Category Archives: Gameboard Upgrade

Improved Wiring

I finished up my custom Super-Pac-Man-cabinet-to-JAMMA wiring harness tonight. I removed all of the unused wires from the JAMMA harness, bundled the necessary wires into wire loom, and sealed the exposed solder connections in hot glue. This really help to unclutter the cabinet and I’m quite happy with how it came out.

Here’s how a connector looks with hot glue sealing it up:

Nothing a little hot glue won't solve...  :)

In addition to protecting the connector from shorting out on exposed metal parts in the cabinet, it also prevents strain on the solder connection. Bob Roberts’ switching power supply harness used this technique and I basically imitated it. If you’re really observant, you might have noticed I switched to a different style of pin header as well. I found a longer strip that could be custom-sized to the exact length I needed instead of using three of them in a row. Using three pin headers in a row would have made the hot glue application much more difficult.

I’m sure I could clean the wiring up a little more, but overall I’m satisfied with it. Here’s how it looks now:

Improved wiring...

Multi Game PCB

I ordered a Programmable Multi Game JAMMA PCB from ArcadeShop.com and I found JammaBoards.com had a full JAMMA wiring harness for only $10. I noticed they also sell a selection of multi-game PCBs for far less cost than the ArcadeShop multi-game PCB. I was back and fourth deciding which multi-game PCB to buy and finally decided to go with the more expensive ArcadeShop board because it generally gets better reviews in the forums, is more customizable, and has a prettier menu system. I’ve decided not to include the cost of this PCB in the Total Cost section because it’s not really necessary to the project and the cost of the ArcadeShop multi-game PCB alone exceeds the entire cost of the project. (and that sort of depresses me)

I did have a good time assembling a custom Super Pac-Man cabinet to JAMMA harness. It really wasn’t too difficult because the pinouts for JAMMA are an established standard and the pinouts for Super Pac-Man are easily available as well. I bought some connectors to fit the cabinet wiring and soldered the leads from the JAMMA harness to the correct pins in the connectors. Here’s what they look like:

Sound and control harnesses.

Video harness.

Note the arrow on the video harness. It’s pointing to two pins for the negative horizontal and vertical sync signals. I found out these two must be bridged to give the Electrohome G07 monitor the signal it needs to sync the picture when getting output from a JAMMA-connected PCB. Without bridging these two pins, the picture was nearly impossible to stop from rolling on the screen. I really don’t understand monitor circuitry well enough to explain why this is. Here’s some corroborating evidence that helped me out. Also, a big thanks to the monitor experts on the BYOAC forum for helping me spot this subtle detail. I will eventually seal the ends of the connectors to prevent any short circuits, but I was impatient and wanted to try it out.

With the harness assembled, I just had to put it all in the cabinet. The right side of the machine was bare from the factory, so it looked like a perfectly good place to relocate the power supply and install the multi-game PCB. I also reinstalled the old linear power supply, but it’s not hooked up to anything. It’s just there because I have no other good place to store it. Here’s how it looks:

Multi-game installed.

I know, I know… I need to clean up all the wiring I added, but it does work for now. I’ll post some photos or video of the screen soon. It’s pretty slick.

Update On The Game Board

It’s been quite a while since I wrote about the main game board. My last posting mentioned that I was going to install a code upgrade and a non-volatile SRAM chip to make this machine preserve high-scores after being powered off. I did actually complete this upgrade about 5 years ago and didn’t post anything about it. It was a lot fun too! I bought a EPROM programmer from eBay for about $50 and figured out how to use it. Then, I bought the two chips I needed, programmed, and finally installed them into the sockets on the game board. I remember the first power-up with the new chips resulted in a garbled display. I powered it off and was about to pull the new chips to test them. For whatever reason, I decided to power it on again and to my surprise it worked perfectly from there on. I guess the first power-up was some sort of initialization of the memory chip or something. Anyway, high scores are now able to be saved and I’ve been quite happy about it. I recall the SRAM chip has roughly a 10-year lifespan which is pretty decent considering how small it is. I don’t recall the data size it can hold, but I believe it was 12KB. (probably 11.9KB larger than it needed to be)

Why bring this up now? Well, partly to trumpet the progress I made but also to mention my recent change in direction with this cabinet. Since I fixed the original power supply issue and returned it to playability, my goal has been keeping the cabinet as close to original as possible while fixing up any cosmetic issues. That’s still the goal, but I recently decided it’s OK to expand upon the usefulness of the 4-way leaf-switched joystick and vertically-oriented monitor by adding some new games to the cabinet—as long as it is done cleanly, tastefully and is able to be completely reversed with minimal effort.

I already own a few dedicated MAME cabinets and I’m not aiming to turn this into another one. In fact, I’m not even going to mess with the original wiring in the cabinet. The only thing I’m going to add is a selectable game menu upon start-up. It will be along the same lines as what Jeff Hanson did with his Super Pac-Man. The only games will be a small selection of classics that were built for this sort of cabinet. (i.e. Pac-Man, Ms. Pac-Man, Super Pac-Man, Galaga, Donkey Kong, Dig Dug, etc.)

How is this possible without fully MAME‘ing the cabinet? Simple—I’ll build a custom JAMMA harness to interface with the original cabinet connectors and add a Programmable Multi-Game JAMMA PCB. I’ll be able to unplug the original game board and plug the new board in using the exact same connectors. Very clean and very easy to reverse. More details on what this will look like are on their way…

Upgrading Software From 1982

Now that the game is playable, I’ve set high scores which are lost after power off. That kind of sucks. Luckily, I found this today.

This guy reprogrammed two 2764 ROMs and upgraded an SRAM chip to achieve high score retention after power off. That’s insane, but I still intend to reap the benefit of his hard work since he offers the binary ROM images free for download.

I could buy them preprogrammed from this place for $45, but frankly I need an excuse to buy an EPROM programmer. One can be had for under $50 thanks to Willem. I don’t think the blank chips will be more than $10 either. The chips are all socketed, so it’s a plug and play swap once I have them programmed. 🙂