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goldhiller
Re: Reset button

Impossible to say from here exactly what the problem is......but it could be one several different potential problems.

If you haven't already, check first to see that you have current to the saw motor as per the normal wiring it runs on; breaker hasn't tripped, wiring hasn't been compromised, any/all switches are working properly, etc. Heavy loads can easily take out/melt switches that aren't up to it because they were of marginal ability in the first place or aren't up to it anymore. Stuff wears out.

If you find no fault there, I'd suggest you take the motor to a local electric motor repair biz. Hopefully you have one there and will find it in the yellow pages. Saves you all the shipping costs associated with a return to Sears. Warranty is up anyway, not? They can run a few quick tests with a meter on the motor wiring, windings and misc parts to ascertain exactly what is at fault.

nalamahgni
Re: Reset button

Thanks for your response.

The wiring is okay. In looking at the reset button I found an adjustment on the back side which got it "clicking" again. I reinstalled the button and the motor is now getting power.

Unfortunately, the motor isn't turning. It sits and vibrates rapidly back and forth as though it can't make up its mind which direction to turn and changes its mind with each pulse of alternating current.

I triple-checked all of the connections to the button, starter ballast, overload relay and motor, and all appears correct unless my pencil diagram was wrong.

Any last thoughts before it goes to a shop?

canuk
Re: Reset button

If you are 100% sure the wiring is correct especially for the capacitor , then I suspect all the problems seem likely to be a faulty capacitor.

Here is a procedure for testing it :

1- take a screw driver and bridge the two terminals of the capacitor ... this will discharge the cap. Start capacitors store electricity, that is why you need to discharge them .:eek:

2-With an ohm meter set at the 1000 ohm ( 1k ohm ) if it's a selectable type ... auto ranging types won't matter.

Touch the two terminals of the capacitor with your ohms meter test leads. The meter will display some numbers for a second then it will return to OL ( open line or infinity ).

3- Reverse your ohms meter test leads on the two terminals and the same condition should happen.

It should do this every time that you switch the ohms meter test leads position. If it does this the start capacitor is good.

If the readings stay at a numerical value and doesn't go to OL or infinity , then the capacitor is faulty ... known as leaky.
If it stays at 0 (zero) then the cap. is shorted. Either case the capacitor would need to be replaced with the exact same value.

The reset switch is likely the thermally controlled type. In that when over heating occurs inside the motor it trips to open the circuit for the motor. A faulty capacitor will over heat the start windings and the life of the motor will be shortened due to overheated motor windings.

Another possibility is there is shorted windings then the motor will have to be repaired or replaced. At least the above procedure is a cheaper and faster method of finding out.

Hopefully this helps out :)

nalamahgni
Re: Reset button

Thanks Canuk for the advice. I should be able to check the capacitor myself following your instructions.

I will mention two things:

1) There's a remote possibility that I switched two wires when reassembling the relay bus. For anyone with intimate knowledge of this motor the two wires are the black and yellow on the underside of the bus. I could describe the connections in much greater detail but probably no one out there has a wiring diagram for this motor anyway, so there's little point.

2) The reset button appears to operate on centrifugal force. It looks as though a spring/counterweight system keeps a switch in the open position while the motor spins, and if the rpm drops below a certain point under load, the springs pull the counter balances away from the switch allowing it to close, thus tripping the reset button.

goldhiller
Re: Reset button

The centrifugal switch you refer does not likely have anything to do with thermal protection. Rather that switch is responsible for engaging and disengaging the start windings and/or capacitor.

If the motor seems to attempt starting when you turn it on, but doesn't..... then most likely either.....1- the contacts on the centrifugal switch you refer to are either burned/carbonized/missing, 2- the start capacitor is kaputt, 3- the start windings are burned/fused together rendering them worthless, 4- the springs of the centrifugal switch are broken, weak or missing...or 5- the motor is incorrectly wired.

(If you need one.......a new CS should be readily available at any motor repair facility)

If the motor got too hot (thermal protection failed to trip in time) while doing heavy duty work, then the insulative coating that separates one wire of the windings from it's neighbors may have been melted/damaged. This would render the start windings inoperative. Park your nose close to the motor and see if it has even a slight burnt odor. This would not be a good sign, but you *might* be able to effect a repair. You'd have to disassemble the motor to some degree in order to attempt/perform a repair. Check the windings over closely for any signs of burns/melts. Sometimes these can be simply repaired, sometimes not. To attempt a repair you would very carefully separate the involved copper winding wires in the immediate area of damage from one another just a tad...... and then spray them with a can of aerosol varnish or lacquer....from all available angles of attack. Allow to dry overnight and push the wires back down tight to the rest of the windings. (This is the procedure I learned many years back when I worked at a GE motor factory here in Illinois and it has saved numerous motors from the junk pile. )

If such damage is extensive, the above may be futile.

See these links and note that .............."Other split-phase motor characteristics: Maximum running torques range from 250 to 350% of normal. Plus, thermal protection is difficult because the high locked-rotor current relative to running current makes it tricky to find a protector with trip time fast enough to prevent start-winding burnout. And, these motors usually are designed for single voltage, limiting application flexibility."

