Need help with troubleshooting AC ELectric Motor

Jan 31, 2007 3 Replies

Gentlemen (and Ladies) -



Helping out a friend. Craftsman 10" radial arm saw. Was told it worked when put away. Now the motor hums when turned on. Giving it a little push gets it turning slowly.



The 120V motor has a very slim profile. I found a capacitor external to the motor. Replacing it made no difference. I also observe that the wiring from the motor (3 leads, wht, blk, red) as well as the AC from the on/off switch and the capacitor connect to a square gadget with spade lugs. The L1 line apparently goes through a heavy wire coil that bridges two of the terminals, to what I assume is the run winding lead of the motor. (blk)


This gadget has a marking "3CR 118 931". I would like to know what it is and also the likelihood of it being the problem. There isn't much to it, I don't know if it is actually anything more than a terminal block.



If it will help I can scribble up a wiring diagram or even attach a photo of the device.



Regards - Tony


Possibly a PSC motor with one burned out winding.

. . . . . . . .

Have you looked into getting a manual from Craftsman? Most decent power tools have replacement parts available and the manual will show what everything is.

The "gadget" turned out to be a motor start relay. The start winding was not getting switched in. Google up "3cr motor start relay" if you are curious.

Thanks for taking the time to respond.

- Tony

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