Long story short. Bought the game probably 13 years ago, GI was a mess then, just completed a second rebuild of J120 and J121 after re-doing all the caps and bridges. Game plays super fast and amazing...

HOWEVER, J120 backbox GI does not work in the standard configuration. There are 11 pins on the J120 connector. And according to the manual and all pics I've seen (and mine prior to this recent rebuild), The White-Yellow wire goes to pin 9 (third from left), the White-Orange to Pin 8, and then solid Yellow on Pin 3, and Solid Orange to Pin 2.

MY ORANGE - WHITE GI only works when the White Orange is connected to Pin 7 (five from left)!!!

So in the standard factory config with white orange on Pin 8, my white-orange backbox string is entirely out (voltage reads ZERO). Nada. Nothing. However, if I move the white-orange wire to Pin 7 (five from left), I get the full 7.6V or whatever.

More information- I have buzz continuity between pins 9 and Pin 7, and I also have buzz continuity on Pins 9 and 7 to both fuses 109 and 110. I also have buzz continuity from Solid Orange pin 2 to Q10.

Test Point 8 is 16V

WTF? Suggestions?