JAMMA SuperGun

A SuperGun is a device which allows you to play real arcade games without requiring the whole cabinet they'd usually be installed in. Instead, you provide your own joysticks, monitor (usually a home TV set) and power supply. The SuperGun basically provides the wiring and electronics to connect these things together. There are a number of commercially available SuperGuns, but they're not incredibly complicated and therefore make a nice project you can build at home. Over the following pages, I'll describe the process of building a SuperGun to my own specifications. The total cost of this project came in at about €100, the most expensive parts being the power supply and the case. If you already have a power supply (one form an old PC will do fine) and a case, or you don't need a case at all, you should be able to build one similar to this for a lot less.

Disclaimer

This documentation is written to be easy to follow, but does assume that the reader has at least basic "hobby level" knowledge of electronics. If you don't understand terms or concepts used in this documentation, please do any appropriate research before continuing.

It seems common sense to me, but just for the record: The author cannot and will not be held responsible for any damage or injury caused by following the directions in this documentation. The documentation of this project is provided as-is, with absolutely no warranty, and you use the information therein at your own risk.

Requirements

Building your own SuperGun means you get to pick exactly which features it's going to have. The main points for me were:

Primarily for use with a Neo-Geo MVS board to be mounted on top of the unit. Must however have the ability to connect standard JAMMA boards. This means catering for slightly different pin-outs and the Neo-Geo's extra buttons.
SCART RGB video output with adjustable brighness for red, green and blue signals. No need for composite, component or S-Video.
Audio output to two RCA (cinch) connectors and the SCART conenctor. Must be able to switch between JAMMA mono sound and MVS stereo.
Neo-Geo joystick ports. This is somewhat the norm for SuperGuns anyway.
Separate coin buttons on the unit, but also the option to use a joystick button for credits.

Basic Design

As I wasn't worried anything complicated like video conversion, this SuperGun was going to be predominantly a matter of wiring. The block diagram shows the main components.

JAMMA connector: Standardised connector for arcade game boards. The actual pinout for this project wouldn't follow the specification exactly, but it's referred to as the JAMMA connector for convenience.
Power Supply (PSU): Provides the essential juice to the system.
SCART connector and potentiometers: Used to connect the JAMMA video signals to the TV. The potentiometers (variable resistors) are used to adjust to brightness of each component colour (red, green and blue) separately.
Audio level converter and mono/stereo switch: Converts signal level audio from the JAMMA board to line level at the RCA connectors. Switchable between mono (JAMMA) and stereo (MVS) modes.
Joystick ports/front panel: Connectors for the external joysticks. Buttons for coins, service mode and test mode.
Coin/Button 5 switch: Allow a button on the joystick to be used for credits or as a fifth action button.

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