Anyone in the US able to diagnose RGB cables?

Long story short I have three I may want a checkup on. Issue is, I'm in USA where not many people own RGB equipment to help me. Overseas would add extra cost/delay to getting this done.

Genesis 1: jailbars
Genesis 2: jailbars
Saturn: incorrectly becomes composite video rather than RGB from my Japan console, using the HDMI upscaler I've got

Thanks! These are Euro SCART wired by the way. If your devices accept only JPN RGB input they won't do any good here.