Techno Stuff
How They Work - Shutter Panel and Reset

playfield bottom
magic ring
playfield bottom

Hopefully we all know by now that the shutter panel is the gizmo that slides beneath the playfield and allows the balls to drop through the holes when the panel is open.

What is surprising the first time you look under the playfield is the amount of switches controlled by the position of the shutter panel. Basically, Bally is being frugal with the circuits. A bingo machine is generally in one of four main states:

  1. replay reset
  2. spinning to advance scores/features
  3. playing the normal balls (usually five)
  4. extra balls
  5. bonus games (e.g. double-or-nothing, golden game)
Oops, that's five. Oh well, very few machines have bonus games (if we don't count OK/red letter games as bonus games, since they are really just normal play with the machine reset to a state with certain score/feature levels already set).

While the shutter panel is open, we are in spinning mode. Every time you push a button to cycle the game, the start relay closes to initiate a machine cycle as described in the replay reset and start cycle section. The shutter panel stays open the whole time. We are lots more interested (for the moment) at what happened just before and just after the machine is in spinning mode, which is when the shutter motor powers and turns 180 degrees to open/close the shutter panel.

Panel Switches

The highlighted circle in the above picture shows the panel switches. On the schematic, these are usually cleverly labelled "panel switch" and they never appear in the manuals. Basically, it is just a bank of switches that get pushed by an adjustable metal bar on the shutter panel itself. These switches logically belong on top of the shutter cams, but there are too many of them, so Bally mounted them on the playfield and let the shutter panel itself move them.

For some reason, these switches cause a lot of grief, especially in screen game payout circuits. The bar that is pushing the switches tends to work loose over time, and instead if it pushing the switches, the switches push it. It's a good idea to check these switches if your game has them to make sure the bar is adjusted to operate the stack correctly.

You can turn the drive cam at the shutter motor to release the panel and slide it to it's open and closed position. Adjust the bar or switches as needed so they operate correctly.

how they work | Open the Shutter | Close the Shutter