Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

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  • jczarniak
    Senior Member
    • Oct 2015
    • 179
    • UK
    #1

    Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

    Hi,
    Got now Samsung LE40B652
    Backlight is on only for few seconds after switching TV on.
    Power supply:
    BN44-00264A
    Checked the voltage on the two filter/PFC 450V/82uF caps:
    Fluctuating between 382-402V when TV is ON
    Standby: 332-346V
    Not sure if that's what I should expect for this power supply.
    PFC chip?
    Read online something about backlight transformers also.
    From your experience what it could be, please?
    Thanks a lot for any support.
    Regards.
    Tags: None
    • tvtimmy
      Badcaps Legend
      • Mar 2015
      • 1160
      • usa
      #2
      Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

      Most likely bad transformer. Compare resistance readings from each one. Odd reading one is bad.
      It also could be a bad bulb. Use a florescent bulb and touch the transformers on left and right sides when powering up the set. Bulb should light up a bit.

        Comment

        • jczarniak
          Senior Member
          • Oct 2015
          • 179
          • UK
          #3
          Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

          Originally posted by tvtimmy
          Most likely bad transformer. Compare resistance readings from each one. Odd reading one is bad.
          It also could be a bad bulb. Use a florescent bulb and touch the transformers on left and right sides when powering up the set. Bulb should light up a bit.
          Checked the transformers.
          Got same readings on all of them, about 1530-1540 Ohm.

            Comment

            • tvtimmy
              Badcaps Legend
              • Mar 2015
              • 1160
              • usa
              #4
              Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

              Check capacitor CI892.

                Comment

                • jczarniak
                  Senior Member
                  • Oct 2015
                  • 179
                  • UK
                  #5
                  Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

                  Originally posted by tvtimmy
                  Check capacitor CI892.
                  Very interested.
                  I'll check that this evening and I'll let you know.
                  Thank you very much.

                    Comment

                    • jczarniak
                      Senior Member
                      • Oct 2015
                      • 179
                      • UK
                      #6
                      Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

                      Originally posted by tvtimmy
                      Check capacitor CI892.
                      Done, replaced.
                      Still same

                      Two filter caps 82uF/450V also replaced
                      Still the same.

                      What else can I check?

                        Comment

                        • tvtimmy
                          Badcaps Legend
                          • Mar 2015
                          • 1160
                          • usa
                          #7
                          Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

                          You may have a bulb that is going bad. You can check the small blue disk capacitors by the transformers.

                            Comment

                            • vinceroger69
                              Badcaps Legend
                              • Mar 2012
                              • 6714
                              • uk
                              #8
                              Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

                              https://www.badcaps.net/forum/showth...er+testing+cfl
                              https://www.badcaps.net/forum/showth...x+dx-40l261a12
                              Last edited by vinceroger69; 02-14-2018, 06:39 AM.

                                Comment

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