This is an Addams. Putting this in a new thread to see if I can generate an idea or two. Long story...bottom line: when I boot up, I see a msg pop up for less than 1 second GND. SHORT ROW 1 STUCK CLOSED. The game then goes to attract mode. If I start a game, most of the time the game serves two balls on ball 1. If I replace the ball in the trough, I can usually complete a game normally, and everything functions properly.

I’ve tested all trough switches, and they register as they should. I’ve jumpered the pins to test all switch matrix combinations and they test fine. I started going through edge test for the Row 1 switches, and the were all fine, until I got to the Shooter Lane Switch. Activating that switch causes it and all of the bookcase optos in that switch column to flicker on the edge test. I have no idea what that means or what I should be looking for.

Thoughts?
Thanks!!

Thanks guys!!

I unplugged J209 and through several power cycles was unable to reproduce the GND. SHORT Row 1 error. Looks like the problem is on the playfield, which is a relief, except for the part that is terrifying. I'll start with replacing the diode on the shooter lane switch and go from there. Interestingly, in examining the shooter lane switch, I found a bit of a mess on the upper swamp millions switch. It has been replaced at some point, and it looks like some of the wires brushed against the soldering iron, with cooked plastic and exposed wire in some places. Might not be related, but I've got some additional work to do on this switch, too.

Replacing the diode on the shooter lane switch produced the same result. Brief flash of the GND. SHORT error, flickering swich edge test.

Nuts.

Thanks Lloyd!!! Didn’t even have to heat up the soldering iron. I was following wires to make sure I had the correct switches identified, and there it was on the Bookcase Open switch. The lamp socket on the Jackpot lamp was resting against one of the lugs on the switch. One scientific bend later, everything is working properly.

Welcome back Addams, and many many thanks to Lloyd and all the great minds on Pinside!!!