RCA 21CT55 B8802897 is Alive!
 

I've got this 21in roundie in 1965 from a newspaper want ad, for $50 I think. It didn't work but I got it running with a few tube changes. Picture looked good on the 21AXP22 metal but was was very dim. I exchanged it at the CRT re builder for the brightest rebuilt he had, a 21FBP22 glass for $45. He told me the "FB" meant Full-Bright", what did I know? When I started the conversion from metal to glass, I decided to cut-up the cabinet and mount the chassis vertical so I could get to the under side much easier. This was no big deal since it was never going into the house and would reside in my garage TV repair workshop.This B88002897 proved to be the highest serial and last discovered 21CT55 with CTC2B chassis on a list of only 15 known to still exist!Anyway, I got it working this week after 38 years of storage. I'm using external video since the tuner/video IF isn't passing chroma yet. The 21FBP22 sure is bright, no problem with room lights. The reds are closer to CT-100 then most TV I've seen. I've got a 3in Pilot and a Norelco projector TV that I intend to get working next.
I am truely grateful for the interest that John Folson, Pete Dexnis and Ed Reitian took in this reactivation project. I only wish I didn't destroy the cabinet, but that's life. I'm not a restoration person. In 1957, I installed a 346ci Olds V8 engine in my 1954 Healey roadster. Then in 1964 and 2000 I reworked the car's frontend to resemble a Cobra roadster and installed a 418ci Olds V8. I now I have over 400hp in a 2500# car that is a drastic improvement over the original. These modifications made it virtually impossible to restore the Healey to its original configuration even if I wanted to, much to the disappointment of the Healey restorers. This RCA 21CT55 reactivation is history repeating itself 50 years latter. I hope the restoration members of this forum are more tolerant of my efforts to restore and possibly improve the performance of this classic color TV then the restoration members of the Healey car clubs. I hope this explains where I'm coming from, thanks.....Tom

Great job getting 'er going again. Do you plan to restore it to original?
Mark

Awesome picture, and great story! Glad you came on and shared!

I congratulate you on your great success! Back around 1975, I saw an ad in a magazine by RCA that featured a 21CT55 that had supposedly been bought new by a family, and had been under contract with RCA Service Co. since. The ad showed a screen shot of a macaw, and told of the "updating" of the TV with a new CRT (presumably a 21FB), the idea being that they can keep your RCA TV going forever, IF you have a service contract. Don't know which mag it was in, but it made an impression.
I have yet to see a 21CT55 in operation, but we do have that CT-100 in the museum in Windsor, CT. Fired it up last Sat night for our holiday party using a "Cinderella" DVD. The CTC-2 and 2B are incredible chassis!
Kevin

Wait a minute... What's with that horizontal cabinet with upright chassis ???????

I am assuming that it was some sort of custom built-in, or something? Is there any RCA model number on the cabinet (other than 21CT55), or is that a custom cabinet, or a Clubman series?

When I first glanced at your avatar photo of the set, I thought it was a CTC-4. Then I saw that it's a 2B.

Charles

I recall that ad. I was in Jr. High and thought that was the neatest thing I had ever seen. I could not remember exactly what model it was but I remember the colorful macaw. If I recall properly, there was an older lady (the owner) standing next to the TV. I think it was either in Time or U. S. News or something like that. It was in a class where they had us read from magazines or periodicals for part of the class, must have been english or literature or something like that. I thought that I would like to have a set like that sometime and many years later, I do!

Gilbert

It's a 21CT55 with a CTC2B chassis for sure. I cut up the cabinet so I could mount the chassis vertical. I used the removable top as the base and cut the front panel's lower control portion off and mounted it to the front panel side. I explained all this in my thread's introduction, please read it. Attached is my original 1960's concept drawing and some recent detail pics.....Tom

Thanx for posting the detailed photos...since this set is more rare than a CT-100 I am glad to see it operational in any configuration..Great picture on the set btw

...

At least you kept it! Forty years ago, who knew how rare these would be.

21CT55 Progress with Background
 

Thanks for your response to my 21CT55 postings. Seems the screen display keeps getting more impressive as I learn thru trial and error how to get it setup properly. It operates as a video monitor with the imbedded IC video op-amp I installed that presently allows two matched switched inputs to the CTC2B's 1st video amp grid. This 3vpp level matches the original RCA designed diode video detector output. Those engineers did everything right on these first CTVs in 1953. I went to work for RCA in west Los Angeles in 1953 straight out of high school as a lab tech. Made engineer in 1956. I did defense stuff, no interest in color TV until my Dad won a new '56 CTC4 in a raffle. I stayed up the first night till 3am trying to "improve the convergence". Not a good start in color TV but I was hooked on the technology.

