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TFT monitor repair tips

Discussion in 'Electronic Repair' started by CheetahHugger, Aug 17, 2007.

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  1. Hello,

    Can anyone point me towards some websites which can be of
    help when dealing with lcd monitor repair.
    Schematics, panel reference lists, repair tips, troubleshooting...
    Any help would be welcome as google wasn't so helpful.

    Cheetah
     
  2. Jerry G.

    Jerry G. Guest

    I don't want to dissapoint you, but component level service for the
    LCD and Plasma display's are not normaly supported by any of the
    manufactures. They are mainly serviced at the module level only, as
    like servicing a PC computer. After warranty, they are usualy
    considered not feasible to service, unless the fault is something
    simple.

    Full service manuals for many of these types of displays are usualy
    difficult or impossible to obtain. After the warranty periods for most
    of this type of technology is finished, spare modules and parts may
    not be available unless you can find a scapper unit with good parts.
    The exception is if you can find some generic parts that will work.

    When factering in the cost of the circuit boards and the laour, the
    dropping of the replacement cost, after warranty service is usualy
    considered not worth the cost. When troubleshooting and servicing this
    type of technology the tools, and instruntation required is fairly
    expensive.

    If you want to service these types of monitors, try to see if you can
    negotiate warrenty contract with some of the manufactures. Be
    prepaired to invest a fair amount of dollars to get going with this.


    Jerry G.
     
  3. James Sweet

    James Sweet Guest

    There's two fairly common problems with these which I've had good luck
    repairing. One is the backlight CCFL tubes and inverter, and the other is
    the power supply. Both of these areas can be fixed using basic
    troubleshooting with little flat panel specific knowledge.
     
  4. This is what i am looking for, especially tips and tricks engarding
    those inverters.
    As well any other tips, i don't wish to service the mainboard but
    am sure that i can do a little more then just looking for a smashed
    identical screen and swap the board.

    Cheetah
     
  5. justmanuals

    justmanuals Guest

     

  6. Regular, Low Sodium, or Turkey?


    --
    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
     
  7. Regular please, with a pepsi!

    Cheetah
     

  8. No Pepsi! Mountain Dew!!!


    --
    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
     
  9. Andy Cuffe

    Andy Cuffe Guest

    At least 8 out of 10 LCD monitors I see have power supply, or back
    light inverter problems.

    The most common power supply problem is defective caps. Poor quality
    caps are finding their way into everything now. The bad ones will
    have the tops bulging out, but it's usually best to replace them all
    if a few are bad.

    The inverters are more complicated to fix. Any number of things can
    go wrong. I see bad transformers, shorted transistors, shorted
    diodes, and bad caps. No schematics are available and the SMD
    components are often not marked in any meaningful way. I have
    repaired a lot of them, but it often requires doing a lot of research
    to ID parts. Once thing you can check is the tiny surface mount fuse
    on the inverter board. When they are blown, about half the time
    there's nothing else wrong. Fortunately, the inverter is the one
    board that can sometimes be replaced for a reasonable price.
    Andy Cuffe

     
  10. Mountain dew cheetah?
    LOL

    Cheetah
     
  11. Andy Cuffe schreef:
    Yes, this is what i found out as well, seems we are conned as usual
    with bad quality caps.

    Cheetah
     
  12. Guest

  13. Either that's a spampage or it doesn't work.

    Cheetah
     
  14. Guest

    How do you isolate a CCFL/inverter problem without swapping parts?
    I have a panel with a backlight that goes out about two seconds after
    power on. Transistor/diode junctions all look OK, no visible cap
    problems,
    tubes have no telltale black bands. Shorted transformer winding,
    perhaps?
    How to test for that?

    Thanks,
    TM
     
  15. James Sweet

    James Sweet Guest


    I have a few lamps and inverters that are not in monitors, it's pretty easy
    to wire one or the other up for testing without tearing things apart too
    much.
     
  16. I use a scanner lamp driver to test individual lamps in the screen.
    Yesterday i fixed an inverter that was shutting down, it had a shorted
    diode and a damn small one.
    Cap problems are not always visible, i use the atlas esr60 meter and
    it tells me a lot of caps simply go high esr but don't bulge.

    Cheetah
     
  17. Guest

    Along those lines, I have a Sampo QPWBGL993IDLD inverter with a bad
    transistor (Q8, one of two that drive the transformer windings). It's
    an
    SC-62/MPT3 package, with 'CF', 'Å', and 'RT' markings. After much
    online research, I identified two possible devices that this could be:

    Sanyo 2SC3650 NPN, 25V, 1.2A (hFE = 1500 typ)
    http://www.ortodoxism.ro/datasheets/sanyo/ds_pdf_e/2SC3650.pdf
    or
    Rohm 2SD2150 NPN, 20V, 3A (hFE = 180-390)
    http://datasheets.ru/datasheets/107892/data-2SD2150.html

    Which one is it (or is it some other transistor)?

    Thanks,
    TM
     
  18. justmanuals

    justmanuals Guest

    http://www.justmanuals.com
     
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