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Trying to do it right this time  Rating:  Rating
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 Posted: Wed Nov 13th, 2019 04:13 pm
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Ron Sherry
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I have bought a lot of old fan over the past few years and have decided I really enjoy bringing them back to life. Up until now I have just been a parts changer. I have robbed parts form what could be an easy future project to complete what I'm currently working on. I have to end this practice before I ruin more good fans. YouTube is limited in what I can learn about fans and I have exhausted that resource. To be up front, I don't know as much as I need to about electrical schemes but I am gaining momentum. I am currently working on a Emerson Silver Swan and seeking advice on the following....

First:
I can't determine if the speed coil is bad or not. There are three insulated wires going from the controller to the switch. Two of the wires have only 1 copper filament in them while the third wire has 2 copper filaments in it. I can't find an explanation for this on line. Help needed here. Also when I ohm the wires (as instructed by google search) I don't come up with a consistent ohm reading. For instance, I ohm line one on the transformer and it reads 3.7 ohms. Thirty seconds later I ohm it again and it reads 69.6 ohms?? Same with the other 2 wires on the transformer. Another thing I don't understand is why do I get continuity on all wires in all three of the switch settings?

Second:
When I test the 3 wires going to the motor windings, for continuity, the 1&3 wires beep on the meter. Yet, when I test the 2&1 or 2&3 I get no beep on the meter?? But..... The 2&1 wires show 219 ohms and the 2&3 wires show 182 ohms. What do I not know? What do I need to know?

If these questions would be more easily answered over phone, please reply and I can send you my number.
Thanks in advance for any schooling you can impart on me. I can send pictures If needed. Once I learn how to use this site a little better.
Ron


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 Posted: Wed Nov 13th, 2019 11:27 pm
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Mark Olson
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Digital meters with the beep function for continuity do not beep if the resistance is over a set value.
In this case, 182 ohms is above that value.
 

From your measurements, the motor windings are okay.
The connection with two "filaments" on your speed coil is the middle tap, the other two connections are the ends of the coil.


As to why you don't get consistent ohm readings testing the speed coil, most probably bad test probe connections
while testing, wiggle the probes past any corrosion or insulation and hold them tight.


Hope this helps.

Last edited on Wed Nov 13th, 2019 11:40 pm by Mark Olson

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 Posted: Thu Nov 14th, 2019 12:25 am
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Lane Shirey
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Well described Mark!  

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 Posted: Thu Nov 14th, 2019 01:40 pm
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Ron Sherry
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Mark, what do you consider a good ohm reading in determining if the speed coil good? Too, what do I look for (the main tattle tell) to determine if it's bad? Lastly, if I determine it is faulty, where might I send it for repairs or is it even worth repairing? I want to keep the fans as original as possible.

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 Posted: Thu Nov 14th, 2019 08:09 pm
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Mark Olson
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The resistance of speed coils vary between manufacturers and fan models.
They are usually fairly low resistance as far as measured ohms, and sections of the coil should add up to the resistance of the entire coil.
For instance, if A to B is 2.5 ohms and B to C is 2.5 ohms, then A to C should be 5 ohms.
There should be infinite resistance from any lead to the laminations or coil frame.

If there is continuity from any lead to the frame, the coil is shorted.
If there is infinite resistance between any two leads, the coil is open.
Those are the two failure modes of coils, chokes, motors, and transformers. Open or shorted, some may be both.
Turn to turn shorts are the hardest to determine without known values to compare measurements with.

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 Posted: Fri Nov 15th, 2019 01:44 am
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Ron Sherry
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Thanks, I'll re-ohm it first thing in the morning.

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 Posted: Fri Nov 15th, 2019 01:33 pm
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Aaron Hardy
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Mark Olson wrote: The resistance of speed coils vary between manufacturers and fan models.
They are usually fairly low resistance as far as measured ohms, and sections of the coil should add up to the resistance of the entire coil.
For instance, if A to B is 2.5 ohms and B to C is 2.5 ohms, then A to C should be 5 ohms.
There should be infinite resistance from any lead to the laminations or coil frame.

If there is continuity from any lead to the frame, the coil is shorted.
If there is infinite resistance between any two leads, the coil is open.
Those are the two failure modes of coils, chokes, motors, and transformers. Open or shorted, some may be both.
Turn to turn shorts are the hardest to determine without known values to compare measurements with.


I wish there was a way to "like" and/or bookmark a post. These simple rules are the sort that would be great in a beginner's manual or a quick start guide for fan restoration. :wondering: 

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 Posted: Sun Nov 17th, 2019 10:39 pm
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Richard Daugird
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You can rate the topic up to 5 stars.

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 Posted: Tue Nov 19th, 2019 01:16 pm
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Aaron Hardy
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Richard Daugird wrote: You can rate the topic up to 5 stars.
It's a good start. I guess I've just been too conditioned by social media these days. 


In either case, I'm tacking Mark's "rule of thumb" up on the wall behind my bench. An old fashioned post I know I'll be able to find easily. 

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 Posted: Tue Nov 19th, 2019 01:52 pm
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John McComas
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One thing I have noticed about the resistance of inductive speed coils is that they are not a linear function.
That is to say, that high to medium is 3 ohms, and medium to low is 3 ohms.

I have found the resistance from high to medium has the highest resistance.
For instance: High to medium is 4 ohms, and medium to low might be 2 ohms.

I don't know if this holds true for all inductive speed coils, but it helped me hook them up to the switch
and get it right the first time, without having to connect with jumper leads and trial and error.
A watt meter can also be a big help determining speed coil connections.
Happy Fanning!

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 Posted: Fri Nov 29th, 2019 04:44 pm
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Charlie Forster
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Its not so much how much difference is than that there is a difference.in the connections.

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