How to identify a burnt resistors value?

Discussion in 'Electronics & Electrics' started by partybear, Sep 11, 2019.

  1. partybear

    partybear Member

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    Hey guys I have a minor problem with my vacuum cleaner. A resistor in it seems to have burnt and now the spinning brush doesn't spin anymore. I can't be sure what its value is since its been destroyed so I don't know what to replace it with. The vacuum works like normal and charges fine it is just the brush doesn't spin anymore.

    The resistor connects the vacuum motor negative trace to the brush motor negative trace, both motors are the same voltage. The brush motor is directly wired to the SM+ and SM- plug on the board, it has no electronics past that point. It looks like all the bands on the resistor were black, which is zero ohms isn't it? It seems like that would make sense, but why use a large resistor? Is it acting as some sort of fuse?

    I thought I would ask some smarter people then myself for some more opinions just to see if this is the case or not, because it seems stupid to me but at the same time it is the only explanation I can think of.

    I have two resistor, because I have two of the same vacuum and both failed in the same spot.


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    Last edited: Sep 11, 2019
  2. mtma

    mtma Member

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    It could be a sensing shunt of a low value. There seems to be some connection off the high side of the resistor to some other circuitry so this could be a possibility, but if had some sort of current control I'm not entirely sure if it makes sense that it was able to blow the shunt. Perhaps the shunt was improperly sized for dissipation to begin with.

    Otherwise fusible link resistors with close to zero value do exist too.
     
  3. JSmithDTV

    JSmithDTV Member

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  4. OP
    OP
    partybear

    partybear Member

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    Thanks for the advice guys!

    I am pretty sure it was just acting as a fuse. I just replaced it with a thin bit of wire, I have two of these vacuums broken in the same way and I figured if it kills the whole thing who cares. Jaycar won't have a resitor/fuse like that in stock so I would have had to wait and I needed to clean badly. I just finished cleaning the whole house and the bodge wire worked for now. I will try to get the proper part, either that or I will just put a small fuse in its place. But for now this will do.
     
    Last edited: Sep 12, 2019
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  5. merlin13

    merlin13 Member

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    Off topic somewhat, but Make/Model plz? If nothing else to warn others here that that make/model has a potential design flaw...

    And did they die if/when the brush thingy stalled, or that part smoked itself in both cleaners just because it wanted to?

    And that needs to be added to a Sticky somewhere around here perhaps...
     
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  6. JSmithDTV

    JSmithDTV Member

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    Agg


    JSmith
     
  7. merlin13

    merlin13 Member

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    Nostic?

    Riculture?

    Revation?...

    *sorry, been sniffing paint and thinners fumes all day rebuilding fishing rods...*
     
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  8. Hive

    Hive Member

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    Need to get you a paper bag and some 98 premium, thinners are no good.
     
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  9. JSmithDTV

    JSmithDTV Member

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    [​IMG]

    :leet:


    JSmith
     
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