# Magnetic Starter: In Search Of The Elusive Ohm



## Uglydog (Nov 30, 2015)

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


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## jim18655 (Nov 30, 2015)

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.


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## jim18655 (Nov 30, 2015)

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.


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## Uglydog (Nov 30, 2015)

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


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## jim18655 (Nov 30, 2015)

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.


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## David VanNorman (Dec 1, 2015)

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


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## stupoty (Dec 1, 2015)

David VanNorman said:


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



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

Stuart


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## Uglydog (Dec 1, 2015)

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


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## mzayd3 (Dec 1, 2015)

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.


Sent from my iPhone using Tapatalk


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## jim18655 (Dec 1, 2015)

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


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## AnthonyTVA (Dec 5, 2015)

You have your voltage coil wired for 240.  You need another jumper and you need to move the one that is on there now to the left or right.  Look at the wiring diagram on the dual voltage coil.


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## Uglydog (Dec 5, 2015)

Added the jumper last night~
She works!
So simple a fix....
Thanks all.


Daryl
MN


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## Wobbles (Dec 8, 2015)

Uglydog said:


> 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.



I have yet to find a internet user group forum for wives of handy husbands. Therefore, based on your statement, I must conclude that your wife and my wife are somehow related and/or in contact with each other.


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## Wreck™Wreck (Dec 11, 2015)

In simple terms, the ohm is a measure of electrical resistance, Ohm's law states the the current that will pass through a resistor is limited by the voltage and resistance.

A resistor is a current limiting device, an excellent example of this is the incandescent light bulb which contains a conductor connected across a power circuit, why does this this not cause an over current condition? (a short)

The simple answer is that the light filament is a resistor which limits the current, at higher voltages the current increases which will cause the resistor to fail, at lower voltages it will cause the bulb to be dim due to the lower current.

In your case of trying to determine the problem with a magnetic starter coil, a measurement of  infinite ohms across the inputs, which often looks like this "OL",  is an open circuit as the coil is no longer making a circuit itself at all therefore infinite resistance therefore it is finished.

A magnetic coil is also a resistor, due to this a 220 volt magnetic coil may not allow enough current to pass to work at say 110 volts, in my experience all magnetic starters have a coil voltage printed on them, this is often on the coil and not the contactor part itself, look for the coil voltage on the coil which may be well hidden or unreadable due to age.


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## Uglydog (Dec 11, 2015)

Wreck Wreck,
Huge heaps of thanks.
This is helpful. Understand that I will have multiple questions as I move forward with your words.

Daryl
MN


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## Wreck™Wreck (Dec 11, 2015)

Uglydog said:


> Wreck Wreck,
> Huge heaps of thanks.
> This is helpful. Understand that I will have multiple questions as I move forward with your words.
> 
> ...


You are welcome, this is only a general explanation however, be aware that electricity can be very dangerous at high voltages.

Have you ever thought about why installing a new battery in your car (300 or more Amperes)  does not kill you if you make a closed circuit, which is easily done?


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## coolidge (Dec 11, 2015)

Wreck™Wreck said:


> You are welcome, this is only a general explanation however, be aware that electricity can be very dangerous at high voltages.
> 
> Have you ever thought about why installing a new battery in your car (300 or more Amperes)  does not kill you if you make a closed circuit, which is easily done?



My brothers high school auto shop teacher giving a safety briefing to the freshman class grabbed both lugs on a car battery and shook and grimaced then challenged the class to man up and give it a try, no takers. lol


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## middle.road (Dec 12, 2015)

Wobbles said:


> I have yet to find a internet user group forum for wives of handy husbands. Therefore, based on your statement, I must conclude that your wife and my wife are somehow related and/or in contact with each other.


Simply demonstrate. Next time you affect a repair using pieces & parts from your stash,
do a cost analysis and show it to the Better Half with a web search of retail price to back up the data.
My Honey was always wondering why I just didn't haul 'those' boxes to the curb.
Then we got this house. It always nice to repair something with a part you picked up on the cheap than 
having to run out and pay retail.


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## Wreck™Wreck (Dec 12, 2015)

coolidge said:


> My brothers high school auto shop teacher giving a safety briefing to the freshman class grabbed both lugs on a car battery and shook and grimaced then challenged the class to man up and give it a try, no takers. lol


Human skin can have a resistance of many  thousands or as little as 1000 Ohm's depending  on environmental conditions, sweaty skin has less resistance then dry skin Etc. This is one of the reasons that one may touch an automotive starting battery with your hands and feel nothing. Someone with soft skin devoid of callus and plain worn out skin(my hands are in such bad shape that I am at the high end) may feel a shock when you would not. If the Wife/Girlfriend/ Significant Other complains about being lightly shocked by an appliance yet it never happens to you there is no reason to think that such a thing is not actually occurring, they can feel it and you can not, thanks Mr Ohm.


