Using S-VHS cable for RGB

15 Nov 2005 9:34 AM

Baz

Hi,

I need to be able to send the video content of an RGB scart via an
existing S-VHS cable.

It appears that the S-VHS pinout will give me 5 connections including
the shield so I was thinking of wiring up an adaptor at each end of the
S-VHS cable to convert the pinout back to RGB scart.

Unfortunately RGB Scart seems to need 7 pins

7 Blue
11 Green
15 Red
8 & 16 H-Sync
17 Ground
18 V Ground
20 Comp Sync

Can anyone tell me if all these pins are needed for RGB scart as I need
to get things down to only using 5 wires.

Cheers

Baz

15 Nov 2005 10:01 PM

Andrew Rossmann

[This followup was posted to rec.video and a copy was sent to the cited
author.]

In article <1132047290.077246.263***@g47g2000cwa.googlegroups.com>,
baz.8***@virgin.net says...
Show quoteHide quote

> I need to be able to send the video content of an RGB scart via an
> existing S-VHS cable.
>
> It appears that the S-VHS pinout will give me 5 connections including
> the shield so I was thinking of wiring up an adaptor at each end of the
> S-VHS cable to convert the pinout back to RGB scart.
>
> Unfortunately RGB Scart seems to need 7 pins
>
> 7 Blue
> 11 Green
> 15 Red
> 8 & 16 H-Sync
> 17 Ground
> 18 V Ground
> 20 Comp Sync
>
> Can anyone tell me if all these pins are needed for RGB scart as I need
> to get things down to only using 5 wires.

As far as I know, an S-Video (not S-VHS, which is a tape format)
connector only has 4 connections. Signal/ground for luminance (B/W), and
signal/ground for chroma (color.) Both are typically shielded cables.

You might be able to combine the two grounds, but it looks like 6 may
be the minimum.

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16 Nov 2005 8:04 AM

Dave Martindale

"Baz" <baz.8***@virgin.net> writes:

>I need to be able to send the video content of an RGB scart via an
>existing S-VHS cable.

>It appears that the S-VHS pinout will give me 5 connections including
>the shield so I was thinking of wiring up an adaptor at each end of the
>S-VHS cable to convert the pinout back to RGB scart.

It won't work. You might be able to do it with 2 or 3 Svideo cables.

A single S-video cable is set up to carry two independent signals. Each
signal is carried in a coaxial cable, which is a centre conductor plus
surrounding shield. You can only connect the shield in each coax to
ground; you can't carry a signal on it without damaging the signal
that's supposed to be carried by the centre conductor.

>Unfortunately RGB Scart seems to need 7 pins

>7 Blue
>11 Green
>15 Red
>8 & 16 H-Sync
>17 Ground
>18 V Ground
>20 Comp Sync

>Can anyone tell me if all these pins are needed for RGB scart as I need
>to get things down to only using 5 wires.

That's just the pins in the *connector*. It sounds like there are 5
independent signals present (R,G,B, Hsync, composite sync). To carry
those signals in a *cable*, you need 5 independent pieces of coax. The
centre conductor of each coax is connected to a signal pin, while all of
the grounds of all of the coaxes are connected to ground. To carry 5
signals, you'll need to rewire 3 Svideo cables.

It is possible that the end device doesn't use Hsync, and only uses
composite sync. In that case, you could get away with 4 signals.

Dave

20 Nov 2005 8:32 PM

fiveiron