S-Video Information

      4  3
    2      1     pinout of a 4-pin male, looking down at the connector
       ==

    1 = GND (ground Y)
    2 = GND (ground C)
    3 = Y (intensity, luminance)
    4 = C (color)

To make an S-video to RCA adaptor, connect pins 1 and 2 to the outside (ground) of the RCA plug, pin 4 to the inside connector, and leave pin 3 unconnected.