Quoted from diesel:
This is what i did.
First i disconnected the connectors from the MPU board and row 2 did not appear. After reattaching the connectors back onto the MPU board i then disconnected the connectors from the 7 Opto board and again row 2 did not appear (on DMD).
Also every time I switch on the machine the trough and goal popper start to fire.
7 Opto board or MPU?
Just letting you know i've replaced the LM399 chips on the 7 Opto board. Could the chips be faulty?
Possible, and likely - since row 2 is grounding WHEN the 7opto board is plugged in, something on the board is grounding the row. I'm at work and don't have the manual to glance through, but obviously check traces, diodes, etc. If you socketed the LM399 chip, take it out and see if the row is still grounded. (If you DIDN'T socket the LM339, replace it again, this time with a socket. ) If the row is still grounded with the ship pulled, then it's not the chip, it's a trace or diode or shorted resistor.
(Edit: I may be wrong about pulling the chip; again, I'm working from memory here.)