Here is my section dedicated to Arcade Gaming.  Arcade PCBs are designed to suck in your money at record pace, providing a fast-paced immersive gaming experience that makes you wanna come back for more.

There are only 2 ways to enjoy arcade games at home:
1)  you can go out and buy a full arcade cabinet, or 2) you can buy or make a supergun.
The Supergun is essentially the necessary parts of an arcade cabinet put into a box with outputs to your TV and some sort of video game controller.  It is a universal unit used to play your arcade games at home.

Most arcade games operate using the JAMMA standard (from the late 1980's onward).  This page will dive into the details of that standard and some custom circuits you can build for your own unit.  Note, I won't be going over JAMMA wiring and I suggest using a search engine for a beginner's guide on this.  The information here assumes some electronics knowledge.

Superguns I've built:

My first project making a supergun was actually pretty brave: I decided to build an all-in-one supergun/power supply combo.  Rather than having a box with the supergun components and a separate PSU (or Power Supply Unit), I built everything into a power supply.  This took some skill and focus since I used the original PSU case and had to cram all the additional goods inside.  It turned out pretty nice though, and I added an illuminated cooling fan, power LEDs, and a headphone input in addition to the usual outputs.  The blue pots are for RGB adjustment and the DB-9 is an RGB output for gaming monitors.  I used DB-15 connectors for Neo Geo contoller inputs (this is the easiest, since they support up to 6 buttons without logic ICs).

My second attempt was actually the same setup but simplified to reduce customer cost.  The result is a cleaner look  that still has a conveniently enclosed PSU. (nw with S-video)

My third supergun took things a good step further.  I made a few improvements and added some extra features, per customers request.  This setup includes a detachable JAMMA harness, 2x autofire circuits, and better power regulation.  I decided to make this setup using a clear case so that it would illuminate in the dark (via blue LEDs) and show off my the internal work.

My fifth supergun (need to get pics from my 4th) is by far the finest of the bunch as is my personal copy.  I spent over a year working on this beast and have made some recent upgrades.  It includes:

  • Detachable harness (made of diecast metal that doubles as a heat sink)
  • 2x LM555 autofire circuits (scroll down for schematic)
  • Stereo and low level audio capability (in progress to updgrade with proper audio isolation)
  • RGB video amp + buffer stage and LPF (using THS7314)
  • Luma trap + rainbow banding control
  • TTL Sync cleaning (using ISL59885)
  • Voltmeter (using Maxim's ICL7107)
  • Adjustable PSU output (LM1084, 5A constant output up to 8A)
  • Chroma encoder auto-shutoff with RGB input (power saving)

Not only that but it is the smallest supergun (...in the world?) with a fully built-in power supply.  It has an enclosed 12v 5amp supply with Every circuit is thoroughly shielded, diode protected, and fused to ensure maximum protection and quality.  This project took my maximum shrinking/cramming work and the finest soldering skills to date.  Here are some pics of the inside:

Note, this has been vastly updated recently (pics to come).  and here is a schematic I made for the voltmeter circuit inside (note, you can buy these now for $3 on ebay....this was built 10+ years ago when that option wasn't available, heheh):


(Right click for full size)

I am also planning to add a Y/C buffer/summer stage with my own LRC bandpass Luma Trap (see AD725 datasheet for info).  Other planned upgrades include MUXs for switching autofire circuits, cooling fan speed control (reducing noise), mapping autofire A to the D button on Neo Geo pads, +5v regulator LEDs, -5V output, better power saving with DC-DC reg (prior to 78M05 for video ICs) and proper audio isolation transformers.

