LG 50PK550 - Screen flash, then gray

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  • L33TN00B
    New Member
    • Jan 2014
    • 5
    • South Africa
    #1

    LG 50PK550 - Screen flash, then gray

    Hi there,

    I have a LG 50PK550 Plasma. Last week, the TV suddenly powered off while playing music from my RASPBMC setup. I disconnected the TV from power and reconnected, tried to power up....
    The screen flashed for a second then went gray and stayed like that. The remote and front panel controls are unresponsive.

    I removed the back cover and tested the SMPS's fuses, diodes and power resistors, which all work. Then I tried the AUTO_GEN test pattern, with the LVDS cable disonnected from the mainboard.
    The test pattern worked!

    Does this mean that the mainboard is defintely the culprit?
    I've read some posts on these forums saying that a bad firmware flash could be the problem aswell. I will try using as null modem cable this evening to see if it is indeed the case.
    Another thing I'd like to try is resolder the BGA chip and the surrounding components on the mainboard.

    Please let me know if my troubleshooting has been correct so far...

    Thanks
    Tags: None
    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK
      #2
      Re: LG 50PK550 - Screen flash, then gray

      Yes, you have a bad main board. This is a common fault on LG's premium plasmas.
      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

        • L33TN00B
          New Member
          • Jan 2014
          • 5
          • South Africa
          #3
          Re: LG 50PK550 - Screen flash, then gray

          Ok, thanks, I'm going to try see if I can get into the board using the serial port and using Putty to see if overwriting the firmware would work. How would one overwrite or flash the firmware using the serial port? What are the commands I'd use?

            Comment

            • anotherdude
              Badcaps Veteran
              • Feb 2013
              • 488
              • uk
              #4
              Re: LG 50PK550 - Screen flash, then gray

              Originally posted by L33TN00B
              Ok, thanks, I'm going to try see if I can get into the board using the serial port and using Putty to see if overwriting the firmware would work. How would one overwrite or flash the firmware using the serial port? What are the commands I'd use?
              check the service manual a lot of info about the service port is usually in there

                Comment

                • tom66
                  EVs Rule
                  • Apr 2011
                  • 32560
                  • UK
                  #5
                  Re: LG 50PK550 - Screen flash, then gray

                  The RS232 is mostly for control only, to allow you to remotely change channels or volume. There's possibly a limited service mode, but I wouldn't bet 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

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