lg 50pg30

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  • gdawg
    Senior Member
    • Sep 2012
    • 170
    • USA

    #1

    lg 50pg30

    Just wanted to start off by saying what a great forum this is. Fixed a lot of tv's just by reading. Ok, I have a 50pg30 lg that I am having trouble diagnosing. Sorry my camera is down so cant post any pictures. If I power up the tv it stays on and the panel primes but no display. I have all the right voltages Va, Vs, Vsc. If I disconnect the upper buffer, then the lower part of the screen will display vertical lines in bands and they change in size and color depending on what input, menu, channel, volume I push on the remote. If I put the upper buffer back on, it goes back to no display at all. I thought about buying an upper buffer, but I am concerned it may be the y sustain. I dont have a scope so I thought I would ask for anybodys help. I also checked the transistors on the heat sinks and one group of transistors read Vs voltage, the other group flashes over load on my meter.
  • MagicSmoke
    Badcaps Veteran
    • Feb 2011
    • 275
    • USA

    #2
    Re: lg 50pg30

    Test upper buffer as shown here https://www.youtube.com/watch?v=51SZsfH60EY

    Then test bottom just to be sure. If they test OK them Y sus is suspect.

    Comment

    • gdawg
      Senior Member
      • Sep 2012
      • 170
      • USA

      #3
      Re: lg 50pg30

      Thanks for the reply. I wish my camera was up and I might have to wait till it is. With an ohmeter the buffers check the same. These have the two tabs that stick out of the buffers and plug into the sustain. It has a big pad for grounds and a bunch of smaller pads. The black probe on the ground and the red on the smaller pads shows every other as a ground, I saw a post before from tom66 and he mentioned something about odd even.. I thought maybe thats why every other pad is a ground, but both upper and lower test the same, The pads that read are in the mega ohm range.

      Comment

      • gdawg
        Senior Member
        • Sep 2012
        • 170
        • USA

        #4
        Re: lg 50pg30

        I think I have a picture of the buffer. I never put attachments before but I guess it worked. I was swaying toward the sustain board but it was a little weird how it responded by removing the upper buffer
        Attached Files
        Last edited by gdawg; 01-02-2015, 06:26 PM.

        Comment

        • gdawg
          Senior Member
          • Sep 2012
          • 170
          • USA

          #5
          Re: lg 50pg30

          I tried to edit but dont know if it woked
          Attached Files

          Comment

          • gdawg
            Senior Member
            • Sep 2012
            • 170
            • USA

            #6
            Re: lg 50pg30

            Just an update- I took a chance and replaced the upper buffer and had a good picture on the top half but had the lower half had horizontal lines like every other line. I thought it was the ribbons and reseated them numerous times and had no change. So off to find a lower buffer and hope it works. This is a 1080p plasma so the top half looked great.

            Comment

            • pk7tanner
              Senior Member
              • Apr 2013
              • 98
              • United States

              #7
              Re: lg 50pg30

              Consider yourself lucky. Mine had a cascade failure when the buffer went it took down the ysus, which in turn took out the zsus. Needless to say, I never fixed it.

              Comment

              • gdawg
                Senior Member
                • Sep 2012
                • 170
                • USA

                #8
                Re: lg 50pg30

                Just a reply. replaced the lower and picture was great. After testing all the inputs found I had no digital audio thru hdmi or optical. So looks like main board problem. I get audio for about 10 seconds and then gone. Think I will sell it as is. All analog audio works fine. I have about $250.00 into the tv and its maybe worth that much. I guess chaulk it up to experience

                Comment

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