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Philips 42PFL4606 No Backlight

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    Philips 42PFL4606 No Backlight

    Hello Guys

    This time ive got an 4606 again but with totally different issue
    When powering on the unit you see the logo for an few second and after that only with an flashlight, ive tested the tv with an 47 SMPS and the all is working fine, So problem must be located in the 42 SMPS.

    When measuring ENA and DIM i get 4,9V and 2,6V this while the tv is powered on.
    Also between PIN 17 and 22 iam getting an High ohm reading 83K.
    Which section do i need to check ?
    Attached Files

    #2
    Re: Philips 42PFL4606 No Backlight

    Changed IC801 (UBA2071AT) no difference

    Comment


      #3
      Re: Philips 42PFL4606 No Backlight

      Iam getting the 395V on the inverter side
      Attached Files

      Comment


        #4
        Re: Philips 42PFL4606 No Backlight

        Does the VDD on pin 16 of IC801 stay present after the backlights cut off?
        The 395VDC PFC Boost Voltage also stay when the backlights cut off?
        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


          #5
          Re: Philips 42PFL4606 No Backlight

          hello Budm,

          the pfc 395v is present even when BL cut off,
          on pin 16 ive an stable 12v

          Comment


            #6
            Re: Philips 42PFL4606 No Backlight

            Check the resistance of the two high Voltage windings (PIN 5 & 6, 7 & 8) of the inverter transformer T803 and also compare it to the working 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


              #7
              Re: Philips 42PFL4606 No Backlight

              Hello Budm

              Both boards measure an 12ohm between pin 5&6 and 7&8

              Comment


                #8
                Re: Philips 42PFL4606 No Backlight

                Hi i did some very intensive research i measured all resistors in the Inverter part.
                Where needed i desoldered them of the board to measure.
                iam not sure how to measure the ceramic capacitors ? any ideas how to do that on a good manor
                Attached Files
                Last edited by trunks81; 10-11-2020, 04:37 AM.

                Comment


                  #9
                  Re: Philips 42PFL4606 No Backlight

                  I would have thought that R801 and R892 resistance to be identical.
                  Have you check C802. These high voltage capacitors in series with transformers do tend to fail.
                  Willing to help but I'm no expert.

                  Comment


                    #10
                    Re: Philips 42PFL4606 No Backlight

                    Hello

                    C802 is checking out oke, Desoldered it an did an measurement it reading 330nf
                    Did you mean R829 ? and R801

                    Comment


                      #11
                      Re: Philips 42PFL4606 No Backlight

                      which section does the checking for the inverter

                      Comment


                        #12
                        Re: Philips 42PFL4606 No Backlight

                        Who has an idea ? with the spare board the tv is running! So CCFL tubes should be fine

                        Comment


                          #13
                          Re: Philips 42PFL4606 No Backlight

                          What is the Voltage on EN pin 15?
                          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


                            #14
                            Re: Philips 42PFL4606 No Backlight

                            Ive got 5.8V on EN pin 15
                            Last edited by trunks81; 10-22-2020, 12:25 PM.

                            Comment


                              #15
                              Re: Philips 42PFL4606 No Backlight

                              What does that voltage mean ? while measering on the other board i accendently made an short so for now i can not use tjat board

                              Comment


                                #16
                                Re: Philips 42PFL4606 No Backlight

                                That means the Backlights on command is still present on the EN pin but the IC is in protection mode some how.
                                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: Philips 42PFL4606 No Backlight

                                  mmh difficult now i need to find out why

                                  Comment

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