7 pin mini-DIN female connector at the computer.
Power Macintosh 7200, 7500, 8500, 9500
Apple’s S-Video connector is a 7-pin mini-DIN rather than the standard 4-pin S-Video socket, with the three additional pins carrying an I²C control bus (clock on pin 5, data on pin 7) and a +12 V supply rail (pin 6, 250 mA maximum). It appeared on the AV cards of Power Macintosh models from 1995 onwards, including the 7200, 7500, 8500, and 9500. The Power Macintosh 8500 provides both S-Video input and output connectors; the 7500 provides input only. A separate RCA adapter allows composite video to be routed through the same physical port.
S-Video INPUT
| Pin | Signal |
|---|---|
| 1 | Analog GND |
| 2 | Analog GND |
| 3 | Video Y (luminance) |
| 4 | Video C (chroma) |
| 5 | I 2 C clock(Philips serial bus) |
| 6 | +12 V at 250 mA maximum * |
| 7 | I 2 C data (Philips serial bus) |
S-Video OUTPUT
| Pin | Signal |
|---|---|
| 1 | Analog GND |
| 2 | Analog GND |
| 3 | Video Y (luminance) |
| 4 | Video C (chroma) |
| 5 | Composite Video |
| 6 | Unused |
| 7 | Unused |
Signals
- Analog GND — analogue signal ground reference; two pins (1 and 2) are bonded together for noise reduction.
- Video Y — luminance component of the S-Video signal (pin 3).
- Video C — chrominance component of the S-Video signal (pin 4).
- I²C clock — serial clock line of the I²C (Philips) control bus; used by the AV card to communicate with downstream video equipment (pin 5, input connector only).
- I²C data — serial data line of the I²C control bus (pin 7, input connector only).
- +12 V — 12 V DC supply rail at up to 250 mA maximum; powers compatible downstream devices (pin 6, input connector only).
- Composite Video — composite NTSC/PAL video output signal routed through pin 5 of the output connector when an RCA composite adapter is used.
Notes
- The physical connector is a 7-pin mini-DIN female on the computer. It is mechanically incompatible with the standard 4-pin S-Video plug; a dedicated Apple 7-pin cable or adapter is required.
- The input and output connectors on the AV card are physically identical; they are distinguished only by their labelling on the rear panel.
- The I²C lines and +12 V supply are present only on the input connector; the output connector uses pins 5–7 for composite video and leaves pins 6–7 unused.
- The +12 V rail on pin 6 is limited to 250 mA; exceeding this may damage the AV card.
- An RCA adapter plugged into the output connector routes composite video via pin 5, enabling simultaneous or alternative composite output without an additional port.