Another RCA CT-100 discovery B8001599
 

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.

You lucky dog! Fingers crossed on the CRT.

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

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.

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

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!

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.

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

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.

Hopeful results.

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

Great - onward!

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

Excellent news.

Great results it appears in the tester. I have a question about the background of your photo on the shelf. Are those 78 records? I can make out Rachmaninoff on the back of the spine on one of them.

Yes I am an inveterate 78 collector. The Rachmaninoff is the 1929 recording with Stokowski and the Philadelphia Orchestra and Sergei Rachmaninoff at the piano.

"Rachmaninoff Plays Piano Concerto No 2 (1929)" on YouTube
https://youtu.be/X_7O09ucelM

With the 15GP22 showing life and promise, I am now proceeding to the chassis.

It is filthy although relatively complete. The selenium rectifier shield is missing along with the back cover and four knobs. The cabinet is in surprisingly good shape apart from the speaker rust. (I plan to dismantle the original speaker and derust via electrolysis).

But the main concern is first to clean up the chassis and remove a fair bit of corrosion from the mouse home. It is pretty extensive in the corner next to the first Video IF but not irreparible.

I noticed that the front part of the chassis contains almost all the corrosion. I see that the corroded front section is attached to the rest of the chassis with self tapping screws. So I plan to begin carefully documenting and photographing the wiring crossing the chassis bridge and separate the chassis away to attend to the localized rust.

I have photographed the front chassis attached to the main chassis below.

If you need the large roundie socket I have an extra one for the B&K 467.

Thanks for the tip. I have a box of BK467 sockets I will look thru.

I found an old label attached to the CRT leads.

The label reads Judd Electronic and the address is 16931 Schoolcraft.

I Googled Judd Electronic and nothing. I did find on Google Maps a Schoolcraft Road from just across the Canada US border where the set was found. Looks as if it was an early Detroit color tv.

You will see the label below, a Google map shwing a red dot to the right where I picked up the set and the Google Maps flag where 16931 Schoolcraft Road is. And finally the empty building where once stood Judd Electronic.

I believe (and don't quote me on this as roads in Michigan and Indiana use very different naming conventions) that the name "Schoolcraft Road" refers to the fact that if you follow the road long enough it will eventually take you to a Village called Schoolcraft, Michigan (which is between Three Rivers and Kalamazoo, Michigan on US 131 N.)

But like I said I don't know if that's why that road was named that or not, because like I said, in Indiana a road that was named after a nearby town was named that because that road would eventually take you to that town if you followed it long enough, which like I said I don't know if Michigan followed that rule or not when naming their roads.

Just my two wheat pennies worth.

Interesting story about Schoolcraft Road. I will study the map!

Yesterday dismantled the rusty loudspeaker and put the frame into an electrolysis bath. Painted the frame silver this morning and will wait a couple of weeks before reassembling. Spent last night and this evening documenting and photographing the front chassis section which suffered from the mice next. I have removed the front chassis and have begun dismantling it. Fortunateltly pretty weel all the rust is around the first video IF stage and the audio amplifier. I shall concentrate cleaning this section up before proceeding to the rest of the chassis.

I have a small 78 RPM Collection myself, and one of the 78 RPM recordings I have is Rachmaninoff Playing his Piano Concerto No. 3 in D Minor with the Philadelphia Orchestra w/ Eugene Ormandy Directing (I'm assuming the recording was from the same time period as your Rachmaninoff recording which would fo been between 1929 and 1931 and it is a recording meant to be used on a record player with an electrical pickup as opposed to an old mechanical pickup device like the old crank-up victrolas had.)

The records and the case/jacket are in mint condition.

The Rachmaninoff 3rd Concerto was recorded by the composer in 1939-40. By that time apart from portable record players, the living room record player was electronic. However in 1929, phonographs were still predominantly acoustic hence the recording equalization characteristics were governed by them. The characteristic in 1929 was "constant velocity" whereby the velocity of the stylus across the audio bandwidth governed loudness.

To improve disc signal to noise and also to increase playing time, a constant amplitude charactistic was introduced in the 1930's. Hence 1940 recordings played on an acoustic phonograph would have diminished bass frequencies and boosted highs, making the records sound shrill.

Unfortunately record equalization remains a little understood technological evolution which leads us to having to endure an obnoxious cacophony of Elvis Pressley and Eddie Fisher 78's on vintage 1910's era Victrolas at antique markets.

Been studying, photographing, drawing and documenting the construction of the mouse affected chassis. I have decided to dismantle the affected areas, clean the chassis bright and apply a coat of zinc silver paint over the cleaned portion. I shall only begin dismantling after the total documentation leaves no ambiguity how to accurately reconstruct.

Meanwhile, the speaker de-rusting was complete and a coat of silver paint applied. The speaker has been reassembled and tested.

Your B&K socket is likely the 14-pin one, that is what my 467 included and what fit all of the 21-inch round color CRTs. The 15GP22 needs a similar size but 20-pin socket. I would very much like to have one of those if I could find one; I either made an adapter with a bunch of alligator clip leads, or I just used loose clip leads, when I tested my 15GP22.

Penthode, this will be a great project!

You’re in luck, this guy says he has like 17 of them...
I’d buy one, but I already have an adapter of my own.

https://www.ebay.com/itm/174268516102

Thanks! Although the universal leads work well on the Sencore tester. But it would be nice to use the B&K.

