Month: March 2014

Playfield :: Hardware :: Posts

Playfield Posts are essentially an evolution of the original “pins” that gave us the name “Pinball”.

The modern Playfield Post comes in three main styles, and many colors. Since you are building a Custom machine, and not a restoration or reproduction, you have the freedom to chose which style and color to use, and there are several artistic considerations. But first, here are some examples of what is available today:



Plastic Molded Post Types:

  • Faceted – These were used fairly early on a lot of Bally and Stern games, usually molded in red.
  • Finned – These are slightly more modern, used on a lot of Bally / Williams games.
  • Star – Less popular, but still available today.




Artistic Considerations:

There are several things to consider when choosing a post design that will effect the overall look of the games. The questions you should ask yourself when making these creative decisions are:

  • How the post looks in direct or ambient light?
  • How the post looks when lit from behind?
  • What type of light goes it project onto the playfield?




Playfield :: Electronics :: Switches

Switches are probably the single-most important device on a Pinball Playfield, and are fundamental to the game itself. The entire Pinball Machine is essentially an electro-mechanical interaction, with the switch being the all-important middle-man between the ball and the active mechanisms…

Switches also pre-date a lot of the other devices we commonly associate with Pinball, like Flippers, Thumpers, Slingshots, etc. and most machines today still use some manner of the traditional wire-form activated leaf-switch we find on older games.

The focus of this blog is on solid-state based Custom Pinball Machines, and one advantage with SS when it comes to switches is that they can be scanned as a matrix. Most SS games since the 70’s have used this technique. With matrix scanning, you can read 40 switches with 5 drive lines and 8 read lines (5×8 = 40), but only use 13 digital I/Os (5+8 = 13). And just to hammer home the math, that saves 27 I/Os (40-13 = 27), putting this in the wheelhouse of a small micro-controller board like the Arduino Uno.

The Layout.

Here’s a typical schematic (below) of a switch matrix from a standard Bally 70’s solid-state (SS) game. I present this because it will serve us well even today since the principles are the same.

Switch matrix schematic

Schematic of a switch matrix designed to be scanned by solid-state electronics. For our Custom Pinball Machine, we will use a micro-controller like the Arduino Uno.


Scanning The Matrix:

In the case above, there are five drive lines and eight sense lines, which we will model for our own design. The process of scanning works like this:

  • All the drive lines are initially held low.
  • The first drive line is switched high.
  • Each of the eight sense lines are read.
  • These values then represent the state of switches 1 thru 8.
  • The first line returns low, and the second line goes high.
  • Again, read in the eight sense lines.
  • These values become the state of switches 9 thru 16.
  • And so on until all 40 switch states are read…

Notice that each switch in the schematic has a diode on the drive side. This prevents “ghosting” in the case of multiple switches being active at the same time. Without it, the current from one drive column could back-feed through any switches active on the same row, in essence driving a second (unintended) column. An active switch on the second column would create a “ghost” activation on the first (real) drive column.

Below is a spreadsheet I usually create during the design of the game, and reference for the assembly and wiring.

Switch matrix excel spreadsheet

Excel spreadsheet showing switch signal names with drive wire colors and sense line colors.

Most older games made use of two-color striped wire, so there was never a duplicate color combination for any signal. In our case, it’s more feasible to use a limited set of standard colors, and just keep track of where there might be duplicates.

I always create a chart like this early on, giving the switches logical names and grouping them based roughly on where they will be located on the playfield. It helps to use the same name later in the Arduino code that will be doing the scanning.

The Switch.

Almost all older games use leaf-switches connected to a wire-form for activation. These usually have three contacts, and the diode mentioned above is mounted directly on the switch. This make wiring easier and more mechanically stable.


Custom Pinball Switch

This is a typical “spoon” switch used to activate Thumpers. There is a built-in diode, with the drive wire coming in on the positive side (yellow), and a sense wire on the negative side (orange).

The Code.

Below can be cut-and-pasted into an Arduino project. Use this for testing and diagnostics, or as a reference for creating your own game code.

There are several features to this code aside from just scanning the switch matrix, hopefully it will become clear as you read though it:

  • The code compares the previous state of the switch to the current state to determine if the state is “new”
  • It then rotates the state for the next loop so that current becomes previous.
  • It only call the state “new” if it went low-to-high, you can change this in your own code.
  • It implements a de-bounce timer function, which is adjustable, or just comment it out.
  • Prints the “new” switch state to the serial monitor when switch is activated.
// --------------------------------------------

This code will scan a 5x8 switch matrix and print the status of new switch states.


