Motor m4 SPINNING alone

[jordilex7]

Hi, i have a problem with my crazyflies. When I plug the battery in, the motor M4 begins to spin! Can You help me to solve the problem?

Thanks

Jordilex7

[virus.elektro]

You are sure the FET is not broken?
I think you are making a connection via C37 or R28 to DGND. Both are close to the solder header of M4. They both have one grounded pin so I should check there.

[jordilex7]

The attached picture could help You?

image.jpg (41.82 KiB) Viewed 6452 times

[jordilex7]

Also this one

[jordilex7]

How can I check if the FET is broken?

How is it possible that the FET is broken? My Crazyflies is new. It was the first time I tried to flight with!

[marcus]

Could you post the same images but with a bit higher resolution so it's possible to see the solderings?

[tobias]

You soldering looks very well done. The MOSFETs should be tested by Seeedstudio during production so I wouldn't expect it to be broken, but I guess there is no complete guarantee.

If the motor is spinning alone it means the the round pad on M4 has been grounded, either by a short or by a failed MOSFET. There are a couple of DGND vias close to the M4 round pad so there is a chance if a short to them (but they should be covered with solder resist). Can you try to visually check that. I have a attached pictures of the top and bottom layout and you should be looking for short to the vias marked DGND.

[jordilex7]

Hi, thanks Tobias for your reply.

I checked the vias, but I am unable to find a sign of short. I attached the best pictures. What can I do now?


Jordilex7

[jordilex7]

I ave also this picture.

[tobias]

I can't see anything obvious either. How about the back side?

As the MOSFET gate isn't powered when the rest of the board isn't powered the only reason for it spinning when the battery is connected is a short or a broken MOSFET which is shorted.

I've sent you a PM.