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## Uglydog (Dec 12, 2015)

Wreck™Wreck said:


> Human skin can have a resistance of many  thousands or as little as 1000 Ohm's depending  on environmental conditions, sweaty skin has less resistance then dry skin Etc.



This likely explains why touching a 9volt battery to your finger provides a different experience than touching the same battery to your tongue.

Daryl
MN


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## Wreck™Wreck (Dec 12, 2015)

Stop eating the batteries Daryl (-:


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## kingmt01 (Dec 16, 2015)

Also when using Ohms to track down problems like contacts & conections. The closer to 0 the beter but as you can watch your meter the harder you push the probes into the conductor the farther the number will go down.

One more thing & this isn't to be mean but those crimps look really bad & with that kind of current flowing through them they will likely cause you problems down the road. I quit crimping those type of connectors years ago. Some may call it over kill but I slide the strain relife(the plastic on the end) down off from them, solder the connection, then slide the strain relife back up on it. I noticed one of the strain releifs was smashed out by the wire which stops it from doing its job.

I solder almost every conection I want to last more then a month anymore. If it is a solid strain being held under a lug or has a wire nut then that is an exception. If your using wire nuts some grease in it will help ensure it from failing as fast along with sealing the back with some tape. Just FYI in your feture indevers.


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## brino (Dec 16, 2015)

I also do prefer soldered connections, however, crimped ones can be done right.......it just takes a special crimping tool rather than the first set of vice-grips you find......
-brino

EDIT: I have no intent to disrespect the OP's methods. I was just trying to say that soldering is NOT the only reliable method. A good crimp is one that has the proper physical area of contact for the current required and one that makes a good air-tight seal to keep the contact area from oxidizing too quickly.


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## kingmt01 (Dec 16, 2015)

Yelp. I always prefered the ones that put the small dimple in one side. I've never found a good set at a automotive store. HF used to sell a really good set for $3 but that was 20 years ago so I don't know if they still do or not. Those automotive ones will lose their grip & start arcing with that much amprage tho. Well probably start a small arc you can't see then lose their grip.


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## Keith Foor (Dec 19, 2015)

Wreck™Wreck said:


> Human skin can have a resistance of many  thousands or as little as 1000 Ohm's depending  on environmental conditions, sweaty skin has less resistance then dry skin Etc. This is one of the reasons that one may touch an automotive starting battery with your hands and feel nothing. Someone with soft skin devoid of callus and plain worn out skin(my hands are in such bad shape that I am at the high end) may feel a shock when you would not. If the Wife/Girlfriend/ Significant Other complains about being lightly shocked by an appliance yet it never happens to you there is no reason to think that such a thing is not actually occurring, they can feel it and you can not, thanks Mr Ohm.



I do electrical work for friends from time to time.  One that sticks in my mind was a drier that would take forever to dry clothes and the guys wife claimed it would shock her occasionally.  I went over to take a look and found the outlet was wired with one of the 110 legs connected to the outlet ground.  This of course made the whole cabinet charged 110 hot as soon as it was plugged in.  I got a tingle off it but nothing serious obviously.  Point is that a wet hand touching the cabinet of the washer next to it that was grounded and the cabinet of the dryer would have been fatal.  Yet it had not happened up to that point.  Once the wiring was corrected the dryer operated correctly and of course was much safer.  Point is that if you are not sure about doing wiring, don't do wiring.  Those of us that know it, don't believe it to be some black art.  We understand what it takes and how it's done, and it seems simple.  Problem is that doing it wrong, can prove deadly.  This was one of those situations that all the things needed to cause a fatal shock never got in the room together.  Simple things like being dry and enamel paint on the cabinet kept a very dangerous situation in check.  But grabbing a ground or neutral and a 110 leg feed is not typically something you walk away from.


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## rdhem2 (Dec 20, 2015)

Do not really know why but the Code frowns on soldered connections anymore preferring the indented pressure type of connector or mechanical pressure (screw) type.  Just the opposite of some folks experience, I have had more trouble with low voltage crimped connection.  Typically of the automotive sort.  My thoughts being that the low voltage has less ability to force its way through a corroded connection.  Hence the reason why wiggling the wires makes the light bulb blink.  In that realm I also solder.

