All motors run at full speed when power connected

[HacKiwi]

Hi guys.

Just got my CrazyFlie - assembled and tested as per the instructions. As soon as I plug in a battery or usb all 4 motors spin at full speed (before pressing the on/off button). Connects fine to my pc but the motors just won't stop.

Did i screw something up ? hopefully have not just wasted $200

Thanks

Simon

[tobias]

I don't think the Crazyflie has broken but something is turning on the motors at full speed. Let's try to find out why.
You can start by removing the battery. Without the battery the motors can't run but it is still possible to run the board from the USB power.

First inspect the board for any shorts, espscialy around the motor wire pads and the MCU pads (the big chip on the bottom side).

Do the motors run as soon as you connect the battery even if you havn't powered it on? If so there might be a short somewhere. If not it might be a corrupt firmware.

Have you updated the firmware? If not try to update the firmware with the battery disconnected and power it on by inserting the USB connector. After that connect the battery and try again.

Please report back with your results.

[HacKiwi]

Thanks for coming back to me Tobias.

I followed the assembly / test procedure as follows;
- Without the battery I connected the flie to a usb.
- Connected the flie to the pc-client and updated the firmware (cflie-2013.4.bin)
- Everything was working - telemetry was coming back to pc-client
- I soldered the motors on. As far as I could see there are no shorts
- Attaching the battery and/or the usb causes all four motors to power on immediately even if the flie is 'off'
- If i turn the flie on the led's blink and i'm able to connect to pc-client (but the motors continue to spin continuously).

I can only assume I have damaged something while soldering the motors on. I'll re-solder and reflash the firmware this evening and let you know if there is any change.

thanks again.

simon

[pablo_paul]

Is your throttle position in the software showing 0? I hadnt realised when I was using the virtual machine the mapping had changed to another device and the throttle was jammed open to 80% I connected and it shot off into the ceiling worth checking it isn't something simple

[HacKiwi]

Not sure that is an option... I get all 4 motors spinning with my pc turned off.

[atomicdog]

You may have shorts across the transistors (drain to source). Which would cause the motors to run full speed even when the CF is off. It seems unlikely that all four would short like that though.
Do you have a multimeter to check?

Also, if the gates were forced high somehow, like a short to Vcc or +BATT at the gate pin of the transistor.

[HacKiwi]

May be getting somewhere.

I re-flashed the firmware.Now the motors do not spin on connection to usb.

Attaching the battery causes M2 only to spin whether the flie is on or off.

I can't find a short but will get hold of a meter tomorrow and test. What am I looking for ?

cheers

simon

[tobias]

Ok, then we are close and there is problably a short somewhere along the M2 motor driver electronics.

Disconnect battery and USB. Measure the resistance between the round pad on M2 and ground. There should be no short.

Then lets check the output from the MCU. Don't connect the battery only USB to avoid M2 spinning, or do M2 spin with the battery disconnected as well? Then measure the voltage on any pad of the second tiny black resistor (there are 4 in a row) beside the motor connectors on top of the board. It should measure 0V. If not either the MCU is pulling it high or a short somewhere is. Report back.

[HacKiwi]

Maybe not. There was a short between M2 pad and ground. I tried to clean out between the motor pad and resistors. The motors now don't run at all even after connecting to radio and controller. Think I've damaged a track and/or other components in the excitement. Will order a new one when they are back in stock and try to be more careful.
Thanks for the support.

[tobias]

Normally the electronics can take some abuse and you might be on the right track.

So when you power it on, running from battery, the motors doesn't spin during the start-up?

You could manually test each driver by enabling each motor driver transistor. This can simply be done by taking a wire and shorting the gate leg of the MOSFET to VCC. The MOSFET gates and VCC are marked in the picture. The board must be powered from battery for this test to work, and don't do the test with propellers on, it can hurt .