Prototype set is here

[John Folsom]

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.

[miniman82]

Originally Posted by John Folsom

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.

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).

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.

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?

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]

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?

[Steve D.]

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.