When I bought my 21CT55 for $50 in '64, I brought it into the house after I got it working and ran it along side my Dad's old CTC4 he left me. Both had 21FBP22s so it was a good comparison of narrow bw color R-Y B-Y vs. full bw color I Q. The extension of full color into fine detail on the CTC2B was startling! Color persisted in fireworks until extinction which I never saw before. The CTC4 fireworks turned into white long before extinction. The CTC2B carried full color way into the shadows, the CTC4 went gray to black. I kept the CTC4 in the house for the kids but brought the CTC2B back to the garage workshop for further study. Ease of working on the chassis and CRT "forced" me to destroy the cabinet and configure the remains into the vertical chassis configuration I am blessed with today. That’s alright with me. I respect the original CTV restores but that’s not my thing.

Since ota NTSC is headed for oblivion in Feb '09, I see little incentive to go thru the futile exercise of getting the chassis's tuner, video and sound IF sections operational. I intend to open the heater string to all involved tubes and just let them hibernate. Probably lose about 100w off the present > .5kw it draws from the "mains". I've got plenty of quality NTSC composite video sources to keep the "old guy" demonstrational indefinitely. In addition to the C-Band Big Dish analog and 4DTV digital I've got a Koss DVD player (don't laugh) and a Magnavox Laser Disk player with about 20 disks including most of the Star Wars transfers. And of course, I expect to get my ASTC tuner coupons any day now (sic) for ota digital reception. I'm sure I'll be disappointed with the PQ of network SDTV, but then its free.

Big problem now is the poor quality of off-screen digital camera images. I get really awesome displays on the 21FBP22A with vibrant, accurate colors. Having the CTC2B's super wide dynamic range due to full bandwidth I Q demodulators feeding low level I-Q-Y matrixing to the CRT grids only. So I grab my Canon S40 digital and try to capture what I see. Results are disappointing to say the least. I tried everything possible with this full feature camera to no avail so far. If I manage a good shot, its got moiré that I can't get out. Surely there must be a technique described that will allow me to convey the picture quality of this 53yr old beast in digital camera form for emails and on the web? Anyone out there have good results or is my disappointing experience typical? I need to show the CTC2B's picture to some knowledge person on site in real time to get their opinion and critique.

I live in the country, 25mi north of Santa Barbara CA. This is wine and horse country, not techi antique Hi Fi, color TV and classic car country, so I don't communicate with anyone who shares my interests. If any of you ever get out my way, let me know, I'd surely like to show you what I got here. Right now is the best time, all the hills are lush green and the oak trees are fresh with new leaves .....Tom

I have long been impressed by the engineers who developed these sets; I think they would be impressed by the experiments still taking place with them. I wouldn't want everyone to do this with their 21CT55, but I'm glad you can.

I think you must be some sort of a mad genius..And that's meant as a compliment...But I think most of us in the Olde TV hobby are about a half-bubble or so off center anyway, at least...(grin)

A few comments:
Color saturation on fireworks details - yep, that's what wideband chroma will do for you - you get the same effect only better when you run a digitally mastered DVD through component inputs into a modern set.

Full color into the shadows - actually, in a dark room, any set *should* do that - but the CTC-4 and some other sets after yours apparently had very non-linear chroma amps, since the color control operated by changing the bias of the amplifier tube. We noticed this at ETF when trying to adjust the color level on "The Wizard of Oz."


Screen shots - On the moire' problem, it of course comes from the phosphor dots on the TV screen vs. some other regular structure - maybe the pixel structure of the camera, but maybe in the computer program that is scaling the image for viewing on the computer monitor. Try zooming your viewing program to 1:1 view and see if you have a clean image without moire'. If so, then try looking for some other viewing software. Sometimes the viewing software does a cleaner job of reducing resolution for file storage than for display. Try reducing the resolution and viewing the reduced file. If nothing works, you may need a different camera with more Megapixels. Note also, if you are really clearly resolving the phosphor dots, your image will either look somewhat dark, or the dots will be overexposed since they are only a part of the image area. The latter can ruin the contrast and saturation of the image. [Note: There used to be a similar problem taking film pictures of black and white sets that had clearly resolved scanning lines.] So, examine what you are getting at 1:1, and try reducing the exposure somewhat when you take your pix if necessary. Slightly dark will look better than compressed gray scale and chroma.