  -  Set the first drive line output.
  -  Scan first input.
  -  If state was low, and now high, set new switch flag.
  -  Send message out to Serial Monitor (optional).
  -  Loop through all eight inputs.
  -  Loop through all five drive lines.
  -  Delay.
  -  Repeat.
For questions or comments, check the blog:


//  --------------------------

//  --------------------------
unsigned char j = 0;	//
unsigned char i = 0;	//
unsigned char k = 0;	//

//  --------------------------
unsigned char switchStateNow[40];	// start no digit selected
unsigned char switchStatePrev[40];	// start no digit selected
unsigned char switchNew[40];	//
unsigned char switchDebounce[40];
// --------------------------
// optional for this test code, but good idea
// if you are going to build on this as a game later.
SWITCH_A, // was 1
SWITCH_B, // was 2
SWITCH_C, // was 3
SWITCH_D, // was 4


SWITCH_LANE_DROP_3, // kicker / shoot again




#define SWITCH_DEBOUNCE_DURATION 10 //10 loops

void setup() 
  pinMode(14,OUTPUT); // analog in used a row drive out
  //pinMode(18,OUTPUT); // if only using four drive lines, no need to set this

  pinMode(2,INPUT); // analog in used a row drive out
  pinMode(3,INPUT); // analog in used a row drive out
  pinMode(4,INPUT); // analog in used a row drive out
  pinMode(5,INPUT); // analog in used a row drive out
  pinMode(6,INPUT); // analog in used a row drive out
  pinMode(7,INPUT); // analog in used a row drive out
  pinMode(8,INPUT); // analog in used a row drive out
  pinMode(9,INPUT); // analog in used a row drive out

  digitalWrite(2,LOW); // pull up on
  digitalWrite(3,LOW); // pull up on
  digitalWrite(4,LOW); // pull up on
  digitalWrite(5,LOW); // pull up on
  digitalWrite(6,LOW); // pull up on
  digitalWrite(7,LOW); // pull up on
  digitalWrite(8,LOW); // pull up on
  digitalWrite(9,LOW); // pull up on

  Serial.begin(9600);           // start serial for output

//  --------------------------
  for (j = 0; j < 40; j++) 
    switchStateNow[j] = 1; //
    switchStatePrev[j] = 1;//
    switchNew[j] = 0;
    switchDebounce[j] = 100;
} // end setup

void loop() 
  //  *****************************************
  //  -----------------------------------------
  //             START READ SWITCH
  //  -----------------------------------------
  //  *****************************************  

  for (j = 1; j < 5; j++) 
    // START ALL LOW (no signal)
    digitalWrite(14, LOW); // pins 14-17
    digitalWrite(15, LOW); // pins 14-17
    digitalWrite(16, LOW); // pins 14-17
    digitalWrite(17, LOW); // pins 14-17    

    digitalWrite((j+13), HIGH); // pins 14-17

    delayMicroseconds(400) ;
    for (i = 0; i < 8; i++) 
      switchStatePrev[((j*8) + i)] = switchStateNow[((j*8) + i)]; // rotate variable
      switchStateNow[((j*8) + i)] = digitalRead(i + 2); // pins 2-9

      // check for a "new" state
      if ((switchStateNow[((j*8) + i)] == switchStatePrev[((j*8) + i)]) || (switchDebounce[((j*8) + i)] > 0))
      if ( switchStateNow[((j*8) + i)] == switchStatePrev[((j*8) + i)]) 
        switchNew[((j*8) + i)] = 0; // same as old
      } // end if
      else // must be new if not old and new equals one
        if (switchStateNow[((j*8) + i)] == 1)
          switchNew[((j*8) + i)] = 1; // new
          #if (DEBOUNCE_MODE)
            switchDebounce[((j*8) + i)] = SWITCH_DEBOUNCE_DURATION; // set timer
          #if (SERIAL_MONITOR == 1)
            Serial.print("Switch = ");
            Serial.print((j*8) + i); // TODO check this formatting later
      } // end else
    } // end for i
  } // end for j    

    for (j = 0; j < 40; j++) 
      if (switchDebounce[j] > 0) 
        switchDebounce[j] -= 1; // ramp down to zero

  delay(10) ; // 10ms loop time
  // end read switches

//return;// end MAIN LOOP



Cabinet :: Electronics :: Display

In recent years, reproduction components and other products have surfaced to help repair and restore vintage pinball machines. Some of these reproductions make use of the latest technology internally, essentially a re-design that is more reliable than the original. One case in point is the Classic LED Pinball Display from PinScore. We can take advantage of the great work being done on the restoration side, leveraging this market to create our Custom Pinball Machines. But in this case, we need some way to easily interface these devices to whatever control system we happen to be using. Which is the subject of today’s post…

PinScore display

PinScore makes reproduction displays, using the latest technology for higher reliability.

PinScore Display:

If you’re building a four-player game, you can buy a set of these for a little bit of a discount. I usually purchase from Marco Specialties Pinball Parts when I can, a direct link to the products you’ll need can be found here:

PinScore display custom pinball machine

An Arduino can be used to drive a PinScore display, while also communicating serially with a game controller.

