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Strange shrunken capacitor(?)

Discussion in 'Electronic Repair' started by Yattaro, Jun 12, 2007.

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  1. Yattaro

    Yattaro Guest

    I have an old Gateway EV700 monitor which shuts down after a few minutes of
    use. It sometimes sort of flashes the screen as if maybe it's trying to start
    back up, but is never able to on its own. It will come back on for a few
    seconds if power cycled, but will then shut down again.

    After it's been off for awhile it will come back on and last a few more
    minutes, but then exhibits the above problems again. When it shuts down, it
    has a sort of rainbow swirl pattern in the center of the screen.

    I opened it up to see if there was anything obviously wrong, and saw what
    looks like a capacitor which has been twisted and shrunken, but I'll admit
    that my knowledge is limited enough that it could be something else entirely.

    Here are some pictures. The white goo on the side is just glue, it didn't
    come from inside the object. I didn't see any obvious signs of leakage or
    damage, but this thing certainly looks unnatural.

    Any idea what this is, if it's bad, and if replacing it might solve the
    shutdown problem?

    Thanks for any info anyone can provide.
  2. Meat Plow

    Meat Plow Guest

    Looks like a coil or choke.
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  3. Guest

    Looks like an inductor that was shrink-wrapped and damped against
    vibration with a bit of either RTV silicon or elephant-snot.

    Peter Wieck
    Wyncote, PA
  4. PeterD

    PeterD Guest

    Repeat after me: "Inductor, not capacitor" and you will be OK!
  5. w9gb

    w9gb Guest

    1. The "white goo" appears to be hot glue use to hold the component
    (possibly during wave soldering step)

    2. This circuit board has silk-screened legends, such as C102, L302, etc.
    The first character used to identify this component will tell you what it
    "C" - capacitor, "L" - inductor

    3. The component appears to have a polarity stripe, like electrolytic

    4. IF this is an electrolytic capacitor -- I would replace it based upon it
    physical condition -- but you would need the correct value and voltage
    From your photos, really can not tell -- no value markings other than the
    marking of: LO5G
  6. ian field

    ian field Guest

    Its definitely an inductor - quite likely a linearity coil (polarising
    stripe is an obvious clue) close examination may reveal that the ferrite
    bobbin has an extra bit glued on the end opposite the leadout wires, this
    will be magnetic which is easily confirmed by offering it the tip of a

    Mark the base of the bobbin as per the polarising stripe and peel off the
    shrink wrap to inspect the winding for heat damage.

    If the part is knackered it will be practically impossible to order a
    replacement - go down the dump and claim a monitor of similar size & spec to
    salvage the part from, but try it first - you may get lucky.
  7. Guest


    This should be a start, if nothing else.


    Peter Wieck
    Wyncote, PA
  8. ian field

    ian field Guest

  9. The line appears to be an indicator of the position of the leads.

    When was the last time you saw an electrolytic made with a molded
    ferrite core?

    Which indicates that its an inductor, not a capacitor.

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    Michael A. Terrell
    Central Florida
  10. Steve Sousa

    Steve Sousa Guest

    Could you elaborate on this type of inductors?
    Polarized? what does the magnet do?

    Thank you.

    Best Regards
  11. ian field

    ian field Guest

    Makes it easier to saturate the core with current in one direction than the

  12. It prevents the core from saturating, due to the DC current flowing
    through the winding(s).

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  13. b

    b Guest

    you'll need to look at the pcb underside and check for cracked solder
    joints. especially in the power supply and line stages where larger or
    hotter components are. this sort of intermittent problem is often
    caused by poor solder.
  14. James Sweet

    James Sweet Guest

    They're very common in monitors and power supplies. Don't mess with it, it's
    not your problem.
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