First you will need a PS2 style joystick, I've used this Thumb Joystick Module for Arduino (Works with Official Arduino Boards) from DX.com and removed the pins.
To install the joystick you have to cut the case so it's a "no way back" mod. In the back shell I've followed the shape of sticker below the pot because the joystick fit well and the plastic is thinner in that area . Only a little bit was carved beyond to make room for the button of the joystick which is located on the back. Also there are two reinforcements inside the back shell, just below the pot, that you have to trim for the joystick to fit closer to the shell wall and avoid colliding with P3 in the front shell.
Only a little carving in the front shell was enough, no photos but can be seen later in the top view of the mod finished.
NOTE: To cut the plastic I've used a hot blade
Once the cutting job is done, you have to solder the wires. First unsolder the three cables from P1. and only center one for P2. This one needs to be extended to reach the joystick.
Signal is the center one, mark it, but since colours are different for + and GND between pots on mine, you will have to check with a polymeter for + and GND (with the polymeter set for "continuity" touch the unsoldered cables and GND of the board one by one to see which one is connected)
Once you have identified polarity, solder the cables to the joystick board (remember I've removed the pins to use the holes):
+5 and GND are ovbious, VRx is P1, VRy is P2 (in my setup) and SW is the momentary switch which i've connected to THR switch for the convenience of proximity and moved the 2 position switch to TRN but could be connected directly to TRN if you extend the lead.
Once soldered, you only have to place the joystick on its place and apply some hot glue to fix it in place...
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[/td][/tr][/table]And then close the TX shell (after checking all functions).
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[/td][/tr][/table]Now the Mod works but is a bit too rough so I've done a simple bezel with fimo paste. since FIMO will not harden until cured in the oven, you must use something to be able to remove the molded part without bending. In my case I've used cooking film to avoid adherence and over it paper tape to create a base strong enough.
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[/td][/tr][/table]Obviously, do it at your own risk. I only want to show the mod to inspire others.
PS: Now I have a free switch and a free pot on my 9X. Since it has the Telemetrez board installed and the Tez has free inputs. Would be nice to rewire them to the tez, actually two switches would be better (WKM ,ZENMUSE an IOsd together are a switch hungry setup) Does someone tried to add more switches on the tez firmware and OpenTX. my next mod will be adding a second TX to the 9X to use 16PPM channels and more switches on the TX would be nice
