Originally Posted by DaddyLongLegs
Turns out I'm a bit of an idiot. The SCART to YUV/Component adapter works just fine with my SNES and DVDO Edge. I finally got a picture when I thought to myself "this sync input has to be here for a reason". So I soldered an RCA cable from the SCART cable that is supposed to be known as "composite sync". I got a picture! A horribly discolored and wavy picture, but I got one. At least it shows I am on the right track.
The SCART standard only supports RGBS (R=red signal, G=green signal, B=blue signal, S=sync signal). RGBS was the original "component" signal.
It was later bastardised by some manufacturers to support YUV/YPrPb/YCrCb "component" signals, which unfortunately used red, green and blue leads similar to the leads for RGBS, causing great confusion, as the signals carried by each lead are very different between RGBS and "component".
I have no idea whether the older games consoles support RGBS or "component", but it is important to know which one is being output and to connect accordingly.
The Sync lead is very important for RGBS as no frame synchronisation information is carried on R, G or B leads. Sync is usually equivalent to the composite video output minus colour information.
Component YUV/YPrPb/YCrCb is different in that Y is equivalent to the RGBS Sync signal but the other 2 leads are colour difference signals. Synchronisation is carried on the Y lead and with the colour difference leads, 3 is all you need for YUV, but RGBS does need 4 leads with the appropriate signals on each.
Considering the age of SNES, I would say that it might support RGBS if it has a SCART connector. Ideally you would want a SCART to RGBS cable to match the RGBS output signal. If you use a SCART to YUV adapter, it will not be outputting the required RGBS signals on the right leads (for a start Y is on the green socket when it is not a green signal but equivalent to the Sync signal, so you would be feeding Sync to green and not getting any green signal at all to the Edge).
Only use a SCART to YUV adapter if you know positively that the games console is outputting YUV/YPrPb/YCrCb "component" signals.
It is sometimes possible to use a composite video output from a device as the Sync signal. If you could get into the YUV adapter and re-assign the pins to make the RGB coloured sockets actually output red, green and blue signals, then in conjunction with the composite video as sync, you might actually get true RGBS. However, if possible, a true SCART->RGBS cable is best.