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Old Sep 13, 2012, 06:17 AM
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Danny_Swe's Avatar
Joined Jul 2011
222 Posts
Question
Compass 5026-540 resistance

Got my new motor today but the top case is loose and shakes around and might have damaged the winding (actually in particular in one spot the coating is scratched). So I thought of measuring it.

The resistance between any lead and the shaft is about 100-200 Ohm.


That can't be right!? Or is this motor different in some way to my old 4035 that have no indication at all?


The motor is Y-winded in some way and here is a video:

Compass 5026-540 resistance testing (3 min 3 sec)
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Old Sep 13, 2012, 06:47 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,218 Posts
That is an unusual motor with that stamped metal end plate covering the backplate/bearing tube.

But you should not see any continuity between the motor leads and the shaft or any other metal parts of the motor. That means you have windings that are shorted to the stator.

The low fraction of an Ohm resistance you got between two of the motor leads is normal and all three pair combinaions (1-2, 1-3, 2-3) should give you the same low steady readings.

Be carefull about trying to test that on an ESC, sometimes a shorted winding can results in the ESC being damaged too.

Looks like a candidate for replacement or rewinding...

Jack
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Old Sep 13, 2012, 07:36 AM
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thanks Jack.

looks like I have to send that one back then
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Old Sep 22, 2012, 06:22 AM
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Joined Dec 2011
53 Posts
Watching the readings, it looks like the Y-termination point is touching the stator - Ask for a replacement, it's not meant to be like this. Using this will result in a crashed model - sooner or later.

And yeah, interesting design with that stamped metal housing, never seen one like that before!

// Per.
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Old Sep 22, 2012, 06:39 AM
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222 Posts
yes, quite odd motor. One guy said to me that this is basically an old motor called Actro (either this brand or a clone of it).

The stator legs are really tiny and lots of them. Check out photos.

And I have returned it and now have a custom wound Pyro on order instead (PowerDekker).
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Last edited by Danny_Swe; Sep 22, 2012 at 08:33 AM. Reason: found the correct name
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Old Sep 29, 2012, 07:28 PM
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United States, FL, Pompano Beach
Joined Oct 2011
1,425 Posts
I've seen brushed motors using that odd winding technique, didn't know it would work for brushless. Seems like allot of extra wire in the circuit with long stretches between teeth. I imagine it must make it cheaper to wind.
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