Treadmill Motor Speed Controller MC-80 diagnostics

Discussion in 'The Projects Forum' started by TM1, Feb 15, 2011.

  1. TM1

    Thread Starter New Member

    Feb 15, 2011
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    Have a NordicTrack treadmill that won't go faster than 2.5 without shutting down momentarily. When it does shut down, the LED on the speed controller flashes indicating a high amperage draw.

    The problem might be a worn belt, but it appears OK and I'd like to verify the speed controller is operating properly.



    [​IMG]
    [​IMG]

    How should I proceed?
     
    Last edited: Feb 15, 2011
  2. TM1

    Thread Starter New Member

    Feb 15, 2011
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    Added information, R14 becomes very hot in use.

    I've removed the charred paper since taking the photo and it reads 5W 5KJ6 / Royal 562.
     
  3. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Check the motor brushes

    By the way..Welcome to AAC
     
  4. TM1

    Thread Starter New Member

    Feb 15, 2011
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    Brushes looked fine, springs intact and no sign of burning. All connections are solid, visually everything looks great except for that charred label in the photo.
     
  5. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    The label is charred over time. It is on a power resistor u know.

    So, what seems to be the problem, can u explain ur problem in a bit more detail.
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    See that u can measure 12V at the 12V test point.
    If 12V is there when the tread operates then that "charred" resister is fine.

    U are having some other issue
     
    Last edited: Feb 17, 2011
  7. AresROC

    New Member

    Jan 3, 2011
    19
    1
    I have a similar issue. After I replaced the SMD relay switch transistors with through-hole equivalents, the motor has no torque at all and would drew upwards of 15 Amps. The motor would become extremely hot after use.

    Brushes are fine.
     
    Last edited: Feb 17, 2011
  8. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    if your overcurrent light is coming on, that usually indcates an overload condition. Your R14 is a shunt resistor used to measure current, and will run warm.

    First thing I'd do is go through your belt mechanics and pull out all the string and debris that may have wound into the rollers/transmission, then setup the belt tension correctly (?).

    The controller itself should be capable of driving the motor, which may have a nameplate on it. By measuring the output terminals of the controller for voltage, and the voltage drop across R14 to calc the current, you can make some assumptions as to it's status.
     
  9. SG1_Guy

    New Member

    Nov 21, 2011
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    Here's hoping TM1 is still around and has email notifications of responses...
    But I have the same controller board with issues, R27 has Fried.
    Hoping for a bigger blow-up of the resistor, or a reading on the ratings ?
    While Blue in healthy form, mine is now black from end to end... :-(
     
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