One other thing - the picture quality with a converter box (especially for prime time stuff broadcast in HD) should be excellent - the converter boxes usually have fairly wideband chroma, feeding the wideband digital R-Y and B-Y into a chroma modulator.

Digital Camera Screen Capture
 

I'm using a Canon S-40 with 4Mpixel and 3X optical zoom. My photo processing program is Ulead PhotoImpact SE which I've used for years. I intend to checkout the suggestions of " old_tv_nut " but have tried just about every combination already. Maybe there's a silver bullet in there somewhere? I even tried my wife's 7Mpixel Olympus with 18X zoom, no better.

Presently I'm attempting a precision dynamic conversion on the CTC2B which feature separate vertical and horizontal coils on the three magnetic assemblies. Uses 9 pots and 3 trimcaps which should reduce the interaction of horz and vert during optimization. So far I've come close but not good enough. Its really driving me crazy going round n round, getting nowhere.

Now that doesn't seem right - you should be able to get a reasonable result with one of these two cameras - hope your experimenting bears fruit.

...

...And now, we're gonna flush NTSC down the terlet. Nice. Way to go, FCC..

21CT55 Convergance and Screen Capture
 

I've finally got the dynamic convergence acceptable, not perfect. Best advice..... "Know When to Quit" or you'll drive yourself nuts!

The CTC2B's original 21AX22 had the first magnetic convergence and was straight foreword but highly cross-coupled. No control was completely independent.The very next RCA, the CTC4 ,was simplified and designed for quick setup. All remaining RCA's continued refining the dynamic convergence and presumably improved its performance??

Once I had better convergence I noticed a major improvement in the fine detail inthe screen pictures, as expected. I then went back to making digital camera screen-captures as close to the real thing as possible. The CTC2B using the 21FBP22A was capable of greater brightness dynamic range then the Canon S-40 4mpix! Even going fully manual shutter speed and aperture settings with ISO 400, I couldn't capture the dark areas on the screen without driving the brighter areas into saturation.

The Canon's native resolution is 2272 X 1704. My CRT computer monitor max is 1280 X 1024 but I use 1024 X 768 for all my photo editing and display. This mismatch, in addition to the TV's CRT pitch makes for hideous moiré on lmost all captures. I started to mess with my Ulead PhotoImpact editor to reduce the 2272 X 1704 Canon shots to exact multiples of the monitor's 1024 X 768 resolution. At 1:1, suggested by "old tv nut", the moiré was greatly reduced but replaced with a uniform artifact that gave a grainy affect to large areas of saturated color. I then went to 2:1 or 2048 X 1536 resolution which was much closer to the Canon's native. The residual moiré was no worse then the 1:1 and the artifact remained, but was much finer and not nearly as noticeable. Since the edited picture had twice the resolution of the monitor, the displayed fine picture detail was obviously better than the 1024 X 768. Needless to say, work will remain in progress in this picture quality area.

I see line structure in all the pix except the convergence pattern. Since I don't see any shutter effects, I presume your shutter is slower than 1/30 second and captures both interlaced fields. Then the visible line structure could come from some degree of line pairing.

Something to try: turn the vertical hold very slightly and see if the line structure changes.

Regarding the moire' problems - are you defining a picture reduced to the monitor resolution as 1:1? That's not what I meant. I meant the same size as the camera original (2272x1704). Set the photoimpact zoom at 1:1 to get this. The picture will exceed the size of your monitor screen, but don't worry about it. You should get the least moire' problems with this setting. Then, if you do see moire' with smaller zoom settings, you can ignore it since you know thje capture is good and it's just a display problem. Once that is settled, you can work on reducing the size for posting. Whatever you do, view the reduced picture at 1:1 zoom setting also for minimum moire'.

One other thing to try, in case there is some problem with the scaling between the monitor native resolution and the 1024x768 input you are using, is to temporarily set your video card to 1280x1024. You may not like the small icons and text you get, but you will elminate any possible scaling problem there. In general, it's best to not do any resolution changes anywhere along the chain when trying to determine if the original capture is clean.

