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    37pfl7605h/12 power supply

    hello folks
    i recently bought a broken 37pfl7605h/12 TV
    the pre owner said it broke during watching tv. then he brought it to a technican and now i got it here. it seems like the fuse has taken out. guss there was some kind of shortcut? i couldnĀ“t find any topics for this type of power supply (p973a)
    maybe someone can tell me - what parts are the most common shortcuts... is it a good idea to just buy another fuse and set it on power ?
    any suggestions are more then welcome =)

    Just found this topic
    https://www.circuitsonline.net/forum/view/134865
    and i also have some burnt marks in this area.. guess this is the spot we are looking for ?!
    Attached Files
    Last edited by storexxm; 10-20-2020, 02:04 AM.

    #2
    Re: 37pfl7605h/12 power supply

    More details of the burnt area-
    Attached Files

    Comment


      #3
      Re: 37pfl7605h/12 power supply

      Has that blue capacitor burnt? If so that will need replacing. You would also need to check the two mosfets alongside.
      Attached Files
      Willing to help but I'm no expert.

      Comment


        #4
        Re: 37pfl7605h/12 power supply

        The fuse blew for a reason, don't just replace it. You've tested the components in the photo to see if any are shorted ? ?

        Comment


          #5
          Re: 37pfl7605h/12 power supply

          hello dick-
          i bought this tv from someone else.. and he told my a technican already changed a component...
          and this is the only area where obviosly something happened =)
          so this SHOULD be a good capacitor... but for sure if i buy new parts i can change it.
          but the real question is.. what caused a shortcut :/ i think its only one mosfet... and a diode. i am more a newbie.. so i measured only resistance in the circuit... no shortcut...
          L603 has a very low resistance...

          Comment


            #6
            Re: 37pfl7605h/12 power supply

            @ diif just q602 d602 (high)
            and L603 (low)

            Comment


              #7
              Re: 37pfl7605h/12 power supply

              Use you meter set to ohms and with the set discoonected from the mains supply check the 4 legs of the bridge rectifier.
              bridge rectifier legs 1 - 2 -3 - 4

              Test
              leg1 to 2, then to 3, then to 4
              leg 2 to 3 then to 4
              leg 3 to leg 4

              and what readings do you have in ohms
              Attached Files
              Willing to help but I'm no expert.

              Comment


                #8
                Re: 37pfl7605h/12 power supply

                1-2 98,5k then 130k
                1-3 109,5k then 115k
                1-4 15,05k then 15k

                2-3 2,11M
                2-4 96k then 135k

                3-4 146k

                but its changing.. !?
                are those values useful ? i measured the bridge on the board.. didnt solder it out-

                Comment


                  #9
                  Re: 37pfl7605h/12 power supply

                  The bridge rectifier looks OK with no short circuit. Sometimes when there is a major short circuit it can damage the bridge rectifier.
                  I would check the mosfets for short circuit and also test as many of the diodes as you can with the meter set to diode mode.
                  Willing to help but I'm no expert.

                  Comment


                    #10
                    Re: 37pfl7605h/12 power supply

                    Can we see good clear straight shots of the whole bottom side of the power supply board?
                    Never stop learning
                    Basic LCD TV and Monitor troubleshooting guides.
                    http://www.badcaps.net/forum/showthr...956#post305956

                    Voltage Regulator (LDO) testing:
                    http://www.badcaps.net/forum/showthr...999#post300999

                    Inverter testing using old CFL:
                    http://www.badcaps.net/forum/showthr...er+testing+cfl

                    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                    http://s807.photobucket.com/user/budm/library/

                    TV Factory reset codes listing:
                    http://www.badcaps.net/forum/showthread.php?t=24809

                    Comment


                      #11
                      Re: 37pfl7605h/12 power supply

                      For sure!
                      Attached Files

                      Comment


                        #12
                        Re: 37pfl7605h/12 power supply

                        What were the results when you checked those two mosfets on the heatsink alongside the blue capacitor.
                        What is written on that capacitor?
                        Willing to help but I'm no expert.

