Dust Collector Motor Won't Start

Hums but doesn't move? Probably a blown starter capacitor. August 21, 2012

I have a Delta AP400 dust collector; itís fairly new with low hours on it. I had it hooked up to my planer this weekend and it died. You can hear the motor humming but it wonít spin.

I took it out of the collector housing. Nothing caught up in the impeller - if you give the impeller a slight push, it spins right up. I took the motor apart, cleaned the armature, blew out the little bit of dust inside, reassembled, no change.

Can I buy a new motor? Is it worth it? Or should I take it to a small electric motor shop for repair? I couldnít find brushes on this motor?

Forum Responses
(Dust Collection and Safety Forum)
From contributor S:
It sounds as though the start capacitor is defective. The start capacitor tells the motor which direction it's supposed to run, and provides a little extra current to get it started. The capacitor is normally enclosed under a sheet metal cover and attached to the side of the motor.

Since you were able to start the motor by giving it a little help, I'm betting the capacitor is bad. Most capacitors spit some nasty stuff out of the end where the wires connect when they blow, but not always.

A motor shop can test it and fix you up with a new capacitor. There are two ratings printed on the old capacitor, one stated in "mfd" (microfarad), and the other in volts. You can exceed the capacitor ratings some, but never go less than the ratings.

If this is a three phase motor, there will not be a start capacitor, in which case you have other issues.

From contributor L:

The DC has a 1HP 1PH motor. It should have a starter capacitor. Probably bad. So I agree with the above assessment. Should be a simple fix if you can find the correct capacitor.

From contributor D:
Yes, a bad capacitor is #1, but other things can also cause the problem. The motor has some sort of a starting switch, either mechanical or electronic. If it is mechanical, make sure it is making contact when the motor is stopped. If it is not making contact, the start winding will not be active and the motor will not start. If you are able to make an adjustment, also make sure the switch is open when the motor is up to speed.