Your comment about dynamic range is interesting. I see you are using the video essentials DVD to feed the TV. Your computer monitor must also be set to the correct black level, or you will have dynamic range viewing problems. Check out http://www.daproducts.com/calibrate/ for example. It is also possible to use the video essentials DVD to calibrate video playback on your computer, but caution - this calibration will occur within the
dvd player program and will not adjust still image viewing with other programs.

21C55 #B8802897 installed
 

The 21CT55 with a 21FB22A rare-earth CRT is operational and installed in my tiny lab where it will stay as long as I stay. IMHO, it has demonstrated it is capable of displaying a picture that is comparable to a Sony PVM1334 broadcast monitor at normal viewing distance of 3ft to 8ft. The comparisons of Sony vs RCA is presented here:

http://www.picturetrail.com/sfx/album/view/19914223

Like all my projects, work will always be in progress. Right now I am attempting to replace all the generic ferrite cored low SRF video peaking and filtering coils I used to replace the original RCA custom air cored, high SRF, universal wound coils that open circuited. Hopefully this re-coiling will reduce the slight ringing on video transitions and the chroma bleeding into the Y luminance video due to improper demodulator filtering. Click thumbnail to enlarge, than click lower right corner to super enlarge....Tom

Wow...

That's all I can really say.

One of the rarest TV's in the world, akin to the CT-100, except with a larger screen.

Wow...

I'm in love...

...

Thats awesome! Just think, these are photo's we are looking at. I can only imagine how much better the picture looks in person. Great job!
-Tony

Those screenshots are absolutely STUNNING!

Questions on the 21CT55
 

After a few months activity on a couple of my 70s rectangle ss tvs I got back to my "custom installed" 21CT55. It had been ignored for about four months and I was curious if would come up with the same demonstrated picture quality it had before. It did after a 15min warm up and all was well.

I'm now running the AC power input off a computer power stabilizer and a big Powerstat so I can maintain the same voltage out of the silicon rectifiers that replaced the original selenium rectifiers. I adjust the Powerstat for a nominal B++ of 400v specified by RCA. This occurs with an AC input of 110vrms. Since I don't have access to an ultor HV meter probe I run the HV adjust fully cw max. At this setting I read a boost of 1010v! Nothing seems stressed, everything in the HV cage looks normal and the HOA 6BC6 has no plate glow or blue gas. I get very good focus and run the horz size at minimum. Gray-scale is near perfect, with very good PQ. RCA rates the
21FBP22 ultor at 27.5kv max. I may be exceeding this, but ignorance is bliss.

The only real problem I see with this operation is a very slight uniform screen glow in a totally black room with no video applied and the brightness, contrast and color fully ccw. No glow is seen at turn on and holds black for about 5min then ever so slowly starts becoming noticeable. This increases with time and becomes quite noticiable when compared with the Sony monitor after about 30min. I reduced the HV adj to min with no difference in glow.

I used my newly acquired Sencore CR70 (ebay $149) to check for element leakage that prevents complete gun cutoff, all read good. Cutoff on the CR70 all made the Good Box and all emissions were at half good meter reading. the lifetime test on each gun went into the bad zone when the heaters were reduced 25%. Seems like a good candidate for a mild Auto Restore. Only problem is the CT70 increases the heaters from 6.3vrms to 12.5vrms for 40 seconds during each gun test! That bright yellow heater glow scares me on such an old crt, so I'm reluctant to rejuvenate.

I would appreciate any comment on this cutoff glow phenomena and the advisability of submitting this really neat crt to unnecessary abusive. Tom

Your set works and looks gorgeous! I would just use the 'ol 8 volts method if you are unsure of a restore. It sounds like that is all you need. I would let it sit at 8 for about 2 hours and then test after it has cooled down. I too have the CR-70, I don't often use the restore, but did try to damage a dead CRT one day just to see what I shouldn't do, well, it just wouldn't hurt it. It shut down before any damage was done. This almost dead CRT is still functional. The CR-70 is probably one of the safest on your tube. But, like you said, why take a chance on such an old and rare CRT. The most I have used the auto-restore is on a weak tube that didn't come back on 8 volts. I interrupted the restore after the first 7 or so second burst that it gives. I didn't let it go all three times as per the instructions. It also says that interrupting the restore is ok if you want. Tube came back nicely. I try to be as gentle as possible.

