FlySky FS-TH9X Modifications
The FlySky FS-TH9X transmitter also branded as Turnigy, Eurgle and a few others, IMO is one of the best RC transmitters on the market for those that like to hack electronics and it is cheap. That is cheap price. The quality is rather decent except for the buggy factory firmware. I paid under $100 for it and with all mods it ran about $103 but I already had some items required. There are a number of mods that can be done to it. So far I have added the USBasp programmer to allow firmware updates, upgraded the firmware to the ER9X firmware, modified it to accept 2200mAh S3 20C batteries, switched the sticks from mode 1 to mode 2 and added 2-way telemetry.
Firmware cable mod
The circuit board I will be modifying. Take note of the red/white wires that are under the metal tension arm on the gimbal. That is how it came from the factory but on the opposite side. I have since moved the wire to just outside of the tension arm as I noticed it was binding up every now and then. Would not want it to crimp or cut the wire while flying.
The circuit board with the USBasp programmer wires soldered in place. The USBasp programmer is the one that comes with the $23 GLB KK blackboard. Considering the cost of a typical USB programmer you could say that I got the flight controller for free and the programmer at a discount if you can get beyond the terrible confusions in shipping that you get with GLB purchases.
The USBasp programmer attached through the battery compartment. Even though the battery mod is not shown or discussed further please note that the bullet connectors for the battery connection are not installed properly and the way I have it is/was very dangerous. If the battery pack for whatever reason happens to unplug then the male ends on the battery are exposed and could touch and arc which could damage your battery, transmitter, yourself and even your home.
The FrSky DHT 8ch Telemetry module. Note that I carefully removed the heat shrink tube so I could unplug the antenna.
The circuit board were I will be adding the telemetry module.
I had to un-solder and then re-solder the pins on the side to get the new heat shrink tube on the module and now that I know where the antenna is plugged into the board I will just make a small incision next time rather than remove the protective wrap.
Installing the three position switch for firmware update/1 way/2-way.
Everything in place and a few dabs of hot glue to keep it all snug.