We found more than we could have hoped for.
Behind the building in the snow drifts there were several cabinet in various states of decay. We took the two best ones there and hoped to be able to piece one cabinet back together. Within these two cabinets we found a 19 inch monitor, various buttons, switches, and joysicks, and a SEGA sytem 16 board with Golden Axe on it.
We had the makings of a real machine!
Now to find out how much of it worked. I set out to evaluate and repair the electronics and the others set out to fix the cabinet.
I found the pinouts of the connector on the spies.wiretap ftp site and fired up the board. No smoke, but no sounds either... Time for better test equipment. I got hold of an osciliscope here on campus and went looking for signals. I found the video and sync signals alright, but there was no sound.
The next weekend we fired up the monitor from the other cabinet and discovered that it worked. Next we connected the system board and the monitor. Nothing. Hmmm, oops, forgot the return line for the video. Connect that. Fire everything up and no oscilation on the monitor and SMOKE! Pulled the plug fast enough. Didn't hurt anything. Turns out that the monitor is a hot chassis design with a polarized plug and a ground. I guess the idea was that if you plugged the thing in backwards there would be a hot to ground short and the fuse in the game (or the building) would pop. Turns out that the extension cord we were using had hot and neutral reversed and no ground. When we connected the return line on the video, we provided 120V AC across some of the input circuts.
We trashed the extension cord and tried again. Cool! The FBI anti-drug propaganda screen came up followed shortly by the game demo. Neat!
Needless to say, we had the controls patched into the game in less than 15 minutes and we were playing Golden Axe... without sound.
I found a number for SEGA's service department and gave them a call. They were most helpful. Turns out that the Z80 processor responsible for the sounds was bad. I replaced it with a pull from some random piece of computer equipment and we got sounds... really loud obnoxious clanging and rumbling and stuff... Hmmm, a few more calls to SEGA and we discover that one of the audio ROMS was pulgged in wrong. Now it is dead. Well, no problem, a quick visit to one of the various ROM archives on the web and we had an image of the deceased ROM. I burned it to an EPROM and tried it out. Now we have the right sounds except for a few of the voices. I think the tests indicated that voices 11-15 are wrong. Anyone have any ideas about that?
Next we made up a new front panel for the controls and wired the cabinet.
We now have a 95% functional SEGA Golden Axe machine.
Recently the monitor gave up the ghost. The flyback transformer kind of ate itself in a ball of orange fire. We replaced it and the focus dividers ate themselves. A few phone calls later a local arcade operator offered us a working 19 Wells Gardner monitor for free. We picked it up and ran a few tests. Unlike the Matsushita monitor we slavaged, the Wells Gardner was not going to play without an isolation transformer (I measured 140V from the chassis to ground no matter which polarity the thing was plugged in). Since we had to buy a transformer anyway, Ben elected to rewire the cabinet from scratch. We installed an isolation transformer for the monitor, a brand new JAMMA harness, and two new joysticks. The service, tilt, and reset switches were installed properly this time and the speaker got a volume control.
Next on the project list is refinishing the cabinet. We already cut stensils of the defender artwork and are ready to strip and repaint the cabinet. Should be a good dusty summer project.
back one level