Hi all,

I need some help interpreting the attached log file.

Scenario :

I was flying my Arducopter Y-6, (What a machine, by the way!)
APM 2.6


Stock hardware, no mods or changes.

5300mah 3S Lipo

Took off, flew around for about 30 secs, hit LOITER at about 3m Height. Held perfectly.
Throttled up, climb out to about 30 meteres, still in LOITER.

Hang around at this altitide for around 2 minutes, slowly yawing left and right to get some nice camera shots.

SUDDENLY, no power, ALL the motors stop, and the copter falls to the ground tumbling from about 20 meters up. During the fall I changed to STABILISE, and applied full throttle, nothing.

Amazingly only damage is one broken prop, this is one tough bird!

Now I have tried to decipher the logs. I have checked the following graphs:

VOLTS - battery was 12.4 at full , dropped quite quickly, but never below 11V

Satts - 7 satellites all the time, HDOP 1.8VCC - 5.0 to 5.5 V all the time, so no brownout on the APM

the only funny I can see is the graph of Throttle in vs throttle out, As the motors quit, the throttle out goes haywire, but no indication WHY.

I think perhaps I just dont know where to look..

Any Ideas? Any help will be greatly appreciated.


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So finally (I hope) this long saga comes to an end.


After crashing numerous times this weekend, I decided to re check and strip down the Y6 to see if I can find the problem. First some checks, Compassmot ok, Motor tests revealed that one motor was occasionally not starting cleanly.

Some troubleshooting swop-outs later, it became clear that the ESC's are fine, but it looked like one motor was faulty. We took the motor off, and re-soldered the bullet connectors. We ran it with a servo tester, no joy.  So we stripped back the joins on the motor side and resoldered there too. Still the same problem. The motor spins up fine if you advance the throttle slowly, but with sudden changes in throttle, the motor will stutter and hunt. (See attached video).


The reason why it was so hard to pinpoint was that, especially in the beginning, one is quite careful with the throttle, and its then easy to miss. I do think that it would have been iester to spot if my Motor logging was turned on. We have now measured the motor, and one winding is way out of spec to the others.


An easy way to check this would be to put the APM in throttle calibration pass-through mode, get someone to hold the craft down, then aggressively work the motors to see if any one behaves differently than the others. Alternatively make a test setup, like we did in the video.

A good thing we stripped the machine down tho'!


On closer inspection , I found 2 dry joints on the PDB, and the signal wires on the PDB were soldered really badly, just lightly touching them caused one to come loose. I suggest that you re-solder all the wires using QUALITY solder, then secure the wires against movement with some epoxy, or like I did, with a hot-melt glue gun.

Good Call Bill and Randy! It was hardware after all, there were times I had serious doubts.
Thank you to everyone who commented on the post,and tried to help. Thanx to Gustav too for helping with the troubleshooting, and for being there to bounce ideas off of.


Next step : Apply the new PARAM file, and see what difference that makes.


I suggest that you re-solder all the wires using QUALITY solder

That means good old fashioned Rosin and LEAD/tin solder, in the trade trade, we have endless hassles with lead free solder.

I work on 30 year old equipment, solder joints still perfect, and 1 year old equipment, from really big name suppliers and a lot of faulty solder joints.

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