How They Work - Closing the Shutter Panel
Closing the shutter panel happens a couple different ways.
- Bally usually draws the switches as they would be when the game over
- sometimes the manual or schem actually says. In this case, the description of switch 4B in the manual says "closed when shutter open".
- look at the switches and see what the cams are doing
- what makes sense
If it's confusing, just looking at the switches helps. Even if the switches are misadjusted, you can see how they must work based on what the cams do to the stacks. Of course, it's always possible that someone did something bad like screwing up the cams, but that's really rare....oddly, it happened on my surf club, but it was easy to figure out when the game did all sorts of odd things every time the shutter panel opened and closed.
Anyway, in the case of the purple circuit, tilting the game will cause the shutter panel to slide closed, which means that the next machine cycle will open the panel and reset everything. Note that if you turn off the power while the panel is open, you can turn it back on again and the scores/features won't reset on the next machine cycle because the panel never closed. That reduces the penalty for tilting before you shoot the first ball.
The blue circuit is the normal way the panel closes. When the timer unit advances to step 2 (and 3, for some reason), the shutter motor will power through switch 4B. When the shutter powers at step 2, the panel closes and switch 4B opens, so the motor is not powered again at step 3. I assume shoving 50V onto switch 4B at step 3 is a safety in case there is some kind of sequencing error. The timer unit is covered elsewhere, so maybe it'll make more sense when we get around to looking at it.
The orange circuit is the carry over circuit to keep the shutter motor powered until it turns 180 degrees.