Gimbal initialisation stuck - overload etc

[lee82gx]

My Mavic which has zero crash and maybe less than 50 flights started to show gimbal problem.

I must say it is quite typical for me to start the aircraft with gimbal clamp ON.

but this time it was not attached, and during the startup on the last action of the gimbal it would get stuck. That action is the Roll of the camera / gimbal whereby it rolls clockwise from the front view around 45 degrees and it gets stuck.

subsequently it’ll flash an overload error or clamp on error. Gimbal calibration will not complete. Stuck and fail at 68%.
Currently during the startup if I were to gently unroll the camera counter clockwise it would go fall back to the correct orientation.

during power off if I roll the camera to the same location I can feel it gets there with very high amount of friction, it would make sense that the gimbal motor cannot achieve the torque togo backwards. Is the startup overshooting too much or is my gimbal damaged inside?



Video is here

 

[old man mavic]

starting with the clamp on will and does cause errors and can damage the motors in the gimbal,and wiring have you tried a gimbal calibration,and reset

 

[lee82gx]

Ok, I'd like to chronicle my own "fix" if it helps others.
1. The gimbal being stuck was a real symptom. IE during initialization, one of the movements of the gimbal was to roll at a certain angle and back to initial. In my gimbal where I noted some friction at the extreme end and stay stuck, while another replacement gimbal that I purchase can absolutely travel to that extreme with no friction and bounce back.
2. I believe this is the real root cause to my issues.
3. Since I bought a used replacement gimbal and a bunch of gimbal flex cables as accompaniment, I proceeded to dress it with the new flex cable and transferred the replacement gimbal + camera assembly to my drone.
4. Unfortunately during the removal of the Vision sensor board to board connector, the black glue that DJI seems to love to apply to the connectors as a secondary securing method flowed under the connector, and when I unplugged to sensor flex it pulled and broke the connector on the Gimbal Control Board.
5. This set me back another 2.5 weeks and US$80 waiting for a replacement, used Gimbal control board from China.
6. While waiting, I was curious and actually initialized my replacement gimbal + camera on the damaged gimbal control board. Weirdly the first boot up resulted in the gimbal doing crazy dance on all extremes and just vibrating like mad. But after shutdown and power up it works as normal.
7. At this point I also had nothing better to do due to Covid isolation, so I attempted to salvage or tear down the damaged gimbal for "research". By some trial and error and monkey test, I found that with a flat tip screw driver and some firm force on the roll motor, rotor side, I managed to unstuck the gimbal when it rotated to the extreme. I believe that actually there is a small coaxial misalignment between the rotor (the moving part) vs the stator (the static part), possibly at the bearing mount surface.


8. Anyway having already transferred my camera to the replacement gimbal, and dressed up the flex and camera signal cables, and verified it once, I did not want to test my theory further that the gimbal as been properly fixed.
9. When my replacement gimbal control board arrived I just plugged in the connectors and all relevant parts re-fastened to their mounts and have flown tested it twice now, without error.
10. In summary it is definitely true that the aircraft will report a too large current or overload if the motor is jammed. It should really be freely rotating to the point that the it should bounce back instantly after reaching the extremes. This is true for roll, yaw and pitch. Do advise anyone having problem to see to this point first.
11. I have no idea why this happen for my case where the roll rotor would be misaligned, months after gentle use no crash. It does not make sense that starting with gimbal clamp ON can cause this as this just causes very high current to initialize, it wouldn't cause misaligned force to appear. My only theory now is there could be some tolerance issue by design that will manifest eventually.
12. Unfortunately for roll axis there is no option to have both sides supported (eg. Mavic 2 is supported on both sides for pitch axis).

Cheers and happy flying.

PS. @DJI - I also design flex cables as part of my day job. It is NOT necessary to affix with glue even as a security measure. Many designs even pass drop tests and crash tests without the use of glue. I could have avoided USD80 and 2.5weeks waiting for the replacement, even then it is a used part.

 

[Mavic Driver]

My Mavic which has zero crash and maybe less than 50 flights started to show gimbal problem.

I must say it is quite typical for me to start the aircraft with gimbal clamp ON.

but this time it was not attached, and during the startup on the last action of the gimbal it would get stuck. That action is the Roll of the camera / gimbal whereby it rolls clockwise from the front view around 45 degrees and it gets stuck.

subsequently it’ll flash an overload error or clamp on error. Gimbal calibration will not complete. Stuck and fail at 68%.
Currently during the startup if I were to gently unroll the camera counter clockwise it would go fall back to the correct orientation.

during power off if I roll the camera to the same location I can feel it gets there with very high amount of friction, it would make sense that the gimbal motor cannot achieve the torque togo backwards. Is the startup overshooting too much or is my gimbal damaged inside?

View attachment 98498

Video is here

Hi; for what it’s worth I’ve just been through exactly the same nightmare as well. My Mavic has also not been crashed and had hardly been flown. The cost of a full gimbal/camera/cable repair was scary, as was the limited subsequent warrant period. I therefore went at it myself. First I replaced the cable - no joy. Then bought a replacement gimbal & cable for about £30 off eBay. Not much better although the gimbal seemed to be more free. Then replaced the cable with the one that I had originally bought - bingo! Now works fine! The bottom line is that the Mavic gimbal appears to be a weak point, that often goes wrong. For me, replacing the gimbal motor assembly and cable did the job. Total cost about £40, rather than about £200 for a repair. It’s a fiddly job, but there are some good videos on YouTube. Good luck!!

 

[lee82gx]

Hi; for what it’s worth I’ve just been through exactly the same nightmare as well. My Mavic has also not been crashed and had hardly been flown. The cost of a full gimbal/camera/cable repair was scary, as was the limited subsequent warrant period. I therefore went at it myself. First I replaced the cable - no joy. Then bought a replacement gimbal & cable for about £30 off eBay. Not much better although the gimbal seemed to be more free. Then replaced the cable with the one that I had originally bought - bingo! Now works fine! The bottom line is that the Mavic gimbal appears to be a weak point, that often goes wrong. For me, replacing the gimbal motor assembly and cable did the job. Total cost about £40, rather than about £200 for a repair. It’s a fiddly job, but there are some good videos on YouTube. Good luck!!

Thanks for coming in, I’d like to ask if you managed to calibrate the gimbal or not?

 

[Mavic Driver]

Hi. I wasn’t able to calibrate the gimbal whilst it had the fault. It stuck at 5%. It was OK once I had fixed it. One point worth mentioning; I did read that a temporary fix to the gimbal overload is to boot up the Mavic on its side! However, this didn’t work for me. [emoji853]

 

[lee82gx]

After my fix which was literally another used gimbal, a new 3rd party flex cable, another used gimbal control board, and my original camera and camera cable, I still could not calibrate past 68%. It is working though. I suspect something to do with firmware. I Am on 1.04.5

 

[masray]

I had the exact same symptoms (mavic pro). I fixed it by replacing the camera to the gimbal assembly. After I switched the camera component the gimbal breezed through the auto gimbal calibration and worked well after that

side note: I have multiple misc gimbal parts I have had to purchase from how often the gimbal breaks.