***OK. Round two. So my previous Instructable added a joystick to an NES MAX controller. While I liked the outcome, I still prefer the precision of a standard D-pad (at least for digital controls). This Instructable will be much the same as my previous one, but instead of adding a joystick to the NES MAX, I'll be adding a D-pad from a GameCube controller.***
I found a couple of beat up GameCube controllers at a yard sale. One 1st party and the other is 3rd party. Both have bad thumb pads on the main joystick, but I snapped them up for parts so I didn't care. It feels wrong to cannibalize the 1st party controller when I have a perfectly inferior 3rd party controller to dismantle, so I'll be using the D-pad of the latter. Unlike my previous mod, this mod will be permanent due to the fact that the D-pad will need to be glued in place.
Step 1: What You'll Need
1 - NES MAX controller
1 - 3rd party GameCube controller (preferably broken). You can use a 1st party GameCube controller, but you'll need a tri-wing screwdriver to take it apart.
1 - Small Phillips screwdriver
1 - Hand drill or rotary tool (like a Dremel)
1 - Grinding bit for the drill/rotary tool
1 - Piece of course sand paper
1 - Pair of safety glasses to wear when grinding
1 - Tube of epoxy for bonding plastics
1 - Toothpick for mixing and applying epoxy
1 - Metal bottle cap for mixing the epoxy in
Step 2: Begin Tearing Down the GameCube Controller
Using the small Phillips screwdriver, remove the six screws from the back of the GameCube controller.
*If using a 1st party GameCube controller, you'll need a tri-wing screwdriver that you can find on EBay. I included a picture of mine.
Remove the back of the GameCube controller and put it to the side.
Step 3: Removing the Circuit Board From the GameCube Controller
Gently pull on the green PCB of the analog C-stick until it becomes loose. Then grasp the rumble-effect motor and pull out the entire circuit board. Place the circuit board to the side.
Step 4: Removing the D-pad From the GameCube Controller
Remove the rubberized conductive resin from the back of the D-pad. Then, remove the D-pad and place it to the side.
Step 5: Begin Tearing Down the NES MAX
Using the small Phillips screwdriver, take out the seven screws on the back of the controller. Remove the back and place it to the side.
Step 6: Removing the Circuit Board of the NES MAX
Gently pull upward on the section of cord nearest the controller to separate it from the controller. The circuit board will come out with the cord, set it to the side.
Step 7: Removing the Cycloid
Remove the rubberized conducting resin from the back of the cycloid and place it to the side. Then remove the cycloid.
Step 8: Taking the Cycloid Apart
There are four retaining tabs holding the front of the cycloid to the back. One at a time and GENTLY, push the retaining tabs inward allowing the back to separate from the front. Then, remove the sliding thumb disc; You won't be needing it for this modification.
Step 9: Grinding and Sanding the Back of the GameCube D-pad
The base of the D-pad from the GameCube controller is too thick to fit inside the cycloid. This means that the back of the D-pad will need to be ground down to fit inside the cycloid. Also, you'll notice that the back piece of the cycloid isn't exactly flat. This means that the D-pad will have to be glued to the front piece of the cycloid in order to achieve a flush finished product (I'll get to that in a later step though).
Put on some safety glasses and grab the hand drill/rotary tool. Then grind off the fulcrum on the back of the D-pad using the grinding bit. There are four support members that will also need to be ground down. I did my best to remove most of the support members and the center post and then switched to sandpaper for the outer ring. Don't sand off too much though, the idea is to sand off just enough so that the cycloid will snap together around the D-pad. Rinse off any residual plastic powder and allow the D-pad to dry.
Step 10: Glue the D-pad to the Cycloid
Squeeze a small amount of the two-part epoxy into the bottle cap. Use a toothpick to mix the epoxy together. Then, using the same toothpick, apply a small amount of epoxy around the hole on the back side of the front piece of the cycloid (see 3rd picture). Then place the D-pad into the hole and center it, making sure to line up the directions (up, down, left, right) with the triangles on the face of the cycloid (see 4th picture). Snap the cycloid back together to help hold the D-pad in place while the epoxy sets. Make any fine adjustments to the position of the D-pad now before the epoxy sets too long. Allow the epoxy to set for 20 minutes and then remove the back of the cycloid again. Mix another small batch of epoxy and apply it around the outside of the D-pad base (see 5th picture). Finally, apply some epoxy to the back piece of the cycloid (see 6th picture) and snap the cycloid back together. Allow the epoxy to cure for 24 hours.
Step 11: Put It Back Together
Put the cycloid back into the controller and put the rubberized conductive resin back in place. Place the circuit board and the cord back into the controller. Put the back of the controller on. Using the small Phillips screwdriver, fasten the seven screws to tighten the controller back together.
Step 12: Troubleshooting
No response when pressing the Up and Down directions on the D-pad.
I'm not sure if every NES MAX has this problem, but I've always had trouble getting a response when pressing the Up direction and the Down direction (even before modding). I've had to press harder than the Left and Right directions in order to elicit a response from the controller. Thinking that something might be wrong electrically with the conductors, I removed the controller casing and played a little Fester's Quest using the rubberized conductive resin and circuit board alone. The portly Addams family member responded immediately upon pressing all four directions, indicating that there was nothing wrong with the conductors. This meant that there was a mechanical problem having to do with the throw distance of the Up and Down directions.
The only way to correct this problem is to beef up the cycloid where it rests on top of the Up and Down conductors. To prove this theory, I put a piece of cardboard from a 12 pack of Sprite across the Up and Down points of the cycloid and it worked. So in my case, I just needed to apply a dab of epoxy, equal thickness to Sprite cardboard, on both points ;) The nice thing about this epoxy is that it doesn't shrink and it can be sanded if applied too thick. Let cure for 24 hours before putting back into the controller.