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Typhoon H IMU related problems


Premium Pilot
Mar 23, 2016
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Bavaria / Germany
During my investigations regarding "Stuck in Aquiring state" the IMU on the Flight controller board got attention as source of different problems.
Details can be found here: http://h-elsner.mooo.com/pdf/GPS_acquiring_problem.pdf

It looks like MPU6050 chip as heart of the IMU has an aging problem when the drone was stored somewhere and not used for some time. That's why my recommendation is to power on the drone from time to time and do a accelerometer calibration. Of course it is best to fly it.

In case the IMU has a problem, usually, only the exchange of the flight controller (MCU-board) will help. But since this is quite expensive, we could try to replace only the IMU (make-one-out-of-two-method).
I added a guide how to replace the IMU on the flight controller of the Typhoon H to the HowTo collection on my homepage.
Here it is: http://h-elsner.mooo.com/pdf/HowTo_Replace_IMU.pdf

The most important part is to find the right place to lever the old IMU to avoid damaging conductive paths on the PCB.

br HE
Nov 15, 2022
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I wish I had come across your posting before I started investigating this issue, would have saved me a lot of time; but it was fun so cant complain. A little bit of backstory, I bought a TH from fellow forum member PEVO a few days ago. On arrival, I tested it and it would not fly. This is my first typhoon H and I did not have any knowledge on common issues. I got together with PEVO who walked me through what could possibly be wrong and zeroing in on the FC I decided to get it fixed at a qualified tech and got that sorted out. Unfortunately the GPS module was also weak on this, the received signals were about ~25 db even with clear views of the sky. So thats another thing that got replaced.

My curiosity on the issue grew and the retired engineer in me wanted out over the long weekend. I went hunting on craigslist, bought a Parted out Typhoon for ~50$ and got to experimenting. As rightly pointed out by you, the sensor IC is contained within the brass enclosure and filled with resin is the culprit. The STM32 microcontroller uses a lookup table to correlate GPS positioning data with sensor readings to validate everything. When it does not pass the check, it just assumes the GPS readings are at fault and gets stuck in acquiring. From a safety standpoint, the job is done as the TH is locked out of flying. However, given the contradictory nature of readings, it does stop you from flying out with GPS disabled. I think the engineers at yuneec implemented this considering this situation, only that they did not want to write additional status messages to let us know that it could be either GPS or the positioning sensors that could be bad. Without a third input - a redundant GPS or IMU, it would be impossible for the TH to perform self diagnostics.

I remembered something I used to do to fix robotic arms that were subject to similar malfunctions- bake the PCB. This would reflow the solder taking care of any oxidation that caused issues and the would get the machine running again. I decided to be a bit brash here instead and brought out my blow torch :D heating the enclosure to a 120°C. Once it cooled down a bit, I Installed it and the error went away :) or atleast temporarily coz it came back after a bit. I think baking it at 180°C for 15 minutes should get rid of it for good. Also, once hot, the resin just peels off, so you could take it off and install a new IC in there. To do this however, you would need a SMD solder station. A heat gun might work, but YMMV.

Now im off to restore this craigslist TH480 and maybe install the PX4 firmware. Fun weekend ahead :)

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