Arduino Uno:

The Maker community has already discovered that the Arduino series of boards is an easy and inexpensive way to get into programming with micro controllers. Here are links to get you started:

The Arduino IDE is a free software download, with a large support community, and can be downloaded here.

PinScore display custom pinball machine

Detail shot of Arduino showing connections and pinouts.

Using the parts list above, you should have everything you need to connect the PinScore to the Arduino as shown above and below.

PinScore display custom pinball machine

Detail showing connection side of PinScore with header pinout to Arduino.

I’ve provided some test code at the bottom of the page that can be cut-and-pasted into an Arduino project. The photo below shows the display being mounting into the front of the light board, with the test numbers “123456” loaded. The Arduino project is set up to use the Serial interface, which for diagnostic purposes can be accessed over the same USB programming plug, and the Serial Monitor built into the Arduino IDE.

PinScore display custom pinball machine

Display mounted from the front into a standard Bally score bracket.

Below shows all the displays installed, waiting for the backglass.

PinScore display custom pinball machine

Finished installation showing all five displays and the lit up back-board.

The Arduino code below can be used as a reference in your own controller, or directly as a diagnostic test tool. The procedure to test a unit is as follows:

  • Plug your target board (with PinScore display attached) into your computer via USB.
  • Power the PinScore with external 5V supply.
  • Download the program to the target.
  • Open the Serial Monitor built into the IDE Tools.
  • Type “$pinXyyyyyy” and press return, where X is the number you assigned the display (i.e. player 4), and yyyyyy is the number or score you want to display. For example, “$pin4123456” is what I typed in to display what is in the photos above.
  • If your score is less that six digits, use an underscore. For example, “$pin4_98765” will display the number 98765, with the first digit being blank.
  • If you have a fifth display for Balls/Credits, you would sent something like “$pin5_03_10” for Ball = 3 and Credits = 10.

Arduino code here.

Cut and paste text into a new project, then download to your target device.


Using the serial monitor, type in the header "$PIN" followed by the ID you've chosen
for the PinScore display (ie, 1, 2, 3, 4 etc), and then the actual score for that unit.

EXAMPLE: Typing in "$PIN4100000" to the serial monitor and hitting return should read
the score "100000"  player four's display.

For questions or comments, check the blog:


String inputString = "";         // a string to hold incoming data
boolean stringComplete = false;  // whether the string is complete
unsigned char selectDigit = 0;	// start no digit selected
const unsigned char selectLatch = 12;	// start no digit selected
unsigned char cDataPinScore[8];
unsigned char cPinScore = 4;
unsigned char digitBCD = 0;	// start no digit selected

#define ASCII_A 65
#define ASCII_B 66
#define ASCII_C 67
#define ASCII_D 68
#define ASCII_E 69
#define ASCII_F 70
#define ASCII_G 71
#define ASCII_H 72
#define ASCII_I 73
#define ASCII_J 74
#define ASCII_K 75
#define ASCII_L 76
#define ASCII_M 77
#define ASCII_N 78
#define ASCII_O 79
#define ASCII_P 80
#define ASCII_Q 81
#define ASCII_R 82
#define ASCII_S 83
#define ASCII_T 84
#define ASCII_U 85
#define ASCII_V 86
#define ASCII_W 87
#define ASCII_X 88
#define ASCII_Y 89
#define ASCII_Z 90
#define ASCII_EQUAL 61
#define ASCII_DOLLAR 36
#define ASCII_COMMA 44
#define ASCII_CR 13
#define ASCII_LF 10


#define LED_CHAN PLAYER_ONE // change this to the PLAYER that the unit will be driving

void setup() 
  DDRB = B00111111;  // sets Arduino port B pins 0 to 4 as outputs
  DDRD = B11111111;  // sets Arduino port B pins 0 to 4 as outputs

  // initialize serial:

  // reserve 200 bytes for the inputString:

    for (int i = 0; i < 8; i++) 
    cDataPinScore[i] = i + 48;


void loop() 

// continuously scan the PinScore display, outputing the most recent data
  for (int i = 2; i < 8; i++) 
    selectDigit = i;  

    PORTD = (0); // clear all


    PORTB = (cDataPinScore[i-2]- 48); // subracting 48 converts an ASCII char to its equivalent int


    delay(3) ;// hold each digit for a period


  SerialEvent occurs whenever a new data comes in the
 hardware serial RX.  This routine is run between each
 time loop() runs, so using delay inside loop can delay
 response.  Multiple bytes of data may be available.

void serialEvent() 
  while (Serial.available()) 
    // get the new byte:
    char inChar = (char);

    // add it to the inputString:
    inputString += inChar;

