Another RCA CT-100 discovery B8001599

[Penthode]

Hi All,

I responded to a Facebook Marketplace ad for an RCA CT-100 near Windsor Ontario for sale for just C$10 (US$7.80). I messaged the seller and told him the history and said it was the first color tv from 1954 and it was too cheap. He said okay. How about C$100? I texted back sure lol!

So I made a 3 hour drive to arrive at the gentleman's doorstep at 8am the next morning. It is unusually cold for this time of year and the temperature was -5 Celcius (29F). The set was in the open and had sat for a couple of days at least outside. Fortunately there had been no rain.

I honestly thought the ad may be a sham but I was game to drive and have a look. It was indeed a CT100 and is as depicted below. The gentleman told me he susequently received a flood of calls telling him. the set was worth $1500. But his residence was flooded with tons of old electronic stuff and I asked him directly if the C$100 was okay and he said sure as long as I haul it away.

The set came from an estate near Windsor Ontario. I could see sometime ago some work had been done with quite a number of orange drop Sprague capacitor replacements evident. The is mouse nest damage in a corner of the chassis because the bottom chassis plate was missing. The speaker frame also suffered considerable rusting from what appeared due to mouse urine. But the set otherwise was in fairly reasonable complete state apart from the missing chassis bottom screen, the knobs and the back cover.

On site I carefully dismantled the cabinet and removed the chassis and 15GP22. On it's ride back hope, the CRT was carefully cushioned on the rear seat of my car. A cursory glance shows no white round the getters and it still looks like there is a good vacuum. I plan to bring out my CRT tester and carefully scrutinize the status of the CRT.

For you information, the chassis number is B8001599, cabinet 170. I am in the process of revising my plans this summer to include time to begin resusitating this set. This will be particularly so if the CRT shows any sign of life. I shall use this thread to maintain a running discussion.

[old_tv_nut]

You lucky dog! Fingers crossed on the CRT.

[zenithfan1]

Nice! Haven't seen one of thee pop up in a while!

[Jeffhs]

I also hope the CRT in your new (to you) CT-100 is good, and the TV itself works well, considering its age. However, I would not expect the set to work "like new", considering it was built in 1954. You will almost certainly have to replace tubes and perhaps rotted wiring under the chassis, not to mention doing a full reconvergence of the color CRT. I would not even think of plugging the set into an AC outlet and turning it on before the set has been thoroughly tested. As I am about to explain, this television is extremely rare and probably has the proverbial "million and one" things wrong with it, such as bad tubes, defective capacitors (especially power supply filter caps), off-tolerance resistors, and other things too numerous to mention.

The CT-100 is a very rare TV, as it was one of the first (if not in fact the first) mass-produced color sets, very likely with a very steep price tag as well. My guess is very few people owned one of these unless they were rich, had won the lottery, or had inherited a fortune (before taxes, of course) from a deceased relative.

There weren't that many TV stations in the United States broadcasting color programming when this TV was new, so the chances are most of the programming seen on these sets was broadcast in b&w, with the occasional (I stress the word occasional) color program in prime time.

Most network news broadcasts of the 1950s were shown in b&w, with the exception of NBC's nightly news which was always broadcast in, as that network always put it, living color. NBC was America's "full color" television network, and of course they made a big point of that every chance they had. "The following program is brought to you in living color on NBC" was always announced before every color show on the network, with a full-color peacock spreading its feathers during the announcement.

BTW, I would guess anyone who saw the NBC peacock in b&w (given the steep price of color television sets in the '50s, most homes with TV had only one b&w TV in the living room) wished they had a color TV. However, most viewers did see the bird in black and white until color sets became affordable. No doubt most American living rooms with color TV were showplaces during the 1950s through the eighties, as most folks, as I said, could not afford the first color televisions; those who did have a color set probably guarded the set as if it were made of gold, and did not allow children anywhere near it unless an adult was present.

[etype2]

Wish you the very best in the restoration of this set. Hope the CRT is okay.

[dtvmcdonald]

Other than bad caps and perhaps the selenium rectifiers and some green rectangular power resistors, and ... the worst ... the white (not brown) peaking coils in the video, these things are uisually in pretty good shape.
Mine really had only one nasty problem area, the horizontal sync was intermittent. It was fixed only by replacing each and every resistor in the horizontal sync and oscillator.

On the other hand, the alignment was horrible. I very carefully counted and there are 81 adjustments (counting only one channel in the tuner) That includes the yoke tilts.

Good luck!

[ARC Tech-109]

I've been around the back of color TV's for the better part of 40 years and had never seen the CTC-100, was this a unique CRT? I'm not seeing the customary convergence or triad gun layout so I'm somewhat puzzled on this one.

[Electronic M]

Originally Posted by ARC Tech-109

I've been around the back of color TV's for the better part of 40 years and had never seen the CTC-100, was this a unique CRT? I'm not seeing the customary convergence or triad gun layout so I'm somewhat puzzled on this one.

The 15GP22, Its advanced phosphor deposition CBS equivalent the 15HP22, and the much rarer 19" version (19VP22?)...All used electrostatic dynamic convergence (something like 6KV DC with 3KV AC riding on it) instead of the electromagnetic dynamic convergence the 21AXP22 and all later color tubes used until inline gun tubes eliminated dynamic convergence.

