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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 19th Jan 2019, 1:21 pm   #1
mhennessy
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Default RGB signals from a VCR

I've never seen a VCR that outputs RGB. I guess it's possible that some of the teletext-equipped model did, but certainly I can't see the sense of having a complete PAL decoder in a VCR. S-video is as advanced as I'd expect to see from a VCR.

The later DVD or HDD recorders mostly had RGB inputs because they were capable of recording in much higher quality than VHS. As you say, they made handy HDMI converters

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Old 19th Jan 2019, 1:57 pm   #2
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Default Re: BBC Micro RGB - SCART INPUT VIA VCR

Quote:
I've never seen a VCR that outputs RGB.
I have had several, mainly Panasonics. I have an obsession with using an RGB connection wherever it is available, so I always notice if a unit does or does not support it. The ones that did so may have done so for the same reason as many recorders also had RGB inputs: To get around that pesky Macrovision protection.

Last edited by AC/HL; 19th Jan 2019 at 6:06 pm. Reason: Thread split
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Old 19th Jan 2019, 5:36 pm   #3
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Default Re: BBC Micro RGB - SCART INPUT VIA VCR

Could you remember any of the model numbers? I'd be keen to understand why they did that. Did they contain a PAL decoder so that they could be used with RGB monitors that lacked their own PAL decoder, or did they generate RGB internally for on-screen graphics or teletext, or did they pass through RGB from other devices connected to them, such as a DVD player?

In the scheme of things, there is relatively little difference between S-video and RGB (or, to put that another way, I remember being pleasantly surprised at how little difference there was!), providing the saturation control is set correctly. There is quite a large difference between composite and S-Video, of course. On a tape that was recorded off-air, the "damage has already been done", so there's no difference between composite and S-video connections between VCR and TV set, assuming the YC filters in the VCR perform the same as the ones in the TV. So what comes off the tape is S-video at best (if it came from an S-video source), and in practice the quality is often no better than composite. So going to the trouble of decoding to RGB won't bring about an improvement in picture quality, assuming the VCR's PAL decoder performs equally to the one in the TV...

Back in the days of only one RGB scart on TV sets, I would have loved a VCR that passed through RGB from the DVD player. I can't remember exactly why now, but there was something not quite ideal about having to go VHS -> S-VHS -> DVD player -> $ky box -> TV set, but that was what I had to do to get RGB from the sources that generated it, while still being able to pick up the audio from the right place to feed to the hi-fi.

Every Sony DVD player I've seen with 2 scarts had a bunch of relays to pass through all the signals - including RGB - when powered down. The $ky box didn't use relays, but was powered all the time, so made do with analogue mux ICs. I seem to recall that there was a slight degradation of picture quality, but not enough to be noticeable from normal viewing distances on a 21" TV.

Anyway, I completely agree about the superiority of RGB, but am keen to learn what those VCR did with it.

Also, given that Macrovision inserted spurious pulses in the blanking period, how does RGB avoid this? All domestic devices that I've seen that output RGB will simultaneously output composite video at the same time, providing a fallback for when you connect to a scart input that is composite only. The sync separator in the device receiving this signal would therefore see no difference. Macrovision is something that occasionally caused us grief back in the '90s, and from what I can remember of those times, I can't quite see how RGB outputs from a VCR would help, unless the machine incorporated a Macrovision cleanup circuit that was disguised as something else - which would be genius marketing if true. Any information you can point me to would be greatly appreciated.

Mods, I realise how off-topic this has become, so might it be worth splitting off these posts into a separate thread?

All the best,

Mark

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Old 19th Jan 2019, 6:32 pm   #4
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Default Re: RGB signals from a VCR

Thanks to the mods for splitting the thread! Just for context, my first post in this thread was prompted by post #9 of the original thread: https://www.vintage-radio.net/forum/...d.php?t=153245

Quote:
Originally Posted by SiriusHardware View Post
Good that the OP has decided to go for a historically correct monitor, but for the record, many of the later generation HDD/DVD recorders did have RGB -input- via SCART. I think this was intended to be used for connection of RGB-out from a VCR so you could transfer VHS original recordings to DVD or HDD, bypassing the Macrovision 'protection' which prevented similar activity via a composite connection.

