Hi, newbie here, electric motor problem,

[philip sadlerParticipant @philipsadler66781]

I have a 250v 370w (sing/phase) motor with start problem, it has separate start cap, switched it on & sparks out of the back & it just hums trying to start, spin it by hand & it runs fine, I've replaced the start cap but still just hums, centrifuge engages/disengages on spin up & stop, just won't start with start cap, does anyone know what the problem might be, any help would be greatly appreciated, thanks

[philip sadlerParticipant @philipsadler66781]

[Neil WyattModerator @neilwyatt]

Hello Philip,

Welcome to the forum.

Assuming it has both a start and run capacitor, it sounds like the centrifugal switch is stuck open. When you switch off you should hear the switch click shut as it slows down.

Neil

[EmgeeParticipant @emgee]

Hi Philip

Did you replace the capacitor with a motor start capacitor with the same value and operating voltage as the origiinal ?

Also as Neil says double check the centrifugal switch closes completely with a very distinct click.

Emgee

[john fletcher 1Participant @johnfletcher1]

If you have a multi meter then you can test the start circuit. Set the meter on the low ohm range. Disconnect the capacitor altogether and connect the meter across the wires to which the capacitor was connected, you should have a complete circuit. The value in ohms will depend on the manufacturer, but around 10/20 ohms. If you don't have a complete circuit then it must be open circuit in the start winding. Has the motor that burnt varnish odour ? As some one else has already said was the replacement capacitor of the same value as the original that is important, exact value is not important as they are +/ – 20%. Be careful if and when you dismantle the motor the start winding wire is very thin and is easily broken. Oh, and before you do dismantle the motor put scratch marks across the end shields to the stator, two scratches one end and one the other. These marks will enable you to re assemble the motor and will ensure the rotor rotates freely. John

[colin hawesParticipant @colinhawes85982]

sounds to me that a wire is adrift or the insulation is faulty on the start circuit. Colin

[larry PhelanParticipant @larryphelan54019]

Check if the switch is stuck with muck. I have had a single ph motor on my saw bench for 20 years or more and from time to time,the switch gets clogged with junk,no problem ! just clean it out and away you go.If you dont hear the click,she is stuck.

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