On many pinball machines like early solid state Bally and Stern games, you’ll often see little capacitors on most of the playfield switches. Sometimes they’re there but a leg is cut off. Why are they there? What do they do? And are they important? We’ll talk about that.
What are these capacitors? Originally they were 0.047 uf 50v. There are various versions you can use. I will sometimes replace them with a 0.1uf and it works fine.
After getting my Trident operational, I installed the BSOS system and have been working on fine-tuning the custom code and sounds. Here’s a short demo of what the new Arduino-based controller does to a standard Bally 18/35/Stern early solid state game.
Resources (courtesy Dick Hamill):
The code is all available on GitHub. It’s broken down into a base library and then machine-specific implementations. Rewriting other games requires a moderate knowledge of C/C++. https://github.com/BallySternOS
Here’s a suggested parts list. If you bought all these things, you could create 6 of these boards. If you don’t need that many boards, you might find cheaper ways to source smaller quantities. I haven’t done any work to figure out if this is the cheapest way to source any of this stuff.
Cheap Arduino knockoff x6 ($20.99) – needs CH340 driver for programming / has to be ATmega328P https://www.amazon.com/ATmega328P-Controller-Module-CH340G-Arduino/dp/B08NJNJCTX/
0.1″ 40-pin connector (40 pieces for $7.99) https://www.amazon.com/Honbay-Single-Female-Connector-Arduino/dp/B06Y4S6G29/
32-pin Prototype PCB (2 pack for $9.99) – this won’t work for Alltek or MPU-200 because they have a 34-pin connector https://www.amazon.com/Prototype-Snappable-Arduino-Electronics-Gold-Plated/dp/B081QYPHHP/
Wire ($7.99) – tons of wire https://www.amazon.com/REXQualis-Breadboard-Assorted-Prototyping-Circuits/dp/B081H2JQRV/
Boot switch – x2 ($8.99) this switch will work for activating the Arduino board and toggling the speaker (see the writeup here to find out why: https://ballysternos.github.io/install.html) https://www.amazon.com/gp/product/B07XMH174C/
I found this old video the other day and realized I didn’t have a post on my main site showcasing this video so I wanted to add it (also, this was before I learned the proper pronunciation of “Bally” LOL…. bah-lee).
This is a short video going over the steps to repair/rebuilt/refurbish early solid state pinball flipper assemblies, such as those on Stern and Bally games (but this also basically applies to most pinball machines). I go over the process specifically on a Stern Trident and show the specific style of plunger and assembly they’re using, but most games use similar parts. You can use these techniques to rebuild/refurbish pinball flippers on most games.
Also, there’s another thing I don’t cover on the video that may also be a cause for stuck/sticky flippers, and that’s crud around the flipper button. Sometimes the flipper button assembly can be dirty and the button may stick – that can also cause the flippers to not behave properly, so be sure to check and clean the flipper button regularly too!
Here is a series of three short videos covering the process of removing and refurbishing the drop target assembly on early Stern/Bally games. This is done on the Trident I’m working on restoring.
After unscrewing the switch stack and the reset coil, you can remove the drop target assembly from the game. Then you an remove the individual drop target coils from the assembly by unscrewing four small screws.Note the inner plate behind the drop targets that has slid down – this is what the switch stacks screwed into, so you’ll want to connect them back to the assembly first, before putting the individual drop coil bank back in place.Since I wasn’t replacing the targets, I simply soaked the assembly in hot soapy water, then made sure to dry it completely before applying some dry spray lubricant. I also shortened the springs by just a tiny amount to make them work better. If you have replacement targets, they should be removed and replaced, which is done by removing the retaining clip and axle holding the assembly together at the bottom.
I’ve run into this problem at least 3-4 times in the last month with different early Bally/Stern solid state games: The game boots and appears to work but you can’t start a game and/or many switches/buttons don’t seem to work? Before you dive deep, try this simple, easy trick.
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which connectors on the Bally/Stern MPU board go to which areas of the game.
I’ve been working on a new project that I’m very excited about. There’s been a movement to create an inexpensive, non-destructive and simple way to mod early Bally/Stern solid state games and add more features. In this video, I demonstrate an early prototype of the system used to modify a Bally Mata Hari pinball machine to include new features such as a skill shot, modes and even a wizard mode.
