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Toshiba 42WLT68 - Standby Issue

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    #1

    Toshiba 42WLT68 - Standby Issue

    Hi,

    Here are the symptoms:

    1. Power up - Red LED then shortly followed by relay clicks and green LED.
    2.Inverter attempts to light for a split second and then the set goes back into Red LED standby.
    3.The above can be repeated continuously.

    Tried removing the two 24v PSU cables to both Master and Slave Inverters. Set then remains on - Green LED.

    Reconnected both 24v cables, and monitored "power on" signal back to PSU. When the Inverter momentarily lights the "power on" signal drops to tell the PSU to switch off main supplies and go back to standby. Protection rail stays up during the cycling. (dont think the 24v rail uses the main protection system as per other rails)

    Any ideas?

    Cheers,

    Matt
    Tags: None
    #2
    Re: Toshiba 42WLT68 - Standby Issue

    do the back lights come on or stay on?

    Comment

      #3
      Re: Toshiba 42WLT68 - Standby Issue

      Hi,

      The lights come on for like 1/10th second then go off!

      Cheers,

      Matt

      Comment

        #4
        Re: Toshiba 42WLT68 - Standby Issue

        maybe try unplug bl-on cable from main board or power supply, see if back lights stay on.

        Comment

          #5
          Re: Toshiba 42WLT68 - Standby Issue

          You likely have a fault on your inverter board, you can test for common faults with your multimeter, I marked up the picture below for the main tests, first all fuses should be under 1 ohm. If you find an open fuse then you likely have one or more fets shorted in that area. If all fuses are good then fets are probably ok and you can test the primary of each transformer, as I recall they should be around 900 ohms, they need to be very close to each other to function properly if you find one that is more than 50 ohms or so out of compliance with the rest it can cause it not to function.
          Attached Files
          Liberating magic smoke one part at a time

          Comment

            #6
            Re: Toshiba 42WLT68 - Standby Issue

            "If all fuses are good then fets are probably ok and you can test the primary of each transformer, as I recall they should be around 900 ohms,"
            You mean Secondary, the primary will have very low DCR.
            Never stop learning
            Basic LCD TV and Monitor troubleshooting guides.
            http://www.badcaps.net/forum/showthr...956#post305956

            Voltage Regulator (LDO) testing:
            http://www.badcaps.net/forum/showthr...999#post300999

            Inverter testing using old CFL:
            http://www.badcaps.net/forum/showthr...er+testing+cfl

            Tear down pictures : Hit the ">" Show Albums and stories" on the left side
            http://s807.photobucket.com/user/budm/library/

            TV Factory reset codes listing:
            http://www.badcaps.net/forum/showthread.php?t=24809

            Comment

              #7
              Re: Toshiba 42WLT68 - Standby Issue

              Yes of course budm you are correct secondaries are around 900 ohms, my bad. PicWhiz as budm pointed out primaries will be low resistance.
              Liberating magic smoke one part at a time

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