The FlySky TH9x transmitter is well known as the best budget transmitter on the market but the end user experience is somewhat lacking. The software is bulky and limiting. The instructions are horrible. There’s no backlight. The plus and minus buttons are backwards. The TX “module” is not removable. To the right is an actual excerpt from the included user manual.
There are tons of tutorials out there on how to mod the various 9x series of radios. The four mods I did here are programmer cable, install er9x firmware, lithium battery adapter, and backlight. I did all these in one go so I wouldn’t have to open the case repeatedly and risk stripping the plastic screw holes.
I didn’t want to spend $40 on the SmartieParts backlight and programmer board so I bought the $5 backlight from HobbyKing and used an old floppy disk cable. Unfortunately, the pinouts I found for the AVR programmer were wrong so I had to trace them back with a multimeter. The pinout for the 6pin USB ASP AVR on hobbyking is pictured above.
Here’s the finished cable soldered on. I used heatshrink to fashion a shroud for the six pins. The cable is long enough to snake around through the battery compartment. While I was back there I soldered a female 2pin JST right where the old battery snaps were connected before to allow the transmitter LiPo pack to connect up. I had to file away some of the battery compartment to get the cables to go where I wanted.
The backlight was super simple. It came with a wiring harness and a replacement foam spacer for a perfect swap. There were even step by step photo instructions on HobbyKing. I had to figure out which side was the front and then hot glue the corners to make it stay in place during reassembly. I put mine in with the wires on the left instead of on the right because it seemed to fit better that way.
The backlight looks fantastic! I got white and it’s slightly greenish/blueish but it makes a huge difference in all lighting conditions. The er9x firmware is worlds more advanced than stock. And the documentation is in English! The ability to create loadouts, mixes, and custom switches and save/load models on a PC is a lifesaver. The 9x with these simple mods now rivals any $500 + radio system.