# Electric Motor Failure



## ED2747 (Apr 7, 2008)

i Have A 1 Hp Capacitor Start Motor That When Energized Will Lock Up And Not Start. The Start Capacitor Has Been Replaced. It Operates A Sears 10" Table Saw And Is 30 Years Old And Has Been Stored, Inactive For Several Years. But Has Been Running Ok For About The Last Month. Rotating After Energizing Results In What I Believe To Be A Magnetic Lock And Hummimg Noise.
I Intend To Disassemble But Don't Know What To Look For. Any Help Or Ideas Will Be Greatly Appreciated Thanks Ed2747


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## cwwozniak (Nov 29, 2005)

Do you know if the motor has an internal centrifugal switch to disconnect the starter winding as it comes up to speed? An open switch would give you the humming and some shaft vibration.


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## JohnWill (Oct 19, 2002)

I suspect there is indeed a centrifugal switch in there, older motors frequently had them.


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## john1 (Nov 25, 2000)

check the windings for continuity.


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## Zeppfan (Apr 20, 2006)

Capacitor start single phase motors have two sets of copper wire windings (Coils). One set is for starting the motor and the other is for running at full potential.

Your motor would have a centrifugal switch in it to remove the start winding from the energy source after it had reached full speed. Then, the run winding keeps it running until the power is shut off.

The bad news is that your start winding has experienced a short. It is probably cheaper to replace than repair.

In order to repair it yourself, you would need a full compliment of electric motor repair items, like coated copper wire of the correct size(Circular mils), conductors, winding forms, varnish, bake ovens, and test equipment.


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