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Brief motor failure

Posted by Scott Penrose on March 26, 2014 at 8:25pm

Hi there DIYers.

I have my first 3DR X8 with Pixhawk. Arrived 2 days ago. Beautiful condition, well packaged. Today I have been for 3 flights - all just hovers in stable (although I also briefly tested loiter).

In each flight, I noticed a sudden movement back right. On the 2nd and 3rd I noticed a preceding beep (short, sounded like an ESC startup) and on the 3rd flight I noticed the back right bottom motor stop spinning.

2 out of the 3 it gently hit the ground (no damage, just some small mud on the props) but only because I was close to the ground already. I strongly suspect the other motor would have compensated with height.

My gut feel is it is therefore an ESC or motor or wiring problem. But I was wondering what can be viewed from the logs? What are the best parameters to look for when trying to diagnose such as problem?

Should add, that when this did not happen it was super stable.

Log attached.

Thanks

Scott

2014-03-27 13-54-41 1.log

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Replies

  • Scott Penrose April 1, 2014 at 11:57pm

    Thanks Richard. 

    Awesome news. I replaced the ESC and it has fixed it. I also found the cause. During manufacture the wires from the motor are pulled through the aluminium arms. In two places this had pulled back the insulation showing the coper underneath, which would have caused intermittent shorts. I will bench test the ESC later to see if that is actually damaged, or if it was only the wires.

    Just did a 10 minute flight - 5 stabilised, then 5 loiter - didn't move at all ! Phew :-) And now I know more about the inside of my X8.

  • T3
    Richard Boyhan March 30, 2014 at 7:12am
    Try moving ESC to another motor and see if the problem follows. Then try the motors. Good luck.
  • Scott Penrose March 28, 2014 at 4:16am

    No luck :-( Still going badly, still hits the ground unless high. Just can't figure out what component is failing. Worst was using Loiter as it would over correct when the motor failed, then the motor would come back... oscillating between.

  • Scott Penrose March 27, 2014 at 4:13pm

    I've done some more experimenting. I can't narrow down the exact problem. If it was the motor or the wires it should have a problem straight away. But instead it seems to always be a 1+ minutes into the flight. Could be a problem with the ESC as it heats up?

    How would you go about trying to isolate the problem? Trial / error - replace components one at a time?

    Thanks. Scott

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