Single phase motor problem

[Fred]

I have an old single phase 110V 5.6amp 1/3HP 1200rpm induction motor that operates a scroll saw..The motor ran well in the past but now it won't start, it just sits there drawing current. If I spin the motor by quickly moving the belt it will start.

It has capacitor start and the cap measures 84 mfd. Can't read the cap rating printed on the cap clearly but it looks like its a nominal rating of

72 mfd. I'm assuming the cap is OK because I can measure what seems to be a reasonable value.

Any idea what the problem could be?

[Henry Bibb]

Check out the start switch. Blow out any dust accumulated in the motor. I've had dust shut down some of my non TEFC motors in the past, but just blowing them out solved the issue.

Hope it helps, Henry Bibb

[Al Reid]

Assuming that the capacitor is, indeed, good, it is possible that the centrifugal switch is stuck open or has failed in some way.

-- Al Reid

"It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so." --- Mark Twain

[bw]

Unplug the motor. direct some compressed air into the vents. Look inside the vents, while rotating the shaft by hand. You may be able to see the centrifugal switch assembly on the shaft. Carefully use a screwdriver to push on the switch, it should go back and forth on the shaft. Sawdust in the switch can jam it open, defeating the starting coils.

[Wilson Lamb]

A washing machine or dryer motor will work if you can't get the original going. If the air doesn't work, taking off the end bell is not hard, then you can see and clean everything. Take your time and don't bend the little springy contacts.

Put a little roof over the motor to stop some of the dust, if you can.

[George E. Cawthon]

Cleaning it is good, but may not be enough. I had a motor that started doing that and found that the contacts on the start switch were badly burned. Light filing and polishing returned it to operation, but burning and pitting are likely after a period as much of the hard surface of one contact is gone.

[J. G. Gregory]

I have a VERY lightly used Delta 8 inch band saw that suddenly stopped working yesterday. Flip the power switch nothing happens. I have a pipper, and I can detect ac getting to the motor, but no action at all. Is this a common thing? This thing really hasn't been used much, but did spend some time in a damp basement.

It is a single phase 1/5 hp motor.

I really like this saw, but have only used it about 12 times in several years (while my shop was being rebuilt). Now I really want to use it, and it is dead. I don't dare try to start it by moving the blade. The capacitor (I don't have a way to measure it) looks brand new. The whole thing is practically brand-new.

--Jack Gregory

[Micro*]

(snip)

How did you measure the cap.???

-- "Shut up and keep diggen" Jerry