Prototype set is here

[colortel]

To the Color Gang,

Nick and I have just had a wonderful 1 1/2 hours on the phone tracing his chassis circuits from the CRT grids back through the 6BL7 color crt drivers,and 6AS6 demodulators. We had discussed the evolution of NTSC standards, back through the Feb. 2, 1953 NTSC Field Test Specification, and further back to the initial definition of the NTSC field test standard published on November 26, 1951. See http://novia.net/~ereitan/NTSC_overview.html

This November 26, 1951 standard used quadrature modulation of 1 MHz. B-Y and R-Y color difference signals, CPA (Color Phase Alteration), a 3.898125 MHz. subcarrier, and reference burst on a pedestal on the back porch of horizontal blanking. . In doing our tracing Nick discovered a transformer labeled "CPA".

Our initial conclusion is that it is a chassis probably used during the CPA Field Testing during 1952. There were several manufacturers who built field test receivers during that period.

We have yet found nothing to confirm that it was built by RCA or by any other manufacturer.

The chassis may have been modified from CPA up to the later NTSC Feb. 2, 1953 standard. We will see.

Further tracing of the circuit and documenting the circuits will be don.

Ed Reitan

[miniman82]

Thank you Ed for the revealing and informative conversation, the amount of information that the early color crowd is providing is astounding to say the least. The collective knowledge shared here cannot be found anywhere else on planet Earth, of that much I am certain and I am forever grateful!

As Ed indicated, we started out following the wires though the various components connecting each stage to the previous one. I was poking around in an area that I had assumed would have something to do with demodulation, positioned in the circuit just prior to the 6BL7 grid driver tubes, and containing 6AS6 tubes. That's when I struck gold: Hidden under some passive components was a chassis stamp in black ink right under a tall transformer, which reads CPA.



It's a pretty tall can, so I was curious what it had inside. Taking much care not to damage or disturb anything, I slowly removed the nuts holding it to the chassis and this is what's inside. It's only about half the total height of the can, and appears to be some sort of transformer. I cannot see any kind of slug in the center of it, so I'm assuming it's an air core non-adjustable type.

[ohohyodafarted]

Originally Posted by colortel

The chassis may have been modified from CPA up to the later NTSC Feb. 2, 1953 standard.
Ed Reitan

From Pete Deksnis @ Bob's place: I had the same thought; but I suspect the transformation was not completed; hopefully so, as it would simplify the reverse engineering.

Pete

[John Folsom]

Very interesting indeed!

[Eric H]

This get's more interesting by the day! Probably one of the most interesting things that's happened here yet.

The genesis of Color TV being uncovered before our eyes, it's one thing to read about field tests and demonstrations for the FCC, quite another thing to see the actual hardware rediscovered and brought to life.

It's only been 60 years since this was being created but so much seems to have been lost.

I suppose it's lucky there's as much written documentation as there is, I wish there was a few hundred hours of period Technicolor footage to go with it.

They must have filmed some of their tests??

To go back in time with a HD Flip Camera hidden in my pocket.

[Sandy G]

Do you guys know if this set was EVER actually fully functional ?

[miniman82]

Originally Posted by Sandy G

Do you guys know if this set was EVER actually fully functional ?

<shrugs>

At some point it probably did, but being a test bed of sorts it seems to have been in a constant state of change since day one. I wouldn't be the least bit surprized if upon power application the horizontal and HV section started spooling up, same thing goes for vertical deflection. The real mystery here is how does it handle color, and how do we get that color image to appear on the developmental CRT?

[TVtommy]

This is waaaay cool!

[zenithfan1]

That's effin' amazing Nick! too bad I was so busy this weekend! I'da loved to see that light up for the first time in person! That tube looks like it could have a great picture on it once a chassis is set up right for it. I think your money was wisely spent on this piece of history. Now, if that chassis can be made operational, I think people will be knocking on your door from states away to see it work!

[miniman82]

Originally Posted by zenithfan1

That's effin' amazing Nick! too bad I was so busy this weekend! I'da loved to see that light up for the first time in person!

It was a good day for color TV history, but don't worry there will be other opportunities in the future to view this one in the flesh. My hope is to have the entire thing ready and working for next years ETF, but we have a lot of work in front of us to get to that point.

That tube looks like it could have a great picture on it once a chassis is set up right for it. I think your money was wisely spent on this piece of history. Now, if that chassis can be made operational, I think people will be knocking on your door from states away to see it work!

That could be, Pete already drove 5 hours to see it!

If I can't make it to next years ETF for whatever reason, a video will be made to show the masses in the banquet hall. Probably be a good idea to have something better than my Handycam to take the pictures with, though.

[Pete Deksnis]

1. Hello. What’s in there?

2.
Out of the box comes a C73547.

3. Beltron test of C73547.

4. Here Bob is checking numbers discovered on the tube rim. I found them while cleaning dust and grit from the tube. They were hand-punched, obviously before final assembly. It is unclear what they represent.

5. Only seconds after first raster.

Pete

[Pete Deksnis]

6. Overall CRT light-up configuration.

7. Another view showing, in better perspective, the location of the 15GP22-based yoke on the C73547 neck. We were mindful of the 20 kV covering the bell and being so close to the yoke. The purity coil is positioned on the neck based upon the proper location for a 15GP22 installation. In this flash shot the screen is washed out, but there’s Dorothy shining through!

8. Nick and Tom, who’s gotta be the luckiest vintage TV devotee on the planet, enjoying some Wizard of Oz footage on the C73547.

9. Who was there? Seven people witnessed the event. Tom (Electronic M), his Dad, his Mom, Bob Galanter, Nick Williams, his wife, and Pete Deksnis. The ladies it seems quickly turned their attention to more pressing discussions. After the hi-fives, I called John Folsom in Florida (that's his cradle the CRT is resting on). A bit later, Ed Reitan and John Folsom were on a conference call with Nick.

Pete

[Steve D.]

Great stuff Pete,

That's what you want to see when you test a tube. Simply incredible.

Thanks for posting,
-Steve D.

[ceebee23]

This just has to be one of those .... oh my gosh!!! moments!!!

[Aussie Bloke]

I'm keeping up to date with this thread skim reading the main parts and looking at the pics and I am so impressed with the progress made with this set in such a short time!!! It is totally amazing to see that the picture tube is excellent and displaying a picture and I look forward to seeing colour pictures on this tube once you get the prototype chassis up and running with the tube mounted in and configured to display colour pictures! This is absolute amazement and I look forward to further progress with this TV set in terms of restoration work and also identifying exactly what prototype it was and when it was manufactured, keep up the good work mate!!!