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Blown resistor please help

Discussion in 'Troubleshooting and Repair' started by TUNEIN, Apr 2, 2014.

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  1. TUNEIN

    TUNEIN

    3
    0
    Apr 2, 2014
    Hi
    I am trying to find the value of a blown resistor so that I may replace it.
    Its from a Circulation Booster V3 circuit board.
    The marking on the board where the resistor lives is marked L1
    It is green and can be seen in place and burned out in picture 1.
    It is in close-up in picture 2.

    Thanks for any help
    John

    1.jpg 1

    2.jpg 2
     
    Last edited by a moderator: Apr 2, 2014
  2. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    My guess is that it is not a resistor. The mark L1 would indicate an inductor as would the wound wire inside.

    The problem will probably be a short in the circuit causing excess current.
     
  3. TUNEIN

    TUNEIN

    3
    0
    Apr 2, 2014
    Thanks for your reply.
    Yes you are correct.

    I bought The item for a elderly disabled friend who lived in Spain.
    Unfortunately they thought the ac/dc adapter was a normal English plug and replaced it with a Spanish one and plugged it into the mains.
    I though that I would replace the inductor in the hope of repairing it but I don't know the specification of this component ?
    Thanks again for your help.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Are you saying that they applied mains voltage to the unit?
     
  5. TUNEIN

    TUNEIN

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    Apr 2, 2014
    Yes I am afraid so.
     
  6. davenn

    davenn Moderator

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    Sep 5, 2009
    the chances of a repair would probably be very low
    tho you can see that one blown component, it is highly likely that many others have suffered internal damage

    Dave
     
  7. duke37

    duke37

    5,364
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    Jan 9, 2011
    If it is a power input inductor, then it may have saved the rest of the circuit. Pehaps it could be replaced by a link.

    If it is an inductor in a buck or boost convertor then it will need to be replaced by the correct value.

    Dave is right !
     
  8. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    That style of inductor isn't used as the energy storage inductor in switching supplies - at least, I've never seen it. I think they're too lossy. All the SMPS inductors I've seen have complete magnetic loops - RM-series ferrite cores and similar, even ring cores, but not axial like that.

    As duke37 says, you could temporarily replace it with a wire link.

    I think the chance that at least the main regulator has lost its magic smoke is about 99.999%. And the chance that the CPU followed suit a few nanoseconds later is about 95% too.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Yeah, the CPU is the big thing. It will have firmware on it, so even if you could replace it, you'd have to reprogram it and that may not be possible.

    Give it a go. Replace the inductor with a link and carefully power it up. Maybe use a lower voltage (5V perhaps) adapter at first.

    If it's not a direct short anywhere you may see some activity. That would be encouraging.
     
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