Article about Chromatron Tube

[dtvmcdonald]

I think that clears it up: its a Frankentron!
Neither Chromatron nor Trinitron.

Still, I want one!

[rca2000]

I guess that the attraction from the selection grid against the screen anode voltage caused the aluminum "sputtering" issue in these--and it was NEVER cleared up--which ended the chromatron.

[etype2]

Originally Posted by rca2000

I guess that the attraction from the selection grid against the screen anode voltage caused the aluminum "sputtering" issue in these--and it was NEVER cleared up--which ended the chromatron.

I believe your right. When I first got it, I had an all blue screen. A few days later I turned it on, still an all blue screen, but an odd small bright spot appeared in the lower corner. After the service work was done, good picture and the bright spot was still there. I had it on for maybe 50 hours after service and it is stable, nothing else happened, crossing my fingers. I think the bright spot is from the aluminum flaking off onto the selection grid.

Anybody ever see a service manual for the Sony KV 7010U? I have one for the KV 7010UA.

[etype2]

Update: July 28, 2022
Nine years later, we now have the service manual for the Sony KV 7010U Chromatron and I got brave enough to open the cabinet and tweaked the drives, cleaned the tuner and replaced an antenna wire which looked deteriorated. I found a new Digital Stream digital converter box which has RCA A/V outputs. I set the box and channel selector to channel 4 and used an OTA signal from Phoenix PBS channel 8.5. All three inline cathodes within the single gun measure extremely low emissions, especially the red. The last two photos give an expression of the bad red, but we were still able to get reasonably bright images, a testament to the lack of a shadow mask or aperture grill. The colors are not accurate, but watchable. I don’t believe I posted screenshots prior, so see 4+2 static images below. Photos shot with an iPhone X, processed with Affinity Photo editor.

https://visions4netjournal.com/wp-co...A524877E6.jpeg

https://visions4netjournal.com/wp-co...0F43C9EBB.jpeg

https://visions4netjournal.com/wp-co...0A32F9130.jpeg

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[Popester]

Marshall, that last image I assume was when it was turned off. Even though it tests weak, the picture is very watchable. Sony really was an innovator back then. Thanks for posting those.

[etype2]

Originally Posted by Popester

Marshall, that last image I assume was when it was turned off. Even though it tests weak, the picture is very watchable. Sony really was an innovator back then. Thanks for posting those.

Hi John,

Yes. The lens flares are exaggerated by the camera. Normally, the residual light looks like the second last photo. The red is almost non- existent, but if there is a strong red signal, this Chromatron displays it. I agree with you about Sony, now the Koreans took over television development. Sony seems to focus more on photography these days. They innovated mirrorless cameras. Just read this week that Nikon and Cannon are abandoning DSLR’s for mirrorless only. Thanks.

[old_tv_nut]

Thanks for firing it up and posting the shots.

Do I understand correctly that it has a grille voltage adjustment for purity? Is that accessible to the user? If so, could you get some shots of its effect?

[etype2]

I think this is true. There is a hole directly under the power socket on the Chromatron in the same location as on the Trintron which I read on the Trinitron adjusts the convergence. I have not adjusted either. Purity is not to be confused with convergence, correct?

I’ve located the background and drive adjustments, but not sure where the purity control is located. Have to check the schematic.

[old_tv_nut]

Originally Posted by etype2

Purity is not to be confused with convergence, correct?

Correct.
Purity is each electron stream hitting only the correct color phosphor.
Convergence is all three streams hitting the same area on the screen (no color fringes on a white object).

[etype2]

Originally Posted by dtvmcdonald

I think that clears it up: its a Frankentron!
Neither Chromatron nor Trinitron.

Still, I want one!

The original Lawrence Chromatron experimented with both single and tri-gun electron guns. The one gun version got all the attention for obvious reasons. The Sony Chromatron KV 7010U is a true Chromatron. It has a single gun with three inline electron beams, post deflection focus thru a HV charged wire grid, also vertical unbroken RGB phosphors. Last week we improved the performance and I will post a video.

[etype2]

Sony Chromatron KV 7010U video.

https://videopress.com/v/n8ux4nBu

When viewing the video segments, keep in mind that all three cathode emissions are extremely low, especially the red. Video consists of a brief history, screenshots and three video clips.

Lots of moire and my camera lost focus numerous times. Haven’t had this problem with other sets. I wonder if it has something to do with post deflection focusing by the CRT?

[old_tv_nut]

Originally Posted by etype2

Sony Chromatron KV 7010U video.

https://videopress.com/v/n8ux4nBu

Lots of moire and my camera lost focus numerous times. Haven’t had this problem with other sets. I wonder if it has something to do with post deflection focusing by the CRT?

I think it's more likely your camera trying to re-find focus as the moire' moved around. A contrast-based autofocus could be very confused by the contrast of the detail changing so critically.

[etype2]

I tried all the various focus settings and settled on “Single-shot AF” and “Expand Flexable Spot.” Found FL under 25mm made the moire less objectionable.

I forgot to try different shutter speeds under 30fps. The videos were at 1/25fps.

Edit: Just happy the thing works. :-)

[etype2]

We found new information about the Chromatron. Here is a summery of General Electric’s work. We tried to send this to the ETF, for some reason it won’t go through.

Filling in the gaps of Chromatron history, we recently researched General Electric’s work in developing their version of the Chromaton. It was called simply “PA” or Post Acceleration CRT.

Work started in 1954 and by late 1956, GE developed a three gun inline post deflection tube with a wire grid and vertical phosphor stripes. The wire grid was charged with 7KV and the screen was at 25KV. The design was easy to deflect and converge, but GE encountered difficulty in aligning the grid wires with the phosphor stripes. Additionally, the back scattering of secondary electrons created haze. The haze problem was later ameliorated. Unfortunately this tube never went into production. Thank you John Atwood for releasing the documents of Avon C. Campbell, a life long engineer at General Electric. Later in 1966, the world’s first 3 gun, in-line cathode ray tube went into production as the GE “Porta Color”. See the Porta Color here.

As a side note: Westinghouse worked on this approach with a prototype 20 inch PA CRT. We also learned that RCA tested the GE one gun PA and said to have “reservations”. RCA avoided at great cost, paying royalties to its competitors (think about the Philo Farnsworth litigation). RCA and GE were closely intertwined by cross licenses. Being cynical, perhaps the above described RCA one gun color tube was a GE design?

We have extracted the relevant discussions by the General Electric engineering department pertaining to the PA color CRT.

https://visions4netjournal.com/wp-co...D46DAFCC2.jpeg

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Evaluation by General Electric of their own development CRT above.

Summery and recommendations above.

Internal General Electric engineering department photos.

https://visions4netjournal.com/wp-co...86B6F6471.jpeg

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General Electric focused on five competitive systems and in the end, decided to contribute development to the Apple Super-Index system as the most viable cost effective technology to compete with RCA’s tri-color shadow mask CRT.

This information is in the public domain.



I see the photos won’t copy see my site. 10 photos partial post here. Please credit Mr.Campbell, Mr. Atwood and myself if these photos are posted elsewhere. https://visions4netjournal.com/422-2/.

UPDATE: Just now, we were able to send this to the ETF. I guess the email system did not like the photo links.

[ChrisW6ATV]

Thank you for finding and sharing this information, etype2. It is quite interesting.