Motor vibrating but not turning, is it dead?

[Luisclement]

One of my motors on my DJI F450, original from kit, was not moving but oscilating. Measured the resistance of the motor and is the same a al others. Is it dead or there is a fix anyone could share?
Thank you.

 

[DennyR]

Could be a dry solder joint on one of the phases. or overheated Pad on the ESC

 

[kloner]

if you unplug and replug, it might fire back up. alot of times it's like he mentioned a crappy solder joint, but others it's just one of those things that metal to metal stops making connection and just needs to be touched. do one at a time cause switching them around will change a motors spin direction

 

[SkySlider]

Luis,this is how i check motor and i have not had a bad one get by yet.chuck your drill to the motor shaft.hold the stator stationary with a vice or such.attach both leads of a volt meter to either two of the motor leads.your are going to repeat this between all leads.

set the volt meter to A/C volts.be sure to set ac because your are going to then spin the shaft with the drill and measure the ac output across the leads.the voltage will be nominal but they should all read close.this test turns the motor in to a small generator the meter acts as enough load that this test also checks the insulation hold value or (dielectric strength) of the insulation.i run the drill wide open to ensure a consistant rpm for the test.hope it works for you.

 

[Luisclement]

Dear all, this was of great help. At the end you guys were right it was a bad cable but not at the connector but closer to the motor winding. Just a new solder and all is good. Thank you all for the great help and fast response, lost just a day of flying...BR//Luis.