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Old 06-26-2010, 09:55 PM
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The elusive Indextron

I was watching this one on that auction place. A rare version in a white cabinet. But with the usual problems. "3/4 of a picture" as described. The hammer went down at $405 and it was only 5 miles from me. Way above my checkbook. Seller found it at a yard sale. Note to self...check more yard sales and be kind to the Indextron I already have.
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Old 06-26-2010, 09:58 PM
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What is it? A portable TV?
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Old 06-26-2010, 10:22 PM
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The Indextron was a Sony name for a variant of the Philco Apple beam-index CRT color picture tube from the late 50's that Philco gave up on. Sony ended up with the patent. It was a Watchman-sized SS set at 3.5" or so.

It had no shadow mask and relied on a rear-mounted photocell to track the single-gun beam crossing the vertical phosphor stripes, switching color at each stripe. The photocell monitored the beam position and made the color change as the sweep went on.

Each stripe was separated by a black stripe to prevent cross-color contamination and allowing the clean switch during the black stripe. IE, the beam hitting the red and overlapping in to the green.

Red/black/green/black/blue/black and so on. The beam focus is the most critical to prevent overlap in to the next stripe and illuminating two stripes. Red plus green = yellow, etc.

The big problem was that 25% or so of the screen was black stripes and diminished the brightness. No shadow mask should be a bonus but the black stripe killed any gain. Aside from that problem, it does make a very sharp picture. The other big Sony problem was cheap surface caps. Mine needed around 20 or so replaced to make it operative. This one needs the full re-cap.

Sony only made it for a while in 1988. Most are dead and only a handful have shown up. This is the first white cabinet seen by me.
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Last edited by Dave A; 06-26-2010 at 10:27 PM.
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Old 06-26-2010, 10:22 PM
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I'd like one, but they aren't worth (to me) what they often go for.
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Old 06-26-2010, 11:28 PM
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Did this design use UV phosphor stripes as the index reference?
I have never seen one in operation... how good is the contrast?... it would seem that some minimum beam current must be landing on the screen at all times in order for the photocell to detect the index reference stripes, wouldn't that wash out the back level somewhat?

just curious,
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Last edited by jr_tech; 06-27-2010 at 01:45 PM.
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Old 06-27-2010, 05:45 AM
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IIRC, part of the "lore" of these things is that Sony soon realised they had a "turkey" or "Edsel" of biblical proportions on their hands, & recalled them, & most were destroyed...Very few survived, & even fewer work...
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Old 06-27-2010, 10:55 AM
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WHITE ONE!!!!!!??????????????? I had no idea they made that set in white... My gray Indextron just fell in lust, and needs a companion

Although it's bad etiquette to discuss price & value on items already sold, I have to say I'd be thrilled to get it at that price (assuming funds on hand, of course).

Quote:
Originally Posted by Sandy G View Post
Sony soon realised they had a "turkey" or "Edsel" of biblical proportions on their hands, & recalled them, & most were destroyed...Very few survived, & even fewer work...
That white one and mine would look great, displayed on the hood of my 1982 Cadillac with the Olds 350 Diesel engine, LOL. Turkeys of the century....

Charles
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Last edited by kx250rider; 06-27-2010 at 10:58 AM.
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Old 06-27-2010, 12:08 PM
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Aww, shit, Charles, the 350 Weasel was a Paragon of Mechanical Virtue compared to the 262...That morphodite should have never seen the light of day past GM testing labs...
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Old 06-27-2010, 05:59 PM
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To save a lot of space here, this Wikipedia article does a good job of explaining the original Apple tube and the beam-index tube;

http://en.wikipedia.org/wiki/Beam-index_tube

The photo is my Indextron on the left next to my Sony KV-5000 CRT 5" set. The stripes are obvious.

More on the Apple can be found at Chuck A's website. Lots of original Philco documentation;

http://www.myvintagetv.com/philco_apple_tube.htm

And the schematic of the Indextron is attached if you want to reverse-engineer the thing . The photocell is on the "N" board. Courtesy of Jerome Halpen. There are previous VK threads on the Indextron if you search.
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File Type: jpg index6.jpg (43.6 KB, 146 views)
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File Type: pdf Sony_KVX-370_Indextron-04.pdf (353.2 KB, 54 views)
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Last edited by Dave A; 06-27-2010 at 06:02 PM.
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Old 06-28-2010, 01:42 PM
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Thanks for all the info! The picture IMHO, shows that these sets were better than I would have expected... the black does not appear to be "washed out" by the "index beam" current... Purity at the edges might have been an issue, but the set does not appear to be a "turkey" either. Gotta find one.
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Old 06-29-2010, 04:09 AM
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Hi Guys,

so who is the lucky winner of the US $405.00 Indextron, one of us ?

If he hangs out here, i can give him the full service data (schematic & tune-up), just ask for it or send a PM.

Best Regards

jhalphen
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Old 07-02-2010, 08:26 AM
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I seem to remember Popular Science doing a thing on a single gun color tube back in the 70's......... Anyone ever seen it? After reading the Wikipedia page I think the one in PS was the Advanced Apple tube with the photomultiplier.
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Last edited by Username1; 07-02-2010 at 08:31 AM.
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Old 07-02-2010, 08:46 AM
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I think it was a "Turkey" not so much because the concept wasn't sound, but because of Sony's up-til-then uncharactaristic poor execution...Wasn't it about that time that Sony's quality started slipping badly ?
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Old 07-02-2010, 10:13 AM
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Quote:
Originally Posted by Sandy G View Post
I think it was a "Turkey" not so much because the concept wasn't sound, but because of Sony's up-til-then uncharactaristic poor execution...Wasn't it about that time that Sony's quality started slipping badly ?
It really wasn't Sony's fault. It was a good design, and used top quality capacitors, which turned out to be defective. Apart from the caps, I don't think I've seen anything else go wrong with one. The demise of the Indextron as a concept was mostly due to the rise of LCDs for hand held TVs.
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Old 07-02-2010, 12:56 PM
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Quote:
Originally Posted by andy View Post
The demise of the Indextron as a concept was mostly due to the rise of LCDs for hand held TVs.
It would appear that the concept could have been applied to the "lollipop" tube design that was used in the small "Watchman" series... Perhaps the only way that color might be obtained in such a CRT design. What might have been!
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