Archive for category: Pinball


New Photo Gallery Added!

28 October, 2010 (09:32) | Arcade, Pinball, Restoration Logs | By: admin

I have added a new photo gallery to the site. This is something I planned to do a long time ago and finally got around to doing. This gallery will let me share many more pictures in much higher resolution than I have been sharing up to this point. I’ve already added a bunch of [...]

Bally/Stern MPU Repair #2

13 September, 2010 (10:25) | Pinball | By: admin

A fellow collector from the KLOV forum acquired a Xenon machine recently and needed an MPU. I offered to sell him one and he accepted so I pulled one out of my huge pile of MPUs needing repair and did a bunch of work to get it working and make it reliable. This is the [...]

Peripheral Interface Adapters Have Been Assimilated.

1 September, 2010 (08:29) | Pinball | By: admin

I have conquered the Motorola 6820/6821 peripheral interface adapter! Last week I got another batch of prototype PCBs and one of them was the latest version of my Bally/Stern CPU socket based daughter board that adds a microcontroller connected to all of the CPU pins needed to let the microcontroller run in parallel with the [...]

Pinball Hall Of Fame: Part 1

31 August, 2010 (03:36) | Pinball | By: admin

If you are ever in Las Vegas you owe it to yourself to visit the pinball hall of fame. I was lucky enough to visit the pinball hall of fame on 2 occasions over the 4 days that I was in Las Vegas. I played about 90% of the machines that were available and had [...]

Pinball Hall Of Fame: Part 2

31 August, 2010 (02:37) | Pinball | By: admin

Part 2 of the Pinball Hall Of Fame pictures:

Adjusting Bally/Stern MPU Clock Speed

18 August, 2010 (04:13) | Pinball | By: admin

Update: I found some instructions online to replace the original 470pf capacitors on -17, -13 and MPU-100 MPUs with 220pf to convert them to the MPU-200 clock speed. I tried this conversion but measured the clock speed at close to 1Mhz. That’s too fast for MPU-200. I was able to get close with two 50uf [...]

Bally/Stern MPU 27c256 single EPROM conversion.

13 August, 2010 (00:07) | Pinball | By: admin

Recently I have been experimenting with methods to replace the EPROMs on Bally/Stern MPUs with a single EPROM. This is the direction I’m planning to go with the more advanced version of my MPU daughter boards. Initially I was planning to use a 2764 EPROM to replace the original 2x 2732 EPROMs but the Motorola [...]

More Bally/Stern MPU Hacking! – Replacing 5101 RAM with 6116

16 July, 2010 (06:13) | Pinball | By: admin

NOTE: Updated June 20, 2011 to include MPU-200 specific instructions. While looking at the Stern MPU200 schematic trying to figure out how I was going to add RAM to my MPU daughter boards I realized how easy it would be to install a 6116 SRAM in one of the unused EPROM sockets to replace the [...]

Another new Bally/Stern test board!

16 July, 2010 (05:26) | Pinball | By: admin

A lot of my projects are finally starting to come together. These boards are another step toward a dedicated lamp driver board testing system. These boards connect to J1, J2 or J3 on the lamp driver board and connect an LED to each SCR output. There is a chart screened on the board that shows [...]

Bally/Stern MPU Test Board Version 2

7 July, 2010 (22:05) | Pinball | By: admin

A while back I designed some boards to replace the EPROMs on Bally/Stern MPUs. Once I started using it to test boards I realized that I needed to design another board geared more toward testing. What you see below is the result of this effort. It’s basically the same board but I’ve added a test [...]