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TV Backlight on in standby - can't turn on

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    #1

    TV Backlight on in standby - can't turn on

    The tv is a Trutech 19in PLV16190 and when it's plugged in the backlight comes on shortly after while the TV is still in standby. The power button does nothing (none of the buttons do anything). The power supply is putting out 12.1vdc. I'm not an expert but I have some knowledge in troubleshooting electronics. Could someone point me in the right direction?

    Power board: LS1904006A
    Video board: PLV1619-02-01
    Tags: None
    #2
    Re: TV Backlight on in standby - can't turn on

    Can you post a picture of your power supply and main board?
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

      #3
      Re: TV Backlight on in standby - can't turn on

      I've uploaded the pictures and included one for the power connector to the video board.

      The power connector is
      12v - measured 12.1v
      12v - measured 12.1v
      12v - measured 12.1v
      GND
      GND
      GND
      DIM - measured .02v
      BLK - measured 2.0v (I think this is what has the backlight on)
      Attached Files

      Comment

        #4
        Re: TV Backlight on in standby - can't turn on

        OK, I've highlighted some voltage regulators for you to test.

        Both red ones are definitely regulators. Test as in this tutorial by Retiredcaps:
        https://www.badcaps.net/forum/showthread.php?p=273417

        The blue one... well, I -think- it's a regulator. But, it looks like they've soldered on a heatsink to the tab of the device. Poor design, the regulator likely gets very hot and may be prone to early failure. Please check if underneath it looks like one of the other two (no need to remove the heatsink just look carefully.)

        I honestly wonder what goes through the minds of the companies making these TVs. YDIW!!
        Attached Files
        Last edited by tom66; 10-14-2012, 05:41 PM.
        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

        Comment

          #5
          Re: TV Backlight on in standby - can't turn on

          Some of main boards could have components on the backside and there may be voltage regulators there as well.
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          We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

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          Comment

            #6
            Re: TV Backlight on in standby - can't turn on

            Blue IC
            IC line 1: 1117
            IC line 2: 6E01
            Pin 1: 0v
            Pin 2: 1.29v
            Pin 3: 4.96v

            So Pin 2 is supposed to be Pin 1 + 1.25v It's off by .04v

            Red (next to blue) IC
            IC line 1: LD33
            IC line 2: L627
            Pin 1: 0v
            Pin 2: 3.27v
            Pin 3: 4.96v

            I'm not sure I found the right datasheet but it says it's a 3.3v regulator

            Red IC (one across board)
            IC Line 1: LD33
            IC Line 2: L627
            Pin 1: 0v
            Pin 2: 3.27v
            Pin 3: 4.88v

            Same as above

            Thanks for helping me.

            Comment

              #7
              Re: TV Backlight on in standby - can't turn on

              All those regulators are within specifications and good.

              Let's get some more info.

              1) If you hookup a source like a DVD player, do you get sound?

              2) If you hookup a source like a DVD player, do you get a picture?

              3) If you hookup a source like a DVD player, do you get backlight?

              4) If you hookup a source like a DVD player, can you see the picture with a flashlight (if no backlight)?

              5) What is the power LED color for all the above?
              --- begin sig file ---

              If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

              We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

              Please do not post inline and offsite as they slow down the loading of pages.

              --- end sig file ---

              Comment

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