I've used my Pioneer 545 HDD/DVD recorder (which has RGB input via SCART) as a way of converting RGB SCART in to HDMI out, to view the output from an Atari ST on an HDMI monitor.

I can't remember if that Pioneer machine also outputs a modulated RF out signal or whether the RF-out is just an aerial passthrough signal.
Any information about VHS machines with RGB outputs will be gratefully received
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Old 19th Jan 2019, 8:50 pm   #5
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Default Re: RGB signals from a VCR

I only have one remaining VCR and that is my Panasonic NV-F70, quite high end but I don't know if that one has RGB-out. I probably still have the manual but I am not where it and the machine are at the moment. No doubt someone here knows the machine well enough to be able to tell you before I can.

Other than the other machines being Panasonic (probably) I unfortunately do not know what the model numbers were - it's not really my area of interest, VCR mechanisms terrify me. They were later models than the F70, but when I thinned my gear down I 'rewarded' the F70 for its long and faithful service by choosing to keep that one.
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Old 19th Jan 2019, 10:24 pm   #6
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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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Old 20th Jan 2019, 1:31 am   #7
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Default Re: RGB signals from a VCR

Just checked the manuals of my VCRs.

The following have RGB in/out

SVHS VCRs:
JVC HR-6855EK, HR-6856EK, HR-6857EK
Panasonic NV-HS950B


Panasonic DV recorder with VHS deck: DMR-EZ48VEB.
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Old 20th Jan 2019, 9:23 am   #8
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Default Re: RGB signals from a VCR

I've got an NV-HS950 here and it does have RGB passthrough, but doesn't record or play back from RGB signals as far as I remember.

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Old 20th Jan 2019, 10:00 am   #9
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Default Re: RGB signals from a VCR

Quote:
Originally Posted by mhennessy View Post
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.
The Grundig VS500 series used the G-deck IIRC, the VS510 and VS520 had teletext for definite, I cannot remember if the VS500 had text though.
There was also the 530, 540 and 550 in this range of machines, however whether they had text or not I cannot recall for sure but I suspect they did
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Old 20th Jan 2019, 1:16 pm   #10
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Default Re: RGB signals from a VCR

Quote:
Originally Posted by emeritus View Post
Just checked the manuals of my VCRs.

The following have RGB in/out

SVHS VCRs:
JVC HR-6855EK, HR-6856EK, HR-6857EK
Panasonic NV-HS950B


Panasonic DV recorder with VHS deck: DMR-EZ48VEB.
Hi,

Have been searching for manuals for each of these - all good fun, but I've exceeded my daily limit on Elektotanya for today!

The JVC machines are simple loop-through only. RGB is not generated or received by the machine. The only wrinkle being red, because of the later revision of the Scart standard that allowed it to carry S-video, where Y is carried on the composite connection, and C is carried on the R path (pin 15).

The Panasonic HS950 machine is also a simple loop-through - it has the same notice that I quoted earlier in post #6. Like many Panasonic S-VHS machines, it has a switch on the rear panel to select whether Scart 1 works in S-video or normal mode.

Of course, the DV machine is a different beast, and it makes sense to use RGB connections (or YPbPr professionally) as DV supports much better picture quality than VHS. Without a manual, I can't say for sure what goes on with the VHS deck - it's possible that they do similar things to the Philips to extract best quality from non-composite sources, and given the progress in technology since the Philips, it's a lot easier/cheaper to do. I presume also that this machine will take the pictures from VHS and decode them internally to RGB (no significant difference in quality if the tape was recorded from a composite source). Of course, the on-screen graphics will take full advantage of the quality of an RGB connection.

I imagine that combined DVD/VHS machines will have similar things in common. With that in mind, I think I need to limit my search to VHS-only machines. Remember what started this - the premise that an RGB connection from a VHS machine to a TV set gives best pictures - and my counter that RGB would not improve on S-video, so apart from Teletext and pass-through, what would be the benefits?

And from studying the Philips VR-813 manual, I've learnt that there is a potential benefit from taking in RGB pictures and turning them to YC for recording. Upon playback, there is still no benefit from RGB compared to S-video, of course (ignoring the teletext/OSD for a moment). Back when this machine was launched, there were relatively few RGB sources out there, so this benefit must have been rather under-utilised - for that reason I do feel sorry for the designers of such a heroic machine!

