Back when arcade games first came out every game had a different wiring scheme which made trying to swap a board from one game to another a very difficult task. This problem compelled the arcade manufacturers to get together to create a standard and thus the JAMMA standard was born. In this post, we will help you get familiar the JAMMA standard.
Getting Familiar With The JAMMA Standard
Before we get started, I would like to mention that I have posted a printable version of the JAMMA pinouts for your convenience. This will come in very handy if you are dealing with JAMMA at any point in the future. Please click the link below to access this document.
JAMMA is a wiring standard that was developed to make switching arcade boards from one arcade cabinet to another easier. JAMMA stands for Japanese Arcade Machine Manufacturers Association and was developed in 1985. Any arcade game that predates this will not be JAMMA and even some games after this are not JAMMA. We recommend checking your manual or the internet before assuming that your arcade board is JAMMA.
A JAMMA harness is composed of a 56-pin connector (28-pins on each side) with wires coming from each of the pins. There are two sides of a JAMMA connector: the parts side and the solder side. The parts side of your board contains all of the surface mounted components while the solder side just contains traces and solder dots. It is important to identify which side is which so that you don’t plug your board in the wrong way. As luck would have it, many JAMMA connectors are labeled so that you can easily identify which side is which along with what each pin goes to.
If your JAMMA connector is not labeled with the pinouts, your first task will be to identify where pin 1 is located. The easiest way to located pin 1 is to use pin 7 which is known as the key and is usually blank. Once you have located pin 7, you’ll noticed that it divides the harness in two 2 halves. The shorter half (pins 1-6, A-F) should contain pin 1 along with all of the wires that go to your power supply. While these wires usually go straight from the power supply to the board, you might notice that someone has jumpered off of them to send power to another part of the cabinet. This is fine and a common practice.
As we look at the longer half of the connector, you will notice some wires going to the monitor. These wires (pins 12-14, N-P) are used to send the display signal to the monitor. There should be a wire for each of your colors (red, green and blue) along with a sync wire and a ground wire. If we look further down the connector, we will find the wires for our joysticks and buttons (pins 17-26, U-d). All JAMMA harnesses support 2 players, however, they might not have the all wires hooked up for each of them. Games that have more than 3-5 buttons per player or more than 2 players usually require a kick harness to work properly. A kick harness is an extra harness that attaches to the board along with the JAMMA harness to allow for the extra inputs.
You might also notice that there are not enough ground wires located on the connector to wire up all of your arcade controls. In this case, you will need to use a technique called daisy chaining. Daisy chaining is a wiring scheme that consists of jumpering a wire off of each connector so that the ground signal will carry over to the next connector. We’ll talk more about daisy chaining when we talk about control panel wiring.
JAMMA wired arcade cabinets take the work out of switching boards between cabinets. In face, the majority of the arcade games that you see today are wired using the JAMMA standard. Knowing the JAMMA standard will carry you far in your arcade repair endeavors. Please leave any questions or suggestion in our comments section below.