LG 42" LCD TV 42LG60FR picture goes black, sound still on

Discussion in 'Technical Repair' started by sonic999, Jun 21, 2013.

  1. sonic999

    Thread Starter New Member

    Jun 21, 2013
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    Hey guys, I need help with my LCD TV. The problem started out of nowhere, with some sort of glitch... the picture would flicker and make a noise as that of interference... sometimes it would go back to normal, and some other times it just went black, but the sound was still there. I had to turn off the TV and back on to get the picture back. After having done some research on the net, I found that there was an easy way to check if the source of the problem was faulty inverters: I turned off the lights in the room and checked the screen with a flashlight at an angle... bam, the images were there, so I'm guessing there's a faulty inverter, or maybe both of them. Now the thing is I can't seem to find the inverter boards when I remove the back cover: :confused:
    [​IMG]
    Could they be hidden behind the metal board???
    Any help will be greatly appreciated. Thanks in advance.
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    The inverter board is right there.
    Do not dismantle the screen, u might be sorry.

    The Inverter & PSU is built onto one PCB. The one to ur left or the right side of the bottom corner ( picture).
    To be accurate, it's the PCB where the power cord is connected.

    Show me some good pictures of that PCB.
     
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  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Dont know if this manual may help?
     
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  4. sonic999

    Thread Starter New Member

    Jun 21, 2013
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    Thanks R!f@@! I just took these:
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    Yeah, I had found that too.. in spanish and another in english (11MB), but unfortunately there's not much info... there's an exploded view, with numbers for each part, but then they forgot to write down what each number meant! LOL
    Here's the service manual in spanish: http://pdfcast.org/pdf/service-manual-42lg60fr (some parts were not translated from english to spanish though)
    Here's the service manual in english: http://pdfcast.org/pdf/42lg60fr-service-manual
    In case anyone else comes looking for these... I saw some sites that were charging 20 bucks for these manuals, go figure. :confused:
     
  5. sonic999

    Thread Starter New Member

    Jun 21, 2013
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    [​IMG]
    Another pic, it wouldn't let me post 7 pics in one post.
     
  6. Externet

    AAC Fanatic!

    Nov 29, 2005
    758
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    Before futzing with the inverter; you should try new or known good fluorescent back light tubes. They do wear out, and they do behave as you experienced when old.
     
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  7. sonic999

    Thread Starter New Member

    Jun 21, 2013
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    Thanks Externet! Do I need to have a part number to look them up online, or are those universal? and of course in order to change the tubes, I'll have to dismantle everything... I'm watching a youtube video that explains how to do it

    The capacitors look ok.
     
    Last edited: Jun 22, 2013
  8. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Ur pictures are not good enuf for me to tell u anything.

    In order for me to help u to repair that I need to know ur experience with voltage measurements.
     
  9. sheldons

    Active Member

    Oct 26, 2011
    616
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    first off if you have a ccfl tester that will save you time-why dissassmble an lcd display which has been assembled in CLEAN ROOM conditions when you may not have too-plus theres a good chance you will scrap the set anyway when you find the ccfl doesnt come out easily-the complete pcb for that set is most probably available on ebay-depending on the fault with that inverter/power supply it may not be economic to repair,in that manual there is no schematic of that supply because it is only available as a complete unit.....as is common with a lot of this type of rubbish set which is by no means built to last-
    standard life of an lcd is two and a half years or so max then depending on the fault its a throw away item-unlike crt sets which where properly designed to last-i know of sets that are still working now with by far superior pictures that have failed maybe once or twice after YEARS of use-these sets being about 25-30 years old and can be repaired down to component level every time
     
  10. Externet

    AAC Fanatic!

    Nov 29, 2005
    758
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    Cannot tell if everything has to be dismantled to pull the fluorescent tubes out in your particular unit, or there is provisions that allow replacement with some ease.
    Universal ? At least you need to know lenght and thickness and how many.
    I would first try with some alike tubes connected to the inverter output before dismantling anything. If no light either, you save a lot of time and frustration, then focus somewhere else in the circuit.

    There is several on-line sellers of tubes at stupid high prices.

    I did once replaced the tubes with a string of surface mount white leds supplied with 12V from the inverter input and discarded the inverter.

    It is a lot of careful work, sweat and tears to mount the strip inside the U channel that hosted the tubes, then slides into its screen groove; but had the time and adrenaline. Will never burn out.

    Inverters are smart; they shut down if there is problem with the tubes and can mislead the troubleshooting.
     
  11. sonic999

    Thread Starter New Member

    Jun 21, 2013
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    Thanks a bunch, guys. I won't be able to go any further than verifying that the capacitors are looking healthy, so it's either sending the TV for repair and probably getting ripped, or tossing it out... I guess it won't be any good either for spare parts. Heh.
     
  12. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
    156
    Why can't you go any further ???
    I know sometimes it's not worth the time to fix because it has to many problems ... But you have to decide how much it's worth to you and how much are you willing to spend to fix it ... In the repair business you are going to need tools in order to do the job right or you build the tools you need to fix stuff ...

    But don't give up and keep trying ....
     
    Last edited: Jul 21, 2013
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  13. electrimvolts

    New Member

    Jul 7, 2013
    4
    1
    I fixed a friend of mines lcd flat screen that did about the same it would come on sometimes then the led that let you know the tv was on would dim way down, went from bright blue to halfway lit up...took it apart and replaced 2 caps on the power on part of the circuit board and it fixed it.. did it about 5 months ago and it still works like new...most of the tv makers underrate the caps from what ive come to figure out.. not sure if this was of any help
     
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