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Jerky Gimbal

Discussion in 'Pro/Adv Discussion' started by zryall3, Dec 13, 2015.

  1. zryall3

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    My P3 Pro all of a sudden is exhibiting the jerky gimbal for no reason I can determine. See attached video. I recently recalibrated the IMU cold and that worked great to correct the slightly slanted gimbal I had been experiencing. I fired it up after all that and everything was right. I put the P3 away for a few weeks, and took it out today to show a new P3 friend how to fly his. When I booted up mine, the gimbal went nuts and gave me the "gimbal motor overload" message. I rebooted several time and got the same thing. All firmware on controller and P3 is the latest and it has had no impact damage at all. All three axis of the gimbal rotate freely and with no rubbing or grinding or hesitation at all. On each restart however, the same behavior is exhibited. Any thoughts on anything else I could try? I thought I'd reinstall the latest firmware, but I couldn't get the red and green blinking, beeping. Perhaps because it was already up to date. The GO app tells me all software is up to date. I did take off for a short hop to make sure the P3 could fly fine and it functioned normally. I landed immediately so as not to jeopardize any gimbal components that were getting worn or overheated. Thanks for any advice. I'll send it in if I need to, but can't understand why this would come out of the blue. I recalibrated the IMU cold again and it did not help the gimbal issue.
     
  2. bobmyers

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    Did you try to manually straighten the camera tilt with your fingers? Look like the tilt motor is hung.
    Did you do a gimbal calibration after the IMU calibration?

    If that doesn't work, give @hunch a shout on this forum, he is the resident expert on gimbals.
     
  3. Mako79

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    Check the hidden hex grub screw, It could be loose from change of weather (metal expansion). The 1.5mm hex is located at top of the Main arm opposite side of the flex cable. Tighten it to the flat side of the D shaft.

    Another stab in the dark could be a bad IMU calibration. Don't fly your phantom for an hour and then do the IMU calibration the moment you turn on the phantom.
    And finally, check the compass values. A zero compass value can throw off the camera (this is highly unlikely as you get no red flashes).
     
  4. bobmyers

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    The grub screw on the shaft only affects the camera centering, not the camera level.. DJI recommends a gimbal calibration following and IMU calibration. The camera has obviously shifted on the tilt axis or is stuck-- which could be caused by no gimbal calibration.
     
  5. zryall3

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    Thanks guys. Hex screw was good and tight, so doing another gimbal calibration since the recent IMU calibration to see if that works. If not, I'll try holding the camera again though last time I did that, it just went nuts after I let go. Will report back and also sound out @hunch if no luck.
     
    bobmyers likes this.
  6. zryall3

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    Thanks Bob. I am waiting for Hunch to surface to see if he has any suggestions for troubleshooting. No reply so far. Wondering if it's worth blowing a little air (not too hard) into the gimbal movements to see if something small stuck in there and is influencing the ability of the gimbal to calibrate. Again, it all feels so smooth, doesn't feel like any obstructions at all.
     
  7. bobmyers

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    I think you can send him a PM

    Here is his web site.

    https://www.uavrepairshop.com/
     
  8. hunch

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    Zach,
    this is either a yaw potentiometer or motor has a bumped transistor on the stator.
    i don't think it's a "software" glitch. do you have happen to have an ohm meter ?
     
  9. zryall3

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    HI Hunch, and thanks much. I do have an ohm meter. What should I try?
     
  10. zryall3

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    Also, should have asked you in the first reply, if it is what you suggest, should I not try and repair that myself but just send in to see if warranty would cover it? If not, is this something your shop has experience with?
     
  11. nparker13

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    I had a similar issue and recalibrated the gimbal twice to resolve. Havent flown since, but it was strange to me.
     
  12. hunch

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    Zach,
    i do have experience with these and know them pretty well.
    if you have an ohm meter then start with roll sensor board. on the back casing there are 5 screws, three of the same size and two of the same.
    take them out and carefully unplug two of the ribbon cables attached to the sensor board.
    once out you will notice the potentiometer on one side of the board (little black round case where the shaft of the motor goes through with one solder connection on top
    and three on the bottom). take your ohm meter and position the inner circle that spins all the way around so that the flat part faces the top portion of the potentiometer (where
    there is only one soldered connector) and place one probe of the ohm meter on that connector and the other probe to one of the bottom left or right connectors. you will NOT be using
    the center connector (2) at any time.
    you should see almost identical values when probe is between connector on top and probe on either 1 or 3 connectors which is around 3.5kOhms.
    now spin the center 90 degrees either way and you should read ~2kOhms (kilo Ohm) when probes connected on top and 1 or 3 and ~4kOhms when connected on top and 3 or 1 on the bottom.

    now turn center 180 degrees and values should be reversed. if you measured ~2kOhm between top and 1 and ~4kOhms between top and 3, you should read ~4kOhm between top and 3 and
    ~2kOhm between top and 1.

    If you see crazy readings like 10+kOhm or even in MOhms (Mega Ohm) your potentiometer is cracked and needs replacement or the whole sensor board needs to be replaced.

    do the same with Pitch sensor board and finally on top main board.
    you will have to completely take apart the whole gimbal to get to pitch sensor board.


    let me know if you need more help.
     
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  13. bobmyers

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    I have an ohm meter also-- but the only thing mine is going to do is check continuity. I don't have any issues with mine now-- but when I do, Im putting a label on the case and shipping it to you.:D:D:D
    Thanks for sharing your knowledge and expertise with the folks here. That is a great service.:):):)
     
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  14. zryall3

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    Great, detailed advice and thanks much. I'll get the meter out this weekend when I have time to do this and see what gives. I wonder if I will void the warranty in even examining the boards. Thanks again Hunch.
     
  15. hunch

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    it will not void the warranty.
     
  16. nparker13

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    Any luck? I don't have a ohm meter but wondering if this is the same thing you're experiencing:





    I did IMU calibration no luck. I can do gimbal calibration and it works until I restart it. Note the sound is not from the phantom.
     
    #16 nparker13, Dec 20, 2015
    Last edited: Dec 20, 2015