Supergun

Supergun is a strange name for devices that allows using arcade boards (not only MVS) as consoles. Many different models can be bought as finished products or kits. (Flawed) schematics can also be found.

Power supply

Most often, the supergun doesn't supply power to the board itself but provides a standard socket to plug an off-the-shelf computer power supply.

Impedance adaptation

Video output (RGBS) from the JAMMA edge is high-impedance. Amps/buffers fast enough for video must be used for 75ohms TV inputs. Wiring JAMMA video outputs directly to a SCART cable will produce a very dark (lowered RGB voltage) and distorted (lost sync) picture, and can possibly damage the board's video DAC.

Audio output is low-impedance and (relatively) high voltage, for direct connection to speakers. Impedance transformer(s) must be used for high-impedance TV audio inputs, or they might get damaged.

Sync cleaning ?

Video output conversion

RGBS can be converted to Y/C or CVBS. Conversion to HDMI is way more complex and is often done by a separate device.

PAL/NTSC CVBS burst generators ? Component output ?

Joypad signals translation

A supergun may accept different kinds of joypads (Genesis, SNES, ...) and translate the serial signals to straight parallel signals.

I/O breakout

Special I/O for arcade cabs can be broken out to solderable pads, screw terminals... Coin-in inputs are often connected to momentary switches.

Voltage control

Voltmeters and ammeters can be hooked up between the PSU and board to measure voltage and current.