The heart of the Supergun is a circuit known as the chroma encoder.  It takes your game's primary RGB signals and converts them into an output that a television will accept.  Here are some examples of my early chroma encoders/video modulation circuits:


These were my first prototype video modulation circuits.  They are all on breadboard which I only use for prototyping, so they have a rather large layout and all non-SMD parts.  The 2 on the left side are chroma encoders, converting the RGB lines to composite and S-video.  I built both to test the differences between the 2 most commonly used chroma encoders in superguns: the AD725/AD724 and the CXA1645.  The Analog Devices one is the newest but sadly has pitiful compatibility among games and only mildly improved S-video output.  The Sony (CXA) chip was originally used in the Playstation and Saturn consoles and although older, it has 100% compatibility from my experience.  However, its age gives it a much larger external part count.  Since the AD725 datasheet has a vague schematic I made a simpler and easier one for people to use:

The setup on the right actually has 3 SMD opamps underneath it.  It's a full RGB to Component video converter and was built along the lines of the great schematic I found here.  I made my own schematic with some slight improvements but take no credit for the true genius of elm's work:


(right click to view full size)

Video quality is easily confused with video definition/high definition but they are in fact both very different things.  Video quality is the how the image looks itself, no matter if it is an Atari 2600 game or a DVD movie.  The quality is in the color, noise, clarity, saturation, etc.  While these settings can be adjusted on your TV, the signal going to it from your game system or supergun can rarely be adjusted.  Different superguns will have different video output types that vary the picture quality.

Composite Video (CVBS)

This is the standard video signal used in the USA.  It is a single yellow connector (red and white are audio) that combines all your video data into one wire.  Problems in quality include heavy bleeding of yellows and reds, dot crawl (the static-y movement in blacks), cross-color artifacts (rainbow colors between blacks and whites), over-contrast, and "blurriness".  A truly pitiful form of video but still the most widely used today.  Notice how the red text above (SUPER VEHICLE-001) is almost eligible.

S-Video

Certainly a large leap up, S-video provides 2 lines of video data; Chroma (color) and Luma (monochrome sync image).  Since the color has its own line, there is a large improvement in overall clarity and far less color bleeding.  Dot crawl is nearly eliminated and cross-color artifacts and over-contrast are completely gone.  S-video inputs and outputs can be identified by a 4-pin DIN connection and a single male-male 4-pin DIN cable.

Component Video (Cr Cb Y, Pr Pb Y, R-Y, B-Y, Y)

Component video is the newest form of video modulation.  Represented by red, green and blue wires (NOT RGB), Component video uses 3 wires to send video data.  The 3 wires are known as  R-Y (red minus luma), B-Y (blue minus luma), and Y (Luma+Green).  While the colors are finally separated, there is a very large problem with the Y signal.  Since Luma, Green, and Sync are all combined into one wire, it is extremely difficult to do analog adjusting of this signal.  To get a perfect green with perfect brightness and clarity is pretty much impossible and is the final proof of why RGB reigns supreme.

RGB (Red, Green, Blue, H/V/C Sync)

A pure video signal (highest quality) is an RGB signal, which is composed of 4 to 5 wires: red, green, blue, and 1 or 2 sync (synchronization) signals.  This separates the all the color data to give you the finest image in every possible way.  An RGB signal is not demodulated inside your TV, thus it goes "straight to the guns" as people say.  This is because the actual light signals sent through a television tube are RGB, so the signal coming from your equipment is simply amped and sent straight to the screen.  The result is a razor sharp pixel-perfect image with vibrant and true color.  Sadly, there is no standard and very little use for RGB in the US, only the Japanese and European equivalent of SCART.  However, VGA (your computer signal) carries RGB lines and so do newer HDMI systems, so while it may take nearly 50 years (since the signal has existed), it may yet be possible to make a universal US market of RGB signals.




One problem with arcade games is their necessary tapping of the A/fire button.  In shooting games this can be awfully annoying at home and so I set out to add an autofire circuit to my supergun(s).

The page here is what I used as my first test of the circuit.  Unfortunately this page is quite flawed and is the only main source for schematics of a video game autofire function from a 555 timer.  The resistor values are incorrect and this schematic simply disables the fire button making autofire constant and uncontrolled.  I set out to make an improved design thanks to some helpful info here

I came up with a nice little solution for controlling the autofire pulse without having to hack the controller up.  I used the button to ground the 555 timer and thus power it to initiate the autofire on command.  Here's a schematic I drew up with the correct resistor values and my button design:



Viletim of the GameSX (and many other) forums also came up with his own design that is more sound for multiple autofire buttons.  Check it out here.