The N64 is PAL and completely original (I’m in the UK).
It is connected by scart cable to the OSSC. I have the red/white/yellow N64 cable too and also the N64 aerial cable.
I’ve attached some images below. The first is of the screen that I get when I turn the console and OSSC on, once I press RGBS it turns to what appears to be the correct channel. The music is perfect but screen very very dark and vague.
I get the impression I need to tune it or change the settings on the OSSC but have no idea how to do that 🙁 Could you help in any way?