    // if the incoming character is a newline, set a flag
    // so the main loop can do something about it:
    if (inChar == '\n') 
      int inputLength = inputString.length();

      if (inputString[0] == ASCII_DOLLAR) // check for header
        cPinScore = inputString[4]; // PinScore id held here

        if (cPinScore == (LED_CHAN + 48)) //4 )
          for (int k = 0; k<6; k++) // acount for numbers less than six digits
  	  cDataPinScore[k] = inputString[k + 5];
  	  } // next k

        } // end If received ID matches the one this unit is programmed for

        stringComplete = true;
        inputString = "";

      } // end If first char was $ 

    } // end If new line 

  } // end While// end Sub

Cabinet :: Fabrication :: Stencils

There are several ways to create the look of a vintage stencil for your cabinet artwork. I’ve done it a couple of different ways, and you can make your choice based on complexity and resources available.

I typically go for a three-color design (base coat plus two stencils), in keeping with the classic style, which can also be an artistic challenge.

1) Original method. Vintage machines had their paint applied by spraying, stippling or flicking with a brush, usually masked with some type of stencil. This would have been a rigid, thick cardboard paper (or thin wood), with patterns cut into them, and intended for multiple use, possibly hundreds of times.

Advantages: Multiple use (as in production), and has a classic look.
Disadvantages: Investment to make, not as sharp or modern looking.

2) Hand Mask Method. This is as simple as it sounds: use masking tape and paper to create your stencil directly on the cabinet wood. For smaller details, I usually print out a template I’ve designed on the computer. The larger elements I would freehand with some scale drawing for reference. This works best if using mostly straight lines or slight curves. Something more complicated would need a more elaborate method.

Advantage: Cheap.
Disadvantages: One-time use (possibly not repeatable), not as precise.

Hand-made Cabinet Stencil

Creating a stencil by hand, using masking tape and a printed template. Base is white, first color dark blue, third color orange.

3) Pre-cut Stencil. This is usually a one-time use vinyl stencil, and will cost about $150. This is a method to use if you have a very specific pattern in mind, and usually requires a vector artwork drawn on a computer. You might be able to find a local company that can do vinyl cutting, or use a company like Twisted Pins that makes one-time stencils specifically for pinball machines.

Advantages: Very precise complex shapes, exactly rendered.
Disadvantages: Cost, and probably will only get one use.

Pre-cut Custom Pinball Stencil

Using a one-time vinyl stencil to achieve complex shapes and curves. Again, base is white, first pass is dark purple, then pink.


For reference, if you are following the plans for this cabinet and head unit, here are the PNG files for the Side, Front and Head that can be used as a pattern for creating your own artwork:

Custom Pinball Side Artwork

Side art work for reference or use as a pattern.


Three-color head unit artwork for use as a pattern or reference.


Stencil for front of cabinet. If you have the vinyl cut professionally, the shop should be able to take your PNG file and convert it into vector artwork, then generate two separate stencils for a three-color design (two plus base).

Playfield :: Fabrication :: Slots

If you are going to CNC your playfield, that’s great. However, most people don’t have free access to a CNC machine, and paying someone to do the job for a one-off project may not be cost effective. So, for most of the blog, I will consider that the fabrication sections are going to be done by hand…

The second-most-difficult feature of the Playfield to create by hand is the Switch Slot (the most difficult being an Arrow Lens).  The Playfield Switch is obviously one of the most important hardware features of a Pinball Machine, since the game is essentially a continuous electro-mechanical interaction, where the Pinball activates a Switch, which in turn activates a Solenoid, which in turn impacts the Pinball, and so on, and so on.

We start with a full-size 1:1 printout of our Playfield CAD drawing, but in this example I’m just focusing on the section where the Switch Slot will be. Spot-drilling all of the features at the same time with a full-size drawing will guaranty that holes are placed correctly relative to each other. Here is the Slot creation process in detail from start to finish.

Step 1:

Spot drill both ends of the slot using a 1:1 scale printout of the Playfield CAD for reference. Then, carve a small groove from center-to-center to keep the next set of pilot drill holes in line.

Custom Pinball Switch Slot

Spot drill the ends of the slot, then cut grove.

Step 2:

Establish the center line with an X-acto knife, then drill a set of pilot holes in the groove. Use the finish drill size (.198″) as a visual guide to set the spacing.

Custom Pinball Switch Slot

Drill additional holes in the center groove, using the finishing drill bit as a guide.

Step 3:

Once the spot drills are finished, follow-up with the finish drill (.198″) in each pilot hole.

Custom Pinball Switch Slot

Drill to final size using pilot guide holes.

Step 4:

Using the same X-acto, establish the outside walls of the slot with clean cut, using the outer diameter as a guide. Then come back with angled cuts until the slot is clear. Flip over the the other side to complete the slot.

Custom Pinball Switch Slot

Clean up edges with X-acto knife.