Quick Question Duel purpose SNES scart cable RGB & S-Video

Hello All I just recently built a SNES scart cable from a Wii Scart cable and a couple of old AV SNES cables. The issue I'm having is pin 15 on the scart Connector when both lines are connected from the SNES red from RGB and chroma from the S-video are connected it causes the red to bleed when the chroma line is connected but is perfect when I remove it

I wanted both S-video and RGB so I can use the same cable with both my NTSC gamecube and NTSC SNES

This is all connected to a French Sony CRT

Thanks

 

You could try adding a switch so you can turn the chroma line on or off depending on which output you're using.

 

Yeah thats what I was considering would not be difficult at all and I know it would work I was just wondering if there was any other method