Why do some pinball machines have capacitors on their switches?

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.

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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.

Any .05 or .047 uf at 50 volts or higher mylar or ceramic disc type is fine. Here’s a sample link: https://www.newark.com/vishay/1c10z5u473m050b/cap-0-047-f-50v-20-z5u/dp/57AC4650?st=0.047uf

How to properly clean battery damage off a MPU board

This is the next video in my series of work on Paragon. After the first look (http://pinballhelp.com/first-look-bally-paragon-pinball/) I discovered there were still issues with the MPU board that were the result of continued corrosion even after the battery was removed and the board was supposedly cleaned. Whoever did the previous work didn’t clean the board enough and corrosion continued. I’m going to do my best to salvage the board.

Quick demo of fully-modded Stern “Trident” pinball with new rules and sound

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/

74125 – ($1.95) https://www.jameco.com/z/74125-Major-Brands-IC-74125-Quad-Tri-State-Bus-Buffer_49373.html

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/

OR

@RoyGBev has created a PCB and kit (doesn’t include the Arduino) here:
https://pinside.com/pinball/market/shops/1304-roygbev-pinball/04736-arduino-nano-adapter-for-classic-bally-stern

How to make a test bench rig for Bally-18/35 MPU boards using a PC power supply

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).