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-   -   Prototype set is here (http://www.videokarma.org/showthread.php?t=251369)

miniman82 06-15-2011 01:46 PM

Prototype set is here
 
5 Attachment(s)
Here are the first pictures!

The small pics have been uploaded for immediate viewing, for the large file right click/save as on the URLs below. WARNING: picture files are large, 3+mb. Expect long load times.

http://miniman82.4t.com/images/proto...t/IMGP4529.JPG
http://miniman82.4t.com/images/proto...t/IMGP4530.JPG
http://miniman82.4t.com/images/proto...t/IMGP4531.JPG
http://miniman82.4t.com/images/proto...t/IMGP4532.JPG
http://miniman82.4t.com/images/proto...t/IMGP4533.JPG

miniman82 06-15-2011 01:48 PM

5 Attachment(s)
5 more.

http://miniman82.4t.com/images/proto...t/IMGP4534.JPG
http://miniman82.4t.com/images/proto...t/IMGP4535.JPG
http://miniman82.4t.com/images/proto...t/IMGP4536.JPG
http://miniman82.4t.com/images/proto...t/IMGP4537.JPG
http://miniman82.4t.com/images/proto...t/IMGP4538.JPG

miniman82 06-15-2011 01:49 PM

5 Attachment(s)
5 more.


http://miniman82.4t.com/images/proto...t/IMGP4539.JPG
http://miniman82.4t.com/images/proto...t/IMGP4540.JPG
http://miniman82.4t.com/images/proto...t/IMGP4541.JPG
http://miniman82.4t.com/images/proto...t/IMGP4542.JPG
http://miniman82.4t.com/images/proto...t/IMGP4543.JPG

miniman82 06-15-2011 01:50 PM

5 Attachment(s)
Last 5.

http://miniman82.4t.com/images/proto...t/IMGP4545.JPG
http://miniman82.4t.com/images/proto...t/IMGP4546.JPG
http://miniman82.4t.com/images/proto...t/IMGP4547.JPG
http://miniman82.4t.com/images/proto...t/IMGP4548.JPG
http://miniman82.4t.com/images/proto...t/IMGP4549.JPG

mstaton 06-15-2011 01:51 PM

I did not realize that you bought that set. Congrats! Looks like it will be a fun project! Looks like lots of electrolytic cans in there.

Sandy G 06-15-2011 02:01 PM

Better'n Christmas when you were 5 yrs old...(grin)

miniman82 06-15-2011 02:13 PM

First thoughts:

It's obvious they were trying different things with this chassis; there are holes where parts should be, disconnected parts, and it has a generally unkempt look to it. Wires are routed in a military fashion, tied off and specifically placed. Some circuits like deflection and tuner/front end look like standard fair. Others are a complete mystery- I see no evidence of what would be a dead givaway as a standard looking delay line, but there is an empty spot on the underside of the chassis marked 'delay' (see pic IMGP4543.JPG).

The HV section is strange- there is a 6CD6 output in one of the sockets (the ST shaped one in image IMGP4536.JPG), but then there's also a 6BQ6 in the socket right next to it. No idea what that's about. Damper tube is a 6W4GT, which seems like it should be the incorrect tube for a color set. Most sets use 6AU4GT(A), so I'm not sure what to think there. HV rectifier is a 1B3, which again seems like small B&W style stuff. Color sets typically use higher rated tubes like 3B2 or 3A3. Same thing with focus rect, which is a 1V2 where most color sets use a higher rated tube such as 1X2B.

Picture tube is developmental C-73547, similar to the one at the ETF. Getters look strange to me, I think the tube might have gone to air since one of them is clear in the center. Either that, or they were too close to the glass at the time they were flashed and scorched the glass- I've seen that before on audio output tubes. Other than that, everything else looks pretty good. I now have the monumental task of figuring out how exactly this thing works, and to that end I will be focusing my efforts on the color section first. Bob Galanter has said he will try and stop by this weekend to have a look at it, and I'm hoping Mark will stop by with his tube tester.

Much more to come, stay tuned! :thmbsp:

Phil Nelson 06-15-2011 02:44 PM

Very exciting! Are you going to draw a schematic of what is there?

Phil Nelson

miniman82 06-15-2011 02:51 PM

I might not have to, Ed Reitan has told me he may have a schematic from the early chassis somewhere in his library. I just need to wait and see what exactly this thing is, and we'll move on from there.

