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Old 12-08-2019, 02:30 PM   #1
pintglass
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Default Mitre Saw start capacitor

Hi

My miter saw like lots of things at the moment seems to have given up.

I'm getting 240v to the switch, which I've tested for resistance when pressed giving about 0.08 ohms so i assume is OK

The start capacitor has a rating of 0.47uf and I'm reading about 0.35uf, could this be the issue?

The motor on the machine is a brushed type with two wires connected to it, should I be reading low resistance between these wires.

Is there a way to test if the brushes are worn?
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Old 12-08-2019, 02:51 PM   #2
redwire
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Default Re: Mitre Saw start capacitor

You should get continuity across the motor's terminals at the brushes.
If you don't, try turn the shaft (by hand, it's unplugged) in case there is a dead spot.
Sometimes a brush wears out, or they can get stuck from sawdust.
If there's an open circuit I would take them out and inspect.
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Old 12-08-2019, 03:18 PM   #3
pintglass
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Default Re: Mitre Saw start capacitor

I've just done a test by taking the armature out and connecting the brush terminals together and i get continuity, does this mean the brushes are not making contact.

I'm not sure if this is a valid test, are the brushes there to complete the circuit, sorry if I'm completely wrong here.
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Old 12-08-2019, 04:15 PM   #4
sam_sam_sam
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Default Re: Mitre Saw start capacitor

Check the switch because sometimes one side of the switch only has continuity when the switch is pushed to ON

But just because you get continuity that dose not mean that your switch is good

and yes if brushes are not touching the armature commutator then the motor will not run

sometimes the brush gets stuck in the brush holders
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Last edited by sam_sam_sam; 12-08-2019 at 04:21 PM..
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