Duo Pinball Teardown

Let's take apart the Duo Pinball controller and have a look inside.

Open it Up

Using a #1 Philips screwdriver, remove the seven screws that hold together the case. Note, two of the screws are hiding under the rubber feet, so go ahead and peel them off and save them for later.

Now, pry open the case using a spudger or slotted screwdriver. Be careful not to pull to hard on the wire that connects the LED to the board -- you can remove the piece of tape that holds it in place so you can lay both halves side by side.

Now, pry open the case using a spudger or slotted screwdriver. Be careful not to pull to hard on the wire that connects the LED to the board -- you can remove the piece of tape that holds it in place so you can lay both halves side by side.

Identify the Parts

Inside you'll see a few key elements:

  • Controller board
  • Left flipper button momentary switch
  • Right flipper button momentary switch
  • Plunger momentary switch and IR sensor
  • Plunger/spring assembly
  • Battery box
  • Indicator LED

Remove Old Board

You can unplug each of the cables from the main board now, and then unscrew it. We won't be using it, so you can set it aside in your old electronic junk pile.

One curiosity is the reset button on the back. Mysterious!

Prep the Wires

To prep the wires, first remove the battery box wires, we won't use them.

Next, snip the connectors off of the remaining wires running from both buttons, the plunger sensor, and the LED indicator.

The plunger sensor board is pretty darned nifty! It's got a momentary snap action switch on it to detect the plunger "closed/opened" state, as well as an IR distance sensor to determine the position of the plunger! We'll only use the switch, since the iCade standard doesn't have a way to express the analog value of plunger position to the game.

You can test the button wiring with the continuity testing mode on your multimeter -- the plunger switch actually has two modes you can use depending on which wires you connect. The white wire, labeled SIN on the board, is a constant, so connect your first lead to it. If you connect the other lead to the red VCC wire the switch is normally closed (NC) as seen here.

Instead, if you connect the second lead to the black GND wire, it is is normally open (NO).

You could pick either one and then make an adaptation in software (I chose red originally when I built one on the video live stream and then reversed the key commands in the Arduino sketch to make it work) but let's look at the way the plunger works to decide the best method.

The plunger resting position keeps the switch pushed down. So, when the software checks it, we don't want it to react to the resting state. By choosing the black wire, we can have the software see that switch as open (what we'd colloquially call "unpressed" even though it is physically pushed in). Then, when the plunger is pulled back it will register the switch as closed (what we'd called "pressed" again, even though the button is now no longer pushed in), and send the keystroke to the game.

So, the black wire is the one we'll go with when it's time so solder!

Wire Common Ground

To simplify the wiring runs back to the board later, we can solder all of the black ground wires to each other, and then make a single connection to the Teensy board. This is good if you want to keep things small, since the Teensy 3.2 only has a single GND pin exposed, and this allows us to avoid adding perf board with an extra ground rail.

Cut and strip a short length of black wire to add to the bundle. Twist and solder them all together, or use a wire splice tap to connect them, leaving the free end of the added wire to solder to the Teensy later.

You can add a bit of heat shrink tubing to insulate the connection.

USB Wiring Hole

One other bit of prep to do here is to create a hole in the case for the USB cable. I made mine in the back of the battery box using a 5/8" Forstner bit in a power drill, but you can use a Dremel, saw, hand drill, or any other method you like so long as you can fit the small end of the cable through.

Now it's time to transplant the Teensy!

This guide was first published on Jul 27, 2017. It was last updated on Jul 27, 2017. This page (Duo Pinball Teardown) was last updated on Sep 21, 2019.