gu37fhd1080 no backlight

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  • wreksta
    Badcaps Veteran
    • Aug 2013
    • 508
    • england

    #1

    gu37fhd1080 no backlight

    hi al just got this set in and ive checked the power board megmeet mlt1668tl

    I have only 1.2 v on the 24v connection for the inverter (I don't have any vaults with inverter disconnected at the 24v point)


    I do however have all the 5v at these points 5vsb 5v stb 5v

    but no 12v

    ive measure the big cap on the board and get 344v across it

    any ideas
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: gu37fhd1080 no backlight

    The results should prompt you to check PSON signal...
    and provide pictures.
    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

    • wreksta
      Badcaps Veteran
      • Aug 2013
      • 508
      • england

      #3
      Re: gu37fhd1080 no backlight

      not my pics but you get the idea
      where is the pson on the this





      Comment

      • tom66
        EVs Rule
        • Apr 2011
        • 32560
        • UK

        #4
        Re: gu37fhd1080 no backlight

        What are the labels on connector between main board and power 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

        • wreksta
          Badcaps Veteran
          • Aug 2013
          • 508
          • england

          #5
          Re: gu37fhd1080 no backlight

          hi tom the connector between the power and the main has nothing on the main board just obn the psu which is marked

          12v
          12v
          gnd
          gnd
          5v
          5vsb
          stb
          5v
          gnd

          Comment

          • tom66
            EVs Rule
            • Apr 2011
            • 32560
            • UK

            #6
            Re: gu37fhd1080 no backlight

            STB is PS ON on this unit, check that voltage in standby and after pressing power button.
            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

            • wreksta
              Badcaps Veteran
              • Aug 2013
              • 508
              • england

              #7
              Re: gu37fhd1080 no backlight

              hi tom that voltage is 3.9 both in standby and powered up

              Comment

              • tom66
                EVs Rule
                • Apr 2011
                • 32560
                • UK

                #8
                Re: gu37fhd1080 no backlight

                seems to indicate a power board fault but just to rule it out you could use a 100~470 ohm resistor between 5VSTB and STB with main board out, the voltages should come out. Also try isolating inverter in case it has a short on it.
                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

                • wreksta
                  Badcaps Veteran
                  • Aug 2013
                  • 508
                  • england

                  #9
                  Re: gu37fhd1080 no backlight

                  hi tom nah nothing happened mate the voltages just are not coming

                  should that main cap be 344v on or standby

                  any other ideas for me

                  Comment

                  • tom66
                    EVs Rule
                    • Apr 2011
                    • 32560
                    • UK

                    #10
                    Re: gu37fhd1080 no backlight

                    344V standby is fine, about 390V to 410V when running.
                    It's a power board fault, not sure what else you want me to suggest? Tested the obvious like start-up capacitors, shorted diodes, optocouplers, etc.? All the testing procedures for those are available on the wider internet.
                    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

                    • Kilroys
                      Senior Member
                      • Feb 2014
                      • 70
                      • Sweden

                      #11
                      Re: gu37fhd1080 no backlight

                      I can read MLT668TL on the white label on the psu and this service manual is among the other manuals.

                      Comment

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