"B" Motor issue - Q500 4k

[gn298595]

Had a crash this weekend while using follow me Watch Me. Just clipped the top of a tree (thought I was high enough). Drone crashed down through the tree and into the water (following me on my boat). I was able to find the drone since the lights were still on (in the water for about 5 minutes). Got the drone out of the water, drained it and despite being in the water, I was able to dry everything out and get it fired back up after a few days. Upon first fire, the motors seemed to run fine, the camera looked good and all seemed to be fine. When I took off, the rear left "B" motor began to have issue. I hooked up the drone to the computer and ran tests on the motors using the GUI. All seemed to run fine except that motor. It will spin for 1/2 a second then stop, then on the next try it will continually spin but at a much lower rate than the others. There are no error indications on the ST10+, nor any problem indicated on the GUI. So a few questions. 1. Is this just a motor issue. Should I just replace that motor to fix the issue? 2. Should I replace the ESC also or try to replace it first before trying the motor? 3. Any other suggestions.

As a crazy note, the camera was recording video at the time of the crash, and it continued to record for 2 full minutes while it was under the water.

 

[WTFDproject]

I don't think there is a way to tell for sure whether it is the motor or the ESC with equipment a typical hobbyist would have around. The best guess would come by swapping the two "B" Motors, and looking to see if the problem followed the Motor or stayed with the ESC.
But if I was gonna bet, I would bet the problem is the ESC. Not much can go wrong on the motor unless there is some debris in it, and you would probably be able to feel that when turning by hand.

 

[gn298595]

That's actually a great idea. I'll try swapping the motors to see what happens. Can't hurt.

 

[Murray Martz]

That's actually a great idea. I'll try swapping the motors to see what happens. Can't hurt.

It also couldn't hurt to give the bad motor (if it turns out to still be an issue) a blast with WD-40, then after a day or so blast it with CRC QD Electronic Cleaner, or a similar product.

 

[gn298595]

Wanted to give a final update. I tried all cleaning suggestions. It changed nothing. While using the motor test in the GUI, the B motor would start and stop intermittently. I decided against swapping motors or ESC's with other motors as I did not want to creat any issues that were not there previously. I simply bought a pair of front/rear ESC's. I put one in and after fixing the power solder a second time (never was good with soldering electronics), I got it put back together, and much to my dismay, the exact same problem persisted. So that basically told me the issue was with the motor. I ordered a new motor, just got done putting that motor in, and much to my pleasure, it worked. The motor ran perfectly. I then took it out for a 4 foot trial flight, everything seemed to be fully functional and working normally. Thanks for all the help and suggestions, it is going to be nice to have her back out flying again...this time well above any trees and away from any water!!!