Dead 3/4 hp motor - starter capacitor?

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gangel99
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Dead 3/4 hp motor - starter capacitor?

Post by gangel99 » Tue Oct 08, 2019 6:34 pm

I've had a 13" Jet Horizontal band saw for years - bought second hand from a guy who definitely did stuff to the wiring. However it has worked for me for years until today when it is totally dead. The motor is a 4 pole, 3/4 hp.

There is power to the box that has wires split off to the motor switch, and a separate bunch to the coolant pump. I verified that black to ground (green) and black to white (neutral) are both 120V. However I did see a white and green that go to the starting cap which seems strange.

Next, by dead I mean there is no noise at all, no attempt for the motor to start. Could this be a dead starting cap? The motor goes into a few pulleys so the saw speed can be changed. Can I tell by yanking on a pulley (not risking my hand) and see if it tries to start?

Thanks for your advice.

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rudd
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Re: Dead 3/4 hp motor - starter capacitor?

Post by rudd » Tue Oct 08, 2019 7:41 pm

When I have had a dead start cap, the motor hums but doesn't spin, unless you spin the pulley to start it.

STRR
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Re: Dead 3/4 hp motor - starter capacitor?

Post by STRR » Tue Oct 08, 2019 7:47 pm

It has been my experience when a start cap dies, the motor will not turn but will hum. If you spin the motor, it will run until you shut it off as if nothing was wrong. Being as your motor is dead silent, and the wiring has been reworked, I would not venture any guess as to what the problem is without seeing the machine.

Good Luck,
Terry

gangel99
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Re: Dead 3/4 hp motor - starter capacitor?

Post by gangel99 » Tue Oct 08, 2019 8:35 pm

Thank you both. I found an article on how to test the capacitor so that's my next step. I think after that is checking that one wire to the cap does indeed have power.

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BigDumbDinosaur
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Re: Dead 3/4 hp motor - starter capacitor?

Post by BigDumbDinosaur » Tue Oct 08, 2019 8:42 pm

gangel99 wrote:
Tue Oct 08, 2019 6:34 pm
I've had a 13" Jet Horizontal band saw for years - bought second hand from a guy who definitely did stuff to the wiring. However it has worked for me for years until today when it is totally dead. The motor is a 4 pole, 3/4 hp.

There is power to the box that has wires split off to the motor switch, and a separate bunch to the coolant pump. I verified that black to ground (green) and black to white (neutral) are both 120V. However I did see a white and green that go to the starting cap which seems strange.

Next, by dead I mean there is no noise at all, no attempt for the motor to start. Could this be a dead starting cap? The motor goes into a few pulleys so the saw speed can be changed. Can I tell by yanking on a pulley (not risking my hand) and see if it tries to start?

Thanks for your advice.
The symptoms tell me it's not the starting capacitor.
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warmstrong1955
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Re: Dead 3/4 hp motor - starter capacitor?

Post by warmstrong1955 » Tue Oct 08, 2019 8:54 pm

I've had a lot of caps go bad, but always got a hum or a growl out of the motor when trying to start them. Very often, they turn a bit, but won't gain RPM. And most, can start & run, with a bit of assistance.
My 8" grinder capacitor went bad, and until I got a replacement, I would give it some help starting with a blow gun. Once running, ir was fine.
Today's solutions are tomorrow's problems.

gangel99
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Re: Dead 3/4 hp motor - starter capacitor?

Post by gangel99 » Tue Oct 08, 2019 9:21 pm

The wiring was wonky - fixed it and it started right up so cap is fine as well. Now I've got to work on the coolant pump, sigh ... At least I can cut what I need with a spray bottle of coolant if I get desperate. :D

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warmstrong1955
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Re: Dead 3/4 hp motor - starter capacitor?

Post by warmstrong1955 » Tue Oct 08, 2019 10:15 pm

Good news!
Glad you let us know!
Hope the coolant pump is an easy, dollar free fix too!
Today's solutions are tomorrow's problems.

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BigDumbDinosaur
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Re: Dead 3/4 hp motor - starter capacitor?

Post by BigDumbDinosaur » Wed Oct 09, 2019 8:16 pm

gangel99 wrote:
Tue Oct 08, 2019 9:21 pm
The wiring was wonky - fixed it and it started right up so cap is fine as well. Now I've got to work on the coolant pump, sigh ... At least I can cut what I need with a spray bottle of coolant if I get desperate. :D
Just what it is you plan to cut that requires coolant in a relatively light-weight band saw? I do not use coolant with my horizontal band saw (9 × 13 Wells tool room saw that weights about 800 pounds—it's a substantial machine) and I often cut through heavy steel. If I am cutting certain aluminum alloys, I periodically spray CRC-556® or WD-40® into the kerf to keep chips from packing up.
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whateg0
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Re: Dead 3/4 hp motor - starter capacitor?

Post by whateg0 » Wed Oct 09, 2019 9:41 pm

The only time I really use any kind of coolant, it's WD40 on certain aluminums to keep it from gumming up the blade. Otherwise, I rarely use anything at all. I can see where if you were really aggressive in some steels, it might be beneficial, but for the bulk of what we do, it just makes an unnecessary mess, IMO.

Dave

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BigDumbDinosaur
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Re: Dead 3/4 hp motor - starter capacitor?

Post by BigDumbDinosaur » Thu Oct 10, 2019 10:59 am

whateg0 wrote:
Wed Oct 09, 2019 9:41 pm
I can see where if you were really aggressive in some steels, it might be beneficial, but for the bulk of what we do, it just makes an unnecessary mess, IMO.
I agree, especially if using a good-quality bi-metal blade (my preferred brand is Lenox).
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