OK- mini update.

Picked up fuses at Jaycar, awesome place, installed fuses...not blowing on power up anymore .. 

Disconnected driver board from MPU and fired up MPU on its own...kept blowing the solonoid fuse on power up so i reconnected driver and all is fine.

Put in the known working gorgar driver board and i get the same results as with the existing BK driver... Random sounds on power up, no displays and no cpu controlled lights.

I also changed the MPU's 6808 with the sound boards 6808 and no change !

So i am basically where i started... 5 and 12 v to the MPU board and i have the + and - 100 for the displays... PSB regulator and diodes test OK...

Gavin i tested the PIA pins as you suggested and get voltages ranging anywhere from 2.5 to 5 v. I don't know what i need to check, if high or low etc....