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  1. There's a guy that's already done this with Umatic player that only has composite output natively, though he doesn't detail the exact circuit used in the paper unfortunately. I've also seen other high end refurbs of Umatic machines have S-Video output added, though they won't tell you exactly how since it's probably considered a selling point for their machines. I bring up Umatic because it's also a "color under" format and none of those machines ever had S-Video, though S-Video should be an improvement to the usual composite output they have. Some do have DUB outputs which requires some additional processing to convert to S-Video, but the machines already contain the circuitry to get the chroma to the right subcarrier frequency since they do it to create their composite signal before it is mixed.

    The paper below explains why one would want to do such a mod better than I ever could, but same things would apply to adding S-Video output to a non-SVHS machine. The original question remains however, "to what degree is there a visible improvement on a basic player and how easy is it to do?" Hence why I want to test it and see.

    https://www.digiommel.fi/images/Optimizing%20Digital%20Transfer%20of%20U-matic%20Video...Recordings.pdf

    To reiterate, I'm not saying that adding S-Video output to a machine that never had it makes it overall on-par with a flagship S-VHS machine with TBC, but it does claw back a key advantage of SVHS players - the S-Video output. S-Video output is better than composite - all else being equal, hence the point of adding it to machines that don't have it.
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  2. Capturing Memories dellsam34's Avatar
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    There was actually a guy who tapped into a Y and C on a uMatic machine circuit board and made a cable but I could never find that link, I remember I had to use the wayback machine to get the picture to load, Let me give it another shot.

    Edit: I found it:
    https://web.archive.org/web/20120609002928/https://captain18.livejournal.com/140367.html
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  3. @aramkolt: The practical problem ist just to modify a particular VCR. Download the service manual with circuit diagrams of your VCR and then suggest what to do if one thinks it's worth the effort.
    Access to the separate luma and chroma signals (wires) is probably easier - but less effective - with some old cheapo VCRs which did not even support proper frequency interleaving at the composite output but simply used narrow bandwidth filters to minimize spectral overlap - at the expense of resolution (sharpness).
    Last edited by Sharc; 17th Jan 2025 at 03:39.
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  4. Originally Posted by dellsam34 View Post
    No, uMatic was designed and sold for consumer but later was adopted by some broadcast companies, it is recorded RF just like VHS with chroma under scheme. You're mixing uMatic with another pro digital composite format made by Sony.
    For me umatic VTR is for example Sony VO-4800 - later evolved in Betacam.
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  5. Originally Posted by Sharc View Post
    Access to the separate luma and chroma signals (wires) is probably easier - but less effective - with some old cheapo VCRs which did not even support proper frequency interleaving at the composite output but simply used narrow bandwidth filters to minimize spectral overlap - at the expense of resolution (sharpness).
    In PAL chrominance is around 4.43MHz with bandwidth around +-1.5MHz at best = typical VHS is capable to provide Y and C in non overlapping fashion even in CVBS (VHS is unable to deliver Y with more than 3MHz, C bandwidth is approx 300kHz) - so technically you can combine Y and C and they not interfere at least in theory...
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  6. Originally Posted by dellsam34 View Post
    There was actually a guy who tapped into a Y and C on a uMatic machine circuit board and made a cable but I could never find that link, I remember I had to use the wayback machine to get the picture to load, Let me give it another shot.

    Edit: I found it:
    https://web.archive.org/web/20120609002928/https://captain18.livejournal.com/140367.html
    Definitely never would have found that without the post! Only issue I think is that the levels for chroma and luma probably aren't going to normally be at the levels needed for S-Video at least not on all machines - I'm kind of surprised that they were in this case if he just did a direct tap of those two test points and maintained the appropriate levels when terminated with 75 ohms. Luma actually might be at the right levels on some machines though, I saw on the diagram of the VP-9000 anyway that it lists a "Y output" though there's not actually a connection on the back for that. There is an odd expansion slot on some machines that is usually empty and I've seen what look to be shielded coax going to it which could contain some version of chroma or luma I suppose maybe.

    If wiring up a simple op amp for both chroma and luma lets you set the levels with a potentiometer, it really should only be a matter of putting out a premade board for like $25 that have the op amps and any other components like the potentiometer for levels and solder points for 5V, Ground, Y and C - though that could be wishful thinking that it could be that simple. Prime targets would still be machines that never had S-Video outputs like Umatic and Betamax. However, if it was as easy as what that guy did on say a cheap VCR and it's just an S-Video cable soldered directly to the test points without the use of op amps at all, that seems like a pretty easy mod for most people to do, and also easily reversed.

    The other idea I had was to use certain S-Video distribution amplifiers - some of those have separate adjustments for Y and C which can be done from the outside of the device that I presume use relatively low noise op amps and also allow you to choose if you terminate (with 75 ohms) the input *or not* with a switch also accessible from the outside. Could also be that a regular standalone proc amp could do it as well, but those I think do their own internal 75 ohm termination automatically which may drag the signal down too much to be usable or could damage things. The model that I am aware of that has these features would be the Extron MDA 6SV (or 4SV) EQ. The EQ part denotes you can adjust chroma and luma levels and there's the switch on the back for HiZ vs 75 ohm termination. Not saying you should go seek one of those out for a regular VHS player as basic S-VHS machines will be cheaper to just acquire and requires no mods, but to add to betamax or U-Matic.... maybe.
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  7. Capturing Memories dellsam34's Avatar
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    If you are going to add an external device you may as well get a DPS-295 or DPS-235 that takes the DUB output and processes it into Y-C plus the added built in frame TBC.
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  8. Capturing Memories dellsam34's Avatar
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    Originally Posted by snafoo View Post
    I wanna see the difference in quality between regular VHS and S-VHS. Does anyone know of any youtube videos, or videos on any other site, that would show it?
    This video illustrates just that, This link starts from the money shot but you can watch the entire video if you would like. The portions of the frame are labeled accordingly, so look at the glass bottles middle band and see how S-Video out has more details compared to composite out.
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    Hmmm, I'm, not seeing a significant difference. $500 worth (for an S-VHS VCR with now-unknown-quality heads)? And is the difference going to stand out when the video is running, as opposed to pixel-peeping at stills? I'm not sure that it will.

    Image
    [Attachment 85279 - Click to enlarge]
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