Project 2: Panasonic TH-42PW4UZ green light on, nothing on screen

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  • johnboy1313
    Badcaps Legend
    • Nov 2012
    • 1959
    • USA

    #21
    Re: Project 2: Panasonic TH-42PW4UZ green light on, nothing on screen

    Are you lifting a leg of those FETs off of the board before testing?

    Comment

    • nintari
      Member
      • Jan 2013
      • 29
      • United States

      #22
      Re: Project 2: Panasonic TH-42PW4UZ green light on, nothing on screen

      Just now pulled one off to test it further

      Comment

      • nintari
        Member
        • Jan 2013
        • 29
        • United States

        #23
        Re: Project 2: Panasonic TH-42PW4UZ green light on, nothing on screen

        makes a bit more sense now (again it's all a learning process) with them off the board and explains why I wasn't getting what I should have when reading on testing.

        When I pulled the (for the heck of it one of the 2sk2993's) FET off (meter in diode mode)

        Black on drain red on source 453 reading

        black on drain red on gate OL hold for a second or two, move red back to source not removing black off drain you see the reading raise up slower back to 453 meaning it closed the gate correct?

        so should I pull all of the 2sk2993's off to test them? (going with tom's suggestion of those typically going bad)

        Comment

        • johnboy1313
          Badcaps Legend
          • Nov 2012
          • 1959
          • USA

          #24
          Re: Project 2: Panasonic TH-42PW4UZ green light on, nothing on screen

          To tell the truth, randtek and Tom have way more experience than I do. If you search my posts you will see where I fixed a th-42pz77u with a bad FET.

          Comment

          • nintari
            Member
            • Jan 2013
            • 29
            • United States

            #25
            Re: Project 2: Panasonic TH-42PW4UZ green light on, nothing on screen

            lifted both legs (source and gate) and tested, each one appears to be good

            Testing used:

            meter set to diode

            Black on Drain at all times

            put red on source get reading (all about 453) the put red on gate all read OL, put red back on source hear tone reading goes up showing gate closed and back to 453 or about that.

            tested the FS7VS 14a as well each showed ok with the above testing (assuming that testing was correct.

            Comment

            • nintari
              Member
              • Jan 2013
              • 29
              • United States

              #26
              Re: Project 2: Panasonic TH-42PW4UZ green light on, nothing on screen

              Walked away for a bit to try and clear my head.

              One off thing I noticed, I said earlier that the sc board led would not light up, but oddly when I went to take that board out for testing and removed the connector that supplies the vsus and vbk the led would light for a moment, plug back in it would light briefly again...

              Anyway went back on the service manual and started looking and missed one point asking me to check voltages on the dboard. On connector d6 pin 2 and 3 I should be getting 3.3V but I am only getting 1.8V

              But it doesn't say much past that such as where the 3.3v is supposed to be coming from.

              Trying to trace it out now and figure it out

              Comment

              • tom66
                EVs Rule
                • Apr 2011
                • 32560
                • UK

                #27
                Re: Project 2: Panasonic TH-42PW4UZ green light on, nothing on screen

                That LED lights up when the ERC circuit is working. The ERC circuit should develop approximately 65 to 100V across those red capacitors on the SC 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

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