Building an Arcade Machine? JAMMA Harness Wiring Explanation

Building your new arcade machine and not sure how to wire a JAMMA harness?

If you're new to arcade machines a JAMMA harness can look kind-of-tricky, so many wires and where do they all go? Plus, the edge connector either has Chinese writing or no writing at all to indicate what each pin is for.

It might seam like your worst nightmare, but a JAMMA harness is actually quick easy to wire and once you get your head around the edge connector and the wiring configuration, you will be a pro in no time at all.

We will go through a few simple steps to get you started and hopefully put your mind at ease.

If you have just purchased a JAMMA harness and multi arcade JAMMA board, the board should come with a manual. Open the manual and find the edge connector pinouts:

There are two sides to a JAMMA board. The components side (parts side) and the solder side. It is hard to know which side is which on the new JAMMA multi game game boards as most PCB’s now come in plastic cases and you cannot see the board and the two different sides.

(solder side of the 60 in 1 and Pandora DX3000 in 1)

The wiring diagram for the edge connector will indicate these sides.

You then need to match these sides to the wiring on your JAMMA harness to know which way the edge connector plugs onto the JAMMA game board.

To start, an edge connector has 28 pins. Your first step is to find pin 1 on the JAMMA harness.

Most edge connector pins are normally numbered near where the wire is attached to the pin and the pin goes into the plastic of the edge connector. This can be very hard to see and you may need a magnifying glass! But don’t rely on the numbers being correct as we have found Chinese made JAMMA harnesses to sometimes be wired to the edge connector the wrong way. The numbers may be incorrect and this can lead to you wiring your arcade machine wrong.

What I would recommend to do is look at either end of the harness and the end with the Ground (black wires), 5 volts (red wire) and 12V (yellow wire) pins is where you will find pin 1 to 6. The ground is connected to pin 1 and 2 on the component side but also pin A and B on the solder side. These wires are normally thicker than other wires, connected to multiple pins and may have several wires connected on the same pins (on the JAMMA harnesses we sell the +5, -5 and +12 pins are also labelled on the edge connector. Pin 1, 2, A and B are very close by and have multiple black wires connected).

Once you have found Pin 1 and A you have your starting point. You can now find the components side (parts side) and the solder side. 

Looking at the JAMMA harness, the grounds, +5V, -5V and +12V need to be on your left-hand side (the pins are numbered 1 to 28 in the manual). This is a good way to tell which side is the component / parts side of the JAMMA harness.

If you can see the grounds, +5V, -5V and +12V all on your right-hand side you are looking at the solder side wires of the edge connector (The pins are lettered in the manual A to Z then a-f, totalling 28 pins).

No that you can identify the component side/parts side and solder side, you're almost there and you can begin wiring the JAMMA harness to the power supply, joysticks and buttons.

Now simply count the pins as you go along the edge connector and match each wire to the wiring diagram in the game board manual. The manual tells you what each wire is for. The wires connecter to pins 1,2, A and B are all ground. Unravel the wires in the JAMMA harness and look for the black ground wire with the spade terminal on the opposite end of the wire. This is to be connected to the power supply ground.

The next wire (red) connected to pins 3,4, C and D are for the +5 volts. Connect this to your +5V on your power supply. Be sure not to connect to the -5V. We have had a few of customers connect to -5V instead or 5V over the years and find their game board not working. 

Negative five volts is not used for any of the newer JAMMA multi boards but was used for some original JAMMA game boards back in the day, hence pin 5 and E on the new JAMMA harness do not have wires connected. Miss this pin and move to the next one.

Your next pin is the +12 Volts, pin 6 and F. Connect this wire to your +12 Volts on you power supply.

It’s very important to connect these wires to the correct components as there is a good chance of you damaging your game board if connected incorrectly. You will also damage the game board (in most cases) if you connect your JAMMA harness to the game board the incorrect way, so make sure you plug it in the correct way!

An easy way to tell is by looking at your game board connector. The 28-pin connector has a small gap between the connectors. This is where pin 7 and H would connect but it is not used. The 6 connectors ( looks like 4 connectors as ground and +5V are connected together) are for your grounds, +5V, -5V (not used) and +12V wires.

Make sure they go on the correct end when plugging in your game board!

The next wires you need to connect are for your speakers, pins 10 and L. This is something we normally miss and do last but that is up to you.

When connecting the speakers the manual should show which side of the edge connector is positive and which side is negative. If it doesn’t show this, the component side wire is your positive and the solder side wire is the negative. Connect these is series to your speakers.

Next you have pins 12-14 and N to P, R is not used. This is to connect your monitor Red Green Blue and Sync. If you're connecting your game board to either a VGA or HDMI monitor you do not need these wires. You can connect VGA or HDMI straight to your multi board in most cases (look for the VGA or HDMI output on the game board). If you're replacing an existing JAMMA harness in an arcade machine with CGA screen with a tube and chassis, this is when you need the wires connected to pins 12 to 14 and N to P.

The JAMMA harness will have a plug at the end of the wires connected to pins 12-14 and N to P and is in most cases a standard fitting size for some monitors. This plugs into your chassis.

If you do not need CGA and your game board is VGA or HDMI, simply roll the wiring loom up and tape or cable tie to keep it out of the way.

Pins 16 and T are in most cases your coin or credit wires. Connect 16 to your credit button or coin mech credit wire. Pin T is either your second credit wire or depending on the multi game board you have could be for a pause buttons. Best to read your manual and see what it is for. If it is coin 2 then it is not essential to use.

Pins 17-27 are for your player one joysticks and buttons:

While pins U to e are for your player 2 controllers: 

And finally, you will see pins 28 and f. These pins are already connected to ground. The black wires on your JAMMA harness that have quick connects are to be connected to every button and joystick micro switch. The JAMMA harness will include a ground chain to connect to most buttons and you will also have a few extra grounds with quick connects (not in this chain) for other buttons (such as a credit button). Ground is ground so it does not matter which button you use it on.

Just a quick explanation of a JAMMA harness and its wiring, we hope this helps and makes sense. Please contact us if you think we could explain it better with your example. We would love to hear from you and make the wiring process simpler to understand for people new to arcade machines.

 We are here to help so if you have any questions please call or contact us via Facebook, Instagram or email.

Happy Gaming!

Austin Amusements

For all of your Arcade Parts required, located in Sydney Australia.