I-Pac / J-Pac Custom PS/2 to USB Adapter Cable

[porkins]

I have an older J-Pac in my arcade cab. The kind that has 2 PS/2 connectors on it. I was using a PC with PS/2 connectors, but just upgraded to one with only USB connections. I had hoped I could simply use one of those adapters that allow you to connect a PS/2 mouse and keyboard to a single USB connection, but it did not work. The J-Pac gets power just fine, but the PC does not receive any inputs and cannot connect to it.

So after some research, I learned that PS/2 devices come in 2 flavors. The newer kind have USB circuitry built into the device. Those will work when plugged directly into a PS/2 port, and they usually came with a PS/2 to USB adapter (passive) that did some simple rewiring of the pins without any additional circuitry. The older kind of PS/2 devices have no USB circuitry in them, so you need one of those special dongles which have some USB circuitry built into them to take the old PS/2 signals and convert them to USB.

The J-Pac is one of the newer devices. It has USB circuitry, but it connects over a PS/2 port. To connect it to a USB port, you need one of the passive adapters. These are more difficult to get these days than the active adapters. I have seen some for sale on Amazon and eBay, but I have also read that some of those may not work.

If you have some old cables lying around, and can strip wires, you can make a cable to connect the KB/USB PS/2 port on your J-Pac/I-Pac to a USB port on your computer. You will need a multimeter as well. You *might* be able to go just by wire colors, but I wouldn't bet that they are all color coded the same.

Get a USB cable, and cut off the male end that plugs into your PC. Then get a cable that has a PS/2 male connector on it, and cut off that male end. Make sure the 2 pieces combined give you enough length to connect the J-Pac with your computer.

Now you need to use a wire stripper, or whatever method you choose, to strip off the outer plastic coating of each wire. Also remove any metallic paper shielding.

The USB cable will have 4 wires. Red, White, Green, and Black.
The PS/2 cable will have 6 wires. Mine were Brown, Red, Orange, Green, Blue, and Purple.

You will need to strip the colored coating off of each of those wires to get to the wire inside. Then, we need to connect the 4 USB wires to 4 of the PS/2 wires.

This table shows the wire color and pin number of the USB cable, and which wire/pin number I connected to on the PS/2 connector.
 USB                 PS/2
---------------------------
Red (1)    ->  Green (4)
White (2) ->  Brown (1)
Green (3) ->  Blue (5)
Black (4)  ->  Orange (3)

The USB wire colors should be correct. The PS/2 wire colors may be different. You will want to use a multimeter set to test continuity and check each wire against the pin to make sure they are the right wires. Look at the attached pinout graphics. This labels the pins of the male PS/2 connector, and the male USB A connector, so you know which is which.

The other 2 wires from the PS/2 cable are unused. Clip them off. Twist each connecting wire pair together, solder each pair if you can, then use some shrink tubing, electrical tape, or whatever you can to insulate those exposed wires so they don't touch each other or anything else. See the attached pictures of my cable. I need to finish this last step myself.

If anybody has anything to add, please do so!

[AndyWarne]

This is all correct, there is info on this page about this. www.ultimarc.com/ipacusb.html

Andy

[Matt Berry]

Do your self a favor, before you solder those up, you may want to do an inline wire splice. If you google western union splice, you will see all kinds of examples for it. If you have shrink tube, cut it to length and put it over one end of the wire (Make sure it is far enough back so it doesn't shrink from the heat). Your project will look much cleaner, and the splice will be stronger if you do it this way.