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  #1  
Old 03-19-2011, 01:49 PM
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Working on First GE Color

My recent project was with a GE 15CL100 chassis which I was able to restore to operation with the Wallace Manual available thanks to ETF & J. Folsom.

This set came from fringe suburban Milwaukee WI where according to owners it was one of 70 in an initial production run mainly intended as demo sets for favored GE dealers/locations. Since there was a pioneering color station here in '54, WTMJ NBC, this area got this one (or more?) demo set(s).

There are two schematics in the Wallace, "First Production" & "Second Production". The 2nd production has about a half-dozen minor circuit changes. I have not seen evidence of a 2nd production TV; I suspect production was halted in the anticipation of the coming RCA 21" kine to better complement this set's refrigerator-like cabinet.

As you might guess, the chassis is big and heavy (60 lbs) and consumes the best part of 500 watts. With a high tube count, there is high component density and many capacitors to change. However when paper caps are eliminated, it turns out to be a stable, reliable performer with a conservative, cool-running flyback transformer in a large well-designed HV cage.

There was some horiz AFC foldover on the right side that only upgrading to 2nd Production changes could correct.

Being from the days of pioneering experimentation, there are some peculiarities like the "Hue"(Tint) control being almost hidden (from customer tampering) on the chassis back panel.

Its 15GP22 RCA kine has good guns but too much accumulated atmospheric ingression for effective operation (needs to be re-vacuumed one day)
Attached Images
File Type: jpg '54 GE 001.jpg (124.9 KB, 193 views)
File Type: jpg GE 15CL back 001.jpg (73.7 KB, 188 views)
File Type: jpg GE15CL 005.jpg (140.6 KB, 168 views)
File Type: jpg GE Latest 001.jpg (100.0 KB, 244 views)
File Type: jpg GE Latest 003.jpg (86.5 KB, 209 views)
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Old 03-19-2011, 02:41 PM
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Zowie, an interesting project. What sort of 21" CRT did you use in that workbench setup?

Phil Nelson
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Old 03-19-2011, 02:52 PM
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Nice going Colin! Please tell us the story of how you came to be aware of this set in the possession of the former owners.

Presently I am working on the Helium Leak detector mass spectrometer so maybe some day we will be able to locat the leak in that gassy tube.
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Old 03-19-2011, 09:30 PM
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Quote:
Originally Posted by Phil Nelson View Post
What sort of 21" CRT did you use in that workbench setup?

Phil Nelson
It's a 1960's Zenith with metal band/lugs & implosion faceplate. Has large neck of roundies that's more compatible with 15GP22 yoke. Socket connections had to be extended (don't have a 15GP22-to-21" adapter/extender).
Attached Images
File Type: jpg GE 15CL Pix 002.jpg (138.8 KB, 127 views)
File Type: jpg GE 15CL Pix 004.jpg (54.5 KB, 120 views)
File Type: jpg GE 15CL Pix 005.jpg (57.7 KB, 120 views)
File Type: jpg GE 15CL test2 001.jpg (106.5 KB, 146 views)
File Type: jpg GE 15CL test3 001.jpg (73.1 KB, 134 views)

Last edited by NewVista; 03-19-2011 at 09:53 PM.
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Old 03-19-2011, 09:51 PM
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Quote:
Originally Posted by ohohyodafarted View Post
Presently I am working on the Helium Leak detector mass spectrometer so maybe some day we will be able to locat the leak in that gassy tube.
Hi Bob, That's great. The experiments you guys are doing are making a valuable contribution to the science and progress of this important endeavor of historical discovery & preservation.
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Old 03-19-2011, 10:57 PM
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Wowie zowie! That's incredibly cool.
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Old 03-19-2011, 11:03 PM
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It would be quite a long time before GE would engineer/build such a fine set again! Great to see this one alive.
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Old 03-20-2011, 12:47 PM
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It would be quite a long time before GE would engineer/build such a fine set again! Great to see this one alive.
Surprisingly this set uses simple burst-excited crystal for phase locked subcarrier (a feature of minimalist 60's designs like the PortaColor). Works excellently.

The HUE control with a knurled brass knob can be seen hidden from the customer (for good reason?) on lower back panel. It's a shielded vari-cap that rotates continuously.

