Hacking the MGCD (Part 1)

The MGCD is a console to JAMMA converter created by Taiwanese company Frolicker, and distributed by many Taiwanese arcade resellers. Several versions of the MGCD were produced for Dreamcast, Playstation2, Gamecube, and Xbox. What makes the MGCD unique to other pay-to-play console timer PCBs, was the MGCD could be programed to recognize the start game screen of a particular title, as well as the end game screen, allowing it to disable all input, sound, and even video, until the game was fully loaded and start game screen ready. So in a sense, the MGCD could disguise the fact that you were playing the console version of an arcade game. Here is the manual for the MGCD-B Version, showing all the nifty features and settings.

For a pretty stupid reason, the MGCD isn't exactly plug and play with most JAMMA setups. The problem is in the fact that the MGCD maps 12 player action buttons to the jamma finger board, utilizing the last 2 pins on each side, which are typically tied to ground on most JAMMA looms. If these connections are tied to ground, the MGCD will not boot up properly, and simply not work. To get around this, you must either modify your JAMMA loom connector of your cabinet, detaching the ground wires to these last pins, and connecting them to player buttons 5 & 6, or just leave them off completely. So instead of modifying my cabinet, I just created a fingerboard which lifts these last two pins on each side, allowing me to play on any JAMMA cab. If I wanted to use these last two buttons for fighting games, I could simply run a wire to the fingerboard up to the control panel.


Leave the last two pins on either side disconnected.

Similar to other pay-for-play "timer" PCBs, the MGCD can also play credits for time, although with an annoying timer countdown that is displayed once per minute at the bottom of the screen. With the limited number of games recognized by the MGCD firmware, the timer feature is primarily used by most people, where you can setup a single credit to play for a maximum of 256 minutes. The problem, of course, is that that annoying time displayed at the bottom of the screen.



Figuring out how to remove the timer overlay took some trial and error. At first I tried re-routing the RGB video signal from the console output, directly to the front of the fingerboard. This did work, but the signal was unamplified, and too dark/weak to be displayed on an arcade monitor. So the only other option was to figure out which chip on the MGCD was doing the video overlay, and disabling it. This took a lot of probing around, but eventually I found the chip, and grounded one of the legs to effectively disable it.


Video timer overlay chip highlighted in red.



Connecting these two pins (highlighted in red) will disable the video timer overlay.


Now here is what the output looks like without the timer.



Finally, here is the MGCD installed on my PS2, and ready to be played on any JAMMA machine.




Next, I'll talk about how to take the MGCD Dreamcast version and hook it up to a cabinet at either 15khz or 31khz. (Go to Part 2 here!)