Phantom 3 4K Gimbal Yaw Motor not working

[kawartha]

I picked up a second-hand P3 4K in very good condition. According to battery charge count it has had about 62 flights. It does not look like it has ever been crashed or taken apart, no scratches or scuffs . The gimbal yaw motor is not working. When powered on the gimbal gives no resistance when pushed in yaw. There is also a small white fan on the top of the gimbal that I have not seen running. Roll and pitch motors work perfectly, I am able to fly the P3 and shoot video and pictures which look normal, except video is shaky in yaw because of the lack of yaw stabilization.
So my question is - is there anyway to diagnose whether just the motor is bad, or one of the boards is bad, before taking it apart and figuring out what parts to order? Is the small white cooling fan on top supposed to run all the time or just when it reaches a certain temperature threshold? I have experience repairing P4 Pro but none with any of the P3 models. I have reviewed the few Youtube videos on P3 gimbal repair, so looks straight forward.

Thanks!

 

[jiminyfixit]

I picked up a second-hand P3 4K in very good condition. According to battery charge count it has had about 62 flights. It does not look like it has ever been crashed or taken apart, no scratches or scuffs . The gimbal yaw motor is not working. When powered on the gimbal gives no resistance when pushed in yaw. There is also a small white fan on the top of the gimbal that I have not seen running. Roll and pitch motors work perfectly, I am able to fly the P3 and shoot video and pictures which look normal, except video is shaky in yaw because of the lack of yaw stabilization.
So my question is - is there anyway to diagnose whether just the motor is bad, or one of the boards is bad, before taking it apart and figuring out what parts to order? Is the small white cooling fan on top supposed to run all the time or just when it reaches a certain temperature threshold? I have experience repairing P4 Pro but none with any of the P3 models. I have reviewed the few Youtube videos on P3 gimbal repair, so looks straight forward.

Thanks!

You are correct about the fan. It will turn on about a minute after start-up. A limp gimbal is evidence of a bad yaw motor & needs to be removed & taken apart to see if the 2 tiny, black sensors are scratched or gouged. Also check to see if the motor lugs have a very shiny gloss, on all or partial lugs. This would indicate the motor heated up at one or several times from being restricted in maintaining a "centered" position. Melt can be accumulative. A soft landing into bushes can force the gimbal into unnatural positions for too long a period of time. (can be up to a minute or more) To take a motor apart, go see one of Dronted's YouTube videos, before you try it for the first time. He may be taking apart a P4 motor, but they all come apart in the same manner.

 

[kawartha]

Thank you for your response. I have already taken it apart to clean the ribbon cable connection but I was not looking for the things you mentioned. I ordered a couple of yaw motors from 2 different sources and I once I receive them I will have a closer look at the motor. Also got a new DJI ribbon cable but will not replace that unless new yaw motors do not work.

 

[kawartha]

Success! Replaced the yaw motor and all is good. The magnet ring needs to be realigned, center is off by about 40 degrees. For now I just offset the motor shaft and tightened the grub screw to compensate. Did a test flight and video is nice and smooth as expected.