(11-16-2024, 05:16 PM)SheriDi Wrote: It has been over a year since I have been able to work in my shop and am now finally able to.  I pushed the ON switch to my Unisaw, it powered up for maybe 1/10 of a second, and stopped.  I then bypassed the switch and connected the motor wires to the power wires, and plugged it in.  As soon as I did that, I got a spark from the plug, a little smoke, and the plug got really hot!  

My neighbor helped me remove the motor and we visually inspected the capacitors, and there was nothing visible that led us to think they were faulty.  

Is there any way to determine if they are faulty, or is there anything else I could/should do to keep from having to drop $1000 on a new motor?


Thanks in advance for any suggestions.


Sheri

(11-16-2024, 07:03 PM)Roly Wrote: Look at the centrifugal switch inside the motor, if this is a 3hp motor they have issues with the switch.  Look for damage to it.   By wiring the motor directly from the plug by passiing the contactor you also bypassed the overload protections. which probably worked the first time. If it did not smoke too bad it may still be ok.  Roly

(11-16-2024, 07:23 PM)SheriDi Wrote: Thanks Roly.  I'm assuming that switch is in the vicinity of where the wires enter the motor?  And yes it is 3hp.

(11-16-2024, 07:36 PM)jteneyck Wrote: Most everything you need to know:  Link


John

[attachment=53042 Wrote:Bob Vaughan pid='8207616' dateline='1731817843']That's a great video for Harbor Freight type Asian-made motors but USA-made motors are significantly different.
The motor's label should disclose who made the motor if it was made in the USA.  There will also be a stock number, but several USA makers can make motors that get the same stock number for Delta.

Any chance you can supply a photo of the motor's label?

(11-17-2024, 11:07 AM)Bob Vaughan Wrote: That motor will have to be taken apart to get to the centrifugal switch disconnect.  It is screwed to the back end bell if it is like the 83-651 I have photos of.  Most Marathon motors of that size and era were quite similar.

Checking the capacitors is easy with an analog meter.  Ground the capacitor connection points.  Set the meter on resistance.  Touch the two leads.  The needle should go to the right, dwell slightly, then slowly return to zero.  That's the method I've been using for decades.  It is sort of a go/no-go test.

The centrifugal switch contacts can be observed for corrosion/wear.  Bad switch contacts will be obvious.

(11-17-2024, 11:07 AM)Bob Vaughan Wrote: That motor will have to be taken apart to get to the centrifugal switch disconnect.  It is screwed to the back end bell if it is like the 83-651 I have photos of.  Most Marathon motors of that size and era were quite similar.

Checking the capacitors is easy with an analog meter.  Ground the capacitor connection points.  Set the meter on resistance.  Touch the two leads.  The needle should go to the right, dwell slightly, then slowly return to zero.  That's the method I've been using for decades.  It is sort of a go/no-go test.

The centrifugal switch contacts can be observed for corrosion/wear.  Bad switch contacts will be obvious.