Just opened up the SCART leads for my megadrive and saturn.
The Saturn has no caps on the RGB lines. Or the composite (getting sync from this line). I will add some caps tomorrow to see if that helps with the picture.
The Megadrive pins are loose and look like they are touching inside the scart connector so I will put some heat shrink around them and try to glue some in place so they don’t move about.
Still no clue about the AES though :/