Add LEDs to Your Arcade Stick Sanwa Buttons!

There are lots of LED solutions available for your fightstick or arcade cabinet but the solderless or shop-bought versions can cost quite a bit. Not being in a particularly well paid job but still wanting some LED flair to my fightstick I searched and searched but to no avail on how to do this.

I use Sanwa buttons in my cab and all my fightsticks and I was a bit displeased that they do not have LED options available to buy.

Seimitsu have small holes in their buttons that you can insert LEDs into which makes this a breeze. If you use Seimitsu buttons, then you can just skip straight to the wiring section of this Instructable.

I'm only an electronics hobbyist and wasn't quite sure how to go about this until I attended a weekly FGC tournament local to me and discussed this with a friend. He told me in the simplest terms how to wire up the LEDs so that they light up once pressed. This information stuck with me for a long time and finally I decided to have a crack at it on my stick. Thanks Dan!

Many of the shop-bought LED solutions often require an LED controller board and small boards to insert inside each button which cost a pretty penny. These are fine if you have the money and are not comfortable with making any intrusive mods to your buttons and wiring but I wanted to give this a try and luckily it worked out.

Supplies

Parts

• Clear Sanwa OBSC arcade buttons - get as many as you require depending on your button layout.
• 3mm LEDs - obtain as many as you need and in the colours you wish. It will be one per button, this guide will focus on lighting up all the face buttons on the arcade stick (8 in this case) but if you use 6 buttons then only use 6 or if you want to light up the start or select buttons etc then add accordingly. I used waterclear LEDs as they're a bit brighter than diffused LEDs but this is entirely up to you.
  
• Resistors - Get as many as you need as each one will be put in line with the LED. I used 100ohm resistors, these were calculated using Ohms Law but you can also use an online LED calculator using values according to the LEDs you purchased. This DATASHEET came in handy when finding out LED voltage and current values.
  
  
• Solder - for use with the soldering iron (obviously)
  
• Red equipment wire (0.5-1mm thickness) - this is to join all the positive legs of the LEDs together.
  
• Heatshrink tubing - to insulate the connections and prevent short circuiting all your hard work. If you don't have this stuff then electrical tape will do fine.

Tools

• Drill - you will need this to make a hole in your clear Sanwa buttons for the LED. Use a drill bit that's as wide as the LED and make sure you do as many tests as possible on scrap material or on a spare Sanwa button.
• Soldering iron - you will need this to attach wires and resistors to the LEDs. You will also need this to wire the LEDs to the buttons as well as the controller PCB.

Step 1: Wiring Diagram

Each LED will be placed on the underside of each button. All the positive legs will be joined together in parallel and connected to the VCC/5V connection on the controller PCB; then the negative legs will be connected to the respective button signal point on the controller PCB.

I've provided two wiring diagrams that will hopefully give a decent visual representation of the process.

Step 2: Testing the LED Hole Using a Spare Button

I drilled a hole inside the marked circle on the button, then used a stanley knife to cut away the melted plastic. I then inserted the LED and it stayed in just with friction so if anything goes wrong I can just easily replace the LED.

I got a bit too drill-happy on one of the clear buttons and the LED wasn't able to stay in the hole as it was a bit loose. If this happens to you then DO NOT WORRY as a bit of superglue made it stay in fine. If I end up having to replace the LED then a bit more force will be required but the buttons are easily replaceable if anything goes wrong.

Step 3: Drilling LED Holes on the Clear Buttons.

Now that the test was successful, you are fully clear to start making holes in your clear buttons! Just drill carefully inside the circle, then insert the LED. Test fit each one as you go, if you made the holes a bit too wide just add superglue.

DISCLAIMER/WARNING: As a user of clear Sanwa buttons, I must warn you that the tabs on them are extremely brittle. The buttons manage to stay in my fightstick because the metal plate and the plexi hold them in just fine.

Step 4: Join All Anodes (positives) Together

Take your wire strippers and strip off about 5mm of insulation, then tin the exposed copper using your soldering iron and some solder. Measure, strip and cut several lengths of wire according to the distances between each button LED and tin each end.

Ensure you add heat shrink tubing as you go along to prevent any short circuits, fightstick cases can get very cramped so the risk of shorting something out to the metal plate or with another wire is higher than before.

Do not join the wires all in a loop, I started from one of the end buttons then joined them up as I went along until I reached the button above or below the one I started from. (See picture)

Once this is done, measure and cut a long piece of wire that will go from the button array to the 5V point on the gamepad PCB. Join this to the end of the button array.

Step 5: Connecting Resistors to the LEDs

I tried to have the resistors on a board but this approach didn't work for some reason so I decided to just place a resistor on one of the 2.8mm terminals on the microswitch, then solder the other end to the negative leg on the LED. Also don't forget the heat shrink tubing!

You can solder the resistor to the button terminal but I just inserted one of the resistor legs through the hole in the terminal, then wrapped around it at the base 2/3 times and it makes a solid mechanical connection with the cable crimp connectors. (DEMONSTRATED ON SPARE GREEN BUTTON, SEE PIC)

You can do this on either terminal on the button, but just make sure that it's the one that goes to the button signal point on the controller PCB. If you connect this to ground, the LEDs will always be on regardless of button press. However if this is what you want, then go nuts!

Step 6: Reassemble Your Stick and Admire Your Handiwork!

The terminals with the resistor connected needs to go to the signal button points on the controller PCB and the other terminal goes to GND. The red wire from all the LED anodes just needs to go to the 5V/VCC point on the controller PCB. If unsure, consult the wiring diagrams in step 2

Reconnect the buttons, reassemble your case and you'll have light-up Sanwa buttons!

Any questions, feel free to ask them in the comments or in a PM.