Motors issues (not working and always spinning)

[smallfly]

Hi,

Just got a Crazyflie for xmas. The assembly process went well. But when I turned on the Crazyflie (using the battery) the M2 did not spin.

Then I did the followings:
- I checked for short circuits, and did not see any.
- I used a multimeter to verify the motor resistance, and got the expected 2 ohms.
- Therefore I ended up un-soldering the M2. Then I tested it with a AA battery, and it works fine.
- I soldered it back on the board. This was quite hard. And started to become a mess.

Now….
The M2 is still not spinning, and the M3 starts spinning as soon as I plug the battery. Even if I don’t turn the Crazyflie on.

Reading this thread http://forum.bitcraze.se/viewtopic.php?f=5&t=364 it seems that the M3 mosfet transistor might now be shorted.

I have an other Crazyflie on its way. And hope to be able to fly it. Therefore I want to put all the chances on my side and try to avoid these issues.

1- What could have been the issue with the M2 not spinning?

2- What is the best way to solder the motors to the board? Would it be a good idea to use solder paste (as https://www.sparkfun.com/products/11789) and a small iron tip (as https://www.sparkfun.com/products/9538) ?

3- Could I avoid soldering by using solderless headers (as https://www.sparkfun.com/products/10527) and jumper wires (as https://www.sparkfun.com/products/8672) ? Using jumper would be great because it would make it easy to replace motors.

Thanks!

[atomicdog]

1- What could have been the issue with the M2 not spinning?

Maybe the FET is bad.

2- What is the best way to solder the motors to the board? Would it be a good idea to use solder paste (as https://www.sparkfun.com/products/11789) and a small iron tip (as https://www.sparkfun.com/products/9538) ?

Yes, solder flux/paste helps a lot.

3- Could I avoid soldering by using solderless headers (as https://www.sparkfun.com/products/10527) and jumper wires (as https://www.sparkfun.com/products/8672) ? Using jumper would be great because it would make it easy to replace motors.

The crazyflie PCB probably wasn't designed for press-fit connectors, so there is a chance they would damage the board when you try to put them in.

[tobias]

The M2 is still not spinning, and the M3 starts spinning as soon as I plug the battery. Even if I don’t turn the Crazyflie on.

You probably shorted M3 to the DGND VIA which is just below the MOSFET pin for M3, similar to this but for M3. Have a look at this post.

To test M2 you can do as in this post. If you can't manually turn it on it is broken and you should contact Seeedstudio support, they are responsible for the hardware.

Using flux makes everything a lot easier. When you replace a motor you can heat up the pad from one side and pull out the wire from the other. Do the same when inserting the new one again, link. Don't use a too hot soldering iron though, around 350 degree C works well.