All of my decent VHS and S-VHS machines (e.g. NV-HD100, NV-FS88) predated RGB loop-through, which is a shame as that would have given me more options about how I hooked up stuff. It's good to learn that RGB loop-through did become a popular facility as we went into the DVD and digital TV ages
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Old 20th Jan 2019, 1:21 pm   #11
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Default Re: RGB signals from a VCR

I am afraid neither of my SVHS VCRs are in use at the moment so I wasn't able to check . I used to use the S-Video connections.

Last edited by emeritus; 20th Jan 2019 at 1:26 pm.
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Old 20th Jan 2019, 1:24 pm   #12
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Default Re: RGB signals from a VCR

Quote:
Originally Posted by Red to black View Post
The Grundig VS500 series used the G-deck IIRC, the VS510 and VS520 had teletext for definite, I cannot remember if the VS500 had text though.
There was also the 530, 540 and 550 in this range of machines, however whether they had text or not I cannot recall for sure but I suspect they did
Yes - those look like the thing! I'm not sure which exact model we had, but the photos of the innards of the 510 certainly look very familiar. Thank you

Now, I can't grab the service manual from Elektrotanya until tomorrow, but I'm hoping that this did output RGB from the teletext character generator - it would make sense, as the complicated user interface came from this. As mentioned, we didn't have anything with Scart, so we used it via the modulator - so at the very least it contained a PAL encoder - and if it did output RGB, it would need a PAL decoder (or use pin 16 to put the TV back into composite mode).

Thanks again,

Mark
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Old 20th Jan 2019, 2:12 pm   #13
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Default Re: RGB signals from a VCR

Just for facts sake: (VCRs/DVRs with) RGB signals didn't "get around that pesky Macrovision protection" by default. Some (few) models perhaps did; but RGB signals weren't inmune to MV by design, quite on the contrary.

Also, given that VHS was inherently a (modified) composite format family (it records colour-under), there was NO real advantage in RGB output over S-Video. The latter was as good as (S-)VHS got.


That said, there were a few (S-)VHS VCRs with RGB out —
  • some early ones from Philips (VR813, as already mentioned, but the picture in RGB wasn't that great),
  • some pro series from Panasonic/JVC (e.g. AG-8700, component out)
  • Philips and JVC even marketed (briefly) a couple of S-V → RGB transcoders (at the time, there were few TVs with a S-Video input): Philips AV5181, JVC KMV7
  • and later, the Thomson DVH-8090 could output RGB too (but only recorded composite or S-Video — even from the RGB-in, even in D-VHS!).

And —as @mhennessy & @cmjones01 pointed out— the S-VHS models quoted by @emeritus are RGB-passthrough only.
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Old 20th Jan 2019, 2:17 pm   #14
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Default Re: RGB signals from a VCR

I remember a workplace argument that someone started (perhaps it was me) about this. I was adament that no VHS had RGB except perhaps passthrough.

It looks like I was wrong
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Old 20th Jan 2019, 5:42 pm   #15
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Default Re: RGB signals from a VCR

Oh I don't know - apart from those later machines that support passthrough, it seems to be only the teletext machines that do it. Which does make sense, and therefore I don't think you need the dunce hat

The interesting discovery (for me, at least) is the small number of machines (well, the Philips VR813 at least) that take in RGB and convert that to YC for recording - that possibility hadn't occurred to me.



Tester, welcome to the forum

Thank you for the comments, which help to confirm my thoughts.

Interesting to hear that the Philips machine wasn't so good in RGB - of course in that case, the TDA3561 would be doing the PAL decoding instead of the TV's decoder. I always thought the TDA3561 was a pretty good decoder, but by 1991 it was rather old and perhaps newer decoders had better performance? If nothing else, it's one more part of the machine that has to be correctly adjusted on the production line. Looking at the manual, there's quite a lot to set up.

