I was doing some work on my Stars. I had it playing well for a few weeks. Then it wasn't getting 12 volts DC on the rectifier board (TP3). I corrected that issue (Bridge Rectifier) and now the game will not boot up. It gave me 4 flashes. I found that if I unplugged J1 on the MPU the game would boot. J1 feeds the lamp driver board and displays.
I find that if I connect J1 on the MPU but unplug connectors J1 and J3 on the lamp driver which feed the insert lights on the playfield, the game boots up. If either of these are connected to the lamp driver board, I only get 4 flashes on the MPU.
Where should I be looking from here? What is causing this?
I have a Weebly MPU and the rest is vintage.