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Can this 12 V TV be fixed

Discussion in 'Electronic Repair' started by Nowhere, Jul 16, 2007.

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  1. Nowhere

    Nowhere Guest

    The 12 V DC power polarity to a flatscreen TV was unfortunately reversed

    The TV does not now function and I would like to know if anything can
    be done to repair it or is all lost


  2. Spam Trap

    Spam Trap Guest

    Someone will get back to you just as soon as the crack mind-reading team gives the make and model number
    to the crack diagnosis team.
  3. Nowhere

    Nowhere Guest

    Ok Its a Bush LCD 15DVD008


  4. Meat Plow

    Meat Plow Guest

    How in the bloody hell do you reverse the polarity on that? Did it not
    come with plugs and adapters that prevent such lunacy?
    You may luck out with an internal polarity protection device and a
    fuseable something or other or you may have done greater, more costly
  5. Arfa Daily

    Arfa Daily Guest

    Did the original power supply burn up, and you just found this one with the
    right plug on, and assumed it would be right, by any chance ? I've seen it
    happen a couple of times. Most of those Bush models have a polarity
    protection diode right across the power socket, and it fails short circuit.

  6. James Sweet

    James Sweet Guest

    It could be a very simple fix, or it could be completely junked, but unless
    you have some electronics knowledge there isn't anything you can do
    yourself. Best suggestion I can give is take it to a shop and get it looked
  7. hr(bob)

    hr(bob) Guest

    Do you have any electronics experience, such as with a multimeter or

    H. R.(Bob) Hofmann
  8. mc

    mc Guest

    There are basically 2 possibilities:

    (1) Maybe it blew a fuse and/or a few components in the power supply and
    nothing else.

    (2) Or maybe all is lost.

    Depends on the power supply circuitry.
  9. Nowhere

    Nowhere Guest

    No excuses it was a cock up of great magnitude I was trying an
    alternative adaptor which had been cobbled together with an uncertain
    polarity (unknown to me). My instincts were warning me but I had been
    told that it should not damage the TV Serves me right I suppose

    Normally I am quite handy and sensible with this type of work having
    built 3 computers over the years. If I know what to look for and test I
    could give it a go Just wasn't sure it was salvageable

    Are there any technical specs anyahere I could check


  10. Look for a shorted diode near the input jack as others have recommended. If
    you are handy with a soldering iron and a DMM you might get lucky and be
    able to easily fix this.
  11. Nowhere

    Nowhere Guest

    So far so good

    Got the back off and think I have identified the diode Right next to
    the DC input around 7mm long in glass/plastic The two leads in are
    colored red. It could well be blown but very difficult to see

    If I get a multimeter and plug the adaptor in and check I could verify
    a this I suppose

    If I want to replace it where would I get another from and what would I
    need to look for (Spec etc)



  12. Arfa Daily

    Arfa Daily Guest

    It's been a while since I did one, but as far as I can recall, the diode is
    a pretty 'standard' looking thing, about 5-7mm long, coupla mm or so on the
    diameter, black plastic, white or silver band one end. I seem to recall it
    being pretty obvious, near to the input socket, but that's to the
    experienced eye. To check it, you don't want to be having the PSU connected
    again. You need a normal multimeter, set to its ohms range. If it's an
    alalogue one, and the needle goes right over when you hook it across the
    diode, both ways, or same test with a digital, reading is close to 0.00
    ohms, then you can be reasonably sure that the diode is short circuit. You
    can further confirm this, if you like, by then snipping one end lead, and
    measuring again, directly across the diode, between the intact lead, and the
    lead stump left on the diode. If you still get a short circuit reading, then
    with the diode still snipped, you can try applying power again, making VERY
    DEFINITELY SURE that you have the polarity correct. All being well, the set
    will come back up, and you will be able to verify that there is no
    additional damage. If all is ok, remove the power again, and go ahead and
    replace the diode. Type is not critical - any from the 1N400x series for
    example, but make sure that you fit it the right way round.

  13. Nowhere

    Nowhere Guest

    Its the same size but is clear plastic with the leads colored red as
    they enter the plastic Cant see any bands in silver or black I could
    email you a photo if you wish then I can be sure it is the same thing

  14. Arfa Daily

    Arfa Daily Guest

    I don't think that this sounds like what we are looking for. By all means
    e-mail me a photo if you like, and one of the whole lower part of the board
    as well. If you do them in a reasonably high res and Jpeg or PDF them, I
    should be able to zoom up on them pretty well to see if I can remember where
    the diode was, and spot it. BB connection here, so no issue with size up to
    mailbox capacity - say 8 meg to allow for other stuff that might be in

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