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Electric Wiring on my Milwaukee Grinder Question

Posted by drafted72 Chicago (My Page) on
Wed, Apr 14, 10 at 11:46

I have a Milwaukee Grinder 9" which recently started only working for a minute then shuts down for a day or two. The brushes are fine and so is the motor. It's am not getting any power to the brushes. I called Milwaukee Tools and they told me its the soft start module and told me to 'by pass" it.

My questions is how do I connect the wires to do that?

Here is the wiring diagram

Thanks so much for any help.

Here is a link that might be useful: Grinder Wiring Diagram


Follow-Up Postings:

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RE: Electric Wiring on my Milwaukee Grinder Question

A 9in. grinder has a pretty hefty motor. I find it hard
to believe that Milwaukee would tell you to 'by-pass'
the soft start module. The initial current draw on
that motor might trip your breaker, (if you're lucky).
Why not replace the module?


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RE: Electric Wiring on my Milwaukee Grinder Question

The techical support at Milwaukee disagrees with you. They said they do it all the time at their repair department. They also said it will NOT hurt the motor or my house.

It's a $35 part on a grinder which I only use to sharpen my mower blades with. Then I am not sure(and Milwaukee Tool isn't either) that is the exact problem. The brushes are not getting any electric power when I engage the power trigger.

I can send it into them for repair and it would cost about $100 including shipping to repair it if the module is the problem. A new grinder is about $180. If it is the motor, the it will cost just as much to repair then replace.


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RE: Electric Wiring on my Milwaukee Grinder Question

My best guess is that they jumper the module just to test
and see if that is the problem, but don't leave it like
that indefinitely. There is a reason that the engineers
required the module. Do you have power to the trigger switch?, (possible bad cord). They are 'guessing' it is
the soft start module, so I take that as meaning it is a
very common problem. I say either spring for the $35 module if you think you can replace it yourself, or junk
the whole thing and go out and get a 4 1/2 inch grinder.
I've got a cheapie that I bought for $15 brand new, 5 years
ago and still works fine for sharpening my blades.


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RE: Electric Wiring on my Milwaukee Grinder Question

Thanks for the advice,

I am going to take it to a friend who owns a electric motor repair shop and fixes these all the time, maybe he has a similar grinder "for parts" available.

I was thinking of getting a HF 9" grinder for $49 since I only use it to sharpen my blades. I have a 4 1/2" grinder and I can tell you there is a HUGE difference between the two grinders when it comes to sharpening blades. I have a mower deck that takes 3 blades and I also sharpen my sister's mower that takes 3 also. Therefore I sharpen a lot of blades. One day I was at John Deere and saw how sharp their shargened blades look so I asked how they got them so nice and sharp. They told me they used 9" grinder and once I started using a 9" grinder it made all the difference in the world. IMHO.....


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RE: Electric Wiring on my Milwaukee Grinder Question

Sounds like a plan. If nothing else, your friend should
be able to get the module for you at a discount, being
as he's in the business. Report back with your results
please. Good luck.


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