Hacking a Pinball Machine into a Coffee Table

with no space for a full sized pinball machine I am “forced” to take a 1980 Bally Centaur Pinball Machine and convert it into a working and playable coffee table!

Others have put playfields into coffee tables, and some have gone so far as to light them up, but this project goes beyond that! Once complete, I will have created an interactive coffee table that tilts up and plays just like the original! However, it will rest no higher than 18 inches from the ground when not being played.

In July of 2020, I purchased the 1980 Bally Centaur for $5800

They made 3700 Bally Centaur machines and it’s always been a favorite of mine. Paul Faris laid down some exceptional artwork for this machine. It also meets the criteria for this project as it is a relatively simple early solid-state machine with a single level. This will allow me to squeeze it into a low profile table form factor. In its current state, the machine is completely functional with push buttons wired up to insert coins and a start game.

I have already stripped down the machine, and have all the internal components mounted on a pinball rotisserie of my own design. This workstation will be a huge help in allowing me to play the game during the development of numerous custom components and features.

Build details of the PinTisserie can be found on THIS POST.

The Sound board used on the this machine is the original Squawk & Talk from Bally and was in need of repair. After replacing a blow regular and all the capacitors, along with various other components including the crystal oscillator, it’s back in action and sounds awesome!

In my latest update I solved one of the major design challenges. I removed the backbox that houses the score displays and circuit boards and made progress as follows:

  • Implemented a display decoder chip using the open-source TinyFPGA BX board (Hackaday project HERE).
  • Coding my own SPI core in Verilog.
  • Addressing the display decoder logic.
    • The display decoder logic leverages combinational logic to simultaneously sample one digit which is instantaneously shown to the user. The score values are stored in RAM, created in the FPGA, and an interrupt output is toggled to notify the Teensy 4.1 that a score has been updated from a previous value.
    • The Teensy will then display the score on a couple of test OLEDs using the font of the original game. The actual size, locations and number of displays are to be determined, but getting it to score out reliably was a big challenge as this is my first FPGA project.

Stay tuned for more project updates here!