Trying to solve a problem with my Whitewater. It seems the whole of column 6 switches are out, which causes the whirlpool popper and lock VUK to fire on start up (as the game thinks there are balls there).
I have done the jumper trick to ascertain the problem isn't on the board.
I have then connected a DMM lead from J207-6 to where the blue-green wire goes into the 7 opto board at J3-12. There is continuity to this point, but not beyond the diode there.
This is where I'm stuck, and would love some guidance on where to proceed from here.
Cheers

Thanks PM40, I found F116 was blown and no voltage at TP1. I replaced the fuse and it blew on startup. I had some LED strip lighting piggybacked at J116, J117, J118 and pulled them out.
Column 6 is now showing all switches closed (as it should) so it was a problem with the mods. I'd just taken the upper playfield off and put it back so something's happened when I did that.
Anyway, thanks for putting me on the right track.