1) It's not just 3 and 6 pins, the top and bottom flanges are actually contacts for different circuits. Thus, the working lead has 6 pins (luma, chroma, L/R audio, and 2 grounds) and the nonworking has 12 pins. (additional composite, RGB, and 4 more grounds I guess?)
This makes utter sense.
2) The presence of the additional pins, since they aren't connected to anything at the other end, should not affect operation at all. (Of course.)
So it looks like the non-working cable is miswired somehow.
But I still haven't figured out why it won't work with SNES but it works with N64. ?8-/
> I've checked my connector pins on my s-vid cable and it's also 3 pin. How odd that the 6 pin one didn't work. I wonder if you manually removed the 3 pins to make it look like the 3pin model, if that'd work? =P