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testing a WC coil

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M w J

06-22-2008 16:01:29

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Is ther an easy way to test a coil while it is out of a fairbanks morse J mag ?

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06-24-2008 18:06:40

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 Re: testing a WC coil in reply to M w J, 06-22-2008 16:01:29  
If it is on the tractor and it has a yellow kind of a small spark, it is a good sign the coil is bad. Another somewhat good way is if the tractor runs for a while and then there is no spark as the coil overheats and gets a weak spark.

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John T

06-22-2008 19:18:22

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 Re: testing a WC coil in reply to M w J, 06-22-2008 16:01:29  
Its easily possible to test if a coil is BAD using an ohm meter buttttt ttttt a simple ohm meter does NOT tell you if its good!!!!! !! cuz it can easily breakdown under high voltage and/or operating temperature which the simple ohm meter continuity test doesnt indicate.

The low voltage primary winding of a typical mag coil may be in the vicinity of well under an ohm to no more then a few ohms but if its open ITS BAD. Similar, the high voltage winding would be more in the thousands of ohms but if its open (or shorted out) ITS BAD. Again, however, it can pass both those tests but still fail at high voltage and temperature.

So the correct answer to your question is yes and no lol

John T

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06-22-2008 19:09:51

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 Re: testing a WC coil in reply to M w J, 06-22-2008 16:01:29  
If it has a dead short it will show with a VOM or continuity tester. If it's weak, need other tester.

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06-22-2008 16:05:45

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 Re: testing a WC coil in reply to M w J, 06-22-2008 16:01:29  
There's no ACCCURATE (conclusive) way to test it without a coil tester.

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