Table Saw won’t start

[Andrew Nemeth]

I just tried turning on my table saw, and it won’t start. When I push the start button... nothing, nada, nope. I don’t hear and click like I think I normally hear when I push it. I assume this click is the magnetic switch closing the circuit but I could be wrong. To be honest, I can’t say definitely that it does click when it’s working. Never really thought about it until it stopped working.

I have opened up the switch and made sure all the contacts were unobstructed by dust, but I have not tried actually cleaning the contact points.

Additionally, on my saw there is an additional junction box which holds what I believe is the switch relay . When I open that box up and press the central button (annotated with a red arrow in the photos) the saw will start and stay running as long as I hold the button in. When I release the button, the motor stops. The additional red button in the same photo does not appear to do anything when it is depressed or released.

I have also included the wiring diagram from inside the relay box, although, it is quite faded and of poor quality.

Any ideas on what may be the problem and/or the next steps to trouble shoot the problem?

Any help would be appreciated. Thanks!

[Leo Graywacz]

The stop button is bad likely. If the stop button is open the circuit won't engage. It stops the motor by breaking the connection to the coil momentarily. If the stop button is in the continuously open (off) situation then the coil can't be energized by the on button being pressed.

So clean out the off button, check to see that the wires are still connected to the button and the starter. You could take a set of alligator wire clips and short out the off switch (power disconnected of course) and then reconnect the power and see if the motor will start. At this point if it does the off button won't turn it off so disconnect the power to turn the saw off.

If this works it proves the off switch is faulty or dirty.

[Frank Pratt]

The problem is in the magnetic starter control circuit and could be any of the following:
- open coil - check with an ohm meter
- open control transformer - check voltage on the output
- open or defective overload relay contacts - try resetting, check with ohm meter
- open STOP button - check with ohm meter, should be short circuit when not pressed
- START button contacts don't close - check with an ohm meter, should short circuit when button is pressed
- loose wire

[Andrew Nemeth]

Thank you for the reply Leo! After taking the low voltage switch apart the first time, I was 90% sure it wasn’t the switch. All the contact points looked relatively clean and there was very little dust accumulation. I then disassembled the magnetic relay and cleaned all the contact points in there. All the terminals were tight but the 240v contacts were quite corroded. Put it all back together and still nothing. I was taking a second look at the low voltage switch when I read your post. I figured out how to jump the switch, which was not as intuitive as a single pole switch. I had to jump two of the three wires together, then touch the third wire to jumped pair. That started the motor and it continued to run as I removed the third wire. To turn off, all I had to do was disconnect the original pair that were connected.

So, it was the low voltage switch after all. I disassemble as much as I could and cleaned the contacts with a very small file. After reassembling, everything works like it should. Thank you for responding as I could have easily gone further down the rabbit hole. The lesson I learned is not to trust your eyes when dealing with electricity. I would have been back to work much quicker if I just started working my way down the system verifying the integrity of each component one at a time.

I have one more question to ask, what is the proper name for the low voltage switch should I want to buy a replacement? When I look up magnetic switches, they almost all include the relay and transformer and are quite expensive. I’d like to have a back up on hand, if one can be purchased at a reasonable price. The plastic in my switch is close to 40 years old and was/is quite brittle. Considering I just tightened everything back up, it wouldn’t surprise me if some portion of the plastic structure fails causing a loose connection.

Thanks again!

[Andrew Nemeth]

Thank you for your reply Frank. I did manage to get things up and running again based on Leo’s advice. However, I’m glad you posted this as it may be helpful to someone else in the future.

Cheers!

[Leo Graywacz]

Thank you for the reply Leo! After taking the low voltage switch apart the first time, I was 90% sure it wasn’t the switch. All the contact points looked relatively clean and there was very little dust accumulation. I then disassembled the magnetic relay and cleaned all the contact points in there. All the terminals were tight but the 240v contacts were quite corroded. Put it all back together and still nothing. I was taking a second look at the low voltage switch when I read your post. I figured out how to jump the switch, which was not as intuitive as a single pole switch. I had to jump two of the three wires together, then touch the third wire to jumped pair. That started the motor and it continued to run as I removed the third wire. To turn off, all I had to do was disconnect the original pair that were connected.

So, it was the low voltage switch after all. I disassemble as much as I could and cleaned the contacts with a very small file. After reassembling, everything works like it should. Thank you for responding as I could have easily gone further down the rabbit hole. The lesson I learned is not to trust your eyes when dealing with electricity. I would have been back to work much quicker if I just started working my way down the system verifying the integrity of each component one at a time.

I have one more question to ask, what is the proper name for the low voltage switch should I want to buy a replacement? When I look up magnetic switches, they almost all include the relay and transformer and are quite expensive. I’d like to have a back up on hand, if one can be purchased at a reasonable price. The plastic in my switch is close to 40 years old and was/is quite brittle. Considering I just tightened everything back up, it wouldn’t surprise me if some portion of the plastic structure fails causing a loose connection.

Thanks again!

The on switch is a Normally Open momentary contact. The off switch is a Normally Closed momentary contact switch.