I would have liked to find a replacement 20 pin base for the 15GP22 as the one I have has been epoxied to fill a chunk that was missing. Chance of finding a base will be much less than the socket!

Have been documenting and photographing extensively the IF stages and audio demodulator/ amplifier prior to dismanting the heavily rusted area.

Carefully drilled out the tag strips and tube socket and unsoldered and snipped away around the stages to lift portions complete away from the chassis. I will endeavor to keep as much as possible. But plan to replace at least 3 sockets heavily corroded and the last VIF located in the shielded box. The last IF socket appears very brittle from I suspect the enclosed heat. (I cannot get over there is six IF stages in all. It will be fun to re-align!)

You will see the chassis below cleared of components. I plan to go over the rusted area with Phosphoric Acid this prior to painting with zinc paint. I would like to reconstruct the chassis as close as possible to its original state apart from changing the paper capacitors to sprague orange drops.

Fortunately the rest of the chassis looks really good. Haven't ventured into the HV Box yet however...

RF-IF Alignment is actually not difficult. I had no trouble at all with my set.

Just be sure that if you replace capacitors and
resistors in the IF you keep part size and lead length as close as possible to original.
If you change resistors, it usually means using much higher wattage if you use film resistors (and be sure they are not the spiral cut kind). I replaced resistors in the IF with carbon composition ones; thankfully there were only a couple.

Thanks. Sweep alignment looks pretty straightforward. I inherited from an old TV station its extensive inventory of NOS carbon composition resistors and shall use them to match the original construction. The only improvement I shall include is replacing the capacitors with newer metal film units.

Some of the corrosion was pretty bad and I plan to clean the affected area fully. Sadly, as was the habit of many repair folk, the bottom panel was not refitted allowing the mice to easily crawl into the chassis corner. I was surprised the degree of corrosion the trickle down of the mice urine caused to the speaker below. Fortunately all is fixable: it just requires time and patience.

I considered a chemical de-ruster. However I have had good results using electrolysis. It is cheaper too.

With the chassis half stripped off, the chassis was immersed up to that point. The chassis is the cathode (-) and the carbon slab the anode (+). 5 Amperes for two hours.

Removed the chassis and lightly went over the derusted section with a rotary dremel brush and 0000 steel wool. Most of the cadmium plating remained: all on the top and about 80% on the bottom. I will apply some zinc paint over the affected areas to prevent it from rusting. The poor CT-100 looks like it had a tough early life and I intend keeping it in a climate controlled environment.

I have a lot of cleaning ahead. I want to first clean off the top of the rest of the chassis then proceed with reassembly. I will re-rivet the tube sockets and tag strips as original. Note the tubular rivets are available on eBay for abut $9 for 200 and free shipping from China! The IF tube sockets with shield clamp require 3/32"D x 7/32"L , the non-shielded tubes 3/32"D x 5/32"L and the tag strips 1/8"D x 1/8"L.

Cleaning, cleaning, cleaning. The mice really did a number on this old set.

Making progress. Stripped off the old soldered connections from the tag strips. Repaired a couple of broken lugs. cleaned and repaired the wafer 7 pin tube sockets. The ceramic Cinch brand 7 in socket used for the 6AQ5 audio output tube was fractured and replaced it with a Cinch type bakelite type.

The 6th video IF amplifier phenolic wafer tube socket had became very brittle due to heat and snapped. I think it is because the tube is located in an unventilated little metal compartment. Replaced it with a Cinch bakelite type. Fortunately the tube pin layout and the mounting holes of the replacement matches perfectly the wafer socket.

Dismantled the rusted potentiometers where the mice nested. Used the electrolysis bath to remove the minor rust from shells affected. A badly rusted metal shell I replaced with one that matched from one I found in an old TV shop's hoard I picked up years ago. I was given a car load of old Cigar boxes filled with reclaimed vintage TV and Radio parts from a shop long closed. I am sure the previous owner of all these reclaimed parts must be smiling from heaven.

With the chassis derusted and components cleaned, reinstallation begins. Re-riveted in the tag strips and awaiting now the delivery of the 3/32" rivets to re-attach the wafer tube sockets.

Here are some before and current state photos of the now vacated mouse abode. Note that the red patches in the after photos are the copper plating that was originally between the base steel and top cadmium. The mouse corner has been fully derusted and any exposed steel coated in zinc paint.

Great! Keep the reports coming.

Looks great and mouse damage really irritates me. Glad that you have the tenacity to tackle this step by step instead of chucking it into the bin.

Mouse damage is the worst. The corrosion is intense. Fortunately it was localized. The metal chassis shield in the cacinet immediately underneath the mouse abode was badly rusted. It has since been de-rusted. Fortunately the mouse corrosion results in minor pits where it went through the copper-cadmium plating and the metal has not been too much compromised. Two of the potentiometer connector pins were pretty severely rusted but salvageable.

Last couple of days, while waiting for the delivery of the remaining tube socket rivets, wired up the replacement 6thg (last) IF tube socket.

Also took time to pull the tuner, dismantle, clean and relube the massive tuner drum. Used electrolysis to clean off the surface corresion and nicotine. The original cadmium plating underneath looks pretty decent.

Very good, meticulous work.

"Mo Bettah"! Looks great.

Looks really amazing so far. Can’t wait to see beautiful NTSC color on it again in the future.