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Starting my phantom2 motors turn slowly and grumble

Discussion in 'Phantom 2 Help' started by Sailing Droner, Dec 7, 2014.

  1. Sailing Droner

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    So I put a Gopro mount on the underside of my Phantom 2.
    At the same time I disconnected the two gimbal wires that come taped to the underside from where they connect on the inside and took them off.
    I also took off the canbus, i disconnected the canbus and then threaded the cable up inside and zip tied it out of the way - without re-connecting the canbus.
    Then I tried to start the Phantom. At first nothing happened at all. Then on the third attempt, the motors started turning, but jerkily and very, very slowly, like a revolution every few seconds.
    Does anyone know what's going on?
    Did I mess something up by not having the canbus attached?
    Is it something totally unrelated and just coincidental?
    Any help would be appreciated. I'm in Thailand right now on holiday and would LOVE to get some drone pics here!
    Thanks!
    Mark.
     
  2. CityZen

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    Should be coincidental, unless you managed to short something. Why didn't you just unplug and remove the CAN bus cable also?
    Do the motors turn freely if you spin them by hand? Did you make sure to line up the lid right when you closed it?
     
  3. Sailing Droner

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    Hi and thanks for getting back to me.
    For some reason I didn't think about unplugging the canbus cable.
    The motors seem to turn freely.
    When I first put the lid back on, I put it on wrong, but saw what I had done and put it on correctly before trying to start it.
     
  4. noiseboy72

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    Have you used the correct screws around the motor housings? It is easy to use too long screws - or to just over tighten them and then they penetrate into the motor and damage the motor coils. The motor will still turn, but will not run correctly.

    Lots of people have had issues with this when fitting or removing prop guards, but it would be possible to damage the motors even just removing the body shell.
     
  5. Sailing Droner

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    Thanks. I haven't used prop guards on this one yet, but I'll take the motors out and see if there are any marks or telltale signs.
     
  6. Sailing Droner

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    I've just had a look at each motor with a magnifying glass and the motor coils all look good. There were no screws in the wrong places and none were too tight.
    I also gave everything inside a once over and couldn't see anything amiss with wiring or solder joints.
    So then I tried to start it up and it wouldn't even start this time. It's doing the same thing that it was at first. I go to start it and it lights up as usual, makes the first initial sound, then shuts off...
    Any ideas out there? It's only a few months old. Never had a problem before this.
    The one thing I did not long ago was switch it to Naza M mode. I flew it a few times after that and it was working perfectly in the new mode.
    Thanks in advance!
    Mark.
     
  7. burlbark

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    Did you ever use the prop guards? What you are describing perfectly matches the long screw problem. You would have to look very carefully to see the damage they cause. You cant tell by tightness..... you could have a bad solder joint on your main power lead.
     
  8. CityZen

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    That's usually a sign of something being shorted out.
    Do you have a multimeter? You can try to measure the resistance of each motor coil. This is harder than it looks, since there's a plastic coating over the ESC and the solder joints. But a sharp probe or pin will poke through it. You need to measure between each different pair of colors. All the measurements should be the same. I don't know what the reading should be right now, but I can check later when I've got my Phantom in front of me.

    Edit: Motor coil resistance should be ~ 6-7 ohms.
     
  9. 750r

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    Do you have the GPS plugged in ?
     
  10. Sailing Droner

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    First, let me say thanks for the help. I'm over here in Thailand where there just isn't much support. I've emailed DJI and the store I bought it from, with no response from either.
    You suggested I test the resistance of all the motor wires, which I've just done.
    All the wires and combinations of wires were the same. I got a reading of 2 or 3 ohms for them all. It's not the 6 or 7 you got, but they were all the same which leads me to think that they are probably OK. Would you agree?
    A short in the system does seem to be the most likely problem. I've gone over all the solder joints with a magnifying glass and they all look perfect. I've looked over the ESC boards, all the connections, and they all look like brand new....
    I do have two spare motors with me.
    Anything else you would suggest I try?
    Thanks again,
    Mark
     
  11. Sailing Droner

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    Yes, the GPS was plugged in.
     
  12. CityZen

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    First, check the easy things:
    - look carefully at the connectors where you unplugged the cables. Make sure no pins are bent.
    - measure the voltage at an ESC connector when you turn on the Phantom. Should be same as battery voltage.
    - Is it a Vision Plus? If so, lift up the wifi module slightly and make sure it's not shorting the battery connections.
    (there's tape under the wifi module to prevent this, but you never know)
    If no help there, then, one by one, unsolder each ESC from the main board and disconnect its signal wire.
    Try to power up after disconnecting each. If it powers up fine after disconnecting one, then that one is the trouble.