I’m not sure there’s a solution for you that won’t require spending money.
In a nutshell, Irem M72, Taito F3, and some Toaplan V2 boards are notorious for using non-standard sync (here, 55.01hz is a bit off the 60hz the set expects) and Samsung sets are notorious for being intolerant of non-standard sync.
Your OSSC is getting a signal lock, so it is outputting a signal to your TV-your TV just doesn’t like it. I’m fairly certain that adjusting the OSSC’s advanced settings won’t help because those are usually for helping the OSSC get a sync lock when it can’t get a sync lock.
IMHO, your options are:
1) Try a different SuperGun like the HAS that can buffer or regenerate the sync signal to standardize it.
2) Try a different upscaler with a frame buffer like the RetroTink-5X, DExx-vd_isl, or Framemeister.
3) Try a different display that is more tolerant of non-standard sync, such as a PC CRT monitor, a TCL flat panel monitor, or an LG HDTV.
Hopefully someone else besides me has other suggestions for you to try. You could also try posting in the Shmups or VideoGamePerfection forums since a lot of OSSC experts frequent those forums.