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Getting Familiar With The JAMMA Standard

Getting Familiar With The JAMMA Standard

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

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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.

http://www.arcaderepairtips.com/jamma.html

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.

Parts & Solder Sides

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.

Pin 7 - Blank or Key

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.

Kick Harness

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.

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Comments
  1. kevin

    Hi great article
    I have a MR Do arcade at home can a Jamma board fit in to my aracde machine so i can play more games on this machine

    Thanks
    Kevin

  2. Jonathan Leung

    Kevin,

    Yes you can but you will need to get a Mr Do to JAMMA converter. You can get this converter from Arcade Shop Amusements. Here is a link to their JAMMA converters section: http://www.arcadeshop.com/parts.htm#JAMMA. Just scroll down on the page until you have located the Mr Do to JAMMA converter. That should be all you need to start playing JAMMA games in your cabinet.

    We have also featured your question on episode 18 of our Q&A podcast. Please listen to it for more of our thoughts on your question. Thank you for your question and good luck with your future repairs.

  3. Robert Sprout

    Wait, I thought that THAT adaptor was for putting an old Mr. Do! PCB in an existing JAMMA cabinet. Does it work both ways? I also have a cabaret Mr. Do. It is non-jamma. I wanna make it a 60-in-1. Will that adaptor really do that? Do I need a power supply?

  4. Jonathan Leung

    Robert,

    The JAMMA and Mr. Do! harnesses have the same amount of pins but a different layout on the pinouts. For example, the video output on a JAMMA harness is located at pins 12, 13, N and P. On the Mr. Do! harness, the video output is located at pins Z, a, b and c. Therefore you CANNOT hook a JAMMA board directly up to a Mr. Do! wired cabinet and expect it to work. You would either have to rewire the cabinet to JAMMA or buy/make a Mr. Do! to JAMMA adapter. An adapter can be purchased from Arcade Shop if you are interested in that. You should not have to buy a new power supply if the one in the arcade cabinet is currently working.

    We will also feature your question on episode 22 of our Q&A podcast which should be posted soon. Please listen to it for more of our thoughts on your question. Thank you for your question and please keep us updated on your repair.

  5. Joe H.

    Hey there,
    Was desperately looking for some information and stumbled upon this excellent site!

    I need to install a Coin Mechanism and a Test/ Service button on a cocktail table of mine. Now, thanks to your JAMMA table I know WHERE to put them.

    But I have no clue as to what I need to put on the jamma harness in order to get things going. Does this involve soldering, or is there a special kind of plug, wire, adapter that fits right on the pins?
    Also, assuming I can get any of that figured out, I noticed that there’s 3 coin pins: a coin counter, coin lockout, and a coin switch. Which would I connect the coin mech to?

    I’m sorry, I didn’t mean to just dump all of these questions on you, especially since you’re probably not here to just answer everyone’s little questions. But if you know of anywhere to find the answers, I’d be most grateful. I looked through your other posts, but couldn’t seem to find these specific answers.

  6. Jonathan Leung

    Joe,

    Feel free to dump questions on us anytime. That’s why we’re here! As for your questions, this might require some soldering or might not depending on what direction you want to go. We would recommend getting some terminal connectors to put on the ends of the wires coming from your harness so that soldering is not required. For the coin mechanism, you will want to use the coin switch wires and a ground wire to get it to coin up correctly. If your cocktail doesn’t currently have a test and service switch in it, you can always buy the entire bracket to put in your cabinet then just wire it up.

    We have also featured your question on episode 24 of our Q&A podcast. Please listen to it for more of our thoughts on your question. Thank you for your question and good luck with your future repairs.

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