Hi all, my first support post, please be nice
Stern Lightning 1981, has been sitting for years. It has had mods/updates done through the years (mostly regulator board but test points seem to be within tolerances).
I have removed and cleaned as much as I could and followed "Repairing Bally Electronic Pinball Games from 1977 to 1985 (http://techniek.flipperwinkel.nl/ballyss/rep/index1.htm)", by cleaning battery corrosion (not too bad) and cleaned up and added some new "beefier" supply lines and ground on the MPU.
When it boots, get all 7 flashes and game comes up and plays, BUT I cannot connect both ribbon cables from SB-300 to J5 on MPU-200 as shown, if right side is connected to J5 game will not start or pass "light checks"
This makes sense that the right side of J5 controls 1/2 of PF sounds...
Any help on next steps or troubleshooting is much appreciated, thx in advance.