Twin "Coke Bottle" 6CD6 Horiz O/P only draw a meager combined 1/5-A

Now have CTC-5 hooked up to Zenith Test CRT (2nd pix) - it's more trouble than the GE !
Attached Images
File Type: jpg GE 15CL HV Cage 001.jpg (93.3 KB, 119 views)
File Type: jpg GE 15CL HV Cage 002.jpg (102.5 KB, 120 views)
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Old 03-20-2011, 02:00 PM
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Wow! Great work, thanks for all the pictures!

The pix of The neck glowing did, however bring back a rather unpleasant memory, when the CRT in my avatar died.
Seeing the chassis hooked up to a 21" (fat neck) tube and producing a fair picture raises some questions.

1. Is there room inside that huge cabinet to actually mount the 21" jug up to the bezel in a somewhat normal position temporarily ?
2. Any possibility of a simple add-on convergence driver so that the magnetic convergence coils could be used in a set designed for electrostatic convergence?

Not to suggest something that some might consider as egregious as fish-tanking on a super rare set, but seeing this chassis operating with the 21" jug suggests some interesting possibilities.

jr
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Old 03-20-2011, 02:02 PM
old_coot88 old_coot88 is offline
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Originally Posted by NewVista View Post
Surprisingly this set uses simple burst-excited crystal for phase locked subcarrier...
Um.. not tryin' to be picayunish, but wouldn't that be phase-locked referance oscillator?

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Old 03-20-2011, 06:48 PM
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Smile

I've known about the 15CL100 for years, and have a copy of a schematic, but this is the first time I've seen actual photos and screen shots of that receiver outside of the pic on the ETF website, and other similar pics. Thanks for posting all the info and pics, I really appreciate it! GE's approach to a color set is certainly different from RCA's, and is a great illustration of the history of the art of early receiver engineering and design. The crystal ringing circuit was used in a few other sets later, a Motorola comes to mind. Saved a couple of bucks over a complete oscillator/AFC circuit, I guess.
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  #12  
Old 03-20-2011, 09:42 PM
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Quote:
Originally Posted by old_coot88 View Post
Um.. not tryin' to be picayunish, but wouldn't that be phase-locked referance oscillator?

Bill(oc)
This refers to a crystal "ringing" circuit. It actually does not oscillate on its own, but has a very high "Q" so that it produces a decaying oscillation that lasts longer than 1 horizontal line when excited by the burst. When this decaying waveform is amplified and clipped, it is sufficient to drive the demodulators.
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Old 03-20-2011, 11:24 PM
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Quote:
Originally Posted by jr_tech View Post
The pix of The neck glowing did, however bring back a rather unpleasant memory, when the CRT in my avatar died.
Seeing the chassis hooked up to a 21" (fat neck) tube and producing a fair picture raises some questions.

1. Is there room inside that huge cabinet to actually mount the 21" jug up to the bezel in a somewhat normal position temporarily ?
2. Any possibility of a simple add-on convergence driver so that the magnetic convergence coils could be used in a set designed for electrostatic convergence?

Not to suggest something that some might consider as egregious as fish-tanking on a super rare set, but seeing this chassis operating with the 21" jug suggests some interesting possibilities.

jr
I've wondered about this but never read a solid response. Roundies could be used with later rectangular test jigs, right? Should be plenty of room to fit something in there, though producing a correct picture might be very difficult.
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Old 03-20-2011, 11:36 PM
old_coot88 old_coot88 is offline
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Quote:
Originally Posted by old_tv_nut View Post
This refers to a crystal "ringing" circuit. It actually does not oscillate on its own, but has a very high "Q" so that it produces a decaying oscillation that lasts longer than 1 horizontal line when excited by the burst. When this decaying waveform is amplified and clipped, it is sufficient to drive the demodulators.
Son of a gun. Then it doesn't use a 3.58 referance oscillator at all, right?
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  #15  
Old 03-20-2011, 11:41 PM
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Quote:
Originally Posted by jr_tech View Post
1. Is there room inside that huge cabinet to actually mount the 21" jug up to the bezel in a somewhat normal position temporarily ?
jr
An interesting thought.
The 15GP22 appears to be mounted on a sub-board with bolts. Another sub-board with a 21 could perhaps be dropped in temporarily - without harming any of the cosmetics or construction - until 15GP22 situation resolved.
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File Type: jpg GE 15CL CRT.jpg (61.6 KB, 84 views)
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