The elusive Indextron

[jhalphen]

Hi Again,

To further the topic of the beam-index micro-crts, here are some pictures given to me in 2004, courtesy of Charles Osborne (thanks!) who sometimes posts here.

The CRT is a Hitachi H-6289 single-beam "Indextron" CRT and at 1.5" screen diagonal it is truely a technology wonder.

Hitachi developped the CRT to bring color viewfinders to cameras and camcorders at a time when shadow-mask CRTs were deemed too dim and power-hungry to be acceptable in equipment running off batteries.

The "Wizard of Oz" pictures is courtesy of John Folsom Jr, Thanks! John.

The last document is from RCA cameras CC-030 and CKC-021 Theory of Operation section in the services manuals and describes the screen structure of the H6289 CRT.

One nuisance about repackaging the color viewfinders for use as micro-NTSC monitors is that there are 2 photocells for the indexing system, one sensitive to UV and the other to green (aside from the Green phosphor there is also a Green Index Phosphor) and both must face the screen and be shielded from outside light or the index sync goes haywire and the screen reverts to monochrome.

Another info learned from experience with these viewfinders is that obtained a constantly correct Red is near impossible. Depending on color content, Reds vary from having a purple tone to a dull brown, so flesh tones remind the user of the early days of NTSC - "stop twidling that Tint control!"

This is not the H6289's fault, i suspect some cost-cutting was done in the complex matrix processing required to produce the RGB/Y signals to keep component count and cost acceptable.

OT:
The Sharp 3.5" 3LS36 TV mentioned in this thread (sold in pink, black, white) uses an ordinary shadow-mask color CRT, a 100HB22.

Best Regards

jhalphen
Paris/France

[jr_tech]

Originally Posted by jhalphen

OT:
The Sharp 3.5" 3LS36 TV mentioned in this thread (sold in pink, black, white) uses an ordinary shadow-mask color CRT, a 100HB22.

More OT:
I notice one of these on the 'Bay for about $300 BIN... Is that nutz or about what these little pink ones go for?
http://cgi.ebay.com/Sharp-3LS36-P-3-...item4cf0423038
I am not affiliated with this auction,
jr

[Sandy G]

Originally Posted by jr_tech

More OT:
I notice one of these on the 'Bay for about $300 BIN... Is that nutz or about what these little pink ones go for?
http://cgi.ebay.com/Sharp-3LS36-P-3-...item4cf0423038
I am not affiliated with this auction,
jr

Think I gave $50 or so for mine-But that was prolly 10 yrs ago. Think I gave $40 for the white one a year or 2 later. IIRC, I was either only bidder,or one of a handful of bidders on either one...Seems like for some reason, more pink ones have surfaced...Only seen one-I THINK-of the silver ones & maybe a couple black ones...Think I may have seen a couple of the ivory ones besides mine. Never did see one "In captivity" back in the day for sale that I can remember.

[jhalphen]

Hi to All,

For CRTFool, the photocells are there alright, it CAN't work without!

see this brighter pix with the photocells layed out in front of the screen.

The room was also darkened.

When the viewfinder's case is open, there is a small polished steel mirror at the top of the case, above the CRT. I suppose it's there to reflect the light down towards the photocells as synching the beam position with the RGB sequence is particularly important at the start & end of the TV field.

When you view a Sony Indextron CRT out from the chassis, there is a different appearance phosphor at the top of the CRT and on the left side, running continually from top to bottom.

From Andy's photo (Thanks! Andy) this is a "run-in" area reserved for sync before the active frame begins. The beam is also re-synched at each line start.

Best Regards

jhalphen
Paris/France