The BallySternOS project upgrades your old classic 80s area pinball machine with new CD-quality sound and upgraded rule sets. No more “blip, bloop” oscilloscope sound effects.
All information needed to implement this project is available at: https://github.com/BallySternOS
The games supported by this project include – Mata Hari, Silver Ball Mania, Trident, Meteor, Flash Gordon and Blackjack. Thanks to DickHamill for creating this amazing upgrade – the code, the sounds and even recording the call outs himself!
The upgrade consists of an interface card for the previously unused J5 pins on the MPU, an Arduino with Dick Hamill’s code installed and a Wav Trigger card, the first truly polyphonic embedded audio player, with the sound and music installed on a microSD card.
The Arduino takes over most of the MPU functions and sends triggers to the Wav Trigger card which are then played through an amplified speaker or small amp. The sounds via the Wav Trigger are polyphonic meaning they can overlap.
What is BallySternOS? Arduino-based Operating System for Stern MPU-100 and Bally AS-2518-17 pinball machines.
How to build the J5 Card
https://ballysternos.github.io/
Parts list:
- 0.1” F Headers (1×32 for J5, 2×15 for Arduino)
- 0.1” M Headers (2×15 for Arduino if it didn’t come with any)
- Wire
- Prototype Board
- 74LS125AN (or equivalent)
- Single pole switch (to select boot mode)
- Arduino Nano (has to be based on ATmega328P)
- Alligator clip
- 10k Resistor
What else is needed
MicroSD card for the sounds and music. Not all SD cards will work. We’ve tried this card in three Meteor 2021 upgrades and it works every time – SanDisk 32GB Ultra microSDHC UHS-I Memory Card with Adapter – 98MB/s, C10, U1, Full HD, A1, Micro SD Card – SDSQUAR-032G-GN6MA
Upgrade Your Speakers
Let’s talk about upgrading Meteor’s speakers to take advantage of all the audio wonders this Meteor 2021 upgrade provides.
The original Meteor pinball machine only had a single speaker mounted in the base of the cabinet. Original Meteor was mono.
The new Robertsonics Wav Trigger is a major upgrade to the sound.
- Supports up to 2048** uncompressed 16-bit stereo WAV files up to 44.1kHz – CD quality
- Polyphonic! Play and mix up to 14 stereo tracks independently and simultaneously
- Sample-accurate starting and playback of up to 14 parallel stereo tracks
Also even though the board has a small internal amp that can be wired directly to small speakers, for louder, better sound quality you really want external amplified speakers.
My shopping criteria was the following:
- Nothing overly expensive (Around $100 or less)
- Easy to reach volume controls – on the right side or remote
- 28 inches or less to fit on the top of the backbox
- Separate subwoofer – to fit inside the cabinet or on the floor under the machine
- Good reviews
- Aux input (mini stereo cable from Wav board to soundbar)
- Stylish
I ended up finding this soundbar from Wohome, the S99 which seems to check all of the boxes.
Alternatively – Small amp and small speaker set up
Soundbars provide an all-in-one solution but a soundbar has two issues that you might not like. One, soundbars tend to shut off when there is no sound and then have a few seconds delay upon waking. Second, it’s visible i.e. outside the cabinet.
I actually ended up with a different solution. Noticing the 1×5 inch vent on the left side of the head, I figured I could drill a similar hole on the right side and add speakers inside the head.
I actually found a 1×5 inch oval speaker on Part Express that might just fit that opening. I also looked at unsealed small 2 inch 5w 8 Ohm speakers that could be mounted inside the head with some custom mounts.
Ultimately I decided on these little cube 3-inch speakers from Pyle. They are already sealed and I can play around with their positioning. I can also put them outside the cabinet if need be since they are boxed. They also are rated at 100 watts of power, 8 Ohm impedance and are video shielded – all for around $15 per speaker.
To power these little speakers and the existing speaker in the base of the cabinet for the low end, I picked up this little 2.1 amp.
It has an RCA input on the back and a mini 3.5 mm input on the front. Separate subwoofer output for the cabinet speaker and controls for volume and bass. Mounted near the coin box it will provide easy access for volume control.
Now just add some speaker wire to hook up the speakers.
And a mini 3.5mm plug to RCA plug to run from the Wav Trigger to the amp. Eight feet should be sufficient, I’m getting 10-foot just in case. Also, a right angle on the mini-plug is always a nice feature. (You could use the front input – mini to mini – but let’s keep things neater by keeping all the wires in the back.)
Updating the firmware on the Robertsonics Wav Trigger
I’ve done two Stern Electronics Meteor pinball machine upgrades to the 2021 version. On one of the Meteor pinball machines the background music comes and goes. I suspect it needs a firmware upgrade. This is only possible using what is known as a FTDI Basic Breakout. You need this:
and a MiniUSB cable (the kind that comes with an Arduino)
Information on how to update the firmware can be found in the wav table manual here: https://learn.sparkfun.com/tutorials/wav-trigger-hookup-guide-v11#firmware-updates
Also from the Robertsonics WAV Trigger User Guide: https://static1.squarespace.com/static/62ab6e0d1f3ea036834d4a0b/t/647a2625e5ce402543edf195/1685726759550/WT_UserGuide_20230602.pdf
Other Resources – Pinside Thread “Meteor 2021 – New Code for Stern Meteor 1979”
https://pinside.com/pinball/forum/topic/meteor-2021-new-code-for-stern-meteor-1979
Add some bling to your pinball machine and game room
These LED music bars react to sound and create an interactive light display. You can install them behind the head or under the cabinet for cool lighting effects.
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