Help troubleshooting Unisaw startup issues

[Adam Koren-Roth]

I am looking for some help with diagnosing and fixing a start up issue with a unisaw i purchased over the summer.

the saw:

The saw is a 90s Delta No 83-654 with a 3hp Delta motor (model# 612512B).

the problem:

The saw hums when turned on and the blade tries to turn but doesn't unless i hand start it by turning the fan and then it will start successfully for a few minutes before the problem returns.


https://youtube.com/shorts/Z3uxjSMEzrw?feature=share

where i’m at:

From what ive read it seams like the issue is either the startup capacitor or the centrifugal switch. Using a grizzly maintenance/repair video, i checked the capacitor with a electrical tester and it seemed off but it was hard to tell because it has a bleed-down resistor wired in that i don’t feel confident removing. Next off i tried to get at the centrifugal switch to see if theres sawdust jammed up in it or its otherwise faulty but I’ve been having a heck of a time trying to get the motor cap off. I pulled out the 4 bolts holding the cap on but cant figure out how to get the fan off which seems to be in the way.


https://youtube.com/shorts/48SbC_JeLPc?feature=share

My knowledge of electric motors is pretty weak so I have trying my best to figure it out off of forum post and youtube videos but im not all that confident ive pinpointed the problem so any help would be much appreciated

[Lee Schierer]

The start capacitor is likely bad. Before trying to get to the centrifugal switch, I would replace the capacitor and see if that cures the problem. If it does, you don't have to disassemble the motor.

[Bill Dufour]

Since the problem comes back after it is running it is not the normal start circuit problem. If it is working correctly the start cap is in the circuit after it is up to speed. I would guess the starting switch is bad and not opening or closing completely. The start cap may be bas as well. Possibly the run cap is also bad.
I would first do the easy method and replace the run and start caps with cheap ebay ones. Then, if needed, I would dig into the start switch. If it needs replacing consider a external solid state start switch.
Bill D
Not an endorsement but a good reference of what available.
http://catalog.torq.com/category/sinpac--solid-state-switches

[Holmes Anderson]

Could be start cap, centrifugal switch, aux winding, or start cap and switch because the start cap will fail if the switch doesn't disconnect the start cap.