Unexplainable component. What is it?

Discussion in 'General Electronics Chat' started by stian2405, Jan 12, 2013.

  1. stian2405

    Thread Starter New Member

    Jan 12, 2013
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    I've been fixing a stereo amplifier, and i finally found the fault. But i can't seem to understand what component it is, nor how to search the web for it. I've linked the picture.
    So if you could help me find out what this is i would be grateful!
    Still working on my english, might be some strange sentences. :)
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
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    It is two precission .22ohm 5 watt resistors. With very low inductance. The figure on the PCB show how they are connected
     
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  3. stian2405

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    Jan 12, 2013
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    Any tips for what i could write to search for it on the web?
     
  4. kubeek

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    Sep 20, 2005
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    Dual resistor seems to get pretty good results.
     
  5. stian2405

    Thread Starter New Member

    Jan 12, 2013
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    Thank you ^^
     
  6. t06afre

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    May 11, 2009
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    Are you sure it is broken. You have to take it out of the circuit to know for sure. It can be replaced by any low inductance precession 5 watt 0.22ohm resistor pair
     
  7. stian2405

    Thread Starter New Member

    Jan 12, 2013
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    I took picture of a similar one. The broken one were black. i even opened it and saw that it were burned apart :)
     
  8. t06afre

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    It may also be that this is collateral damage and the real error is some place else
     
  9. stian2405

    Thread Starter New Member

    Jan 12, 2013
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    Might be. But i have gone through the whole circuit board while measuring, and i only pinned down to the one dual resistor.
     
  10. takao21203

    Distinguished Member

    Apr 28, 2012
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    You can use about 2m bell wire + a permanent marker to make a coil. Who cares about inductance at audio frequency of maybe 1uH.

    Such a dual precision resistor might be rare + expensive.
     
  11. nado

    Member

    Dec 17, 2012
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    I have a question. How do you know it is the fault?
     
  12. kubeek

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    There are two possibilities, either the output pair transistors are shorted, or the speaker output was shorted and this resistor was the weakest point. It´s up to OP to find the fault.
     
  13. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Blown output transistor, likely coupled with a speaker wire short, will take out the emitter balance resistor. The amp needs a proper repair.
     
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  14. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    I agree. Resistors don't fail catastrophically on their own. Their value may drift, but if they are burnt, it is because they acted like a fuse for another component that went out of control.
     
  15. K3CFC

    New Member

    Dec 4, 2012
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    I would check both transistors behind it. looks like emitter resistors
     
  16. K3CFC

    New Member

    Dec 4, 2012
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    http://www.mcmelectronics.com/product/DISTRIBUTED-BY-MCM-RGC55--33-/28-0545

    Dual emitter resistor

    link to mcm electronics
     
    Last edited: Jan 16, 2013
  17. codexdj

    New Member

    Jan 16, 2013
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    the symbol on the PCB :) says it all
     
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