For a variety of reasons, the SCART arrangement is the most diabolical interconnection system ever devised for domestic video equipment. Be thankful it has not caught on in America.
The theory when it was devised in France in the 1970s sounded very good. It was supposed to make it easy for the non-technical person to make connections easily with just one big plug, instead of having to worry about left & right audio, composite video, component video, which were inputs and which were outputs, etc. It probably served that purpose reasonably well in the early years, when the majority of people were just connecting one VCR to one TV.
Over the years though, the specification has been amended to allow for S-video connections, widescreen switching, and so on, plus of course a typical domestic TV setup now has half a dozen boxes all interconnected.
Some boxes support some of the SCART video interfaces, but not all (e.g. they might have composite video but not RGB). Even on the same piece of equipment, two different SCART sockets can behave differently. You might find that the AV1 socket has both inputs and outputs, while AV2 has only inputs. Or AV2 might support S-video input & composite while AV1 is RGB & composite. Unfortunately, the manuals often don't include this information, so it can sometimes be a matter of trial and error to match up a suitable SCART socket on one unit with a suitable one on another.
Then there is the dreaded auto-select line in the SCART interface. The idea is that switching on a piece of equipment (VCR, cable converter, or whatever) causes the TV to switch automatically to the appropriate SCART input. Unfortunately, that auto switching can often be more trouble than it's worth, as if you use a SCART socket which supports auto-select for recording, you can end up messing up the recording just because you switched on your TV and DVD player to watch a DVD! I've lost count of the number of systems where mutiple interconnects with auto selection have caused so much trouble that I've just gone through every SCART cable and cut the appropriate line so that the user can switch everything manually.
But to get to the specific case: To work out the best arrangement we really need to know what type and how many inputs & outputs you have on the existing equipment. How many SCART sockets on the TV, VCR, and cable box? Do you have any other sockets (RCA, S-video, etc.)?
