sparking motor brushes

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Old 09-09-15, 06:35 PM
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sparking motor brushes

A Dewalt circular saw that I pulled from the trash so I have no experience with it. The electric motor seems to run ok except when I release the trigger I get a large yellow spark from the brush area.
When running there is blue sparking that I would consider acceptable though possibly needing attention. It is the spark and the sound when turned off that is unusual. It feels like an inductive kickback, but I have not experienced that on other tools.
There is also an accompanying sound that I can only describe as a momentary load when the spark occurs possibly slowing it down a little before it is off and coasts to a halt.
Is it more serious than brushes?
 
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Old 09-09-15, 06:38 PM
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Many power tools have electronic braking which sounds exactly like what your saw has.
Your tools may have it and you don't even realize it. Most, if not all, battery operated drills have electronic braking. When you let go of the trigger.... the tool stops almost instantly.

Probably needs the commutator cleaned and new brushes.
Look on You Tube for "sparking brushes".... there are loads of videos with guys cleaning the commutators and replacing brushes. Here's a few for starters.

you tube/watch?v=4uFFZNv3XEw
you tube/watch?v=MkBLwUG_AdU
 
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