If you put a sun3 board on a table with the extractor levers and serial connectors to your left, on the right will be P1 farthest away from you (on "top"), P2 in the middle, and P3 on the bottom.
We can supply power to the board through pins on the P1 ("upper") connector. Each row of pins is designated by the letter a, b, or c. Then the pins are numbered top to bottom.
The mating connector I have for P1 is nicely labeled. The "a" row is towards the back of the board and the "c" row is towards the front.
5 volts -- a32, b32, c32 -12 volts -- a31 +12 volts -- c31 Ground -- a9, a11, a15, a17, a19 Ground -- b20, b23 Ground -- c9
Tom's Computer Info / tom@mmto.org