John Folsom 06-15-2011 03:15 PM

Nick, first, thanks for all the great hi-res photos. I am not sure when the 6AU4 was introduced, but this set may perdate its introduction. I have production 15" color sets with 1B3s in them, so it is not unheard of. Probably hard on the poor 1B3s, but they work.

You are probably planning to do this, but I suggest you make a tube chart, listing tupe type/mfg/date code. Also, a list of part numbers on all transformers, as these often contain date codes and manufacturer info.

It is anybody's guess if the CRT is still under adequate vacuum to operate, but the signs are encouraging. Of course, my Hawkeye rebuilt 15GP22 tests good, had beautiful getters, and lights up purple like a neon tube when voltages are applied! So you just can't tell by looking.

Do you have the missing tubes, or are these going to be part of the mystery? I don't see tube numbers marked anywhere.

Are any of the control labels readable? I can't tell from the photos.

This a a fantastic set, thanks for sharing. I look forward to your upcoming discoveries.

Electronic M 06-15-2011 03:28 PM

:drool:Wow!:jawdrop:

Holy schmit, you are really gobbleing up some ultra-cool rare stuff lately. Your not trying to compete with the ETF, are you?;):naughty::scratch2:

Hope you can get it to run. If that happens you might just have the earliest working single CRT non-mechanical color set.:thmbsp:

Either way it should be a very interesting restoration.

Good luck!

Tom C.
PS: Now I know what the festive ocasion was, and wow that is one impressive ocaision.

miniman82 06-15-2011 03:41 PM

Quote:

Originally Posted by John Folsom (Post 3006141)
Nick, first, thanks for all the great hi-res photos. I am not sure when the 6AU4 was introduced, but this set may perdate its introduction. I have production 15" color sets with 1B3s in them, so it is not unheard of. Probably hard on the poor 1B3s, but they work.


You're welcome, John! At some point I should probably stitch them together to make one giant one, though it would take a long time to download. I don't know when the 6AU4 came out either, but I know we had previously speculated on the horizontal output tube- the 6CD6 in this chassis is dated the 17th week of 1951! Most of the rest of them date from '50/'52, with the 1B3 in the HV section showing 1958.

Quote:

You are probably planning to do this, but I suggest you make a tube chart, listing tupe type/mfg/date code. Also, a list of part numbers on all transformers, as these often contain date codes and manufacturer info.

Yes, it's one of the things on my list. A lot of the parts on this chassis show RCA stamps, so I'm fairly certain this was made by them. Vert output transformer, power supply choke, some of the other RF cans, and of course the tuner are all RCA items along with some of the tubes (assuming those are the tubes it's supposed to have).

Quote:

It is anybody's guess if the CRT is still under adequate vacuum to operate, but the signs are encouraging. Of course, my Hawkeye rebuilt 15GP22 tests good, had beautiful getters, and lights up purple like a neon tube when voltages are applied! So you just can't tell by looking.

Of course, you are correct. I hope the test this weekend brings good news. I can look through the center of the base, and am able to see a slight patch of green around the evacuation stem which indicates copper corrosion. I hope it has not done any harm.


Quote:

Do you have the missing tubes, or are these going to be part of the mystery? I don't see tube numbers marked anywhere.
It's currently missing 2 tubes, no idea what they are or what they do. Part of the mystery! Perhaps Ed Reitan can shed some light on it?


Quote:

Are any of the control labels readable? I can't tell from the photos.
Yep! The labels are faded, but I can still see what they say. Written in pencil on the front of the chassis going left to right are:

horizontal/vertical hold, power switch/volume, contrast/brightness, and tuner.

On the back:

Pretty much the same stuff as a CT-100 would have. Purity, convergence, drives, backgrounds, focus, ect. Nothing that would make me say "a-ha!", but I don't know much else about the set at this point anyway.

miniman82 06-15-2011 03:45 PM

After following some wires from the CRT socket, it quickly became apparent that there are 3 tubes (6BL7's) that are driving pins 3, 8 and 18 on the CRT socket (which would be grids on a 15GP22). I assume that means these are the adders or some part of the matrix, but the strange thing is there are also 3 diodes on terminal strips for each one as well. They look like the same type of thing that always seems to get used as a detector in IF strips. DC resto, perhaps?

