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View Full Version : Modifying a PS2 keyboard for use with a MAME arcade machine.


ThePCGuy
12-05-06, 04:41 PM
Well I have a tendency to find old keyboards that are still useable but very dirty. Typically (gasp) I put them in the dishwasher without soap, and have them cleaned very thoroughly. Well I filled the dishwasher a bit too much this time, and one of the keyboards was too close to the heater, and it deformed just a bit. It just so happens that I'm looking to build a Mame arcade machine, and had been playing with the idea (have seen previously) of using a keyboard controller. SURGERY TIME. I opened up the keyboard and removed the controller from the mylar matrix that is in the keyboard. I then went through the process of trying to solder to the metal pads on the controller. After the 5th time, I got it right, and each soldering job was much much stronger, and better than the previous 5. I used a 6' CAT5 patch cord that had a broken jack on one end (I keep all junk wire) and used that to create 6" leads that I could solder to these connections. I then coated everything that was exposed in a nice layer of Hot Glue. Have I mentioned how much I like hot glue? I then went about the task of figuring out the matrix by jumping all necessary connections. This keyboard has a setup of 19 rows by 8 columns (so 19 wires on one side, 8 on the other), so that means that each of the 8 individual wires had to be jumpered to each of the 19 wires to see what the output would be. Simple math shows us that 19 x 8 = 152. So after a few more than 152 connections (my eyes started to get a little off after awhile) I had the matrix labeled, and mostly complete. This particular keyboard has a few extra keys that I won't be using such as the internet/email/etc. keys. Basically I will be creating a control panel with the following:

1 player start
1 player coin
2 player start
2 player coin
1 player joystick (2 positions, left/right, up/down
2 player joystick (2 positions, left/right, up/down
1 player - 6 buttons (typical high/mid/low kick, high/mid/low punch)
2 player - 6 buttons (typical high/mid/low kick, high/mid/low punch)

I believe that is all for now, so that leaves me with 20 connections I'll need. The thing to see will be the limit with simultaneous key strokes and such. I believe there are ways around the problem (short of going to an I-pac setup), and that is half of the fun. The idea of my first cabinet will be low cost. I could go out and purchase an I-pac and be done, but I like recycling what I've got lying around, and I think this will work just fine for this machine.

On to the pictures: Many are a bit blurry because of a lack of light in my room at the time I took the pictures.

http://thepcguy.myvnc.com/jim/mame

Anyone else build a Mame cabinet? How'd your system turn out?

- Jim

ThePCGuy
12-10-06, 11:05 PM
Pictures are back up, server had crashed.

- Jim

Sephis
01-01-07, 09:59 PM
I know this is an old thread, but I decided to post anyways. I had a look through your pictures and really like the way you set this up. First off, simulateneous key presses and such usually depend on the controller chip AFAIK. My friends and I are working on a mame cab as well. I just wrote down all the keys that mame assigns to each function. Then I soldered directly to the contacts on the plastic layer. Its ugly as sin, but it works. The cabinet is at someone elses house, so I don't have pics. I used to a similar configuration to you, except the joysticks used 4 connections, one for each direction. We have the electronic stuff figured out for the most part, and the control panel is built and tested. Still have to finish building and painting the machine though. It really is fun to have your own arcade machine.