I’m working on a Bally 2518-22 SDB for a friend. He brought over a box of crap and would like me to see what I can do. I have very little experience and knowledge, but I would dive in and try. I’ve been able to get 4 up and running 100% and that feels great. BUT, he has one that locks on ALL coils on power up and blows playfield fuse. It came in that way. I’ve rebuilt J3 and J4 with new pins. Checked tip102 transistors and they measure normal. Thought it might be the U2 chip on the board, it was nasty looking. Pulled another off a parts board and no change. So, what would lock on all coils at power up? All driver board test points are within range.
Thanks for any help.