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#1 |
Member
Join Date: Jul 2019
City & State: Congleton
My Country: United Kingdom
I'm a: Knowledge Seeker
Posts: 71
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![]() 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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#2 |
Badcaps Veteran
Join Date: Dec 2010
City & State: Alberta
My Country: Canada
Posts: 1,901
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![]() 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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#3 |
Member
Join Date: Jul 2019
City & State: Congleton
My Country: United Kingdom
I'm a: Knowledge Seeker
Posts: 71
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![]() 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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#4 |
Badcaps Veteran
Join Date: Jul 2011
City & State: Sunny Jacksonville FL
My Country: USA
Line Voltage: 120 Volts 60 HZ
I'm a: Knowledge Seeker
Posts: 2,357
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![]() 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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9 PC LCD Monitor 6 LCD Flat Screen TV 30 Desk Top Switching Power Supply 10 Battery Charger Switching Power Supply for Power Tool 6 18v Lithium Battery Power Boards for Tool Battery Packs 1 XBox 360 Switching Power Supply and M Board 25 Servo Drives 220/460 3 Phase 6 De-soldering Station Switching Power Supply 1 Power Supply 1 Dell Mother Board 15 Computer Power Supply 1 HP Printer Supply & Control Board * lighting finished it * These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10% 1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later ) 2 Hem Saw Computer Stack Board All of these had ![]() All of the mosfet that are taken out by bad caps ![]() Last edited by sam_sam_sam; 12-08-2019 at 04:21 PM.. |
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