When using Phantom 3 PRO and LITCHI: I keep receiving a Warning message when launching LITCHI that says, “RC not connected to device”. However, I am able to fly and perform Waypoint Plans without problem, the only thing is that I don’t get in the mobile device screen the percentage of the RC Battery neither the status (strenght) of the Radio and Video link. Can someone help me?
I can think of 3 possible causes:
- A faulty USB cable
- You did not force-close the DJI app (DJI GO)
- “Dry” solder joints on the USB-connector of the RC (a known problem with Phantom controllers):
Easily fix a ‘dry’ or broken solder joint on printed circuit boards | by Ian Anderson | Medium
Thank you TriBar for your prompt response! From the 3 possible causes that you mentioned I discard numbers 1 and 2 because I have done several tests using proved working USB cables and force-close the DJI app (DJI GO). Cause number 3 seems more likely to be the problem. I have a Phantom 4 PRO and doesn’t have the problem that I have with the Phantom 3 PRO. That tells me that probably the problem is related to RC of the Phantom 3 PRO. I will look at the number 3 possible cause that you listed. Thanks!
Hello AIRvision,
Litchi has a pop up dialogue about making sure no DJI products are running in the background.
I thought DJI Fly would stop running in the background if I went to the tablet’s app page and ‘force stopped’ the app. Actually, it was still there ready to run as soon as I plugged in the USB cord. I eventually had to uninstall DJI Fly to get Litchi to run properly. It hooked up immediately.
Hello dumbthumbs,
Thank you for the suggestion. I have verified that no DJY app or any other is running in the background. In any case, I am able to run Litchi app and actually fly the drone (Phantom 3 Pro) however the log information about the power level of the RC and the strength of the Radio and Video signals don’t appear in the mobile device. Instead, it appears N/A (Not Available) for those 3 values. All the rest of parameters and functionalities of Litchi app run perfectly. My conclusion is that the problem is related to the Video Downlink Circuit Board of the RC (very likely related to the third possible cause mentioned by Tribar). I decided to order the replacement part (Video Downlink Circuit Board) and see what happen. I am waiting for the part to arrive.
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Well done. Keep us in the loop when you hook it up.
Follow up: I received the replacement part (“Video Downlink circuit Board” also known as “Remote Transmitter Circuit Board”) and installed in the Phantom 3 PRO Remote Controller. It didn’t solve the problem… 
I still have the Warning: RC not connected to the mobile device. Everything in the Litchi app works well except that the power level of the RC and the strength of the Radio and Video signals apear as N/A in the mobile device screen. I am able to fly the drone and perform the missions and take the videos/photos as planned.
I also have a Phantom 4 PRO and doesn’t show this problem, everything works well.
I wonder if the problem then is associated to how Litchi app communicates with the RC of the Phantom 3 Pro.
Another observation that doesn’t help to understand the cause of the problem is that when running the DJI GO app with the Phantom 3 PRO, everything works well, and the strength of the radio & video signal appear in the mobile device screen as well as the % of the RC battery.
Not a clue of what is causing the problem. Although it doesn’t stop me flying the drone with Litchi app, it is very frustrating not being able to solve it…
Hello AIRvision, sorry about the problems you are having. When all else fails try reinstalling your apps and trying different phones/tablets to see if the results are consistent and that everything was done the same way. Good Luck! 
Thanks Steve, good advice. I’ll try it. 
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