Arcade Button MIDI Controller

Step 6 Soldering

Plug in your soldering iron if you haven't already. Once it's nice and hot, tin the tip of the iron (melt a bit of solder on to it, and then wipe it off on a damp sponge). It's a good idea to do this after each wire/joint you solder. Now tin all of the legs of the potentiometers and arcade buttons.

We'll start by soldering all of the ground connections to the potentiometers. Cut a length of black wire approximately 80mm long, and two more lengths approximately 50mm long. Strip about 8mm of the insulation from each end of the wires. Now line up one end of each wire, and twist the copper of all three wires together. We'll be attaching this group of wires to pin one of the top left rotary potentiometer. The 80mm wire will then go to the ground pin of the Arduino, while the other two wires will go to the adjacent rotary and sliding potentiometers.

Tin the twisted end of the trio of wires with some solder so the wires are fused together. Don't solder it to the potentiometer yet though!

Cut a short length of heat shrink tubing (about 12mm) and slide it over the twisted end of the wires, making sure it's at least 20mm from the exposed copper and solder. Now go ahead and solder the twisted wire to the potentiometer leg. Once that's done you can slide the heat shrink over the leg, protecting the soldered joint. Just leave the heat shrink loose for now, and we'll apply heat to it later once we've done all of the soldering.

Now cut another 50mm length of black wire and strip each end. Line up one end of the wire with the free end of one of the 50mm wires from before. Twist the copper of the two wires together, and then tin the joint. Again don't solder the joint yet, but first cut some heat shrink and slide it over the tinned wires. Solder the twisted wires to pin one of the second rotary potentiometer and slide the heat shrink over the joint.

Repeat this process for each potentiometer leg and arcade button leg, referring to the wiring diagram. Not every joint will be the same, so make sure you know what wire needs to go where. Don't solder anything to the bottom right most arcade button (on pin 13) as it's quite different and covered in the next section. When all of the ground wires and +5V wires have been soldered, roughly measure and cut the analogue and digital input wires and solder them in place. Tin the tips of the free end of each wire and insert them into the Arduino board.

Pin 13 and the Pull-down Resistor
As mentioned in the previous step, pin 13 requires a pull-down resistor so it can be read by the Arduino. Referring to the wiring diagram, solder the resistor to the common (black) wire of button 11. Solder a short length of black wire to the other end of the resistor so it can reach button 12. Now twist together the end of the short black wire with the data wire which will connect pin 13 to button 12. Solder the wires together, and then solder the pair of wires to one of the legs on button 12.

Run a wire from the +5V leg of rotary potentiometer four to the free leg of button 12 (see the long red wire on the right in the photo below). Solder the wire to the potentiometer and button.

Closing the enclosure
Sounds simple enough, but just be sure that none of the components interfere with the wires connecting to the Arduino. Note in the second photo that all of the digital input wires run to the right of the Arduino board. This allows room for the first column of arcade buttons to sit nicely above the Arduino without crushing it.

You may require a little force when fitting the lid to the base. If it won't close properly, try and see what components or wires are getting in the way. You may need to bend a few button legs and rearrange some wires for it to close nicely. Once the lid is on, screw it all together with the included screws.

Add the rubber feet to each corner of the base (not over the screw holes just in case you need access inside) and you're done!