---

I gotta agree with andy, the picture on this set is about as flawless as possible. I gave advise on the CR-70 in general, I apologize for not being more specific about this particular tube. After rereading your post Tom, I see a part I didn't pay close enough attention to. If it drops to bad on the life test, it's not the end of the world or a bad tube. At first, I thought you had a tube with a reading of 25%, not a filament drop of 25%, duh on my part. The life test is somewhat accurate but I wouldn't put too much faith in it. Any tube that tests good and equal on all three guns should be left be.

excellent job of restoration! Congratulations.

I used to have a repair shop, and did home TV service for Sears for several years in the late 1980's and early '90's.

I have NEVER seen a color picture that looked as nice as the images you supplied us here on AK. Your set is incredible!

I could say that my CTC-12 looked similar, but I'd be lying a blue streak, and lightning would strike at any time.

Keep it up!

Bruce

Where Are They Now?
 

The RCA 21CT55 has been permanently installed in my lab, operating as a composite monitor for over a year now. It is powered-up occasionally and has retained its picture quality as posted previously:

http://s677.photobucket.com/albums/v...0TV/?start=all

I am really impressed with the awesome cabinet and chassis restoration performed by AK member Bob Galanter. His serial # B880 1131 is among the earlier production while my #880 2897 is very near the end of production. His is the 17th known survivor, mine is the 16th. What's the latest info on the other 15? Who has them? How many are operational? How many are being restored? Which ones are owned by AK members?

Seems these rare second RCA production CTVs are seldom discussed on AK except when a member starts a restoration or ends one. I welcome any replies from all 21CT55 owners or interested others, regarding their present activity and possible progress towards getting these ultimate roundies operational. I'm aware of at least six AK members that have indicated they have 21CT55s. I would greatly appreciate their replys to this request for current status information. Thanks......Tom

Tom:

My 55 is in working order but still has some convergence issues. I have not had time recently to work on it but hope to get back to it shortly. I don't have the serial numbers here at work but can supply those to you later if you wish.

Steve

21FBP22 Ultor HV
 

When I first got my 21CT55 operational about a year ago, I replaced the two huge selenium rectifiers with a couple of 800PIV, 20A silicon diodes. This raised the 400v B++ buss from a sub normal 390v to supper normal 420v when operating from my local 115vrms mains. Everything worked OK, but I set my Powerstat down to 110vrms which lowered the B++ to 400v. It remained at 400v for all my convergence setup, picture quality evaluations and screen shots. the power transformer's surface was 124F at room temp of 77F.

I never had access to a HV probe for my VTVM so I always ran the Ultor control fully cw max. No problem with focus and the 6BD4 HV reg was running dark as expected. Last week I got two hi voltage spiral film resistors that added up to 940Meg. I was able to calibrate my VTVM to 4v on the 10v range when touching the probe to the 400v B++, indicating I now had a 100 to 1 voltage divider. I read the "boost voltage" at 980v without the probe and 9.7v with probe which translates to 970v or 1% low. I then touched the probe on the Ultor capacitor and got a reading of 34KV ! RCA specs the 21FBP22 at 27.5KV max. I checked the focus at 5800v. Sams and RCA sets the Ultor at 25KV, so I reduced mine to 25KV and had to refocus to 5200v but the convergence, both static and dynamic was way bad.

There is no X-Ray shielding or safety glass on this TV since 1964, when I destroyed the cabinet in going to vertical chassis. I wonder how much X-Ray I absorbed, if any? I could run the CRT between 25KV and 28KV but I must do a complete re convergence which is a real pain. Maybe the 34KV was causing the slight screen cutoff glow by activating the aluminized phosphor and reducing the ultimate black level in dark scenes ? Any suggestions?

Tom, as I think you are aware, I have a 21CT55 which has been restored. Last time I had it fired up, it needed some remedial work, and one of these days I will get back to it.

---

21FBP22A Ultor HV
 

Andy.........I used the wrong wording "the 6BD4 HV reg was running dark as expected" in describing the glow reflected from the tube's plate when running the CRT at max HV of 34KV. Obviously, it was pulling far less current and glowed less bright than it did at minimum HV setting of less than 25KV. This is typical of all shunt regulators. At all settings, it glowed brighter when the screen went black as it should.

My main concern is how much X-Ray did I absorb during the year of running 34KV with no CRT safety glass or cabinet screen glass? Is there any documented evidence that 21in CRTs running above 30KV has resulted in injury to those persons working in close proximity for extended periods of time? If so, what was the symptoms, and prognosis?

Turn off all the lights in the room, if you glow in the dark, you're cooked.