First, sorry if this has been posted, but I couldn't find it in the forum and the first 20 pages of a Google search didn't turn up any substantial information. I'm pretty sure that someone else has discovered this before me since I think that I've seen one or two sites that offer the S-Video mod and, also, I know that some of you might have figured this out way before I did, but I haven't seen this info accessible anywhere so I'm posting it here.
The mod is based on the SNES rev. SNS-CPU-RGB-01 which has the chip U7 "S-RGB" (ROMH BA6595F). That "S-RGB" chip has the same pinout of the chip present in rev. SNS-CPU-1CHIP-01 and SNN-CPU-01 (ROMH BA6596F) BUT different from the U7 chip in older revisions (ROMH BA6592/93/94F):
U7 chip in rev. SHVC-CPU-01, SNES model SNS-001. Notice how pin 12 ISN'T connected.
U7 chip in rev. SNS-CPU-RGB-01, SNES model SNS-001. Notice how pin 12 IS connected. This suggest that it's a different chip.
U7 chip in rev. SNN-CPU-01 a.k.a. SNES Jr. model SNS-101.
The mod:
Pictures:
Those two resistors are 150 Ohm in parallel = 75 Ohm