Philips 42PFL4606 No Backlight

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  • trunks81
    Badcaps Veteran
    • May 2020
    • 265
    • Nederland
    #1

    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
    Tags: None
    • trunks81
      Badcaps Veteran
      • May 2020
      • 265
      • Nederland
      #2
      Re: Philips 42PFL4606 No Backlight

      Changed IC801 (UBA2071AT) no difference

        Comment

        • trunks81
          Badcaps Veteran
          • May 2020
          • 265
          • Nederland
          #3
          Re: Philips 42PFL4606 No Backlight

          Iam getting the 395V on the inverter side
          Attached Files

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #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

                • trunks81
                  Badcaps Veteran
                  • May 2020
                  • 265
                  • Nederland
                  #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

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA
                      #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

                        • trunks81
                          Badcaps Veteran
                          • May 2020
                          • 265
                          • Nederland
                          #7
                          Re: Philips 42PFL4606 No Backlight

                          Hello Budm

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

                            Comment

                            • trunks81
                              Badcaps Veteran
                              • May 2020
                              • 265
                              • Nederland
                              #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

                                • dick_barton
                                  Badcaps Legend
                                  • Aug 2015
                                  • 6642
                                  • Wales
                                  #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

                                    • trunks81
                                      Badcaps Veteran
                                      • May 2020
                                      • 265
                                      • Nederland
                                      #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

                                        • trunks81
                                          Badcaps Veteran
                                          • May 2020
                                          • 265
                                          • Nederland
                                          #11
                                          Re: Philips 42PFL4606 No Backlight

                                          which section does the checking for the inverter

                                            Comment

                                            • trunks81
                                              Badcaps Veteran
                                              • May 2020
                                              • 265
                                              • Nederland
                                              #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

                                                • budm
                                                  Badcaps Legend
                                                  • Feb 2010
                                                  • 40746
                                                  • USA
                                                  #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

                                                    • trunks81
                                                      Badcaps Veteran
                                                      • May 2020
                                                      • 265
                                                      • Nederland
                                                      #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

                                                        • trunks81
                                                          Badcaps Veteran
                                                          • May 2020
                                                          • 265
                                                          • Nederland
                                                          #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

                                                            • budm
                                                              Badcaps Legend
                                                              • Feb 2010
                                                              • 40746
                                                              • USA
                                                              #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

                                                                • trunks81
                                                                  Badcaps Veteran
                                                                  • May 2020
                                                                  • 265
                                                                  • Nederland
                                                                  #17
                                                                  Re: Philips 42PFL4606 No Backlight

                                                                  mmh difficult now i need to find out why

                                                                    Comment

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