Tilt/Switch-matrix problems on Bally-35 Flash Gordon

I was going through some old videos that had been uploaded to YouTube that for some reason were not made public and found this one. It’s a short video on how to go through the diagnostics on these 80s era Bally pinball machines and track down switch matrix issues. I don’t go into how the matrix works in this particular video, but I do demonstrate how a stuck switch can cause odd behavior. In this case, the tilt triggers when a certain target is hit.

Tracking down drop targets that won’t reset – Bally-35 “Mystic”

This is a game that’s been sitting in the back for awhile at my place that I keep meaning to get to, so I finally jumped back into to figure out what was wrong. It’s weird to go over notes you made 6+ months ago and try to pick back up where you left off — remind me not to do that.. LOL But the issue was relatively simple: The center bank of drop targets was not resetting.

In this series of videos, I go over, step-by-step the process of how to figure out what’s causing this problem, how to read schematics and manual diagrams, and the various points of failure, and once again, we are reminded of “Ockham’s Razor” which suggests the most obvious cause is the most likely… OR IS IT?

Interestingly enough, once I figured out where the problem was, rather than solve it the traditional way, I choose to do a “hack”… basically just to see if I could do it. The choice was, do you replace an entire 16-pin IC that’s only using one small part of it (involving adding a socket and a new chip that is pretty expensive and hard to find) or do you “hack” the damaged chip and piggyback a new component on top of it? Normally I don’t do these kinds of MacGuyver stuff on system boards, but it was a fun trick to try and it cost a few cents and about 10 minutes verses a lot more time than would have been used to replace a whole IC.

One reason why this hack job is particularly sloppy is because I had to work on the board in the game due to the previous owner having hard-soldered some wires to one of the connectors – that’ll be another future project to clean up all that mess, but for now, I needed to get this back working.

To understand what I did, here is a substitute circuit board showing the position of various individual 2N4401 transistors overlaid on the CA3081 IC package. Using this you can figure out where to insert a transistor manually on the IC pinouts if one of them fails:

Pinball Stories #1: My first game, “Genie” by Gottlieb

One of the things us pinball enthusiasts love to do is tell stories about how we acquired games. Each game has its own unique provenance and history, and there’s almost always an interesting story behind them. This is the first episode in an ongoing series were we talk about the stories behind the games and how they came to be. I start the series off with the very first pinball machine I purchased, a Gottlieb “Genie” – before I knew anything about how to repair and restore games. It was the game that got me on this path. I hope you enjoy the story – be sure to subscribe on Youtube! Thanks for watching!

Here are some pictures from early on when I got the game and began to restore it.

Building replacement LED displays (from a kit)

This is a fun series of videos of me trying something new. Let’s replace the old gas plasma displays in a Bally 35 solid state pinball machine with new low-voltage LED displays. This reduces the power consumption of the pinball machine and cuts out the high power portion of the power supply board for the display – a whole area we don’t have to worry about any more by switching over to LEDs. The price for this as a kit is quite reasonable (and cheaper than replacing them with used displays usually). But it takes some time and skill to populate your own circuit boards. I’m going to give it a try. Let’s see how it goes!

Here is a time lapse of me doing the lion’s share of the board work:

And here’s the finished product!

All about connectors: Molex, sizes, tools, pins and crimping

Pinball machines (as well as other arcade games) use a wide variety of wires and connectors. The most popular brand of connectors is called “Molex” which is a specific maker, but also a generic term often referred to as the plug/un-plug style connectors you will find on everything from power supply wiring to board connectors.

In this video, I go over the most common sizes and types of connectors you’re likely to find, what tools are available and how to rebuild and re-pin these connectors.

Rebuilding a Gottlieb VUK (vertical up kicker)

As work continues restoring this Gottlieb system 3 pinball machine, “Waterworld”, I rebuild the broken VUK (vertical up-kicker). This is from a series of videos where I rebuild a number of the core components on this game that’s been on location for probably more than a decade.

Diagnosing weird game issues with Gottlieb System 80B (Raven)

Just when I thought I had my Raven running beautifully, it just started acting up. I would press the start button and the game would begin to start, but then not kick out a ball, the sound would stop, and none of the coils would fire. It was very odd. I knew from experience that Gottlieb games can get a bit wonky with irregular power or switch inputs, so here’s a short, 2-part video series of the “rabbit hole” I went down trying to figure out what was wrong? (As always, Ockham’s Razor tends to prevail)

Along the way, we learn a few things about the switch matrix on these System 80 games and how they differ from other manufacturers like Bally/Williams when it comes to trying to trace switch matrix issues. Here’s part one:

And here is part two, where we figure things out…