Brushless motor not spinning (help)

Discussion in 'General Electronics Chat' started by oidium45, Jun 14, 2011.

  1. oidium45

    Thread Starter Active Member

    Apr 24, 2010
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    Hello, i have a few 120v fans that use a brushless motor. Both have stopped rotating. Even when you try spinning them by hand while on they do not rotate. I have taken them apart and cleaned them up throuroughly including lubricating the bearings. Still, nothing works. Anyone have any ideas? Or are they just toast?
     
  2. #12

    Expert

    Nov 30, 2010
    16,248
    6,745
    I don't know your skill level, so please don't be offended.

    Two "known good" parts in a row refusing to work suggests you made an error with the 120V and will have this fixed b4 I can reply.

    However, when a brushless fan goes bad, It is really difficult to do anything about it. Do you have a microscope and surface mount soldering? I didn't think so. They are frisbees.

    There's one opinion.
     
    Last edited: Jun 14, 2011
  3. oidium45

    Thread Starter Active Member

    Apr 24, 2010
    130
    8
    These are not motors that i have wound myself. They are commercial fan motors.
     
  4. #12

    Expert

    Nov 30, 2010
    16,248
    6,745
    I don't think that changes anything. Have we had a misunderstanding? Did I miss something?
     
  5. oidium45

    Thread Starter Active Member

    Apr 24, 2010
    130
    8
    No, i thought it was necessary to specify that these were not motors that wound myself.. These were motors that recently stopped functioning. I am hoping that someone might have a trick to getting them working again. Although, i suspect that one or more of the windings may have shorted over time causing the current problem with them not opperating. This is a last resort before throwing them out and replacing them with new motors...

    Thank you for your reply
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It would help to have some good photos of the motors. If that isn't easy for you to accomplish, do you have a manufacturer and part number for them?


    If the fans had been in a stall condition previously due to frozen bearings, running slowly or otherwise been in a "locked rotor" condition, the windings may have burned up due to overheating. There also may be thermal fuses that have opened up; if the motors are small (like computer fan size) the fuse might look sort of like a diode with a metal cylindrical case. Larger motors might have a thermal fuse that looks sort of like a small TO-3 case screwed into the motor frame.
     
  7. #12

    Expert

    Nov 30, 2010
    16,248
    6,745
    Yes. I think you are right. They are not very expensive compared to the time it would require to repair them, and you might even find a repacement on another piece of equipment. I keep a junk pile just to steal parts from old machines, but I occasionally have to place an order for new parts. I needed a 120 Vac fan that was very quiet (for a music amplifier) and I had to pay for a new one. I think this is what will happen to you.
     
  8. oidium45

    Thread Starter Active Member

    Apr 24, 2010
    130
    8
    Thank you gentlemen! I am just going to toss them out and purchase new ones.
     
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