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Thread: Makita Saw just stopped working - help please?

  1. #1
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    Makita Saw just stopped working - help please?

    My Makita LSO714 sliding compound miter saw just quit! 8 year old saw - nearly daily use.

    Pull the trigger for one cut and all is OK. Pull the trigger for a second cut and quiet is all I got .

    No problems with the outlet and the chord is undamaged (as far as I can tell) - no reason for it to be damaged.

    Anyway - questions are -

    1) How can I tell if the problem is the switch or something else?

    2) If the brushes are worn would the machine just stop working?

    Any advice will be greatly appreciated. Thanks much.
    "... for when we become in heart completely poor, we at once are the treasurers & disbursers of enormous riches."
    WQJudge

  2. #2
    The first thing I would do is( unplug first)blow some air in the trigger and also in the motor .sometimes a piece of dirt or saw dust can create havoc.

  3. #3
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    Probably the switch. Try a blast of high pressure air. If that doesn't do it, unplug the saw, take the switch out, and wire nut the wires together that the switch controls, plug it in and see if it runs with the switch hot wired. If it does, it's the switch. Since you asked, I'm guessing you don't have a multi-meter, so this would be a method of bypassing the switch to see if that's the problem. There would have been other signs if the brushes were getting worn out, but I guess some people might miss them.

  4. #4
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    Sam,

    I'd suggest you try running the saw from a different receptacle that you know is in good working order. And try to run something else from the receptacle that the miter saw is usually plugged into. Just trying to isolate the problem to the saw or the wiring system.

    If you determine it's the saw for sure, then it's probably in the cord, switch, brushes.

    Good luck with it.

    PHM

  5. #5
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    Quote Originally Posted by Paul McGaha View Post
    Sam,

    I'd suggest you try running the saw from a different receptacle that you know is in good working order. And try to run something else from the receptacle that the miter saw is usually plugged into. Just trying to isolate the problem to the saw or the wiring system.

    If you determine it's the saw for sure, then it's probably in the cord, switch, brushes.

    Good luck with it.

    PHM

    Of course I did just as you suggest before posting. Easy enough to remove the brushes for a check but I can't recall ever having a tool just stop because of bad brushes. Usually there is some kind of indication. I'll try hot wiring the switch (after I check the brushes).

    Has to be the switch or the brushes right (after eliminating the cord and receptacle)?
    "... for when we become in heart completely poor, we at once are the treasurers & disbursers of enormous riches."
    WQJudge

  6. #6
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    Quote Originally Posted by Sam Murdoch View Post
    Of course I did just as you suggest before posting. Easy enough to remove the brushes for a check but I can't recall ever having a tool just stop because of bad brushes. Usually there is some kind of indication. I'll try hot wiring the switch (after I check the brushes).

    Has to be the switch or the brushes right (after eliminating the cord and receptacle)?

    Our Bosch Table saw did just what your CPMS did , make a cut fine , next time I turned it on , no joy. It was the bushes.

    Pull them , hit the ends on some sand paper , blow out the armature while the brushes are out, re-install brushes. Worth a shot, next place I'd check would be wires near the switch.

  7. #7
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    Quote Originally Posted by Tom M King View Post
    Probably the switch. Try a blast of high pressure air. If that doesn't do it, unplug the saw, take the switch out, and wire nut the wires together that the switch controls, plug it in and see if it runs with the switch hot wired. If it does, it's the switch. Since you asked, I'm guessing you don't have a multi-meter, so this would be a method of bypassing the switch to see if that's the problem. There would have been other signs if the brushes were getting worn out, but I guess some people might miss them.
    OK - the wire has been inspected, outlet works fine, brushes are good and all the dust is blown out from the wires and the motor.

    Now the question is how to hot wire the switch.

    A) Coming from the cord I have a black and white wire.

    B) Coming from the switch I have a smaller gauge black, orange and yellow wire. (I expected another white and black and maybe a green.)

    SO - Which from A gets connected to which from B?

    Thank you for your help.
    "... for when we become in heart completely poor, we at once are the treasurers & disbursers of enormous riches."
    WQJudge

  8. #8
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    Quote Originally Posted by Sam Murdoch View Post
    OK - the wire has been inspected, outlet works fine, brushes are good and all the dust is blown out from the wires and the motor.

    Now the question is how to hot wire the switch.

    A) Coming from the cord I have a black and white wire.

    B) Coming from the switch I have a smaller gauge black, orange and yellow wire. (I expected another white and black and maybe a green.)

    SO - Which from A gets connected to which from B?

    Thank you for your help.
    A call to Makita tech support should get your question answered.
    Scott Vroom

    I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.

