I purchased a couple "dead" System 11 CPU Boards - 1 board has come back to life, however the special solenoids at Q75 and Q79 are locked on ( top left pop bumper and the down coil on the ramp ). Things I have done - replaced Q74, Q75, Q78, and Q79 they tested fine in the circuit but figured - got the parts just as well use them. This did not fix anything - so I replaced the u49, u50, and the u45 - no change. Could it be the 6821 IC? I think pin 39 gives it the signal and the left sling shot works fine so I am thinking that will not do anything either. What am I missing in the circuit?

Since I am hoping to attract a System 11 expert - my other board does nothing, I replaced the ZR1, ZRR, C30, Q34,Q36, Q38, U11, U13, U25 - tested all the 6821's with a meter on diode test, U10 pin 40 goes low to high on powerup, I have 5 volt on all the IC's where I am suppose to. The 5v led is on solid the blanking and the other one never do anything. What is my most likely suspect. I have tested the 6802's and the ram in another game so I know they are working correctly.

1 more bit of information - I swapped a working CPU board out of another game into the Whirlwind and all the coils work correctly so it is a board issue.

I think this is going to be it - I have check everything else.