I wondered that too. Based upon a reading of Wentworth and Fink plus the preponderance of 1952 tubes, I don't see now how it could be a dot sequential set using three-state communitator circuitry. However, I couldn't resolve one way or the other their flirtation with phase alternation in that time period. So, it probably uses equaband quadrature circuitry for chroma, bypassed luma (of course), in 1952 perhaps a nonstandard color subcarrier frequency, and maybe PAL-like circuits.

My two cents.

Pete

If it were mine, I'd want to restore it to working condition using reliable modern capacitors. Save the removed parts.
But, I would take multiple high resolution detailed digital photos of the entire chassis as documentation history of the set.

You are now part of this TV's history.

Carl

Do you have any information about where this TV has been over the last 60 years?

Carl

But it appears that the set has been used over the years http://www.videokarma.org/showpost.p...8&postcount=24 So it was either built as 3.579 quadrature, or has been modified to be NTSC-compatible.

I really doubt if the set was used over the years. The only evidence of that is the tube date codes, which is tenuous. I don't see any other components that look newer than 1952 ish.

Congratulations on having what appears to be a working tube.

Congratulations on buying this ultra rare prototype colour TV set, I am glad to see it has gone to a good home and to someone of these forums!!! :D Best of luck getting this set crankin again and I look forward to seeing your progress along the way!

I may have missed it, but what's the story of how you got this set in the first place? Inquiring minds want to know :)

It was at auction, on Ebay. I would like to know how Harry Poster got a hold of it though, he never did tell anyone unless I missed it.

Here's my take:

It is a museum worthy piece, therefore it belongs in a museum. For that reason, I am considering placing it at the ETF once I am done with it.

I have always been of the mind that if the set actually works, no one is going to care what's 'under the hood', since 9 times out of 10 it would not have worked on original capacitors anyway. No one walks into the ETF and says about the Model 5: "you know that thing would be much better non-functioning and with original caps". I don't think so. It's a much better thing to see it in operation, it blows away any thought of keeping it original once you see something on screen.

Lastly, I may not have to change anything in the first place. The chassis has what appear to be aerospace grade metal-film capacitors, so it may not need total replacement of the caps. They are not prone to leakage and breakdown like wax/PIOs are, so we'll see if they are any good. The lytics will be restuffed, but thankfully they are all mounted on wafers and secured to the chassis with screws. They will be easy to do.

I use the popular version of Occam's Razor: Don't allow an unproven variable to screw up a comfortable conclusion.:D

As Steve McVoy indicated, there are competing reasons for a post-1952 tube to be in this set. Also, as been stated earlier in this thread, there is not a scintilla of visible evidence that the CRT socket had 4-or-so kV on the convergence element (pin 13) for an extended period.

Still, there are no final conclusions. Perhaps this chassis will turn out to be from Hazeltine Corp.; they were located in the same general area as RCA Labs and where Harry Poster now has his business.

The quest goes on...

Pete

Harry told me he got the set from a picker, and and it probably came from the Camden area, but he didn't know anything else about it.

Hi Nick,
Congratulations! I agree with your statements one-hundred percent.
Also, once you have an operational platform, Pete might consider performing comparitive colorimetry measurements on your CRT.

Looks to me like there is one newer yellow electrolytic soldered under the chassis.
I'm a big fan of getting rid of all the leaky paper caps. But I have also had very good
luck with electrolyics in cans from the pre-wars up thru the mid 50's. I just reform them with a very low charge current and they are not leaky. It is not like they are in a place to cause a lot of damage when they short. My TRK-120 has all of it's original electrolytics and it works fine.. I thought Harry told me he got it from a picker from the Lancaster area.. I'll have to go back and check my emails.

I've been back tonight snooping again through your excellent and detailed photos of your chassis. I found it very interesting that the rear apron red, green and blue screen controls (presumably) have plastic color keyed shafts. That seems almost prophetic in such an early prototype.
For a chassis this seminal, I'd have expected three generic pots, identical in every way, both physically and electrically.

I also remember the Lancaster area being mentioned in an early post or e-mail on this.

-Steve D.

My mistake. Lancaster is what Harry said, but he wasn't certain.

Steve,

Either city would work. RCA had plants in both Lancaster, Pa. and Camden, N.J.

-Steve D.

