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

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  • SurrealMustard
    Badcaps Veteran
    • Jan 2015
    • 486
    • The United States of America
    #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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    • maxvalutech
      Badcaps Veteran
      • Dec 2014
      • 804
      • australia
      #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.

        Comment

        • R_J
          Badcaps Legend
          • Jun 2012
          • 9532
          • Canada
          #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

            • SurrealMustard
              Badcaps Veteran
              • Jan 2015
              • 486
              • The United States of America
              #4
              Foggy, smokey

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

              Originally posted by R_J
              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

                • maxvalutech
                  Badcaps Veteran
                  • Dec 2014
                  • 804
                  • australia
                  #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.

                    Comment

                    • microvibe
                      Badcaps Veteran
                      • Mar 2013
                      • 275
                      • canada
                      #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

                        • SurrealMustard
                          Badcaps Veteran
                          • Jan 2015
                          • 486
                          • The United States of America
                          #7
                          Thanks for the tip!

                          Originally posted by microvibe
                          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

                            • SurrealMustard
                              Badcaps Veteran
                              • Jan 2015
                              • 486
                              • The United States of America
                              #8
                              Fixed!

                              Mainboard replacement fixed it!

                                Comment

                                • dskall
                                  Badcaps Legend
                                  • Oct 2016
                                  • 2905
                                  • usa
                                  #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

                                    • SurrealMustard
                                      Badcaps Veteran
                                      • Jan 2015
                                      • 486
                                      • The United States of America
                                      #10
                                      Aftermath; epilogue

                                      Originally posted by dskall
                                      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

                                        • dskall
                                          Badcaps Legend
                                          • Oct 2016
                                          • 2905
                                          • usa
                                          #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

                                            • SurrealMustard
                                              Badcaps Veteran
                                              • Jan 2015
                                              • 486
                                              • The United States of America
                                              #12
                                              That'd be my guess

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

                                                Comment

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