Treadmill Circuit Breaker Overheat question

Discussion in 'General Electronics Chat' started by bowiefan, Feb 25, 2015.

  1. bowiefan

    Thread Starter New Member

    Feb 25, 2015
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    Would anyone know what could have possibly caused a 15 amp treadmill circuit breaker to get hot enough to cause a light brown surface powder burn (about 1/4" long) on the body and end of the breaker close to the contacts and slightly on the contacts where they attach to the body? The breaker became so hot that it will not even reset. Thanks.
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Poor connections to the breaker causes resistance in the circuit,thus creating heat.
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    And breakers/fuses do generate considerable heat themselves..
    But yes poor/loose connections are the cause 99% of the time..
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Do you have anything to confirm the actual current? such as a clamp on meter etc?
    Max.
     
  5. bowiefan

    Thread Starter New Member

    Feb 25, 2015
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    Thanks for the reply. I am a newbie to electronics so I have very little knowledge. Tested the main motor with a drill battery and the treadmill motor seemed to run properly with no arcing and turning the belt properly. The incline motor works as it should. The digital display works properly. The voltage lights on the power board (+9v, +5v, 120v) are all lit. PWM light is not lit. I didn't confirm actual current. I don't have a clamp meter but I do have a Fluke 87. Since a circuit breaker is basically a reusable fuse, is polarity of the terminals on the breaker important, meaning "does it matter if you install the new circuit breaker in forwards or backwards or which terminals the wires are hooked too, forward or backward?" I didn't see any indication on the breaker for correct connection.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Normally breakers are optional as to connection, especially the thermal type, if electron version, which I suspect it is not, may need a certain hookup, but if so it should be indicated on the C.B.
    I agree with the others, it could well be a poor connection.
    Max.
     
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    If the body/sticker on the breaker says "line" and "load"then connection orientation matters... if not it doesn't
    All the DC breakers I've ever used are marked to indication orientation..
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I missed your PM but the MC-70 info I have mentions that DZ4A & B are 12V 650 ma 5 watt zeners in series and they are a common fail point.
    Also have you seen this on trouble shooting?.
    http://www.mc70repairexpert.com/
    Max.
     
  9. bowiefan

    Thread Starter New Member

    Feb 25, 2015
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    Max, Would you be able to email any info you have on that MC-70 board? Any technical info would be appreciated.
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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  11. bowiefan

    Thread Starter New Member

    Feb 25, 2015
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    Thank you for the link, Max
     
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