have a Williams Blackout and when start a game and Press the right flipper (just once) it will make a "joust sound" from the sound board and then lock up all the playfield. The flippers still work but nothing else does.

If I unsolder the diode on the right flipper then the game all plays great (left and right flipper function normally). But of course I do not have any lane change on the right flipper.

I have swapped a good MPU board in thinking that was it (it was not) , where else should I look?

P.S. The Diode seems to test "good"

Correct, it goes "dead" even if I manually (with diode connected) and I close the "lane switch" without activating the right flipper.

What direction do you have for me please?

I have verified that they are not touching. Yes the machine was working great (even with lane change) and then this issue appeared. Any chance its an issue on the driver board?

Well I narrowed it down to the driver board. I put my Firepower driver board into the Blackout and it works now. However I would like to fix the Blackout Driver board. I don't know what part of the board would be suspect to the failure. Is there a mapping of what does what on the driver board?

Posting solution. I tracked down the schematics and traced it to a bad hex inverter on Driver board. Replaced it and now 100 percent. Thank you for all your help.

SOLVED