Username1 06-15-2011 04:20 PM

I thought the getters looked a little small on that tube too. But it was never meant to live a long life, just test set. I think the same about the 1b3's in later daily use they proved unsatisfactory for color sets. Good luck with it and many thanks for the cool picts!

miniman82 06-15-2011 05:01 PM

John: Almost missed it, but there's a control in the center of the chassis. It's only marked with a 'C', so I assume it's the color control.

ceebee23 06-15-2011 05:30 PM

WOW .. this is going to be the most amazing thread... this is real history .... I sure hope you can get the set to come alive... this really is what all this is about. Good luck and congratulations!

Steve McVoy 06-15-2011 05:54 PM

Congratulations on getting to delivered. It should be an exciting project.

The space marked Delay doesn't look like it is in the video section?

Steve D. 06-15-2011 06:00 PM

Nick,

Great photos. Glad everything arrived in good order. My money is still on this being an RCA prototype. Look forward to what ever you guys discover.

-Steve D.

ohohyodafarted 06-15-2011 06:56 PM

Glad it all got there in good shape Nick. Especially that rare proto CRT. Hard to tell what the getter looks like from the photo, but you could check for continuity on the filiments before I get there on Saturday.

I will bring the Sencor and the B&K along with the adapter for the 20Pin bi-decal base.

From the photo I can tell the gun assembly is definately of the 15GP22 type with electrostatic convergence cup. It has some centering wings that are spot welded to the cup that are not present on a 15G gun but other than that, the gun is a 15G gun.

In the event the crt is a leaker, You could send it to France to be leak sealed with frit glass and re-gunned. John and I will be sending our first 4 15G tubes over there sometime in august. We have special cartons and a crate being built. Each round trip shipment to France and back will contain 4 tubes.

ggregg 06-15-2011 06:58 PM

Good for you Nick. Will enjoy watching your progress. That is quite the set.
Greg

ChrisW6ATV 06-15-2011 07:34 PM

Congratulations for your acquiring this unique set, Nick. I notice the convergence pin on the CRT socket looks like new, so it must not have had much use, though the 1958 1B3 is interesting.

Quote:

Originally Posted by ohohyodafarted (Post 3006177)
John and I will be sending our first 4 15G tubes over there sometime in august. We have special cartons and a crate being built. Each round trip shipment to France and back will contain 4 tubes.

Bob-

I am happy to hear that the RACS 15GP22 rebuild project is moving beyond the one-off stage and into true production.

Steve McVoy 06-15-2011 07:52 PM

One of the things that Harry Poster told me was that he suspected that the previous owner (not a TV person) had plugged tubes in sockets just to sell the set.

Steve McVoy 06-15-2011 08:00 PM

Bob, one of the photos from Harry showed the filaments glowing, so the filament has continuity and the tube isn't fully air.

Mal Fuller 06-15-2011 08:12 PM

The chassis seems to show signs of a normal life and maintenance period during your set's first years in some kind of service. Sprague and Mallory single-section electrolytics and the 1B3 date coded 1958, all suggest a period of "normal" use.
Having no apparent delay line along with a chassis area earmarked "delay" is another unsolved mystery.
I gather reading twixt the lines that this set recently came from Harry Poster. He sure has had some rare merchandise through the years.

old_tv_nut 06-15-2011 09:00 PM

The adventure begins! Have you determined at all if this could be a dot-sequential prototype rather than early NTSC?

MelodyMaster 06-15-2011 09:05 PM

Quote:

Originally Posted by Mal Fuller (Post 3006198)
The chassis seems to show signs of a normal life and maintenance period during your set's first years in some kind of service. Sprague and Mallory single-section electrolytics and the 1B3 date coded 1958, all suggest a period of "normal" use.
Having no apparent delay line along with a chassis area earmarked "delay" is another unsolved mystery.
I gather reading twixt the lines that this set recently came from Harry Poster. He sure has had some rare merchandise through the years.

You know, a luminance delay line can also be a network of peaking coils and resistors in a can, or a long thin shielded wire wrapped around a non-inductive core with an active frequency compensation circuit. Until cheap glass delay lines were developed there were several methods of delaying a broadband signal. - Of course the delay might have been removed.. :sigh: I gather this set does not use IQ demodulation otherwise it would need TWO delays.

Sandy G 06-15-2011 09:12 PM

This is kinda like findin' Gottlieb Daimler's heretofore unknown SECOND prototype of his 1886 car under a tarp in a dry barn somewhere...

miniman82 06-15-2011 09:53 PM

1 Attachment(s)
Quote:

Originally Posted by ChrisW6ATV (Post 3006187)
I notice the convergence pin on the CRT socket looks like new, so it must not have had much use.

I think you might be right....