  9. #9
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    I thought those wires must be for other things like a light. I found this. I didnt' take time to figure out which wire does what, but it's all in here: http://www.makita.nl/images/files/on...S0714FL-TE.pdf

  10. #10
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    Quote Originally Posted by Tom M King View Post
    I thought those wires must be for other things like a light. I found this. I didnt' take time to figure out which wire does what, but it's all in here: http://www.makita.nl/images/files/on...S0714FL-TE.pdf
    Wow, that link was a good find Tom, thanks. Page 24/26 is my situation - no light and no laser (also NO noise suppressor - unlike in the diagram). Still not certain what the diagram tells me as far as bypassing the switch so I guess I will need to call tech support as Scott has suggested.
    "... for when we become in heart completely poor, we at once are the treasurers & disbursers of enormous riches."
    WQJudge

  11. #11
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    do you have simple elect tester ? pull the cover off the handle and expose switch . your outlet is hot .now with your tester shove the probes into where the wires enter the switch .Hot? tester says hot then cord is good .next get the tester leads on the wires coming out of the switch ,hit the switch - does tester say there is current .if there is current after switch - saw goes to the shop or time to replace . if tester fails to read that would mean switch is not making contact . sometimes switches can be taken apart and contacts sanded .but i would sujest doing this only as a temporary fix and get a new switch .

  12. #12
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    Before I take this to a repair shop - here's the update.

    1) New Switch installed
    2) New brushes
    3) Blew out any dust from any orifice

    There is power to the switch. All SEEMS good.

    Still nothing- just silence. One day I made one cut and the next pull of the trigger resulted in absolute silence. That is still the case.

    Any more suggestions as to what I might do before taking it to a repair shop? Thanks!
    "... for when we become in heart completely poor, we at once are the treasurers & disbursers of enormous riches."
    WQJudge

  13. #13
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    Hi,

    The laser light section and the motor section or two independent sections with some common points between them and the 110 V cord supplying the saw.

    Sometimes they both work and sometimes they both don't work. It is unlikely they both would have intermittent problems that occurred at the same time. Therefore your problem is probably somewhere between these two circuits and the power plug on your AC cord.

    Possibilities include a broken wire in the power cord(1), a loose connection in the little terminal block(5), and the connection between the wires under the wire nut(3). The switch is new so it is likely not the problem.

    Check all all connections for tightness. See if the problem goes away.

    You could also, with the saw plugged in and hands clear of the blade, hold the switch closed and use a piece of plastic or dry wood to move the various wires to see if a bad connection/broken wire can be located. This is assuming the saw will not run. You will hear it kick on if movement causes an open connection to close. If you would do this you need to be very careful so do this at your own risk...and only if you are comfortable doing so. If you had a cheap ohm meter you could accomplish the same thing unpowered which is preferable. A cheap multimeter like you can get for free from Harbor Freight(with one of their endless coupons) would be satisfactory for this purpose. You would use the ohms scale.

    Only do what you are comfortable doing. Wear gloves when moving wires even when using a stick just in case you would cause a spark to occur. My guess is that your problem is either a loose connection or broken wire, since you have already eliminated the switch, which at first seemed most likely. Since the laser AND motor were both not working the brushes were likely not the problem, but new brushes are a good thing.

    Edit: As an afterthought, the power cord flexes more than anything else electrical. Replacing it with a temporary cord for test purposes will eliminate the saw power cord as the culprit.

    Hope this helps,

    bill
    Last edited by Bill Space; 08-29-2014 at 4:32 PM. Reason: Add thought and fix typo
    Too much to do...Not enough time...life is too short!

  14. #14
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    Possibly a thermal overload failed? Unless you have a broken wire internal somewhere, or a open field winding. Those would be my guesses.

  15. #15
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    Quote Originally Posted by Bill Space View Post
    Hi,


    Edit: As an afterthought, the power cord flexes more than anything else electrical. Replacing it with a temporary cord for test purposes will eliminate the saw power cord as the culprit.

    Hope this helps,

    bill
    You might be on to something there Bill. This is a switch only problem as there is no light or laser with this saw. I did hold the switch and jiggle the power cord with no effect but dismissed the idea of changing out the cord because I can see that there is power at the switch. The cord has no kinks or "funny spots" along its entire length. But now you are tempting me to change it out in any case . Easy enough to do.

    And Duane are you saying a thermal overload of the motor itself- so a new motor needed?

    I do take this saw with me out to jobs but I work alone ann am not abusive - otherwise the saw stays on its bench in the shop. I tis a pretty pampered tool. Can't imagine broken internal wires.
    "... for when we become in heart completely poor, we at once are the treasurers & disbursers of enormous riches."
    WQJudge

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