Please don't fall into the habit of thinking certain items should have a specific ohmic value.  This was a fault of mine for many years when I first entered the trade.  Two coils from different make starters may have a totally different ohmic value even though they are both rated for the same voltage and come from the same size starter.  Just look for "I have a circuit", low reading, or "No I don't have a circuit", high reading to infinity value.  There are only two ways to do things in an electrical circuit.  Open or closed, it's on or off.  If it is in between then that is what a true ohm reading is good for.  In the case of a single phase motor when wringing out the windings the start winding will have a higher resistance (many turns of fine wire) and the run windings will read lower resistance (fewer turns of heavier wire).  Although both windings are rated for the same voltage.

Ohms are what limit amps when pushed by volts.  Too many, it does not work.  Not enough and it burns up. Just enough ohms to drop the voltage to zero and all is great.  Kind of the long and short if it and Bob's your uncle.

Now if you are doing electronic transistor type work then it is a whole different kettle of fish.  Then ohms are really important because of the low voltage doing the work.  A few ohms one way or another is success or failure.  That stuff is way over my simple brain.

Merry Christmas Mr. Dog.


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## Keith Foor (Dec 20, 2015)

Code don't like soldered connections for one reason, heat.  If you solder and not crimp a lug on a wire and the lug gets hot the solder can get hot and melt.  If the wire in the lug is no longer held in with the solder then it can arc, fall out and touch metal cabinets charging them and all other sort of bad stuff.  Anything that is going to be expected to carry a significant load should also be terminated with an uninsulated lug and if any corrosion exists at the point the lug lands on, it will need cleaned and prepped before being connected.  Crimping should be done with proper crimpers and not the dime store specials.  Fully closed lugs should be used and again, not the cheap stuff at Harbor Freight if it's gonna be carrying 15 amps or more.  It's so much easier to buy the right stuff and do a job once as opposed to doing it every 6 months because the cheap lugs keep failing.


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## T Bredehoft (Dec 21, 2015)

Uglydog said:


> provides a different experience than touching the same battery to your tongue.



YOU GOT IT.


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## kingmt01 (Dec 21, 2015)

Well said Keith Foor.

I actually still use the cheap open ones tho. I almost always use a small dimple in the solid part of the rolled connector to retain the wire then seal with soldier & usually shrink wrap & lastly plastic tape while the wrap is still hot to get a nice tight seal. I don't have to play by code at home tho.  

I also run larger wire then code most of the time. You never know when you going to need to hook something up that needs a little more power then you had planned & in a few things like plug in heaters it doesn't hurt to have a little more safety with them. 

Only exception is my lights. When I write a light it is only a light that nothing else will ever be connected to. I don't like anything else on my light circuits. When I need to see I need to see.


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## mksj (Dec 21, 2015)

One comment on crimping and soldering, there are many different approaches and specifications as to solder or not solder. In general, if you use high quality crimps (alloy copper or brass), a proper crimper and size the wire according to the crimp size, you will break the wire long before you can pull the wire out of the crimp. Different connectors require specific crimpers to completely squeeze down the wire so there is no void space.  Some of the better crimps have an inner and outer crimp shell of different alloys, I tried to get the wire out of one of these and wire was fused to the crimp metal.  One of the biggest problems with the inexpensive crimpers is void space, look at the end of the wire in the crimp and you will almost always see open space on one side of the wire. Never solder a wire and then crimp it, seems logical, but solder will cold flow or melt with any resistance and the wire will loosen exacerbating the heating.

Cheaper crimps are often steel, and do not flow or compress around the wire vs. a copper/brass alloy crimp. In the aerospace industry soldering crimped wire is a no no, main reason is that it does not allow the wire just behind the crimp to flex and will fail much sooner in a high vibration or movement environment. That being said, in the marine or a corrosive  environment I have seen crimps fail due to oxidation. The Coast Guard bulletins on the subject recommended crimping then soldering in certain applications. In some cases some form of strain relief is used over the crimp and extending onto the wire to decrease bending and prevent corrosion getting into the crimp.

I have evolved my crimping technique based on experience (failure) and practices for different industries. If you are going to do more than a few crimps, invest in a knock off decent crimper (about $50-80) that has different size dies, get decent alloy crimps that have nylon insulation (vinyl insulated crimps do not crimp well, nor handle heat and usually fall off), and consider using some fusible heat shrink to provide some strain relief. After you crimp, you can solder the tip of the exposed wire to prevent any corrosion getting into the crimp. On high voltage (120 and above) I crimp, solder the wire tip and use fusible shrink tubing over the crimp. Soldering is controversial in this application. Also when making bare wire terminal connections with stranded wire, do not solder the wire, as the solder will cold flow and the connection will loosen.


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