I've been working on my stern 200 mpu. Had battery corrosion damage, the board is booting now with 7 flashes and it appears the game is working. One major problem, something on my mpu is not allowing the displays to work. They are all blank. The voltages on all the displays are fine.

I know this is a mpu problem because when I put my Alltek board in they work.

So far I have replaced the header pins at J1. I've also replaced the 4572 and 4502 chips at and U20.

Can someone help me track down this issue? Thanks in advance!

I've also replaced the 4572 and 4502 chips at U14 and U20.

Fixed. Started with schematics and traced back. A broken leg at C18. Fixed.