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I have a 1/2 hp. 110/230 A.O. Jones motor for a hoist that did not run because of mud dobbers caked inside.  After taking the end bell off and vacuuming out all the dirt and reassembling it I can not get it to work normal.  If I connect the red and black leads to 110v and then spin the shaft, it starts to run until it gets to full speed then the centrifugal switch kicks out and it slows down then starts again when the switch kicks in again.  The starting cap is good. Any ideas?

That is a indication of a open circuit in the run winding. This could be in the winding itself, loose wire, or contactor not making up. There is suppose to be a schematic drawing inside the cover, so you can check the correct wiring. Trouble shooting these things can be a pain in the a$$. I recommend you have a service center have a look at it.

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Charles C. Jones


Let Me help you with your problems with single phase and three phase electric motors. I can tell you how to troubleshoot your motor problems. From simple testing of capacitors, how to test your windings, replacing bearings, and general maintenance. Before we go any further, remember these words of advice: Disconnect the power before you do anything! Please limit your questions to electric motors and there immediate components. I review each question, and if I can answer or help, then I will. If you receive a rejection, it means it is out of my expertise, and just do not have the answer. I'll be waiting for your question.


I have 40 years experience in the repair of electric motors and related equipment. I am a master machinist in the field of motor repair. I was employed with my company for 35 years, but retired in May of 2013. The downside to that is I lost access to a lot of technical data. I will still try to give you the most accurate advice that I can.

Former member EASA

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