I’ve got my OXO playing really well, but I’ve got one last issue to solve. The 3-in-line relay sometimes seems to slide back off its latch. So at the end of the ball, it resets (extra ball light goes out) and a fraction of a second later it goes back on again. It’s intermittent - sometimes the relay stays reset at the end of a ball. I think the problem is one of three things:

1) the 120V reset bar isn’t pushing the plate up enough.
2) the ‘latch’ is faulty, too slippery?
3) the relay is activated by some combination of misaligned X or O switches.

I think I ruled out (1). I built up the bottom of the plate so that the reset bar pushes it an extra 2mm or so, but the problem still happens. I actually have a spare OXO so I might borrow the relay hardware from it to see if (2) was the problem. And I’ll go over the switches for the 18 X/O relays to rules out (3).

Just thinking out loud, to strategize for tackling this again tomorrow.

Great idea, thanks!

I cleaned every switch in the X/O bank (at least 80 of them), and the problem went away. I’m not sure I understand why, but I’ll take it.

I took some time to admire the logic in the schematic for detecting “3 in a row”, and the gray-wired switches that implement that logic. These EMs really are elegant primitive computers.

That’s great detective work! If the problem comes back on mine I’ll revisit this thread.