Mar 12, 2012, 04:07 PM
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Vienna, Austria
Joined Apr 2007
1,270 Posts
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magic smoke: ESC killed motor, or motor ESC ?
Maybe some of you can offer some insight:
My EMAX 2805 2850kV gave off magic smoke - and I don't know if it was the Turnigy 12A ESC (which was, admittedly, a bit too small for the 16A or thereabouts whicht the motor draws on 3s using TGS 4,5x4,5) which had died first and shorted one of the phases - OR if it was bad insulation of the motor windings which resulted in a short there.
Last time I was firing up the motor to see if the vibrations are ok (if not i rotate the prop a bit on the shaft until I get good balance) I noticed that the RPM sounded rather low, but not having flown the Microjet for some time I thought, hey I am used to the hight EDF pitch, it might be me.
But after some two minutes of flying, the motor stops rather violently. I glide the plane down and hurry for lunch, I was late anyway. After lunch and coffee, rather carefree, next attempt. Less than a minute in the flight, the motor stops suddenly, very abruptly, again (not in the way it does when the ESC gets too hot or when I reach LVC). I glide down, and before landing I attempt to restart again, and there's a smoke from the motor. Also, there is smell coming from the ESC, but the shrink wrap is ok.
At home I fire the thing up again, ESC giving the usual beeping tones for 3s, and as soon as I apply throttle, a LOT of smoke comes from the windings.
Cutting the shrink wrap off from the ESC reveals a burnt transistor...
Since the motor was running rather cool (at least the bell was always cool to the touch) I was thinking that it must have been the ESC giving up ghost and shorting one phase - but I am not sure, and I have never read that a dying ESC would overload a motor. It could still have been bad insulation on the wires.
What do you think? In the attached picture you also see the heat sink (its backside with the burnt double sided sticky tape)...
Thanks for taking some time to ponder and answer.
Clemens
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Last edited by mopetista; Mar 12, 2012 at 05:04 PM.
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