What is this component

Discussion in 'General Electronics Chat' started by @android, Apr 28, 2012.

  1. @android

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  2. #12

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    That shape is also used for MOV's and capacitors, but I can't tell from here.
     
  3. takao21203

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    Overvoltage arrestor very likely. Can you see any imprint on it?
    If there is none, it's an overvoltage arrestor, these don't have imprint (for grid voltage).
     
  4. #12

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    Clarify, takao. What country are you in? Go to User CP (at the top of the page) and type in your location. We have people from all over the planet on this site.

    I interpret "overvoltage arrestor" as MOV and "grid voltage" means the local power grid. True?
     
  5. takao21203

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    yes I updated my info.

    I have edited this reply, because it could be either be transient suppressor, or MOV.

    I have one red transient suppressor here, no marking, reads "high Z" (more than 200 MOhms).
    And I bought it as transient suppressor, when I remember right.

    By random I have one television PCB here where it also has such a component, it's a MOV this time,
    used to limit inrush current. Reads 30 Ohms (multimeter). Also unmarked component.
     
    Last edited: Apr 28, 2012
  6. strantor

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    I vote NTC resistor
     
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  7. praondevou

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  8. @android

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  9. @android

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  10. praondevou

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    Are you measuring this "in-circuit"? If so, is the NC pin connected to anything via a trace?

    If you are you trying to troubleshoot this SMPS I would start by looking for obviously blown components, then leaking/bulging electrolytic capacitors.
    Then check for obvious short circuits on output voltages/rectifiers/regulators and primary side power switches (FETs) and switching regulators.

    If nothing is found then start to draw a schematic, makes further troubleshooting much easier. An isolation transformer and oscilloscope will help.
     
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  11. takao21203

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    More than never with mass-produced power electronics,
    if one components fails, and you repair it,
    soon the rest will also follow.

    Isn't clear from the thread if this is for repair,
    but check the age, and carefully examine all parts of sub-circuit.
    If appreciate, replace all.

    These NC shorts are nothing to rely on, even if the datasheet says not connected explicitely. There might be different revisions, or special edition for mass product. You need to check the function of the part.
     
  12. @android

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    Yes I measured in the ckt. But there are two. One is showing short & another is not. I identified faulty components one resistor(1000MΩ) shorted, FET shorted& one zener shorted. Lets see.
     
  13. @android

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    I don't think the short between NC & one terminal will cause any harm. And it is a optocoupler.
     
  14. praondevou

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    Measuring in-circuit will most likely confuse you, especially when the circuit is unknown.

    Did you mean you had an resistor of 1GOhm which is shorted? First I don't know what a 1GOhm resistor would do in a SMPS and then resistors usually do not short, when damaged their resistance increases or varies a lot with temperature.

    Or did you mean a low resistance which increased up to 1GOhm? That would of course be a faulty component.
     
  15. @android

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    Resistor(Brown Black Grey) I De-soldered first & then measured it(4Ω or 20Ω don't remember exactly what it was), same for FET. But I didn't De-solder optocouplers(two are there). But both are symmetrically connected so both should give same readings! :confused:
     
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