Try to start a game and get a ball missing error. Go into switch test and when I trigger the left coin switch and the start button the ball trough VUK opto switch shows up as well. None of the other switches on that row cause the opto switch to show up. Take the balls out and the coin and start switches register as normal. Replaced a diode on the coin slot switch, it was giving some strange numbers on the DMM. Checked the opto board and everything seems good on it. Anyone have any suggestions on what to try next. Time for a new set of opto boards? I will go over all the other switches and diodes again, but it seems to maybe some surface mounted component on the opto board that has crapped out. My guess anyways.

I was working on the switch matrix again to try and find the source and then I started getting some on and off bank door opto problems during the tests. Took it apart and discovered that the trace on the top circuit board for the bank optos had broken and was only touching sometimes. Need to order a new board for the bank and take a longer look at those diodes. I'm leaning towards the Start button. The only switches in that row that cause this problem are the left coin switch and the start button. Replaced the left coin switch and the diode. Can't see any shorts or problems with the wiring. If it ain't one thing it's another. Hate having a black hole in the line up.