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Old 19th Jan 2019, 10:24 pm   #6
mhennessy
Dekatron
 
Join Date: Jul 2007
Location: Evesham, Worcestershire, UK.
Posts: 4,241
Default Re: RGB signals from a VCR

I've found mention of the Panasonic NV-HD660. But, this is a pass-through:

Quote:
Caution: RGB reservation for only E/E operation when connecting the Pay TV decoder.
Looking at the schematic, it really is just a passive connection between the two sockets.

The Philips VR-813 is rather more interesting...

This takes in RGB from Scart 2 and converts it to YC with an MC1377. This allows recordings to be better than simply taking the "fallback" composite output of an RGB source because Y and C never get combined on the same bit of wire, which is where the bulk of the damage with composite happens.

In addition, it looks like RGB pass-through from Scart 2 to Scart 1 can happen, via amplifiers and analogue switches.

The machine has a PAL decoder (as well as the encoder mentioned above), implemented with the ubiquitous TDA3561. For TV sets that support RGB but not S-video, this will give improved results if the tape was recorded from RGB or S-video sources, where Y+C were never added together to make composite. For off-air broadcasts, there'd be no real benefit, unless the Philips decoder was somehow different/better than what is in your TV set.

This VCR has teletext, so this is inserted on the RGB output of Scart 1, using the standard RGB inputs of the TDA3561.

The RGB from the SAA5243 teletext character generator is also encoded to PAL (with another MC1377) as a fallback in the case of a non-RGB connection to the TV, and also for the UHF output. An S-video version of that is also available.

So, apart from my earlier suggestions of pass-through and teletext/OSD, this machines adds the possibility of better recording from RGB sources. I hadn't considered that earlier because a PAL encoder is not a trivial thing to add to a VCR, especially when few will take advantage of it - remembering that there were not many RGB sources around in 1991..

It's a fearsome machine, with S-VHS, NICAM, teletext timer programming, etc. Panasonic G desk. Not something I'd like to meet on the bench . I've had a fascinating couple of hours trying to make sense of the service manual, and that's a whole load of fun that I wouldn't have had if the question hadn't come up earlier, so thanks for that

In another thread I mentioned that we had a Grundig machine with text built in. I can't remember much about it, apart from the terrible user interface, poor reliability, and the Panasonic G-deck. I don't know if that could output RGB from the text section - we didn't have anything with Scart at that time (late '80s). Does this jog any memories? I'd love to look up the details of it, but I can't remember a model number.

If there's any others, let me know!

Thanks,

Mark
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