Introduction
Sooner or later you'll want to learn more about your arcade game.
Either you'll get curious about how it works, want to make fine tune
and adjustment, or you maybe you're trying your hand at fixing your
first game. This article will give you some very basic information about
an arcade game. It's meant for the first timer/hobbyist who has
never worked on a coin-operated game before but is interested in getting
more familiar with their game.
The Basics: Three Parts of a Game
Whenever I'm explaining an arcade game to a person, I like to describe
the basic components of a game. Most, but not all games1, have just these three basic
parts. They are:
- Power Supply: Powers the game and monitor. Usually located on the
base of the game, and in some older games may be comprised of a few
components.
- Monitor: Display for the game. Common sizes for classic arcade games
are 19" monitors for upright games, and 13" for mini and cocktail games.
- PCB or Board: "Computer" component of the game. May be as simple as
one board, or may contain a series of boards. Can be located in many places,
but typically the PCB is on the side or back of the game. Varies
greatly by game.
While these are the three basic components of a game, there is really a fourth
component: the connectors. Many times this is overlooked, but it definitely
worth mentioning. The Power Supply, Monitor, and PCB are all connected by this
connector or Wiring Harness. For the purposes of this discussion, we'll count
the joysticks and buttons as part of the connectors. If you think about it, this
is pretty accurate: they connect us, the game player, to the game. A large part of
troubleshooting arcade games is finding out which component is causing the problem
and then either replacing or repairing it. One of the first things to check when
looking at a game that isn't functioning properly is the connectors. Make sure everything
is connected up properly before suspecting any of the three basic components.
Power Supply
The purpose of the power supply (PS) is pretty simple: it supplies voltage to the game
and monitor so that they run properly. Typically, a power supply will provide
+5V, -5V, and 12V to the game (Direct Current), as well as a ground line and +/- AC (Alternating Current).
If your game requires those voltages, you're in pretty good shape as a switching power supply is a "modern"
power supply that is easy to replace. Prior to the switching power supply, games
came with custom power supplies. Sometimes they would supply odd voltages such as
+25V, +30V, and even -12V. In some cases this means that a game can not be upgraded
to a switching power supply. Instead the original linear power supply will need to be
repaired.
Generally speaking, the +5V is what will be used to power the
logic on the main PCB. The other voltages, if used, drive power to sound PCBs and amplifiers.
You'll probably hear the term "linear power supply" as well as "switching power supply." These
are basically the methods by which the AC from your house is converted into DC for your game. Linear
power supplies are the older, propriatary power supplies that vary greatly from game to game. Switching
power supplies, or "Peter Chou power supply" are newer and pretty standard.
An example of a Linear Power Supply (Williams) |
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Switching Power Supply |
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Taito Linear Power Supply |
Monitors
We could write many, many articles dedicated to monitors alone. But given that this is just
an introduction to arcade games, we're only going to cover the basics here.
There are a few different types of monitors:
- Raster Scan: The type of monitor that is much like your T.V. Raster scan monitors are used
in games like Pac-Man, Donkey Kong, Street Fighter, and the like. They project images on the screen
by using an electron beam to scan across the screen from left-to-right, top-to-bottom. Raster
Scan monitors are generally available in normal and medium resolution. Nearly all games are normal
resolution.
- Vector: This type of monitor is used in games like Tempest, Star Wars, Battlezone, and
Asteroids. Instead of scanning down the entire screen, the electron beam is used to draw lines. These
monitors operate more like an oscilloscope than a T.V.
The most common work that a hobbyist will do to a monitor is a cap-kit. This is simply replacing
all of the electrolytic capacitors that are used in a monitor. Over time, capacitors wear out as the
material used in the cap evaporates. Do not attempt to do a cap-kit unless you are thoroughly
familiar with discharing a monitor (not covered in this article). A cap-kit usually improves the
sharpness and contrast of a monitor, but usually2 does not fix a broken monitor.
The monitor is probably the most unreliable of the components of an arcade game. If your game is
"playing blind" (that is, you can hear everything, but you can't see anything on the screen), then you
know that your power supply and PCB are working. You have something wrong with the monitor or connection
to the monitor. Monitor trouble-shooting is very specific to the monitor that you are working on. However,
with the appropriate monitor documention and a multimeter, most monitors can be repaired.
Tapper, a Raster game |
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Asteroids, a Vector game |
With the exception of vector games, arcade games were not released with a specific monitor. So, if you find that
your monitor needs to be replaced, you don't have to search for the exact monitor for your replacement.
In many cases you can replace it with a generic monitor, new or used.
PCBs
The "brains" of the game is the PCB. This part of the game can be as simple as one board, or several boards
wired together. For the beginner hobbyist, there isn't a lot that you can do once you've identified the
problem as being PCB related. That being said, there are a couple of cases where the board can be
fixed rather easily. If you think you have a problem with the board, first try reconnecting the board where
the board plugs into the wiring harness. What you're really doing is making sure that the connection to
the board is good. If that doesn't fix the problem, then try pressing down gently on chips that are in sockets.
Sometimes the connection between the chips3 and the board is faulty. In fact our
experience has been that it's just as likely (if not more likely) that the sockets have gone
bad rather than the problem being the ROMs themselves.
An example of a PCB (Donkey Kong PCB, two board version) |
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An example of a JAMMA compliant PCB (Silk Worm) |
One of the most common PCB related questions is game compatibility. Around 1986-87 a wiring interface
standard known as JAMMA (Japanese Amusement Machine Manufacturers Association) was established. Since then,
most, but not all games, have adhered to the JAMMA pinout standard. If you have a cabinet with JAMMA wiring,
it is usually easy for you to rule in or rule out a board being defective. For more information about
board compatability, read Anthony's article PCB Swapping 101.
Conclusion
This article was meant as a primer for understanding arcade games. In the near future I'll write
an article that ties together this information with some basic troubleshooting.
JB
1 : For example, Laser Disc games such as Dragon's Lair include more components such as a
laser disc player and an NTSC card. Pac-Man combines the power supply and the main PCB. In general, though,
these are the three major components.
2 : In some cases, a bad capacitor can make a monitor cease to function because it fails by
open circuit.
3 : These are usually the ROM chips. They are socketed because in a lot of cases games could
be re-released with improved features or bug fixes or the PCB could be used for other games. Other chips
that may be socketed include CPUs, RAM chips, PROM chips, and other chips that may have failed in the past.a
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| Nintendo’s first arcade game, Radarscope did not sell well. In fact 2,000 of the 3,000 games made were converted in Donkey Kong games, leading to the harder to find Donkey Kong games in red cabinets (as opposed to the traditional blue cabinet Donkey Kongs). |
When possible, we install switch power supplies in our arcade games. (In some
cases, this isn't possible.)
QuarterArcade installs new monitors on nearly all games that we sell. For some games, vector games
like Tempest, Battlezone, etc., and lower-end games, the original monitor is used.
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