Being sequestered at home, I decided to attack a long-standing problem with my Segasa Monaco. This problem has existed since I acquired it 2 years ago. I’ve treated it as a one-player machine since then, and in that configuration it works fine.

When you pick 2, 3 or 4 players, the ball count increments before the last player completes her ball. Specifically, the ball count stepper fires *not only* when the last player completes her ball, but when the *next to last player* completes her ball.

In a 2-player game, the ball count increments after every ball for every player.

In a 3-player game, the ball count increments at the end of player 2’s ball *and* at the end of player 3’s ball. By the time player 1 steps back to the machine, she’s on ball 3.

In a 4-player game, the ball count increments at the end of player 3’s ball *and* at the end of player 4’s ball.

I have putzed around with this problem a little bit. I first thought that the coin unit might be straddling two player positions, permitting conductivity across more than one of the current paths between the coin unit and the player unit. I checked that by ohming out the R-W wire with each of the wires BLU-R, R-Y and R-G (which I understand to correspond to the 1-player, 2-player, and 3-player scenarios. Confirmed that for each position of the coin stepper, only one (the correct one) of those wires has continuity with the R-W wire. So I seem to have ruled that out. And, by inspection, the coin unit is well-centered so that the stepper appears to touch only one position at a time.

I then thought that the player unit could be straddling positions. I checked that in a similar way: ohmed out the BLU-R wire that goes to the “A” position on the player unit against the R-Y, R-G, and R-W wires (B, C, and D) which I understand correspond to players 2, 3 and 4. Again, everything seems to track correctly as I move the player unit- in the player 1 position, none of the other three wires has continuity with BLU-R. For each subsequent position, only the wire associated with that player has continuity with BLU-R. And by inspection, the player unit appears well-centered so that snowshoes are dead-center on the contacts they're touching.

So, my initial hypotheses have come back dry. That doesn’t mean there’s not something wrong with the coin or player unit- just that I can’t find it.

My subsequent hypotheses start to get weird. Perhaps there’s a timing issue with the stepper motor, where the impulse 1-B comes too early or too late, and straddles two player positions. But an inspection of the score motor shows that the 1 wheel and the 2 wheel (which furnishes the impulse to the player unit, 2-B) appear to be separated by a reasonable factoryish margin.

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Thanks Mark. I will try your suggestions and report back!

I blocked switch 1B with a piece of paper, and started a 4-player game. The player unit stepped correctly through players 1, 2, 3, and 4 without the ball count advancing past ball 1. So far, so good. After I played player 4’s ball 1, the player unit did not reset to player 1. I was stuck at player 4 ball 1, over and over.

This is in contrast to the machine’s normal behavior, where it is at ball 3 by the time it makes its first reset to player 1. I guess that means there’s no short that’s injecting stray pulses into the ball count unit.

I then monitored continuity between the blue-red wire from the player unit and the red-white wire from the coin unit. I stepped the coin unit to 4 players. I only observed continuity when I stepped the player unit to player 4. BUT I noticed once I got to player 4, the continuity was kinda marginal and cut off if I wiggled the pogo wheel of the player unit. Interesting, although it doesn’t explain the ball unit stepping up prematurely on player 3 (at least I don’t think it does).

I returned to my theory that there was some kind of timing problem with the score motor. I watched wheel 1 turning and filmed it with my phone. Sure enough, switch 1B was marginal and only narrowly breaking contact - very different from how its neighbor switches were gapped. I tweaked that switch and voila- the problem went away. I think the switch was making contact for a prolonged period beyond what’s prescribed by the score wheel indentation. Perhaps that caused a marginality where, as the machine was switching from Player 3 to Player 4, an improperly prolonged and overlapping pulse from 1B allowed the ball unit to increment.

SOLVED