LG50PA6500 No Display, Suspected PSU

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  • bboyzell
    Member
    • Aug 2014
    • 20
    • Australia

    #1

    LG50PA6500 No Display, Suspected PSU

    Hi All

    I have recently been given a LG 50PA6500 50" Plasma with the following problems
    • No Display, Or backlight
    • Audio is Ok, So i have been told by old owner


    Possible Symptoms/Things iv noticed
    • Noticable One off Click/Pop From the PSU When Power is plugged in
    • Plasma instantly Powers Up, Doesnt go directly to Standbye
    • Hit the Power Button and goes to Stand-bye
    • CTRL Panel is Blinking Different Green Codes (Anyone have a guide for these,no luck finding on so far)
    • Input Board has a Single LED glowing red.


    Thinkings i have Checked so Far
    • Run Screen With YSUS/VSUS Disconnect
    • Preempted it being YSUS, so brought another one, this didnt make any difference, Actually the New Ysus Was Louder (buzzing)
    • VA and VS both spot on with readings, VA-55 VS-205
    • Inspected Top PSU FUSE F801 Not Blown, Constant Voltage of 280 (V-500)
    • Inspected the Lower PSU Fuse F101 Not Blown, but Extermely low Voltage of 0.03 jumping to 0.13 with the Multimeter Set at (V-20)


    Tools i have avalible are a Decent desolder/solder station and a Multi-meter

    With the last Two Items on the list, Im thinking that the Bottom Fuse F101 Near the AC Plug, is fine but something that its connecting to is playing up but im unsure what.

    EAX64276501 is the PSU thats in this system

    Anyone have a suggestion of what i could test to see whats giving me low voltage to the F101 Fuse
    Attached Files
  • chrismurphy
    Badcaps Veteran
    • May 2014
    • 251
    • australia

    #2
    Re: LG50PA6500 No Display, Suspected PSU

    [QUOTE=bboyzell;477646]Hi All

    I have recently been given a LG 50PA6500 50" Plasma with the following problems[LIST][*]No Display, Or backlight
    Plasma does not have backlights
    [*]VA and VS both spot on with readings, VA-55 VS-205
    Then the power supply is working and the fuse has not blown otherwise there would be no voltage for the z and y sus boards

    Dont forget the voltage on the fuse is 240 AC

    Comment

    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK

      #3
      Re: LG50PA6500 No Display, Suspected PSU

      Check the Vsc and -Vy voltages on the Y-sustain board....

      I hope it's not another bad LG plasma panel killing the buffer 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

      • bboyzell
        Member
        • Aug 2014
        • 20
        • Australia

        #4
        Re: LG50PA6500 No Display, Suspected PSU

        Originally posted by tom66
        Check the Vsc and -Vy voltages on the Y-sustain board....
        I have found VSC and -VY Resistors on the ysus, is that what you are refering to?

        Am i able to measure it with my Multimeter?
        I own the following one
        Attached Files
        Last edited by bboyzell; 08-27-2014, 01:05 AM.

        Comment

        • tom66
          EVs Rule
          • Apr 2011
          • 32560
          • UK

          #5
          Re: LG50PA6500 No Display, Suspected PSU

          Yes, measure across them on the 200V DC range.
          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

          • bboyzell
            Member
            • Aug 2014
            • 20
            • Australia

            #6
            Re: LG50PA6500 No Display, Suspected PSU

            Originally posted by tom66
            Yes, measure across them on the 200V DC range.
            Thanks

            "VSC" Is giving me a constant Variable Reading of between 03.3 to 00.0

            "-VY" Is Giving me a Reading that is constantly switching With Value similar to the following 14.x - 22.x - 34.x(Highest seen)

            Just Came across this thread again.
            LG 50PA6500 - Sound no Picture
            https://www.badcaps.net/forum/showthread.php?t=30067
            Last edited by bboyzell; 08-27-2014, 01:25 AM.

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK

              #7
              Re: LG50PA6500 No Display, Suspected PSU

              OK, that's not a great sign to be honest. Can you remove the top Y-buffer board; this is the top most board connected to the Y-sustain. Note, you'll have to unscrew the board and pull it out from the white connection blocks. You don't have to remove the orange ribbon cables.

              Then, do you get half an image?
              Do the -Vy and Vsc stabilise?
              Last edited by tom66; 08-27-2014, 03:04 AM.
              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

              • bboyzell
                Member
                • Aug 2014
                • 20
                • Australia

                #8
                Re: LG50PA6500 No Display, Suspected PSU

                Originally posted by tom66
                Then, do you get half an image?
                Do the -Vy and Vsc stabilise?
                Ok, Removed the Upper Buffer Board.
                I am now getting display on the lower half of the Screen

                -VY is Running at a constant 184.x
                VSC is running at a Constant 145.x

                I will visibly inspect the top buffer board and see if i can see anything foul

                Comment

                • bboyzell
                  Member
                  • Aug 2014
                  • 20
                  • Australia

                  #9
                  Re: LG50PA6500 No Display, Suspected PSU

                  I have now just tested out the Upper Buffer Board
                  I tried it the following ways.

                  No Lower Buffer Board + Upper Buffer Board + Panel Connected = Poor Voltage
                  No Lower Buffer Board + Upper Buffer Board + Panel Not Connected = Poor Voltage

                  My Conclusion if a "Faulty Upper Buffer Board" Sadley it seems to be the more costly Than most the the other boards on the Plasma

                  Proceeding to Do this
                  Testing Y-Buffer Board for short Circuits
                  https://www.youtube.com/watch?v=51SZ...Y&noredirect=1

                  Also Note:

                  I have Inspected All 4 of the Ribbon Cables that connect to the upper buffer, all look to be in good condition
                  Last edited by bboyzell; 08-28-2014, 12:27 AM.

                  Comment

                  • tom66
                    EVs Rule
                    • Apr 2011
                    • 32560
                    • UK

                    #10
                    Re: LG50PA6500 No Display, Suspected PSU

                    Your panel is bad. 99% guarantee it. Sorry.
                    The tear is VERY hard to see. You have to take the TV frame off to be sure.

                    Same TV, UK spec model (50PA650T) ended up scrapping it due to bad panel.



                    That tiny dimple on the right of the ribbon? That's where they tear. That seems to kill the top buffer boards.
                    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

                    • bboyzell
                      Member
                      • Aug 2014
                      • 20
                      • Australia

                      #11
                      Re: LG50PA6500 No Display, Suspected PSU

                      Originally posted by tom66
                      Your panel is bad. 99% guarantee it. Sorry.
                      The tear is VERY hard to see. You have to take the TV frame off to be sure.

                      Same TV, UK spec model (50PA650T) ended up scrapping it due to bad panel.
                      Upon a Closer inspection, i think i have found a Crease on the ribbon cable nearest to the top of the Plasma, it looks to almost be at a right angle compared to the rest of the smooth flowing cable

                      I take it them its not worth procedding with trying to fix this unit, replacing the upper buffer would just result in the new one being shorted out by the Panel (wasting $70+)

                      Thanks alot for you time & Input Helping me with this Tom!
                      Attached Files

                      Comment

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