I was ignoring pro machines. I am familiar with a few of those, and have had to show immense willpower when seeing them in the WEEE skips! I've seen some that support YPbPr, but I don't think I've seen RGB - that's much less use in the professional world. I can't immediately recall seeing Scart sockets on them, but perhaps there were exceptions (but would be surprised if they went beyond S-video if present)

All the best,

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Old 20th Jan 2019, 6:30 pm   #16
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Default Re: RGB signals from a VCR

Yes the Philips VR-813 is probably one of my favourite all-rounders with quite an extensive feature list for its time..and no doubt a hefty price tag to match! The only thing(s) really missing was a TBC and perhaps the Cue/Review motor of its Panasonic counterparts. Not quite the semi-professional editing solution in its day..but almost!

It also boasted newfangled Widescreen recording to go with an equally impressive Philips widescreen telly, that was marketed as part of 'The Collection' - all part of Philips' flagship Matchline series. Not bad for 1991!

I believe the VHS-only model (with VPT), was the VR-713, and the VPT-less, VHS-only model was VR-712. Also have a vague recollection of a version with a satellite tuner and polariser fitted, presumably for the European markets only.

IIRC one or two of the later 'Matchline' Philips S-VHS machines also sported VPT, such as the VR948, and the rather fancy VR969 with its lovely little analogue timepiece in the middle. I recall there was a matching 14" portable TV that also had the same analogue style clock. Very posh!

With regards to these later 'Matchline' machines, I'm not entirely sure if they actually processed the RGB signal in the same manner as the VR-813. As mentioned, pretty much all machines with twin SCART sockets will allow 'loop-thru' of the RGB signal for the convenience aspect (e.g. record from a cable or satellite decoder box etc). It's easy to confuse the two scenarios.

As for the Grundig machine you mention, also try running a Google (image) search for something like 'Grundig GV VPT' - the machines that feature VPT all seem to have it as part of their respective model numbers.
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Old 20th Jan 2019, 7:51 pm   #17
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Default Re: RGB signals from a VCR

Thanks for the welcome, Mark (longtime reader, but I only post when I've something to add to the discussion —preferably from firsthand experience).

Quote:
Originally Posted by mhennessy View Post
···I was ignoring pro machines... I've seen some that support YPbPr, but I don't think I've seen RGB···
Indeed, as I mentioned, pro-decks had component out —not RGB Scart— but I though I'd mention them since YPbPr and RGB are 'easily' (and quasi-losslessly) convertible.

BTW, Ceefax-subtitling-VPS compatibility on a VCR dind't automatically mean RGB support, not even for passthrough. Grundig —avid supporters of 'teletext/VPS-enabled' VCRs— often didn't offer it, even on TOTL models.

Then again, to confirm your recollections, there were VCRs with satellite tuners built-in — mostly German or aimed at their market, with their love for DBS signals. Grundig had a couple of models, JVC as well (their JVC HR-S9000 even incorporated D2-MAC!)

RFT Stassfurt, B&O, Grundig again and a few selected other brands also integrated SAT-tuners into their TVs from the mid-80's and up to the 90's.
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Old 21st Jan 2019, 4:50 am   #18
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Default Re: RGB signals from a VCR

The VR833/VR838/VR948 were actually for a large part designed by Grundig in the then fresh joint venture with Philips. I haven't checked the signal processing though, but it could be worthwhile.

I think the Philips VR716 had a sattelite tuner.
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Old 21st Jan 2019, 2:38 pm   #19
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Default Re: RGB signals from a VCR

So I've been able to look at the manuals for the Grundig VS5x0 machines, and no, they don't output RGB after all! I guess it saved them having to add a PAL decoder, I guess...
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Old 21st Jan 2019, 3:14 pm   #20
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Quote:
Originally Posted by Maarten View Post
The VR833/VR838/VR948 were actually for a large part designed by Grundig in the then fresh joint venture with Philips. I haven't checked the signal processing though, but it could be worthwhile.

I think the Philips VR716 had a sattelite tuner.
The VR716 is an interesting beast

Yes, it has a satellite decoder. Looks to be a regular analogue/PAL setup to me - not some form of MAC, which would make RGB worthwhile.

Looking at the schematics, it doesn't output RGB. But it does have teletext. The outputs from the SAA5243 go straight into an MC1377 PAL encoder - and nowhere else. Like the Grundig machines...

But I note the Radio Museum entry claims it has "direct output RGB". That's confusing.

Sadly I can't look at the first 3 machines you mention because I've again reached my Elektrotanya limit. I'll try again later.

All the best,

Mark
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