[S-Video]

Pin Name Description
1 GND Ground (Y)
2 GND Ground (C)
3 Y Intensity (Luminance)
4 C Color (Chrominance)

[SCART]

Pin Name Description
13 R GND RGB Red Ground
15 R RGB Red In / Chrominance
17 VGND Composite Video Ground
20 VIN Composite Video In / Luminance

Pin 1 on the S-Video connector -> Pin 17 on the SCART connector.
Pin 2 on the S-Video connector -> Pin 13 on the SCART connector.
Pin 3 on the S-Video connector -> Pin 20 on the SCART connector.
Pin 4 on the S-Video connector -> Pin 15 on the SCART connector.