Magnetic Starter: In Search Of The Elusive Ohm

This past summer I picked up a 16inch DoAll bandfiler that had been converted to bandsaw ($500). I believed she was (mostly) mechanically in excellent shape. I've since rebuilt the band tensioner using the vintage handle I found tucked inside the base.
I knew she was an electrical Gordian knot when I opened her up and saw a new 1hp 1ph Dayton motor wired up with a tangle of wires and wire nuts suspended near the V belt.

The original on/off switch is used and the 11ov light was wired with the neutral tied into the ground.

This weekend I added a junction box, a transformer, and a magnetic starter. All these parts came out of my pile of misc parts that my wife keeps telling me to take to the curb on Tuesday mornings.

All is well, except I can't get the starter to "click". This starter is a new in box stamped 1963. She has some corrosion on the cover and on many of the screws. I'm guessing this is a contact issue, but am having difficulty learning where the problem is. Thanks to the many threads here and a friend of the family (Don) I've learned enough to use my Ohm Meter to check continuity. The switch is closing the circuit to the starter and I've checked the contacts and wires. I believe the problem might be the starter itself. Don is coaching me to use the Ohm meter to check the starter. Hmmm. #1 What's an Ohm? #2 How do I use the meter to find one?

I found this document. It explains things in a way that I can better understand question #1.
I'll keep digging and divine the Ohm Meter settings for question #2. However, I'm concerned that I may not find a clear explanation of probe placement on the starter. Or how to interpret the results/readings.

Any insight or suggestions. The upside is that all the skills I'm learning now will be used and reinforced soon as I dig into the new/used panel I hope to mount on my VN22LU!!

Any suggestions on how to use an Ohm Meter to check a starter are appreciated.

Thank you,
Daryl
MN

Looks like you don't have 240 going to the coil circuit. From what I can see I think you need to move the red wire on terminal 1 to the line side of terminal 2, same connection as on terminal 4.

I guess I should have asked how you want to turn it on. The connection I told you to make will start the motor as soon as you throw the switch on. You can connect a 3 wire start/stop if you want. I can help you if you need a diagram.

That was my plan. The existing on/off would engage the starter and the motor.
I'll check out your suggestion!! However, I'm not following your mentoring as I'm unclear about the terminology.

I was following the schematic on the cover.
It'd be helpful if I understood how starters actually worked.
Guess that's next months project!

Daryl
MN

The terminology can be as simple or complex as you would like. A 3 wire control has three wires to the start/stop buttons. One wire carries power from a line terminal to the stop button (normally closed, NC) and the start button (normally open, NO) the other side of the stop goes back to the starter and connects to the front side of terminal 1 on your starter which is a NO contact. The wire from the other side of the start button connects to the red wire on top of terminal 1. When you push "start" you send power to the wire that connects to the magnetic coil and it moves the starter to the closed position. This sends power to the motor and also closes the contacts on terminal 1. This closure sends the power from the stop button through the contact and "latches" the coil on. The coil will stay on until you press the stop button and interrupt the holding circuit power to the coil or the over load opens and breaks the connection to line 2 on terminal 4.
The heater assembly on the lower left has a low temperature melting alloy that gets heated by the motor current flowing through the silver wire wrapped around the post. High current flowing too long will melt the alloy and cause a spring loaded contact to open shutting down the the line 2 power to the coil, opening the contacts and stopping the motor. The higher the current the faster it heats and melts, normal starting current won't last long enough to open the circuit but a stalled motor will melt it fairly fast. You reset it with the white button but only after it cools and the alloy hardens.
Hope this helps you understand how starters work.

The contactor coil is most likely 240 and you are feeding it 110.

David VanNorman said:

The contactor coil is most likely 240 and you are feeding it 110.

Click to expand...

Looks like the link at the bottom changes the coil voltage, i think thats what the diagrams on the contactor shows.

Stuart

The description of the how a starter works is helpful!! Thank you.

"move the red wire on terminal 1 to the line side of terminal 2, same connection as on terminal 4"
Please note the picture. Does the black arrow with brown border reflect the wire move you are suggesting?

Daryl
MN

That's it Daryl. Right now you don't have a complete circuit. Move the red wire on the left to where your arrow points.


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If the red wire isn't long enough you could run a jumper from the line terminal to the red wire terminal.