Adding a 'menu' button to the Synta hand controller
Click here for other fixes while you're inside the hand controller


I love having a lot of the options available to the Rajiva MCU update accessible from the hand controller but I hate having to try to press all 4 buttons at the same time. So, it was time to think out how to put a 'menu' button into the hand controller.

The trick is, you want to ground all four buttons from one location without having a detrimental effect on the normal use of the hand controller. I've done this as simply as possible with general rectifying diodes. I had 1N4007 diodes on hand; so that's what I used. You'll also need a small, momentary ON panel-mount switch of some kind and a small piece of perf-board. You can 'dead-bug' this if you are so inclined as long as electrically it is equivalent. Here are the steps in my 'diode-board' build:
  1. Remove the four button caps from the hand controller with a small screwdriver.
  2. Remove the four screws at each corner of the hand controller and remove the top.
  3. Remove the two screws holding down the button board and flip the button board away from you so that the ribbon cable connecting it to the main board is at the bottom.
  4. Create a 'diode-pack' by:
    • Solder wires to the ANODE side of 4 1N4148 diodes (keep them long).
    • Connect together all of the CATHODE ends of the diodes with a stripped piece of wire (keep it long).
    • Wrap the pack with electrical tape.
  5. Solder the ends of the wires from the ANODE ends to the locations on the bottom of the button board as described by the diagram.
  6. Connect the wire from the CATHODE ends to the switch.
  7. Connect a ground wire to the bottom of the button-board as shown by the diagram.
  8. Connect the ground wire to the switch.
  9. Open a hole just big enough to mount your switch in the top of the hand-controller between the two slide switches.
  10. Connect one lead of the switch to the wire going to ground on the button board and the other lead of the switch to the wire coming off of the connected cathodes on the diode board.
  11. Check your work, test on your mount then put the controller back together.


The button board, diode board and connections



The position of the menu button and diode board

A better approach to the menu button

If you have the skill and inclination you can replace the Synta button board with one that has the support for the menu button included. I've done this and it works just beautifully.

To do this you'll need to be able to etch a board. I've done the design work for you and you can find the photoshop file that you can use to print your board here.





The build
  1. Print the board photoshop image at 161 dpi (not 72)
  2. Use toner transfer to mask your copper
  3. Etch the board and drill the holes. The holes for the contacts on the 12.5mm tactile buttons are 1mm, the holes for the spurs on the bottom of the buttons are 1.7mm and the rest are .8mm except for the mounting holes which I've elongated into slots; use a 1/8" drill for these (about 3.25mm).
  4. Set the four 4148 diodes biased AWAY from the connector end of the board.
  5. Buy new switches and solder them in place.
  6. Solder the 8 wires from the bottom controller board in the centre 8 pads.
  7. Solder the leads from the switch to the two outside pads at the connector end; it doesn't matter which goes to which.

Here is how it looks.

  

  


Ain't electronics FUN!

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