Working under a blank check from Sarnoff, engineers developed the tri-color, shadow mask prototypes and finally the 15GP22 in Lancaster I believe. I once owned a wonderful RCA booklet about RCA's tri-color CRT development project. I lent it on request to the late Rudolphus (?) Swan, a retired engineer from Sylvania's tube division who, despite repeated requests, never would returned it.

Several requests have been received for me to label the back panel controls, so here it is!

Since there does not seem to be any main power transformer or power rectifiers present, is the 7 pin male plug on the lower left chassis back panel where a separate power chassis plugs in?

Perhaps the two pin male plug is a power on/off circuit to allow the TV chassis to remotely control the power chassis? And the is two pin socket above it a convenience power outlet to plug your VTVM in?

Most likely, since the early prototypes had a lower chassis which supplied power to the whole shebang.

I looked at the 2 pin thing, and it's wired into the heaters of all the tubes with some really thick wire. I suppose it's possible that the heater circuit is the 2-pin, and the rest is B+ type stuff on the 7-pin one.

There are some pictures, by Harry Poster, of an RCA prototype set that looks like this set showing the CRT mounted. It even shows the black tape. Link: http://www.earlytelevision.org/rca_color_prototype.html

So you don't actually have the power supply for this set? Did it go missing? And won't that slow down getting it going?

It should be possible to make a replacement power chassis. If a schematic could be found it would help.

However that puts to rest the question of whether to recap it or leave in non-working survivor condition. The whole bottom chassis is going to be all-new.

No, and there's no reason to expect it will ever turn up. No one knows where it is, so it is assumed missing. Something like that would be very common looking anyway, so it probably was either tossed or repurposed for something else. It won't really slow anything down, other than the time it takes to build a new one. It's easy to trace the wiring, and figure out what voltages need to go where. I figure I'll start with an old console amp chassis, install a suitably large power transformer, and use the sockets for the rectifiers. Maggie chassis are plentiful, so that's what I'll probably use. That, or I'll strip the old organ chassis in the next room.

Found the heater string connections: the 'main' part of the chassis, that is, everything that is not tuner/IF related, gets it's 6.3 volts from the small male 2-prong plug on the back. The tuner/IF strip is powered from pins 1 and 6 of the 7-pin round plug, with pin 1 connected to chassis ground.

That reminds me: I'm gonna need like 30 tube shields! lol

I've got a box of maybe ten or fifteen assorted 7 and 9 pin tube shields your welcome to.
I've also got an old power supply from a corespondence course that you can have if it will help.
http://i1095.photobucket.com/albums/...y/DSCN0829.jpg
Tom C.

Hey my dad took that same course! I remember playing with that PS when I was a kid!
Its no good for that tv, its going to need to be more current and they'll have to figure out what different voltages are needed too. That PS is for single tube circuits.

Most likely they are going to have to come close to matching the specs on the PS for the ct-100's that some of those guys already have access to, or possibly a model 5, something like that. This tv should have a lot of very similar circuits to what later became the production version of this set.

Anyway it should be fun for these guys, and for us to read about. Thanks guys!

That reminds me of visiting a well known radio dealer years ago. His place was packed with amazing items. I finally broke down and asked, "Where do you find all this stuff?" He shrugged and replied, "People bring things to me."

Phil Nelson

Isn't that interesting? Is the CRT serial number a match to your prototype, Nick?

Harry offered the set to the museum before he put it on Ebay. I tried to get him to donate it and take a tax deduction, but he declined.

They are one and the same.

Despite my misgivings about tampering with this set I very much want to see it operating again :yes::yes:
No point in letting it sit around until the CRT finally goes to air and is useless.

Thinking about the historical importance of this thing is inspiring, Every one of the billions of CRT based Color sets in the world can trace it's DNA back to this set (along with the few other RCA Prototypes).

One more idea, if the tube is gunned the same as a 15GP22 perhaps it would be a good idea to hook it up to a CT-100 chassis and see if it'll actually light up?
If nothing else it would be an interesting glimpse of the Phosphors used.

It's an idea I've tossed around a few times, trust me. I don't have a CTC-2 chassis though, only CTC-2B.

Okay, let's work this out. I just got back from Detroit area where I picked up Bob's 1948 Moto; are you two still getting together tomorrow? (just tried calling Bob. no answer). I can probably stuff my CTC2 and the Moto in the Yaris. I for one am itching to see that tube light up w/Dorothy. What say you?

Pete