There's 3 adjustment screw magnets on purity coil* that are used for static convergence the same as later tubes.

*Instead of degaussing these tubes use a field neutralizing coil on the face and a purity coil on the neck....As a working CT-100 owner it took a little bit wrapping my head around how the adjustments work (and they're still not perfect thanks to a bent shadow mask), but it wasn't hard making them pretty good. There's less to a 15G convergence procedure than most later sets...only problem is HV tends to bloom and fluctuate (especially given I don't have enough high VA voltage regulating line isolation transformers to run my CT-100 off of)and the user pots for focus and occasionally convergence DC have to be tweaked to keep things looking good.
If I had enough room to put my CT-100 and 21CT55 in the same room I could make them share the transformer that feeds the 21CT55.

[dtvmcdonald]

Originally Posted by Electronic M

The 15GP22, Its advanced phosphor deposition CBS equivalent the 15HP22, and the much rarer 19" version (19VP22?)...All used electrostatic dynamic convergence (something like 6KV DC with 3KV AC riding on it) instead of the electromagnetic dynamic convergence the 21AXP22 and all later color tubes used until inline gun tubes eliminated dynamic convergence.

There's 3 adjustment screw magnets on purity coil* that are used for static convergence the same as later tubes.

*Instead of degaussing these tubes use a field neutralizing coil on the face and a purity coil on the neck....As a working CT-100 owner it took a little bit wrapping my head around how the adjustments work (and they're still not perfect thanks to a bent shadow mask), but it wasn't hard making them pretty good. There's less to a 15G convergence procedure than most later sets...only problem is HV tends to bloom and fluctuate (especially given I don't have enough high VA voltage regulating line isolation transformers to run my CT-100 off of)and the user pots for focus and occasionally convergence DC have to be tweaked to keep things looking good.
If I had enough room to put my CT-100 and 21CT55 in the same room I could make them share the transformer that feeds the 21CT55.

Actually the convergence for the CT-100 is a real chore. The reason is that
the tilt and centering of the deflection yoke is super critical. Its more critical for convergence than for purity. The good news is that essentially perfect
convergence is possible. The only reason my set does not have perfect convergence over the whole screen is a bit of ringing in the horizantal sweep.
This makes one vertical line in the crosshatch pattern be off in the blue.
Across the rest of the screen all lines are within 1/2 linewidth of perfect,
and most really are perfect.

In preparation for work on color sets at the ETF next week I checked my own CT-100 last night. In addition to convergence, in a dark room the color rendition is truly perfect, using both my own patterns and "Digital Video Essentials". On the usual "blue bars" matching test, and the equivalents for red and green on my own test patterns, all three colors are perfect.
This was only achieved by tweeking one of the matrix resistors long ago ...
its not needed changing since.

As I have said before ... if the cameras were tweeked as well as the (Model 5) sets for the demo for the FCC, everybody must have been stupefied by the quality. The I-Q system really does the job. I consider the ideal viewing distance for the CT-100 to be three feet! I routinely watch football, golf, and baseball on mine.
the viewers of the

[Penthode]

This evening was the moment of truth: initial test of the 15GP22

I have a BK467 and a Sencore CR-70 CRT testers. I chose the CR-70 as it has the universal leads and the BK-467 hasn't the 20 pin CRT socket connector.

The 15GP22 appeared to light properly. It also looks as if the original 15GP22 socket was damaged and the previous keeper made an epoxy mold to fix it. Seems a satifactory fix and it is translucent which allows the filament glow to pass.

As I indicated earlier, I could not see any trace of white around the getter which offered hope the tube still had a vacuum. My initial setup to test did not allow me to set cutoff on the 15GP22. I decided to try testing a known good 10BP4 with the same negative result. I searched back on this forum to find any information and one post revealed adjusting the the cutoff, the G2 voltage should swing between 20 and 400 volts. I have not been able to find a schematic or any service data on the CR-70 and so took the CR-70 apart to find what was the matter. It appears one of the connectors was loose and reseating it got it working. I was able to test the 10BP4 now with success.

Back to the 15GP22, I set up the Sencore on first the RED gun, then Green and finally Blue. I was able to swing the cutoff adjustment for the needle in the box. Importantly the Cutoff adjustment swing was smooth from minimum to about mid scale deflection without any sudden jumps. I have read sudden jumps adjusting cutoff may imply ionization due to gas. Testing emission, the needle reached a respectible good on RED, GREEN and BLUE as depicted below. It looks like I may be lucky.

The pictures below depict:
1) RED Cutoff
2) RED Emission
3) GREEN Emission
4) BLUE Emission
5) Tube neck glow

So the chassis restore is next. I have read a lot on this forum about the 15GP22 and the use of Vacseal or its equivalent. This poor tube appears to have suffered in storage over the years and would appreciate opinions on the tube preservation.

[etype2]

Hopeful results.

[Tim Tress]

What great news! Looking forward to more on the restoration.

[old_tv_nut]

Great - onward!

[Tim]

Wonderful! This is starting out as one of the best CT-100 stories.

[Electronic M]

Excellent news.