Panasonic th-42px500u random lockup

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  • freakaftr8
    Badcaps Legend
    • Oct 2012
    • 3743
    • USA

    #1

    Panasonic th-42px500u random lockup

    Here's an interesting one that has me puzzled.
    I picked up this unit a month ago. Symptoms he told me are tv worked fine than all the sudden controls would lock up. Only thing that works is power. On the remote and on the panel. All other controls are frozen. Nothing works.

    Now if I'm on hdmi or any other port it's still working at the volume it was at. But controls locked up. Now if I let it sit a few days the osd and controls work for up to 10 minutes. Then go out. If I power down and back on the input osd is there but now frozen on the screen. The longer on and throught power cycles then eventually there is no osd. It just goes to the last used port at the last level of volume. Picture is still perfect but just no controls.

    Now the kicker is after about three power cycles after being plugged in while this symptom is occurring when I power it off there is a 20 blink error code. Now I've done my homework in this issue. Internet says it was an issue on some and a firmware update will fix it. Well it didn't. And a replacement dg board also didn't fix it. Now I'm thinking dt board. When the dt board is pulled the osd never works neither do the controls.

    This set sat for two months or more. And the first time I powered it up I didn't think it actually had a problem as the osd worked for like a day. It seems to be usage sensitive that makes me think cold solder joint on the dt or capacitor issue.

    Your thoughts? Thanks guys
    Last edited by freakaftr8; 10-17-2012, 12:33 AM.
    Did I leave the soldering iron on?
  • freakaftr8
    Badcaps Legend
    • Oct 2012
    • 3743
    • USA

    #2
    Re: Panasonic th-42px500u random lockup

    On this issue I'm having. More research points to the dt board on this. What's the formula for testing silver lytic smd caps when they are still soldered to the board? I get really high and low readings when they are still installed.
    Did I leave the soldering iron on?

    Comment

    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK

      #3
      Re: Panasonic th-42px500u random lockup

      The fact that power works tells you something important. That's usually a separate signal and not treated like a normal button.

      I've seen plenty of TVs that don't register any button input when two or more buttons are depressed.

      Is it possible that a button is intermittently getting stuck?
      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

      • freakaftr8
        Badcaps Legend
        • Oct 2012
        • 3743
        • USA

        #4
        Re: Panasonic th-42px500u random lockup

        No I ruled that out. There was a moderately big issue with the px5 series 8th gen sets with this issue. It was either corrected with a firmware update which I tried and didn't work or just replacing the dt board. That always cured the issue. Something in the lines of whatever circuit on the dt board is in charge of handling the menus and controls goes wonky. But it's not heat related. I've tried heat and freeze. Neither correct it.
        Did I leave the soldering iron on?

        Comment

        • freakaftr8
          Badcaps Legend
          • Oct 2012
          • 3743
          • USA

          #5
          Re: Panasonic th-42px500u random lockup

          However right now on eBay there's a board for the th-42px50u. Mines a th-42px500u. Cosmetically the sets are dofferent and on the dt board they have it is the same part number but there are some components that are not on the board that mine have. I've already tried replacing the dg board and the p board since i had an wxtra one. This didnt help.
          Did I leave the soldering iron on?

          Comment

          • tom66
            EVs Rule
            • Apr 2011
            • 32560
            • UK

            #6
            Re: Panasonic th-42px500u random lockup

            I doubt the DT would be compatible if it has different components...
            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

            • freakaftr8
              Badcaps Legend
              • Oct 2012
              • 3743
              • USA

              #7
              Re: Panasonic th-42px500u random lockup

              True. If a silicon ic went south then my understanding is that the is the the function of rhat ic will not work at all. Ever. Right? Something feeding this circuit has to be dropping off in voltage. Anyone have any info on a tnpa3524 dt board and its component functions? There is a lot of components on this little board and just trying to get the exact location of the ic that handles user interface.
              Did I leave the soldering iron on?

              Comment

              • tom66
                EVs Rule
                • Apr 2011
                • 32560
                • UK

                #8
                Re: Panasonic th-42px500u random lockup

                Originally posted by freakaftr8
                True. If a silicon ic went south then my understanding is that the is the the function of rhat ic will not work at all. Ever. Right? Something feeding this circuit has to be dropping off in voltage. Anyone have any info on a tnpa3524 dt board and its component functions? There is a lot of components on this little board and just trying to get the exact location of the ic that handles user interface.
                Nope, silicon can fail intermittently, too.

                Very common with voltage regulators.

                On a newer Panasonic, everything will be handled by that large SoC (system on a chip) in the middle of the board.

                On an older one, there will sometimes be a "sub micom" or "main micom" for handling the remote control functions.
                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

                • freakaftr8
                  Badcaps Legend
                  • Oct 2012
                  • 3743
                  • USA

                  #9
                  Re: Panasonic th-42px500u random lockup

                  Originally posted by tom66
                  Nope, silicon can fail intermittently, too.

                  Very common with voltage regulators.

                  On a newer Panasonic, everything will be handled by that large SoC (system on a chip) in the middle of the board.

                  On an older one, there will sometimes be a "sub micom" or "main micom" for handling the remote control functions.
                  That's really good info to know. Thanks!
                  Did I leave the soldering iron on?

                  Comment

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