M4 doesn't work

[victorycube]

Hi guys just got done soldering and testing the rotors by turning it on with the battery. M4 doesn't spin...

It doesn't look like there are any shorts whatsoever. I dont have a multimeter handy so I can't confirm. I'm pretty frustrated as well -- didn't realize the soldering would be this difficult. I can't wait to fly this but now it looks like it never will.

Maybe the motor is defective? Is there an easy way to test the backup motor without having to desolder and attach it? I'm sure that will just make a huge mess...

I've attached a picture if you want to take a look.

http://i.imgur.com/6lVzAhw.jpg

[victorycube]

Here's the other side as well:

http://i.imgur.com/QWNLCdb.jpg

I really can't see any problems. I could go into work with this and check using the multimeter there. Is there a guide as to which positions I should be checking?

[tobias]

Let's do our best to find the problem. You can start by checking the spare motor with a normal 1.5V battery like this.

There are some other forum threads you cans start looking at so please have a look at them:
http://forum.bitcraze.se/viewtopic.php? ... 1597#p1597
http://forum.bitcraze.se/viewtopic.php? ... 2360#p2360

If you can get hold of a multimeter you can try checking the motor resistance to see if the motors might be broken or not. It should measure about ~2 ohms. Unplug the battery and measure between the pads on each motors soldering connector.

[victorycube]

Hi! I have done extensive testing with a friend who is competent in electronics, and gone through the posts you suggested. The motors all work on their own, but the 4th does not work on the board...

I have applied VCC to the 4th motor and that makes it spin. But it seems like on bootup the MOSFET is not recieving any signal. We measured the voltage profile on the gate (with oscilloscope) comparing the M3 and M4 positions. M3 produced a large stereotyped response while M4 gave nothing. Since the gate does work (as checked by shorting VCC to it) it seems there is some other more deep seeded problem with the board...

What do you think? Also, here are some pictures of the set up to test.

http://i.imgur.com/yDqbt0N.jpg

http://i.imgur.com/N69F5eN.jpg

[tobias]

Then it is only the signal path left to check. Can you measure, with an ohm-meter, the resistance between the blue-yellow circles and between the blue-green circles in the picture. The blue-yellow should measure 10k ohms and the blue-green should measure 100ohm.

[victorycube]

Hi Tobias,

Apologies for the late reply. Things have been busy and I haven't had too much time for this project lately. I did check what you suggested. The blue-yellow did measure 10 kOhms, but was unable to get any resistance between the blue-green.

Thank you!

[tobias]

Then we are a bit closer to finding the problem. Something is broken between the resistor with the green circle and the transistor leg, blue circle. First can you measure the resistance of the small resistor with the green circle? It should read close to 100 ohm. Then try to inspect the trace going from the resistor to the transistor (green to blue circle) for a broken trace.

[jack86]

Hi Tobias & co.,

I have similar problems like victorycube, but with the M1 motor and different symptoms.

M1 becomes in few second of rotating very hot. And power of M1 is max around 30% of all power. I can see this on pc client - HMI.
I had already make all measurements and tested M1 with AA battery... Al results are OK.
And finally, I change motor with the new one, but problems are still active.

Do you have any advice for me?
I just order GPS receiver today, but...

Best regards from Ljubljana.

Jack

[tobias]

The new motor, does it also get hot? I don't think that could happen other then if the motor isn't spinning freely. Can the Crazyflie fly at all?

[jack86]

The new motor is get also hot. But not from the beginning, firs and maybe second flight with new motor was OK.
Crazyflie is very unstable during flight. I will check what force is needed to spinning rotors, but for this i will need newton meter..
HA, I remember, when I turn power switch ON, motors M2, M3, M4 on Crazyflie do a few 2-3 rotations, but M1 do only half of rotation - 180°.

Yes, it seems that it does not rotating freely.