                        Comment


                          #13
                          Re: 37pfl7605h/12 power supply

                          The blue one says:
                          471k
                          1kv
                          Measured 15k-20k ohm

                          Mosfet Q602

                          1-2 28k
                          2-3 14k
                          1-3 9,5k

                          Diode D602

                          9,1k

                          L603

                          0,3 Ohm

                          D601

                          96k or 1,00M depends on + -

                          R613

                          0,3 Ohm

                          TH601

                          3,3 Ohm

                          Comment


                            #14
                            Re: 37pfl7605h/12 power supply

                            Those readings don't show a short circuit. There's a second bridge rectifier on the board which you can test as you did earlier.
                            Without a schematic it's hard to pin down any fault.
                            Willing to help but I'm no expert.

                            Comment


                              #15
                              Re: 37pfl7605h/12 power supply

                              I measured it already... no shortcut.. but can post values tomorrow.
                              What can happen when I short the missing fuse and look what happens... guess the right fuse will just blow away and I know as much as before... ^^

                              Comment


                                #16
                                Re: 37pfl7605h/12 power supply

                                1) Looking at the solder joints of the Blue Snubber cap for the PFC MOSFET, it does not looks like it was replaced, I do not see any flux residue at all, but then the pictures may not be showing it.

                                2) There is burnt solder joints in the transformer legs, you need to clean it up and re-solder them well. It looks like it has been arcing for quite a while.

                                3) Check those two MOSFET's to make sure they are not shorted.

                                4) You should also check all other solder joints real well too.
                                Attached Files
                                Never stop learning
                                Basic LCD TV and Monitor troubleshooting guides.
                                http://www.badcaps.net/forum/showthr...956#post305956

                                Voltage Regulator (LDO) testing:
                                http://www.badcaps.net/forum/showthr...999#post300999

                                Inverter testing using old CFL:
                                http://www.badcaps.net/forum/showthr...er+testing+cfl

                                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                http://s807.photobucket.com/user/budm/library/

                                TV Factory reset codes listing:
                                http://www.badcaps.net/forum/showthread.php?t=24809

                                Comment


                                  #17
                                  Re: 37pfl7605h/12 power supply

                                  Hello budm. Honestly when i looked at the board closer i had the same thought... looks like this condenser is original... but where are those burnt marks at the surface? From the yellow coil? Will check the two mosfets for a short. Didn't measure on the bottom side yet (shame)
                                  Thanks for your tips!!!
                                  Last edited by storexxm; 10-21-2020, 03:33 PM.

                                  Comment


                                    #18
                                    Re: 37pfl7605h/12 power supply

                                    Originally posted by storexxm View Post
                                    Hello budm. Honestly when i looked at the board closer i had the same thought... looks like this condenser is original... but where are those burnt marks at the surface? From the yellow coil? Will check the two mosfets for a short. Didn't measure on the bottom side yet (shame)
                                    Thanks for your tips!!!
                                    Make sure to look real close at those solder joints I marked in the picture.
                                    Never stop learning
                                    Basic LCD TV and Monitor troubleshooting guides.
                                    http://www.badcaps.net/forum/showthr...956#post305956

                                    Voltage Regulator (LDO) testing:
                                    http://www.badcaps.net/forum/showthr...999#post300999

                                    Inverter testing using old CFL:
                                    http://www.badcaps.net/forum/showthr...er+testing+cfl

                                    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                    http://s807.photobucket.com/user/budm/library/

                                    TV Factory reset codes listing:
                                    http://www.badcaps.net/forum/showthread.php?t=24809

                                    Comment


                                      #19
                                      Re: 37pfl7605h/12 power supply

                                      i will check them asap when home.
                                      Thank you !

                                      Comment


                                        #20
                                        Re: 37pfl7605h/12 power supply

                                        Ooops. Those solder joints u marked... BD401
                                        The two middle legs are a short !
                                        Thank u budm! Can this be the issue ?
                                        Part No. says: D4SBL20U and smaller letters 6304 afterwards.
                                        Is the D4SBL20U enough to look for a new one?
                                        Attached Files
                                        Last edited by storexxm; 10-22-2020, 09:26 AM.

                                        Comment

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