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Hi! to All,
For ChrisW6ATV:
Here is a block diagram of the Beam-Index color VF in the Theory of Operation section. Near the screen, those are not LEDs but 2 photocells, one sensitive to UV light emitted by the beam-index stripe at each color triplet, the other being sensitive to green. Both are used to close the color sync servo-loop and keep the color presented on the CRT's grid at instant X in sync with the color scanned at the same instant by the electron beam.
For drchucksgas:
Come on! why spoil our fun? Sure beam-index CRTs are outdated, but people here have an open mind and are curious. Personally, i got interested in this technology to understand why following sizable research investments in the 1950s and great promises (simple B&W gun structure, no convergence), it never became a market success.
Correction! it was used in avionics displays before LCDs. Thomson-CSF of France made Beam-Index & Color Penetration tubes well in the 90s.
If you look at the picture, a still from "The Wizard of Oz" DVD (Courtesy & Thanks! to John Folsom Jr) the detail and color are quite remarkable considering it's a 1.5 inch CRT.
And BTW, over the last 18 months, John and myself have had great fun tracking down the camera models, sourcing documentation (TOUGH job!) and making them work. I am currently working on a hybrid TV with the VF circuitry in a Plexiglas cigar case and NTSC reception via the RF/IF circuitry of a dead Sony CRT Watchman.
For Findm-Keepm, Hi! Brian
Here is a picture of the Sony XAV-U50, i found one in the UK. I am hoping to find some service data before tinkering with it. From previous discussions on this forum, the general opinion was that it is only a RGB display with no NTSC decoder nor RF section.
Brian, your tiny.url shows me nothing; could you please capture the pix & post here; Thanks!
For Dave A: Your post filled me joy, for now i know that i am nots nuts, there was indeed a Watchman flat color CRT version. I always thought it was a single prototype for trade shows, but if the CRT was referenced by major parts distributors, small market quantities must have been produced. Where are they! not seen ONE in 10 years of E-Bay.
Maybe some of our members understand Japanese and could search on Japan/Asia sites.
Last but not least, Sanyo sold a very limited quantity of the 30-CTV1 4" Beam-Index color TV in the US, 1986. Saw one in the LA area in a pink case, had spent all my $ on a CT-101 and couldn't buy it. Gone forever!
Best Regards
jhalphen
Paris/France
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