Philips Model 30PF9946D/37 Chassis # LC4.6U AA Backlight Problem

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  • foak56
    New Member
    • Jul 2014
    • 7
    • USA
    #1

    Philips Model 30PF9946D/37 Chassis # LC4.6U AA Backlight Problem

    Guys,

    When I power up my TV, the picture & sound are fine. After about 1-2 minutes, the screen goes black, yet I have sound on all channels but a black screen on all channels....

    I have replaced the the backlight inverter board to no avail. Same thing happens with new board in...actually a used board from ( www.myshoptvs.com )
    However, with their board in, the backlight flashes briefly & then goes dark after a couple of seconds on power up.....

    The power to the TV remains...green light is steady......

    Seems I have a power supply board issue or a problem with the standby/audio board...but I am only guessing.....

    I have access to the service manual for the chassis LC4.6U AA.....

    Any leads on troubleshooting would be greatly appreciated.....

    Thanks for your support in advance......

    Jeff
    Tags: None
    • foak56
      New Member
      • Jul 2014
      • 7
      • USA
      #2
      Re: Philips Model 30PF9946D/37 Chassis # LC4.6U AA Backlight Problem

      Any suggestions for a newbie....??? Not even....."take it to a repair shop" or "buy another TV"......lol......

      So anyway, i took it up to a local repair shop yesterday 2 blocks away....I went into the shop & asked as to the progress...he indicated it was my inverter board.....I indicated to him that I had replaced it with one bought off the internet, & that board performed worse....shut off after 2 seconds.....he argued that it may have been the wrong board I bought......I indicated it was the exact same board....proved it to him by showing it to him...he became quiet then about it being the inverter board and then said that he was ordering some parts for the power supply at the component level. So we will see what he comes up with.....his initial charge was $40 up front for troubleshooting....

      So does anyone have any suggestions. I know someone out there has time on these models...common problem from what I have seen here.....

      Any help or advice is greatly appreciated....

      Jeff

        Comment

        • stj
          Great Sage 齊天大聖
          • Dec 2009
          • 31183
          • Albion
          #3
          Re: Philips Model 30PF9946D/37 Chassis # LC4.6U AA Backlight Problem

          could be the backlight tubes.

          search a bit - there are lot's of threads about testing invertors and tubes.

            Comment

            • Ltank
              Badcaps Veteran
              • Jun 2013
              • 776
              • USA
              #4
              Re: Philips Model 30PF9946D/37 Chassis # LC4.6U AA Backlight Problem

              There should be a Backlight or inverter on comand from the main board. There also may be a Dim comand too. Check these while the set is working and after the backlights drop out. A bad bulb may be drawing too much current causing the power supply to shut down power to the inverter. Do you still have 24vdc to inverter?

                Comment

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