:banana::banana::banana::banana::banana:


Took a little time to wake up, but all 3 guns read at the top of the good scale after sitting for 5 minutes and the life test ain't bad either. Anyone wanna hear how the variac powerup of the chassis went? :scratch2:

Pete Deksnis 06-15-2011 09:59 PM

Quote:

Originally Posted by miniman82 (Post 3006209)
Anyone wanna hear how the variac powerup of the chassis went? :scratch2:

You guys are getting all the fun! Don't keep us in suspense...

Eric H 06-15-2011 10:04 PM

Quote:

Originally Posted by miniman82 (Post 3006209)
I think you might be right....

:banana::banana::banana::banana::banana:


Took a little time to wake up, but all 3 guns read at the top of the good scale after sitting for 5 minutes and the life test ain't bad either. Anyone wanna hear how the variac powerup of the chassis went? :scratch2:

You're got to be kidding, this tube tested good!! :thmbsp::thmbsp:
Can it be plugged into a working CT-100 chassis to see if it works.

Username1 06-15-2011 10:22 PM

so is the face of that tube a greyish or a little greenish in color. More like the color of the early 15GP's or more the color of the 21axp's? I wonder if the 1b3's meant the tube was designed to have lower beam current. Too bad there ain't a Sam's you could order for that chassis.

NewVista 06-15-2011 10:45 PM

Quote:

Originally Posted by Eric H (Post 3006211)
You're got to be kidding, this tube tested good!! :thmbsp::thmbsp:
Can it be plugged into a working CT-100 chassis to see if it works.

Still can't be sure until HV or tesla coil present; the getter is a bit worrisome.
But if there's no faint blue neon glow anywhere along guns (viewed in dark) with tube tester, that would be promising.

miniman82 06-15-2011 10:54 PM

From what I learned by using the CR-70, a tube with air will peg the needle after advancing the cutoff control beyond a certain point. You reach the ionization point of the gas inside, and then you get full conduction. Exactly that happened with the 21AXP22 that was in my Director 21, purple neck to boot. But this one is fully variable throughout it's entire range, and the needle rises slowly as it warms up just like it should. So I'm optimistic about it, but we won't know until some HV can be applied.

miniman82 06-15-2011 10:56 PM

Quote:

Originally Posted by Username1 (Post 3006213)
so is the face of that tube a greyish or a little greenish in color. More like the color of the early 15GP's or more the color of the 21axp's?

It looks greenish to me, kinda like the 21AXP22 in my CTC-2B. I have it parked right next to the CTC-4 at the moment, and it's very obvious the difference when viewed right on. The screen on the 2B almost glitters, while the one in the 4 just looks like plain paper.

Dave A 06-16-2011 01:14 AM

This is real history if only the 6-bolt CRT is functioning.

Eric H 06-16-2011 02:06 AM

I think the next question is not if this set can be made operational but IF it should be.

If it's an RCA Prototype it truly is a signifigant piece of history, replacing capacitors and other components would seriously compromise it's historical value IMO.

David Roper 06-16-2011 02:29 AM

I think there's historical value in being able to see just what a dot-sequential or proto-NTSC electronic receiver was capable of. We've now been able to see what the CBS sets were capable of for quite a few years, but when they first came back to life it was quite a revelation.

Phil Nelson 06-16-2011 02:32 AM

I have mixed feelings about whether to restore it and I can think of good arguments for both sides.

Personally, I would find it hard to resist making it work. It was designed as something to be used, after all, not a museum piece.

I would soothe my conscience by doing nothing invasive, restuffing paper caps as well as electrolytics, maybe even finding resistors that look more period-correct. Ideally, when it was done, it would look the same (at least to a casual eye) but WORK as the designers intended.

Just my $0.02.

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

Electronic M 06-16-2011 02:53 AM

I agree with Phill's suggestion for how to go about electronically restoring it.
Better to keep it looking original if you restore it IMHO.

Tom C.

ChrisW6ATV 06-16-2011 03:37 AM

Quote:

Originally Posted by miniman82 (Post 3006209)
Anyone wanna hear how the variac powerup of the chassis went?

If you do get a matching or near-matching schematic diagram from Ed Reitan, you may be able to do just that after some electrolytic restuffing. Absent that schematic, you could draw your own (got a few days or weeks?) and compare it to the CTC2 schematic to maybe narrow down the missing or incorrect tubes.

Either this forum or my browser needs to be taught some of the words we use around here. It doesn't like variac, powerup, or restuffing.


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