Seattle Pinball Museum visit – 2011

17 November, 2011 (16:36) | Uncategorized | By: admin

This year while I was in Seattle attending the Northwest Pinball and Gameroom Show I also had the opportunity to attend a tournament at the Seattle Pinball Museum. I had a blast! What a great facility. All of the games were in great condition and the people were friendly. If you are in the area you should consider it a must to pay a visit to the museum.

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Bally/Stern MPU Memory Expansion Board

20 April, 2011 (13:27) | Pinball | By: admin

It should come as no surprise to readers of my blog that I’ve created yet ANOTHER daughter board for the Bally/Stern pinball MPU. This time the board greatly increases the available RAM and ROM. You might be asking “why would I want that”. Well… most people probably won’t need or want that at this stage of the game. In the future, however, I would like to see a community of developers grow up around this board and use it to create new and amazing game code for older games. At a minimum I would like to see simple things like attract mode added to games that did not originally have any kind of attract mode (think early “chimer” games).

In addition to adding substantial RAM and ROM these boards are also fully compatible with original game code making them a relatively cheap and easy way to upgrade and repair original MPUs potentially replacing as many as 7 ICs which would originally have needed their sockets replaced with a single CPU socket based daughter board. The RAM is all contained in a single NVRAM so there is no more need for batteries. A jumper is provided to select between “Bally” and “Stern” RAM modes allowing compatibility with games that originally used a single 5101 RAM (all Bally and Stern MPU-100).

Unlike my other EPROM replacement daughter boards this board connects to the CPU socket. This was a requirement to achieve maximum RAM and ROM but also makes it easier to use -17 and MPU-100 boards with newer game code. Converting a -17 for use in an MPU-200 game is as simple as installing my board and replacing a couple of capacitors in the clock circuit to increase the clock speed to MPU-200 specifications. I cover that conversion in an article here.

Here are some pictures of my current working prototypes. I expect to have these available within a couple of months. I’ll have some more detail about the exact memory map and usage of the board at that time. In the mean time I can say that there will be approx. 8X the original ROM and 20X the original RAM!

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Williams System 6/7 Sound Board Conversion – Using Old ROMs In Newer Boards

27 February, 2011 (21:39) | Pinball | By: admin

Last year I wrote an article about the Williams System 3/4 sound board. That board was used in the early solid state Williams pinball machines. Later machines (System 6/7) used what could be considered a more advanced version of this board. The second generation board is very similar to the original board with some changes to the address decoding and the addition of an extension header which was utilized for speech in some games.

The System 6/7 sound board was also used in Williams arcade games (Robotron, Joust, Stargate, Defender, etc…) so there were WAY more of these boards manufactured and these boards tend to be cheaper and easier to find than the older, larger sound boards. The later sound boards were intended to be backward compatible with the earlier games but recently I learned that this is not the case when a reader commented on my System 3/4 sound board article pointing me to a problem that had been discussed a few times on RGP recently. That problem being that the ROMs originally used on the older sound boards don’t work in the newer boards with their ROM socket strapped for the same type of EPROM.

The reason the original ROMs don’t work in the newer board is because the address decoding scheme is less strict on the original board mirroring the ROM into several locations. This wouldn’t be a problem in itself if the programmers had not “cheated” and relied on this fact in their programming. Ultimately it boils down to inconsiderate programming.

There are 2 options to solve this problem. One would be to modify the ROM to work within the address decoding of the newer sound board. The other option is to modify the board to “convert” the newer board to act like an older board by re-routing a couple of pins. The latter is the conversion that I found to be easiest to figure out and that’s the conversion I will cover in this article. Once the board is converted you will be able to use an unmodified System 3/4 sound board ROM.

