DC motor does not spin unless giving it an initial spin manually

N

nnam

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This is a low rpm motor. The gear is not plastic. The coil appears good, but I think it's bad.

There is no electronic, just brushes and commutator.

It stopped working and if I spin it, it will run.

Usually, a start capacitor is used in AC motor to start a motor.

For this, I can only think one of the 3 windings burnt out and it no longer pushes at particular angle.

I don't think this can be saved, unless someone gives some idea. This about $12, and it's not easy to take apart (no screw, just punched into the case). I probably just save the gear part.
20220818_124216.jpg20220818_124205.jpg
 
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One winding bad would account for the symptom. Can you inspect the wire-to-commutator
connections? A loose crimp (or bad weld) there can be fluxed and soldered.
Check also to see that the brushes are freely moving; a bit of grit in the works can
spoil electrical contact, but responds well to simple cleaning (pipe cleaners and isopropanol).
 
My guess is that the brushes are not touching the commutator or that the commutator is no longer in contact with 2 windings.
 
Checking the motor resistance as you turn the shaft might tell you something about what's going on. But considering the fact that you have taken it apart, that may not be so easy to do. That type of motor wasn't designed to be repaired.
 
Are you applying the correct voltage? What you describe will happen if you try to run a 24V motor on 12-15V. You have to "jump start" them.
 
I had that happen to a motor out of a circular saw. Wouldn't start from cold, but you could kind of jiggle and pump it and it would start. No fix that I could see so I replaced it with a motor off amazon. Bit gutless, but it works
 
The right most piece in the picture with 3 pieces are the one with the brushes. They're just 2 metal spring piece. I ended up just buy another unit.

This is what I used the motor for. I plan to also make a rotary welding table with these little units.

 
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