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St Model Fox EP Problem w/Power System after Crash _Plz Help !

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St Model Fox EP Problem w/Power System after Crash _Plz Help !


Old 03-25-2012, 02:31 PM
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Default St Model Fox EP Problem w/Power System after Crash _Plz Help !

Hi All,

I have an St Model Fox EP, which can be found here:www3.towerhobbies.com/cgi-bin/wti0001p

I took her out on a very windy day and proceeded to have a short but memorable flight... nosed-dived straight into ground... Frankly, I believe my setup (esp. elevevator or CG) was way off.

Although the crash did not do a whole lot of damage too fuse, etc., the motor mount was cracked in which I proceeded to make a new one (I have all dimensions if someone would like/need).

Put motor back in, and tried to run without success. Basically the motor, when applying throttle, just wiggles back and forth a bit and stops. Bring throttle to off, then reapply throttle, does the same quivering of the prop w/ no real revolutions on the prop/motor.

I tried to check if the ESC brake was on, but to do that, I need to "hear" one or two beeps after power/battery connected, which I do not... nothing.. no beeps whatsoever. Just the twitching of the prop. Without the beeps, I cannot tell if brake is on, so I followed procedure for turning the ESC brake OFF and ON, and off and on.. etc. Same result.

What do you suppose is the problem? The ESC gone? The motor broken? I have no idea, as this is my first electric powered aircraft.

Any help and/or suggestions would be greatly appreciated, as I do not want to replace parts just at random w/o knowing what specifically should be replaced and why.

I thank you in advance for your time and help.


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Old 04-09-2012, 03:18 PM
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Default RE: St Model Fox EP Problem w/Power System after Crash _Plz Help !

Don sorry for the belated reply.

You have a broken lead or bad solder joint most likely, on one of the three wires going to the motor. This causes the windings to fire out of phase and cog the motor.

Do not keep trying to run it up as it's a dead short that's occurring and you could easily burn up the motor or esc.

Go over every wire from the pack to the motor checking for a bad solder joint, loose connection, broken wire, etc.

That would be the least costly fix. Other then that, it is possible that the motor was running when it nose dived, and it shorted itself out or damaged the esc when it did so. Stopping the prop with the motor trying to turn it causes a huge amp spike that could have fried something.

If you find nothing wrong with the wires, try substituting a know good esc for a very brief run up. If the motor spins up, you know you smoked the original esc.
If it doesn't, most likely the motor is toast.
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