My friend brought me a wireless PS2 Guitar Hero guitar and wondered if it could be used for the PC version of Guitar Hero. Well, it would have helped if he brought me the reciever... But rather than trying to find a new one, I decided "Hey, why not wire the buttons to the guts of a PS2 controller?" I have multiple PS2 to USB adapters, and they wouldn't know the difference. To the adapters, it's just another normal controller.
Taking a closer look, you can see it took quite a few wires. I left most of the original ones in tact just in case I ever wanted to revert it back to it's normal state for whatever reason. The controller I used was just some generic PS2 controller I had laying around that was in pieces. Unfortunately some of the guitar's functions are no longer available such as the control pad (I'll explain why in a bit), and the buttons probably don't match up for the PS2 versions of GH. But it's being used for the PC only for probably forever so I don't care. Luckily the controller had a lot of test points which made soldering wires to it very easy to do. There's no real color coding here, other than all browns are ground (except the christmas looking wire).
The whammy bar took some thought because it is nothing more than a potentiometer (variable resistor). This is very different from a button because instead of two states, we are now stuck with an analog signal that can't be mapped to a button. Luckily the PS2 controller has two analog sticks, and I can use one of them to detect the range of the whammy. By default, the controller is not in analog mode. The board is shoved into the guitar so pushing the analog button is no longer an option. The twisted red/green christmas wire runs to a built in LED on the guitar that I used to display "analog on/off", and the blue/white wire which is the analog on/off, is now redirected into the control stick of the guitar to toggle it.
So now that I thought I was finished, I remembered one more important aspect of a GH guitar: tilt for starpower. I desoldered the tilt switch from the guitar's main board, put on a couple of wires, and crammed it into a corner. I snugged it up with a small piece of rubber so it isn't flopping around in there. It can be identified by the orange and blue wires attached to it. It took some time to figure out the 4 pins, but it seems I only needed 2.
And that's pretty much it. I tested it out and it works great. I had to map buttons to the keyboard with Xpadder, which pretty much defeated the whole analog whammy. But, it needed to be analog to be detected in the first place so meh. The control pad with the red LED is how to toggle analog mode on, I just have to press up or down to toggle it. Well that's it, just another guitar to add to my collection, but definitely a fun project.