Also see the troubleshooting section near the bottom of the second link.

http://www.iprocessmart.com/leeson/leeson_singlephase_article.htm

http://www.metalwebnews.com/howto/elec-mtr/elec-mtr.html

canuk
Re: Reset button
Quote:

The centrifugal switch you refer does not likely have anything to do with thermal protection. Rather that switch is responsible for engaging and disengaging the start windings and/or capacitor.

nalamahgni ... this centrifugal switch is usually located on the turning shaft and works as goldhiller mentions. I'm not familiar with these centrifugal switches being associated with a "reset" button. Usually a capacitor start/induction run motor similar to yours may have thermo protection and usually that's what a "reset" button would be for.

Quote:

Unfortunately, the motor isn't turning. It sits and vibrates rapidly back and forth as though it can't make up its mind which direction to turn and changes its mind with each pulse of alternating current.

If we take a stator with a single winding, and apply a single phase voltage to it, we will have an alternating current flowing and thereby an alternating magnetic field at each pole.
Unfortunately, this does not result in a rotating magnetic field, rather it results in two equal rotating fields, one in the forward direction and one in the reverse direction. If we have a short circuited rotor within the stator, it will carry rotor current induced by the stator field, but there will be two equal and counter rotating torque fields. This will cause the rotor to vibrate but not to rotate. In order to rotate, there must be a resultant torque field rotating in one direction only. In the case of the single winding and a stationary rotor, the resultant torque field is stationary.

If we now add a second stator winding, physically displaced from the first winding, and apply a voltage equally displaced in phase, we will provide a second set of counter rotating magnetic fields and the net result is a single rotating field in one direction. If we reverse the phase shift of the voltage applied to the second winding, the resultant magnetic field will rotate in the reverse direction. This would be the start windings.

Since it's impractical for relying on the two start windings for predominately resistance on one winding and predominately inductive winding in the other , a capacitor is included with the run windings. So the resistance of the start windings combined with the capacitance circuit will more readily approach a 90 degree phase shift and allow the rotor to move in one direction.

So if the motor is not rotating then there is a fault with either the capacitor circuit or the start windings circuit... would be my guess.:)

nalamahgni
Re: Reset button

I checked the capacitor with an older analog meter. After discharging the capacitor I set the meter as suggested and touched the terminals with the test leads. The reading jumped from infinity to about 2 on the scale and then quickly dropped back. After allowing the reading to settle back to infinity, I switched the leads and once again got a jump to about 2 and a quick drop back to infinity. Capacitor good?

Just in case someone has some knowledge of the wiring here is a description of how it's hooked up now:

Upper side of connector bus has leads 1 - 8; underside of bus has leads A - E.

1. Blue to motor
2. Open
3. White from wall outlet
4. Black from wall outlet
5. Brown to motor
6. Orange to motor
7. Open
8. Open

A. Blue to reset button. Also connected to leads 1 & 2.
B. Yellow to motor. Also connected to lead 3.
C. Black to reset button. Also connected to leads 4 & 5.
D. Brown to reset button. Also connected to lead 6.
E. Open. Also connected to leads 7 & 8.

Capacitor has a black wire to motor and a red from the centrifugal switch.

Centrifugal switch has a red wire to the capacitor and a second red wire connected to the same lead on the reset button as the blue wire from lead A.

Sorry I can't draw a diagram. Is this of any use in determining if a wire is switched? There was a remote possibility I switched the black and brown wires on leads C and D.

Are we already convinced the problem is the start windings circuit?

wegtbg
Re: Reset button

Were you ever able to solve the motor wiring questions? I too aquired the same saw but the motor has been disconnected and I need the wiring color code. Emerson nor Sears have been any help.

artrose59
Re: Reset button
nalamahgni wrote:

I checked the capacitor with an older analog meter. After discharging the capacitor I set the meter as suggested and touched the terminals with the test leads. The reading jumped from infinity to about 2 on the scale and then quickly dropped back. After allowing the reading to settle back to infinity, I switched the leads and once again got a jump to about 2 and a quick drop back to infinity. Capacitor good?

Just in case someone has some knowledge of the wiring here is a description of how it's hooked up now:

Upper side of connector bus has leads 1 - 8; underside of bus has leads A - E.

1. Blue to motor
2. Open
3. White from wall outlet
4. Black from wall outlet
5. Brown to motor
6. Orange to motor
7. Open
8. Open

A. Blue to reset button. Also connected to leads 1 & 2.
B. Yellow to motor. Also connected to lead 3.
C. Black to reset button. Also connected to leads 4 & 5.
D. Brown to reset button. Also connected to lead 6.
E. Open. Also connected to leads 7 & 8.

Capacitor has a black wire to motor and a red from the centrifugal switch.

Centrifugal switch has a red wire to the capacitor and a second red wire connected to the same lead on the reset button as the blue wire from lead A.

Sorry I can't draw a diagram. Is this of any use in determining if a wire is switched? There was a remote possibility I switched the black and brown wires on leads C and D.

Are we already convinced the problem is the start windings circuit?

Here are the wiring inside the motor hope this helps?

Leads Top
1 – Blue from motor
2 – N/C
3 – Power
4 – Power
5 – Brown from motor
6 – Green from motor
7 & 8 – N/C

Leads Bottom
A – Blue from reset #3
B – Black from reset #1
C – Yellow to motor
D – Brown to reset #2
E – N/C

Reset Button
1 – Black to term B
2 – Brown to term D
3 – Red & Blue (Red to front term block) Blue to term A

You have 2 wires that are on wrong terminals, you need to change the black and yellow wires around and that should fix your problem.

jkirk
Re: Reset button

this is a 6 year old thread. its been dealt with by now

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