I know, I just meant the naked TG16 and Core Grafx on their own. A modded IFU would be the ultimate solution as it does not require any modifications to the actual systems and supports CD games as well.
But I am a little surprised that no one has ever made a SCART cable for just the TG16/Core Grafx systems.
If I am not mistaken the signals on those ports need a bit of boosting to work well on most TV's so that might be the problem.