A Brief Guide To the SCART Socket.

What is a SCART socket?.

A SCART socket is a 21 pin connector fitted on many European TV, VCR, and Satellite products, it provides stereo sound and video signals both in and out of the item of equipment (obviously depending on the particular type of equipment), it can also provide RGB signals, which can be useful for connecting Video Game Consoles or Digital TV Set Top Boxes (STB's). The main reason for using a SCART lead is to provide stereo sound from a stereo VCR, STB or satellite receiver, this is the only way to get stereo from these sources via your TV, a NICAM (or other kind of stereo TV) won't provide stereo sound unless the source includes a stereo encoder (NICAM or other), and these are too expensive for domestic equipment. It may also provide slightly better picture quality, but with the high quality modulators used these days it often doesn't - and in fact sometimes seems slightly worse.

The SCART connector was developed by the French, originally for the sole purpose of preventing foreign TV imports, previously the French had legislation that prevented any TV imports unless the set was capable of receiving the old French 819 line monochrome system. This effectively stopped any foreign sets from being imported, but the demise of the 819 line system prevented this from being a valid reason for banning imports, so in order to try and maintain their private market they introduced the SCART socket, and passed legislation that said all TV's sold in France since 1980 must have a SCART socket. This was obviously much less of a deterrent, it was far simpler for TV manufacturers to add a SCART socket than to produce a dual-standard set, and the SCART was actually useful elsewhere with the development of cheap home video recorders.

SCART stands for Syndicat des Constructeurs d’Appareils Radio Recepteurs et Televisieurs, it is also known as a PERITEL Socket, or a Euro Connector.

SCART socket connections.

Pin	Function	Signal	Impedance	CVBS stands for ‘Composite video, blanking, and sync’ - a standard video signal as output by VCR’s and satellite receivers. SVHS inputs were not included in the original specification, but are usually added (where fitted) using ‘CVBS In’ (pin 20) for the luminance, and ‘Red In’ (pin 15) for the chrominance signal. Depending on the set this may prevent RGB being available on the SCART socket, however some sets allow the use of both RGB and SVHS on the same socket. On a two SCART socket set, it's usual for only one of the sockets to have RGB inputs. The Intercom. lines are used by different manufacturers in different ways, for instance pin 12 of the Decoder SCART on Pace PRD series receivers (among others) is used to connect to an external positioner, and pin 12 of the VCR SCART on a Grundig STR1 Satellite (PRD clone) is used for timer recording from a Grundig VCR - where the VCR selects the Satellite channel at the correct time.
1	Right Audio Out	0.5V	1KOhm
2	Right Audio In	0.5V	10KOhm
3	Left Audio Out	0.5V	1KOhm
4	Audio Earth	-	-
5	Blue Earth	-	-
6	Left Audio In	0.5V	10KOhm
7	Blue In	0.7V	75Ohm
8	Source Switching	varies	10KOhm
9	Green Earth	-	-
10	Intercom. Line
11	Green In	0.7V	75Ohm
12	Intercom. Line
13	Red Earth	-	-
14	Intercom. Earth	-	-
15	Red In	0.7V	75Ohm
16	Fast RGB Blanking	varies	varies
17	CVBS earth	-	-
18	Fast blanking earth	-	-
19	CVBS Out	1V	75Ohm
20	CVBS In	1V	75Ohm
21	Socket earth	-	-

What it all means!.

In general use, most of the connections are not used, from a VCR to a TV the only ones that would require connecting would be the Right and Left Audio Out, and CVBS Out (on the VCR end), and Right and Left Audio In, and CVBS In (on the TV end) plus the relevant earth connections. Normally pin 8 would be connected as well, this forces the TV to accept input from the SCART socket when it goes high, pin 8 from a VCR SCART switches high when play is pressed (or Menu selected on modern VCR's), however, this can give rise to problems. Some TV's are totally overridden when pin 8 is high, preventing any viewing of normal channels, for this reason I would usually advise disconnecting pin 8. It's not normally too bad with VCR's, but with Satellite receivers it can be a real problem, whenever the Satellite receiver is turned on the TV will switch to SCART - a huge problem if (like many people) you feed the Satellite receiver around your aerial distribution system, so never normally turn it off.

Which lead do I need?

There are two normal types of lead that can be bought, a fully wired lead (hardly ever needed) and a partially wired lead (does for almost all requirements).

The partially wired lead has the video and audio connections both ways, plus the pin 8 switching wire, if you have problems disconnect pin 8. This lead would be suitable for connecting from a VCR to a TV, from a Satellite Receiver to a TV, and from a Satellite Receiver to a VCR.

The fully wired lead has all the pins connected, and is only really used if you are using RGB, the main sources for this are Games Consoles and Digital STB's (and some D-MAC decoders), however, there are many problems with RGB from STB's, including horizontal picture shift, and disablement of Teletext on the TV. I've tried a number of different TV's from STB's and haven't seen one yet which gives as good a picture via RGB as it does via composite video. It certainly has the capability of far better quality, but the MPEG compression used seems to reduce the quality well below that possible, and, of course, very little of the programming comes from a sufficiently high quality source.

My personal view - don't bother with RGB, except for Games Consoles - it makes a Sony PlayStation look superb!.

Problems!

You sometimes get problems with connecting a SCART lead to a TV set where the CVBS output interferes with the CVBS input (often when the TV is forced to SCART by pin 8, the set still outputs the original tuner video signal from pin 19), if the lead isn't sufficiently well screened this can give rise to picture problems. Easiest solution is to disconnect pin 19 at the TV end of the SCART lead, this doesn't cause any problems as it's not normal practice to record the output of your TV.
TV stuck on AV - disconnect pin 8 in the SCART lead.
Teletext on TV won't work (or is poor contrast) - disconnect the RGB leads from the SCART lead.
Reliability - as you can see from looking at a SCART plug, they are not a very sturdy connector, and in practice tend to give a fair few problems. If swapping the lead doesn't cure the problem, it may be there are dry joints on the socket. This is quite common in VCR's, the socket is often mounted solely by it's soldered connections, and frequent use can make these become loose, creating intermittent problems.

There are more SCART details (particularly for Satellite) available on Martin Pickering's Satcure Site - Link To Satcure

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Last Updated 25/04/07