On the backplane, pins 1 & 2 are common. +5 vdc on 83 & 84 (2nd row from top). +12 vdc on 7 & 8 (4th row from bottom) -12 vdc on 79 & 80 (4th row from top). 11.8 to 12.2 is the acceptable range for the 12 v +/-. This is right out of the Troubleshooting section of the manual.