Swedx LCD XV1-19TVW - screen flash loop

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  • ocf
    Senior Member
    • Jun 2016
    • 157
    • UK

    #1

    Swedx LCD XV1-19TVW - screen flash loop

    A friend gave me this TV to look at, it recently started exhibiting an issue, when switched on it appears to be stuck in some sort of burn in mode. The screen flashes in a loop between black, white and then RGB Stripes going from dark to light showing across the screen.

    It definitely appears to be a test or burn in mode as there are no artifacts or other issues showing on the screen.

    TV takes 12v DC external power

    There were a few burst 220uf caps on the mainboard that I replaced but this didn't make any difference.

    I cant find any schematics on the board or service manual, there are also no replacement boards form the usual sources.

    Interesting thing to note, when I heated the board with a hot air gun and powered the TV on it did not show the colour loop and started up ok, I got the swedx splash screen and the TV accepted commands from the remote. After 10 seconds of staying on it immediately went back to the flashing burn in mode. Definitley something faulty on the mainboard, what would be affected by heat like this? Do EEPROM chips only react well to cold?

    Any advice on what to check next? I have a good grounding in reading schematics and would consider myself far from a beginner when it comes to electronics, throw some ideas at me!

    thanks in advance

    OCF
    Last edited by ocf; 07-14-2016, 02:30 PM. Reason: bad title
  • ozzy214
    Badcaps Veteran
    • Nov 2013
    • 319
    • usa

    #2
    Re: Swedx LCD XV1-19TVW - screen flash loop

    Sounds like you need to reflow the mainboard. Heating it up may have cleaned up some broken solder joints.

    Comment

    • ReeceyBurger123
      Never Give Up !
      • May 2014
      • 7325
      • Britain

      #3
      Re: Swedx LCD XV1-19TVW - screen flash loop

      Sounds like a faulty regulator, have you tested them ?
      Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

      https://www.facebook.com/Telford-Tel...7894576335359/

      Comment

      • ocf
        Senior Member
        • Jun 2016
        • 157
        • UK

        #4
        Re: Swedx LCD XV1-19TVW - screen flash loop

        Originally posted by ReeceyBurger123
        Sounds like a faulty regulator, have you tested them ?
        No I haven't done any checks on these, I'm not great at picking out parts and testing without a schematic.

        If I post an image of the board can you point out the voltage regulators.

        All the best

        OCF

        Comment

        • ocf
          Senior Member
          • Jun 2016
          • 157
          • UK

          #5
          Re: Swedx LCD XV1-19TVW - screen flash loop

          Originally posted by ozzy214
          Sounds like you need to reflow the mainboard. Heating it up may have cleaned up some broken solder joints.
          I'm quite sure that the board didn't get close to any temp that would allow solder to melt. Board probably got about 60-80C max.

          I have an SMD hot air station on the way which should help me narrow down the issue as I could heat individual parts.

          Thinking to start with the voltage regulators as suggested by ReeceyBurger123

          Comment

          • ocf
            Senior Member
            • Jun 2016
            • 157
            • UK

            #6
            Re: Swedx LCD XV1-19TVW - screen flash loop

            Originally posted by ReeceyBurger123
            Sounds like a faulty regulator, have you tested them ?
            I've located all the voltage regulators on the board they are all CX1084 and CX1117 and all labeled ADJ. I have taken a look at data sheets for the chip and I cant work out what voltge the Adjustable regulators should be outputting. Does the output voltage depend on the resistor used between Adj and Output terminls or do I have this all wrong

            Voltage regulator part numbers I found on the board -

            CX1084 ADJ 7226Y
            CX1084 ADJ 7265Y
            CX1117 ADJ 7382Y


            Any advice welcome, would pictures help?

            Comment

            • ocf
              Senior Member
              • Jun 2016
              • 157
              • UK

              #7
              Re: Swedx LCD XV1-19TVW - screen flash loop

              pics, most of V Regulators are on right hand side of board if that helps

              https://postimg.org/image/tmomz5h4n/
              https://postimg.org/image/ipnbadud3/
              https://postimg.org/image/ryphki393/

              Comment

              • ocf
                Senior Member
                • Jun 2016
                • 157
                • UK

                #8
                Re: Swedx LCD XV1-19TVW - screen flash loop

                One of the regulators is showing 0.15v on input pin, 0.9 on gnd and 2v on output, this seems wrong?

                Dont vregs take a minimum voltage above the required output voltage to drive the regulator itself, so if this has 0.15v and 2v output surely its problematic?

                I'm spitballing here, just trying to make sense with my limited knowledge
                Last edited by ocf; 07-15-2016, 06:10 AM.

                Comment

                • ocf
                  Senior Member
                  • Jun 2016
                  • 157
                  • UK

                  #9
                  Re: Swedx LCD XV1-19TVW - screen flash loop

                  any further help please?

                  Comment

                  • ReeceyBurger123
                    Never Give Up !
                    • May 2014
                    • 7325
                    • Britain

                    #10
                    Re: Swedx LCD XV1-19TVW - screen flash loop

                    Ok that reg you tested is good, the tab is normally the output on them. What about the others ?
                    Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

                    https://www.facebook.com/Telford-Tel...7894576335359/

                    Comment

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