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Identify SMD inductor help

Discussion in 'Datasheets, Manuals and Component Identification' started by bdtprez, Feb 24, 2018.

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  1. bdtprez

    bdtprez

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    Feb 24, 2018
    I have a device that i do not have a schematic for. It is an automobile OBDII scanner that had a cable with a short in it.

    I have checked all fuses and the only thing i see phsically damaged is what appears to be an SMD inductor (L500) that reads shorted on all legs (no resistance on lowest scale between all 4 contact points). From the peices i have been able to scavange, i can read the numbers "100" and underneath "M84". I cannot find a datasheet or cross reference. If anyone can help I would greatly appreciate it.
    [​IMG] [​IMG]
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    There seem to be some parts of the broken package laying about. See of you can find the parts from the top so we can figure what was printed on it.
     
  3. bdtprez

    bdtprez

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    Feb 24, 2018
    I have looked and gathered all of the loose pieces I could find. This is all I could come up with. I was happy to find the peice with the "4" on it!
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Ok... Well although the image is a bit unfocused, the winding appear thick, so if go for 10μH.

    Try to find parts of a similar size and see how 10μH would be marked (100?). A party of the same inductance in the same size package will likely be rated for a similar current.

    What is the size (h x w x d) of this part?
     
  5. bdtprez

    bdtprez

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    Feb 24, 2018
    Thank you very much for your attention to my issue. I am not faimiliar with measuring SMD parts, I assume the measurements are in MM but do i measure what should have been the size of the package before it exploded or from solder pad to pad? I know there are different package sizes for SMD components but I cannot tell the difference by eye. Thank you so much for your assistance.
     
  6. bdtprez

    bdtprez

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    Feb 24, 2018
    If I follow you correctly , by the physical size of the coil winding wire and component itself, we can estimate how many microhenry the component is? I have no formal training on electronics repair, I appreciate your patience!
     
    Last edited by a moderator: Feb 24, 2018
  7. kellys_eye

    kellys_eye

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    Jun 25, 2010
    The inductor seems to be part of a small SMPS circuit to develop alternative voltages within the device. They only 'burn out' if the switching device itself is shorted so you need to check for either a switching IC or a dedicated switching MOSFET that has gone short (or the reason for it going short - could be external to the device itself).

    Simply replacing the inductor will likely result in it just blowing straight away.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The height is from the board to the top of what remains.

    The main part of the body seems circular, so estimate the diameter.

    Those should be close enough.

    If you can read the part number of U948. That's the part which looks like the switching mosfet (or maybe the controller). It could be damaged as well.
     
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