How do I convert 7-pin S-video to 4-pin S-video?

January 6, 2006 4:45 PM

Can I "convert" a 7-pin S-video connector to a standard 4-pin S-video connector by simply cutting off the extra pins?

Background story: I'm connecting a DVR with S-Video output to a DVD recorder with component input. I bought this adapter, which unfortunately has the 7-pin connector. If the DVR had component output, I'd just use that. Unfortunately, it doesn't.

I don't want to shell out $20 for the 7-pin to 4-pin adapter, so I'm turning to pliers. The 3 extra connections include a "Component Video" connector, its ground, and an unlabeled one.

Finally, RCA is too low-quality to use, so this was my solution.

Thanks!

posted by spiderskull to technology (10 comments total)

This and this seem to suggest you can.
posted by j at 5:00 PM on January 6, 2006

My guess is that the three extra pins are for component (RGB) video, since there are three of them. The 4-pin S-Video connector doesn't output these signals, so my wager is that it won't work. If the DVD recorder has a regular 4-pin S-video input, just use that instead.
posted by kindall at 5:08 PM on January 6, 2006

I should add that shelling out the $20 for the adapter also will not work.
posted by kindall at 5:10 PM on January 6, 2006

oops - I should have read more carefully (and looked at your "this adapter" link).
So, I agree with kindall.
But I do see links for 4-pin S-Video to RCA when I search google, so I'm not sure.
posted by j at 5:20 PM on January 6, 2006

The DVD recorder doesn't have S-Video input. RCA would be easy, but the quality is really terrible (it's noticeable on the display we have).
posted by spiderskull at 5:52 PM on January 6, 2006

You can't do the conversion you want easily. You can take a more complex signal and turn it into a simpler signal easily enough, but you are trying to take a 2-wire (simpler) signal and turn it into a 3-wire (complex) signal.

The adapter you bought probably combines the two chrominance channels of a component video signal (the three rca end) with a cap to produce an s-video signal. As I have already said, this simple circuit only works in one direction, from component video to s-video. Here is a similar circuit for converting svideo to composite video.

According to your links 7pin svideo just has a composite video signal in addition to svideo signals. This sounds about right, I have a couple of 7pin mini-din to 4pin mini-din plus RCA adapter dongles which would be consistent with this implementation.

Why not just connect the s-video output to the DVR's s-video input (assuming it exists)?
posted by Chuckles at 6:17 PM on January 6, 2006

The DVD recorder doesn't have S-Video input

That is a real problem... You need a device that can properly separate the two chrominance channels on an svideo signal, I'm sure it exists but it isn't going to be cheap.
posted by Chuckles at 6:26 PM on January 6, 2006

The DVD recorder doesn't have S-Video input.

Sounds like time for a new DVD recorder, or else for a new DVD player.
posted by kindall at 7:13 PM on January 6, 2006

Following on Chuckles' answer, your only hope of this cable working is if your TV is smart enough to notice that it's getting a Y/C signal instead of a Y/Cb/Cr signal. My TV can display a standard composite signal just fine if I plug it into the Y jack alone of the Y/Cb/Cr input. So, you may be lucky and get a picture if you just plug in Y and Cb. And that's if the cable is dumb enough to work backwards (which, from the looks of it, it is).
posted by zsazsa at 11:08 PM on January 6, 2006

I don't think you'll be this lucky, but I asked to same question (about nine-pin HD to S-Video, actually) to XFX, my videocard manufacturer. And even though I hadn't bought the card from them directly, they sent me the adapter free.
posted by glibhamdreck at 9:06 AM on January 7, 2006