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Bally/Stern MPU single 2764 EPROM conversion

21 February, 2011 (10:03) | Pinball | By: admin

A conversation with a fellow collector led me to revisit an old problem that I never really solved at the time. Originally I wanted to develop a method to convert Bally and Stern MPUs to use a single EPROM. Bally had the option to use a single 2764 EPROM on their 6802 MPU so it should have been easy enough to just look at that schematic to figure out how to make the earlier Bally and Stern MPUs work with a single 2764 EPROM. This proved to be true, though a different method would be required for each board generation (-35, MPU-200 and -17/MPU-100). I quickly moved on to using 27256 EPROMs for my single EPROM conversions but I don’t currently see a good set of instructions for a single 2764 conversion for Bally/Stern MPUs and I decided it was about time for me to follow through on an old idea and put together some instructions to benefit everyone.

Click “Read more” for complete instructions.

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Data East Star Wars Repairs

24 January, 2011 (13:08) | Pinball | By: admin

Last year (2010) I bought a Data East Star Wars pinball machine. Overall it was in great condition but there were a few little things that needed to be fixed. One of the stand-up targets was broken and R2D2′s head wasn’t rotating. Fortunately the seller included a new R2D2 motor and stand-up target.

The general illumination lighting was also not working. That was the first thing I fixed. This is not uncommon at all on these games and many other pinball machines. The connectors fail due to heat over time. Below you can see the connector that I replaced. It was quite burned and the general illumination lighting wasn’t working at all. I replaced the plastic connector housing, the connectors and the male header pins on the PCB.

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Preview – Bally Black Jack Restoration

13 January, 2011 (10:34) | Pinball | By: admin

Well… I’m finally getting back on track with restorations. I’m finishing up the Stern Stingray that I started about 2 years ago and the next in line will be two Bally Black Jack machines. I haven’t totally decided what I’m going to do with them yet. One option is to restore one and sell it to fund the purchase of new plastics, bumper caps, etc… for the other one, clear coat the playfield and do a full restoration job on it. The other is to just shop out both of them and sell them both which is what will probably end up happening. I’m realizing that I only have so much room and as much as I love these early solid state games they just don’t hold up to some of the newer titles.

More to come but in the mean time I’ve got some pictures of one of the two machines in my gallery. Click the image below to see the gallery.

2064 NVRAM Adapters

17 December, 2010 (01:13) | Arcade, Pinball | By: admin

I finally got around to testing my 2064 NVRAM adapters and they work perfectly! Well… technically I’ve only tested one in Data East Star Wars but it works perfectly! These adapters replace the original 2064 RAM on many of the newer pinball systems and eliminate the need for batteries. Adapters for older RAMs (5101 and 6116) have been available for a long time and I’ve made those as well but RAM adapters for newer games using larger RAMs have not been readily available so I think these will be popular. I will be selling these adapters through my new site very soon.

Look, Ma! No Batteries!!

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New site preview –

17 December, 2010 (01:07) | Pinball | By: admin

Williams System 3-6 Sound Board Repair

12 December, 2010 (14:48) | Pinball | By: admin

Earlier this year I did some work on a Williams System 3-6 sound board for a friend. At the time I thought I would document the repair and also repair a few more of these boards that I have awaiting repair and do a more in-depth analysis of this board but I never got around to repairing the other ones and probably won’t get to them any time soon (no projects currently needing this board) so I figured I would share the original repair and some general information about this board.

I’ll skip right to the good part and reveal that the problem I found with this board is that someone had removed the key pin from the power supply connector and connected it to the sound select inputs header. I don’t know this for a fact but the owner did tell me that there was no key on that connector and it seems pretty obvious based on what blew up.

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Classic Playfield Reproductions Centaur Playfield 2010 re-run

8 December, 2010 (13:49) | Pinball | By: admin

In November 2010 Classic Playfield Reproductions announced a short re-run of their Centaur playfield. It was offered in 3 different versions and I was lucky enough to get one of the prototype version before they sold out. I don’t currently have a Centaur but I have a couple of leads to acquire one and I couldn’t resist the opportunity.

Click the image below to read the press release from CPR. Lot’s of pictures!