I tried the RetroRGB.com's Brightness / Signal correction mod for my SNS-CPU-1CHIP-02 - but I didn't notice any positive changes.
What I did notice is that now there's this "ghost" image on the background. When starting Super Castlevania IV, right before the Konami logo, I can see it.
Any clues on the reason why?
(silver metal plates for shielding and grounding are mounted; using shielded luma SCART RGB cable )