#31
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Post the part number for that IC when you get a chance.
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Bryan |
#32
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Hopefully tomorrow I'll get around to doing that. I was just watching The Late Show with Stephen Colbert, and if you've ever watched that show, there's a lot of different colors and scene changes. All the different colors drove the Sylvania's color demodulator crazy. It was as if a minion was constantly adjusting the tint control, and sometimes, turning the color control to max and then back down again. Here you can get an idea of what is happening. Flesh tone is correct, but the ocean is both green and blue.
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"If you wish to make an apple pie from scratch, you must first invent the universe." -Carl Sagan |
#33
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Sylvania part numbers for ICs and transistors went something like 13-xxxxxx
edit: I have a schematic which shows a sylvania part # 15-37704-1 IC std 14 pin DIP with a block diagram having two "demod" and three color difference amps. Looks rather simple
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"When resistors increase in value, they're worthless" -Dave G Last edited by DavGoodlin; 04-08-2017 at 07:38 AM. Reason: correction |
#34
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I'm not sure I follow what's going on with the color, so forgive me for thinking out loud. If this set uses an IC for the color section, and it's basically working but varying, it could be the IC, but it could also be the control voltages, including intermittent connections, or problems with bad filter caps if the controls supply DC voltages rather than video signals. Also, does this set have some sort of automatic color switch that could be intermittent?
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#35
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You've heard right. Sylvania was always finding a better processing sequence for their phosphors - the precise formula, heat treatment, grain size, slurry thickness, you name it. As I have posted elsewhere here, when I was at Motorola, Sylvania came up with a thick slurry that was brighter, but when Motorola tried to duplicate it, they had trouble due to swirl marks developing in the screens. The thicker slurry apparently needed a different swirl pattern/rate that the Motorola deposition machinery wasn't designed to do.
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Audiokarma |
#36
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As I recall, Sylvania had a CRT plant first in Emporium, PA then later a modern plant in Seneca Falls, NY. Thier color bright 85 replacements outsold RCA at our local parts house. i usually chose RCA for an RCA set, IIRC.
The RCA CRT plant in Lancaster PA (here I am) and Marion Indiana were also developing a better phosphor All these locations are nowhere near big cities. Those Engineer-Physicist types hated cities and I can understand why. Unfortunately all the old timers I meet from this RCA plant worked in power tubes and orthicons.
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"When resistors increase in value, they're worthless" -Dave G |
#37
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Well, not so unfortunate if you are interested in orthicons. I would love to know the details of how the thin glass orthicon targets were created - like a thin glass bubble, but perfectly flat.
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