of the HV adjustment had opened up, causing the 6BD4/6BK4 regulator tube to conduct real heavy causing the HV to drop way down to around 15KV. Luckily it didn't hurt the flyback or the tubes in the HV section. Getting my hands down into the HV cage was a challenge as I didn't want to pull the entire chassis again. I had to actually clip out the bad resistor, and I tacked the new one on the end terminal of the HV control, running a jumper wire to the other end, where the old resistor was. It's now working again. If I ever have to pull the chassis in the future though, I will put the resistor back into it's original place, but since it only has like 165 volts across it, a jumper wire sufficed. Actually the HV regulates much better than it did before, and doesn't pull in from the sides near as much with increases of brightness. Tried to touch up the convergence but I don't think I will ever get it perfect. It's close but wish I could get it better. In the photo of the HV section, you can see where the resistor was as I temporarily had red and yellow alligator clips clips on to where the resistor belongs.

Titan1a
08-01-2016, 09:44 PM
Good show!

walterbeers
08-02-2016, 08:05 PM
For those wondering about the shadow at the top of the screen, it's just a reflection from my fluorescent light above. I should have turned it off before taking the picture.

stromberg6
08-03-2016, 02:19 PM
For those wondering about the shadow at the top of the screen, it's just a reflection from my fluorescent light above. I should have turned it off before taking the picture.

Great pic regardless of light :thmbsp:. I find that I need to shoot my CTC-4 in total darkness to get good pics because it has a CRT with the original phosphor screen that looks dark green instead of silver-gray color, and is not too bright. It's in the basement so it's not a problem.

etype2
08-03-2016, 06:56 PM
That a great shot Walter. Love to see that again with the light turned off. :-)

walterbeers
03-25-2019, 08:13 PM
For those who is wondering what happened to this set 21CT55, I sold it to another collector in working condition.