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LCD TV, white rectangle

Discussion in 'Troubleshooting and Repair' started by Pelletier, Sep 12, 2014.

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  1. Pelletier

    Pelletier

    5
    0
    Jan 2, 2012
    Hi,

    This is a Panasonic TC-L32C5 LCD TV. There is a vertical white rectangle covering a large portion of the screen. Any hint about how to fix this?

    [​IMG]
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,491
    2,833
    Jan 21, 2010
    A few assorted lines typically mean that the connectors along the edges of the panel have become detached or broken.

    A large contiguous section more than likely means that either a chip controlling a section of the display has failed, or is not getting a signal.

    And it's certainly not the jagged or diagonal effects you get from a smashed panel.

    Is the onscreen display (menus etc) likewise affected?

    Depending on the cause this will either require a new panel (likely more expensive than a new TV) or a board swap. Unless someone has been "inside" playing wihth stuff it's unlikely to be something simple like a connector that's come adrift.
     
  3. Angelo

    Angelo

    30
    2
    Sep 10, 2014
    Yeah, as said above is probably some non-simple fault. Anyway, can you do some stupid / fast checks:

    1 - give some small shots to the TV plastic case, by hand, and see if the rectangle someway blink.
    2 - if you want to open, move slowly connector wires to see if there is some change on the screen.
    3 - taste by hand for some hot component, touching briefly controller IC's here and there were accessible.

    regards
     
  4. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Be careful with this step! Touching ICs responsible for power regulation will be warm or hot normally. There is also the risk of shock if you touch a conductive part of the circuit. I would not recommend this at all for someone who is not familiar with Capacitors or the risks involved with operating on a live circuit.
     
  5. Angelo

    Angelo

    30
    2
    Sep 10, 2014
    I said "controller IC's", not power supply part. Good that has pointed out. Touching body of a big QFP chip/contorller for a moment, never caused to me in several years any issue. But up to you, if you don't feel confident on these operations avoid point 3.

    Any news ?
     
  6. davenn

    davenn Moderator

    13,813
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    Sep 5, 2009
    There's nothing wrong with your advice, when given to some one who knows their way around a circuit board
    but, till we know the experience of a person, we have to be careful in advice given :)
    We have no idea if the OP even knows the difference between controller IC's and PSU parts ?

    It's something we are often trying to establish early in threads

    cheers
    Dave
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,491
    2,833
    Jan 21, 2010
    What flavour is "hot"? :-D

    Often they have none at all. However I'm a *little* more relaxed given the low voltages that drive the screen and that the power supplies are generally speaking pretty obvious.

    However this does have a CCFL backlight and there are some impressive voltages here. The wires leading to the CCFL tubes are generally well insulated, but the board can have very high voltages at points that are easily touched. Fortunately these are also generally near the power supply (or indeed part of it) and just keeping your fingers away from the while power supply is a great idea.

    If the entire TV is integrated onto a single board, you need to take special note of what parts are dangerous if you're going to be poking your fingers onto devices or their heatsinks.

    If you're at all unsure (and perhaps even if you're not) make sure you're wearing dry shoes, on a dry floor, not leaning or resting on anything, and with your left hand in your pocket. Oh, and have someone else around... just in case. This won't prevent an electric shock, but it will likely make it less likely to actually electrocute you. If the very worst does happen, there will be someone else present to turn off the power, see if you're OK, make sure you're breathing, start CPR if required, then call the emergency services (in that order). DRABC
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,491
    2,833
    Jan 21, 2010
    • The bulk of my reply was not directed at you.
    • I can't imagine you work on live equipment in bare feet on a wet floor.
    • People who lack the experience you undoubtedly have can easily make mistakes you wouldn't simply because they're not aware it's a mistake.
    • 220V -- lucky you. We have 240VAC.
     
  9. HellasTechn

    HellasTechn

    1,556
    215
    Apr 14, 2013

    18-25 KV for colour TV's :p
     
  10. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    @Pelletier, have you made any progress thus far?
    Do you have a multimeter, or have you opened the TV yet?
    Once open, send us pictures, they are worth well over 1000 words and will help us point you in the right direction if you are unsure where to look. Please keep in mind that the problem could be caused by something that would not be worth fixing, such as the actual connection to the panel as that would require a pricey replacement.
     
    Last edited by a moderator: Sep 15, 2014
  11. Pelletier

    Pelletier

    5
    0
    Jan 2, 2012
    Thanks to all of you for the info. I asked the question just in case there would be an obvious and easy fix, but it doesn't seem to be the case...

    My son found the TV in the trash... A free TV would have been nice, but it's not a big deal. :)
     
  12. davenn

    davenn Moderator

    13,813
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    Sep 5, 2009

    Yup .. the way it goes sometimes

    one day you may get one that is an easy fix :)

    Dave
     
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