I have made 2 separate scart cables for my genesis and I keep getting a weird double image problem. I tried adding a 220 cap to the Sync and nothing changed. I have 3 different systems I tried my cable on and even tried different power supplies. It looks like a sync issue but I have not idea what is causing it. I tested each with a multi meter for continuity to make sure nothing was bridged. http://imgur.com/a/Zyf6H
Would help if you said what monitor / TV you are using. Have you used it with other consoles? It it is a SCART TV, have you made sure that you are selecting AV (rather then letting it auto switch), how have you wired in pins 8 and 16 on the SCART lead?
Sorry I forgot to mention I'm using a Framemeister with the most recent firmware. I'll try adding a sync stripper and see what happens.
Problem solved. Composite was connected to sync instead of raw sync. Thanks everyone for the help narrowing it down to a sync issue and not something else.