TV Backlight on in standby - can't turn on

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  • jim341
    New Member
    • Oct 2012
    • 3
    • United States
    #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
    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK
      #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

        • jim341
          New Member
          • Oct 2012
          • 3
          • United States
          #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

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK
              #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

                • retiredcaps
                  Badcaps Legend
                  • Apr 2010
                  • 9271
                  #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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                  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.

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                    Comment

                    • jim341
                      New Member
                      • Oct 2012
                      • 3
                      • United States
                      #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

                        • retiredcaps
                          Badcaps Legend
                          • Apr 2010
                          • 9271
                          #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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