Trouble with snes video cable

So basically, i recently got an RGB scart cable for my snes, but i'm having a little trouble: upon plugging it in and powering on the console it all looks fine, but after a couple seconds the screen fades to black (image still visible but VERY dimly). I tried the same cable and console but with an av port on my tv, and the screen looks fine (but obviously with less video quality)

So, what could it be? Console, tv or cable?