The Guitar Hero 3 Bot [Obsolete!]

Hardware

Part 2 - Modifying the Controller



NOTE: From this point on if you open up the GH2 controller it will void the warranty! After every step I plugged the controller into my PC and went to game controllers to check the built in buttons were still working (1-5,7,8 and the POV hat. Plug it in and you will see what I mean).



Step 1 - Open it up


Unscrew all the screws on the back of the white, main part of the guitar. Once you have done this the back should come off easily.

gh3in

As you can see, there are 2 circuit boards (a & b), 2 external connectors (c & d), a potentiometer (e) and some wires going up the neck (f). (Ignore any blue wires you see, I shall get to them later.)

They are:
a: The plectrum switch PCB
b: The main controller PCB
c: The 'pedal' port. God knows if this will ever be used!
d: The headset port
e: The whammy device
f: The colour button wires. There are 2 lots of 4, and if you look on (b) the main controller you will see they are numbered 1 to 8.

Once you are familiar with the insides of the body, unscrew the neck screws and remove it, it should look a bit like this:

in2

The pcb you see in the neck is where the buttons are mounted. You don't need to remove it unless you a curious as I will show you it's layout here:

This is the back of the PCB:
inback
As you can see, the buttons are aparently A, B, Y, X and LB but beware if you use a standard controller you can not use these buttons you must use LT, LB, RB, RT and A because the game can sense the different types of controllers.

Under the PCB are the buttons:
inback


This is the 'front' side of the PCB with the rubber buttons on:
inback

Now if we go back, note the 8 and 1 indicating the wire numbers, so as this is the 'back' side they from 8 to 1, on the 'front' side they will go from 1 to 8 (bottom to top).
inback

And here we are, the button wiring with wire 1 at the bottom up to 8 at the top (on the right of the PCB. inback
If you spend time studying this you will see they use a strange wiring method with 3 'common' wires. (Though wire 3 isn't really common).

This is how it is wired:
GH2 Controller:
Green:  1 and 8
Red: 2 and 7
Yellow: 2 and 5
Blue: 1 and 6
Orange: 3 and 4
 
GH3 Controller:
Green:  1 and 8
Red: 2 and 7
Yellow: 2 and 6
Blue: 2 and 3
Orange: 4 and 5
 

    
Hopefully now you can see why reverse engineering is not desireable and relays are as you can just connect them across the connections the buttons make and the controller circuit will stand no chance of interfering with the controller (assuming good soldering). ep 2 - Away from the guitar and soldering up the relay board (if you want)! Symbols used in my circuit diagrams:
reed

Here is a crude circuit diagram for the relay board (sorry for the crudeness it was done in a hurry):
rwd

Here is a picture of the back and front of my relay board, with annotations to show how I wired it:
rwd
The black squares show where my relays were.
The green dots show the switch contacts.
The red dots show the actuator contacts.
The content of the blue square is a blob of solder where I made the common relay connections.
The content of the yellow box is 14 wires, 7x2. 5x2 for the colour buttons, 1x2 for strum and 1x2 for star power.
The content of the pink box is 7 actuator wires and 1 common wire for the relays.

rwd
As you can see, my relays had a wiring diagram on the top.
The wires in the pink box are the 7 actuators and the common.
The wires heading to the green side are 7 of the switch wires.

If you relay board is about the size of mine roughtly 4cm by 13cm, should fit inside the gh2 controller. If it is not you need to run longer switching wires from it to reach from the outside to the neck.
To summarise you should have 14 switch wires and 8 control (acuator) wires coming from it, so 22 wires in total.
Just check all your relays switch by using the powersupply and a multi meter (if you have one...I didn't!).

Step 3 - Tapping into the coloured buttons

I cut the 8 (2x4) coloured button wires about an inch from where they leave the neck...in reality I should've done it a but further up so that I had more slack - 2 inches would be better.
I used a piece of PCB which was 8 by 3 holes with the copper strips running accross the 3, see below:
rwd

This was done so I could wire the 8 wires to one side, the other 8 to the other side and my wires to override them in the middle.
See below:
rwd
The blue wires are my override wires. They run out of the neck with the 8 original wires:
rwd
The PCB in the red square is the one I described above. The PCB in the yellow is to counter my stupidity. When I wired them into the PCB that links the override wires and the relay board, I connected them in the exact oposite order, so instead of re-soldering I just cut the wires and solder them onto this new board to reverse the order, hopefully you won't need to do this.

Step 4 - Connect the Colour Buttons (override wires) to the Relay Board

(Badly) pictured below, highlighted in the green square is another 8 by 3 PCB, just like the one above with the copper stips running accross the 3. The 8 override wires are soldered to this, as are the first 5 relay switching connections:
rwd

Here is another crude diagram of how it is supposed to look (note I've only shown 5 of the relays as the other two are not used at this stage).
You will see they are connected as the coloured button wiring layout dictates:
rwd

Step 5 - Connect the strum switch

If you refer back to the the first image of the insides of the guitar you will see the circuit board in the middle is the 'plectrum switch PCB', or the strum circuit board.
A closer image shows there are three wires leading to it (red) and there is a common (green) and two strum wires (up and down: blue and yellow):
rwd
As you can see, I have soldered two wires to one of the switches. It doesn't matter which one. These wires lead back to relay 6's switch connection.
Nice....and....simple!

Step 5 - Connect up Star Power (optional as it is slightly more tricky)

For this you need to unscrew the GH2 controller board, as we need to solder relay 7's switch wires to the 'back' button (as this is the easiest way to activate star power.
rwd
The yellow cross hair shows where I've soldered the wires (on the horizontal axis) and on the vertical axis where they must run to avoid being trapped in the plastic casing.

Step 6 - The Connector

Make a hole for the connector. You can do this wherever you want, I did it near the relay board because I didn't solder on very long wires.
Once the connector is mounted in the case you can solder the 8 relay control wires to it.
I soldered the common wire (red) in the middle and the other 7 around it (yellow):
rwd
I didn't make note of the order of the other 7 wires, I just used my powersupply to work it out, with my GH2 controller connected to the computer.
To do this just solder 8 wires to the other part of your connector. Make sure you know which one is common then, with the common connected to (+) test the other 7 wires with (-).
(With relays polarity doesn't matter, but later on we will have to use common as positive.)

Congratulations

If your controller is still working, and the relays also work then you have finished tinkering with the guitar and you can put it back together. That is the trickiest bit out of the way!

It might look a bit like this:
rwd

Copyright © Paul Ridgway 2009 | Pictures by Amanda Taylor | HTML Layout & Base code by James Ridgway