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Sanyo DP50749 Plasma Powers on, no video, then powers off, repeats

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    #1

    Sanyo DP50749 Plasma Powers on, no video, then powers off, repeats

    I'm working on this incredibly smelly Sanyo Plasma and am trying to find out why it isn't working quite right. What happens right now is the power indicator will light up, the set will turn on, the screen will light up, and then the screen will power off after a couple seconds (nothing ever shows up on the screen) before it clicks off. Afterwards, it'll start the process again and try indefinitely to get fully powered up, even though it never gets there.

    In the time that the panel does spend powered on, Vs and Va look good.

    Any ideas as to where to start on this one?
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    #2
    Re: Sanyo DP50749 Plasma Powers on, no video, then powers off, repeats

    From your pics looks as if y and x (left and right from rear) have individual connections from power board so disconnect first one and if no joy with vs staying on then disconnect the other. Not sure how protection circuit works on this set. Main board seems ok in basic operation. Why the smell ? what and where followed by why.

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      #3
      Re: Sanyo DP50749 Plasma Powers on, no video, then powers off, repeats

      heavy smoker. It is posible the caps are bad in the power supply even though they are not bulged, If they are bad the power supply just can't maintain the voltage.

      I just repaired a vizio power supply and the caps on the +5 looked just fine, even the voltage measured 5 volts but as soon as the tv was turend on it would shut down again
      it had 2 1000uf/10v completely open

      Comment

        #4
        Foggy, smokey

        Originally posted by maxvalutech View Post
        From your pics looks as if y and x (left and right from rear) have individual connections from power board so disconnect first one and if no joy with vs staying on then disconnect the other. Not sure how protection circuit works on this set. Main board seems ok in basic operation.
        Same results with either one disconnected.

        Originally posted by maxvalutech View Post
        Why the smell ? what and where followed by why.
        Tobacco; everywhere; owner must have smoked around it a lot.

        Originally posted by R_J View Post
        heavy smoker. It is posible the caps are bad in the power supply even though they are not bulged, If they are bad the power supply just can't maintain the voltage.

        I just repaired a vizio power supply and the caps on the +5 looked just fine, even the voltage measured 5 volts but as soon as the tv was turend on it would shut down again
        it had 2 1000uf/10v completely open
        That sounds reasonable. Are they wired in parallel or can I test them using my capacitor tester without having to desolder?

        Comment

          #5
          Re: Sanyo DP50749 Plasma Powers on, no video, then powers off, repeats

          Yes it looks like it was in the middle of the tip for a year. Samsung boards? Suggest read Samsung Tech Talk vol 4 no 11. (Google it up) testing methods changed 2010. Of course you have cleaned everything up including connectors etc etc.

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            #6
            Re: Sanyo DP50749 Plasma Powers on, no video, then powers off, repeats

            Just repaired one of these. Disconnect main board . Behind main is controller board there is 4 pins in jumper block. Short all 4 I just used screw in middle . Jumper pws-on the psu and plug in. Will show test pattern if the rest of boards are good.

            My tv it was ic1630 which is right by big silver box on main board. Pin 2 didn't have 5v.

            Comment

              #7
              Thanks for the tip!

              Originally posted by microvibe View Post
              Just repaired one of these. Disconnect main board . Behind main is controller board there is 4 pins in jumper block. Short all 4 I just used screw in middle . Jumper pws-on the psu and plug in. Will show test pattern if the rest of boards are good.

              My tv it was ic1630 which is right by big silver box on main board. Pin 2 didn't have 5v.
              Right on! After doing that, the panel immediately came to life displaying the test patterns. Looks like it'll be time to find a mainboard for this thing.

              Comment

                #8
                Fixed!

                Mainboard replacement fixed it!

                Comment

                  #9
                  Re: Sanyo DP50749 Plasma Powers on, no video, then powers off, repeats

                  FYI I just got one of these. The problem on the main board is corrupt IC 5750A flash nand under shield. Available on ebay
                  I assume no responsibility for any stupid suggestions I might post.

                  Comment

                    #10
                    Aftermath; epilogue

                    Originally posted by dskall View Post
                    FYI I just got one of these. The problem on the main board is corrupt IC 5750A flash nand under shield. Available on ebay
                    Good to know. Any ideas as to why they fail so often?

                    Comment

                      #11
                      Re: Sanyo DP50749 Plasma Powers on, no video, then powers off, repeats

                      Don't know this one took eight years.
                      I assume no responsibility for any stupid suggestions I might post.

                      Comment

                        #12
                        That'd be my guess

                        Originally posted by dskall View Post
                        Don't know this one took eight years.
                        That'd be my guess unless somebody fixed the same problem in between then and now.

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