ARGH! My DC Motor Died! HELP!

[Tom LaRussa]

The motor on my Delta 1 1/2 HP DC has decided not to start.

When I press the green button it begins to start up, and I hear that typical "woo-woo-woo" sound it always makes, but when it gets to what I'd estimate as 20% - 25% of full speed the built-in circuit breaker trips and it dies. I press the reset button and it resets the breaker okay, but the same thing happens as soon as I try to start it again.

Any ideas?

What should I check?

TIA

[Michael Gabbay]

Tom - did you take the impeller cover off and check for a clog? Sometimes when I clean up after planing I get a huge clog of shavings at the impeller. It causes my Jet 1.5hp to strain. You might also want to see if there is a lot of dust in the motor (a little ironic for the DC ).


Mike

[Scott Banbury]

It sounds like a dead capacitor (under the little humpback covers on the side of the motor)--take 'em out and take them to a motor shop or a aircompressor service shop and they will test them on a piece of special equipment and sell you appropriate replacements if you need them.

[Tom LaRussa]

Tom - did you take the impeller cover off and check for a clog? Sometimes when I clean up after planing I get a huge clog of shavings at the impeller. It causes my Jet 1.5hp to strain. You might also want to see if there is a lot of dust in the motor (a little ironic for the DC ).
Mike

Mike,

I forgot to metion, but yes, I took the cover off and the impeller spins easily.

What would a lot of dust in the motor tell me?

[Tom LaRussa]

It sounds like a dead capacitor (under the little humpback covers on the side of the motor)--take 'em out and take them to a motor shop or a aircompressor service shop and they will test them on a piece of special equipment and sell you appropriate replacements if you need them.

Scott,

Thanks, I was hoping it would be something relatively simple like that.

[Scott Banbury]

If it's not that, then it could be that the little spring/magnet switch that shuts off the start winding has gone bad (this is just behind the impeller). This would cause the the symptoms you describe.

When I have the problem you're having, the first thing I do is spiff up the contacts on that little spring/magnet switch and then check the capacitors.

Both are inexpensive to replace if need be.

[Jeremy Bracey]

I vote capacitor. Ive been through two of them on mine. It sounded exactly as you describe. The capacitor stores power to help it get started.

[Chris Padilla]

Well, the capacitor stores charge...not power...but your point is made.

If you have a voltmeter or digital voltmeter, it might have a capacitor checker on it. With a digital voltmeter, you could also use the continuity checker to get a "first order" check on the cap. Put it across the cap...it should beep or indicate a short-circuit for a very small amount of time before it open-circuits. What is happening is that the voltmeter is charging up the cap and while it is charging up, it'll look like a short. Once it is charged, it'll look like an open. However, I don't know the typical sizes of caps on these motors so while my idea works on circuit board caps (microfarad range), it may not work on larger caps for motors.