Sharp LC-60LE741E - No Power

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  • Strudul
    Member
    • Apr 2021
    • 18
    • United Kingdom

    #1

    Sharp LC-60LE741E - No Power

    TV suddenly decided it didn't wanna turn on.

    I've got no continuity across the fuse F7001, so that's gonna need replacing, but wondering what else I should be looking out for beforehand to avoid it potentially immediately blowing again.

    Does anything look suspect on the attached image or are there some more continuity checks I should attempt first?

    Cheers
    Attached Files
  • nomoresonys
    Badcaps Legend
    • Jan 2013
    • 12081
    • U.S.

    #2
    Re: Sharp LC-60LE741E - No Power

    Start with checking all the diodes and resistors on the top of the board, duckgo search and youtube are your friends if need to know how.

    Comment

    • Strudul
      Member
      • Apr 2021
      • 18
      • United Kingdom

      #3
      Re: Sharp LC-60LE741E - No Power

      Originally posted by nomoresonys
      Start with checking all the diodes and resistors on the top of the board, duckgo search and youtube are your friends if need to know how.
      The highlighted diode (D7805) seems to be shorted.

      Also found this manual.
      Attached Files
      Last edited by Strudul; 04-02-2023, 08:42 AM.

      Comment

      • nomoresonys
        Badcaps Legend
        • Jan 2013
        • 12081
        • U.S.

        #4
        Re: Sharp LC-60LE741E - No Power

        Ok, suppose the easiest way is too take it out and retest it, to confirm, if read short out of circuit, pop a new one in and give it a go.

        Comment

        • Strudul
          Member
          • Apr 2021
          • 18
          • United Kingdom

          #5
          Re: Sharp LC-60LE741E - No Power

          Originally posted by nomoresonys
          Ok, suppose the easiest way is too take it out and retest it, to confirm, if read short out of circuit, pop a new one in and give it a go.
          The diode was short out of circuit. Replaced it and the fuse, plugged it all back in and the fuse immediately blew again.

          Bit lost on what next now.

          Comment

          • Strudul
            Member
            • Apr 2021
            • 18
            • United Kingdom

            #6
            Re: Sharp LC-60LE741E - No Power

            It does appear all pins are shorted on the rectifier bridge BD7001, but not sure if this is a symptom or cause?
            Attached Files

            Comment

            • Donny2derby
              Badcaps Veteran
              • Apr 2023
              • 228
              • Uk

              #7
              Re: Sharp LC-60LE741E - No Power

              Measure for a short at your incoming? If there’s a short there then at least you know what you’re dealing with.

              Can you find a schematic for it?

              Comment

              • Donny2derby
                Badcaps Veteran
                • Apr 2023
                • 228
                • Uk

                #8
                Re: Sharp LC-60LE741E - No Power

                There’s a few components on there I’d be looking at as well. Hard to be sure as it’s not perfectly legible but capacitor C7138 looks to be slightly ruptured as well?

                Comment

                • Strudul
                  Member
                  • Apr 2021
                  • 18
                  • United Kingdom

                  #9
                  Re: Sharp LC-60LE741E - No Power

                  Originally posted by Donny2derby
                  Measure for a short at your incoming? If there's a short there then at least you know what you're dealing with.

                  Can you find a schematic for it?
                  Where would be the incoming?

                  I can't find a schematic, but looks like like repair kits are sold for this issue which include the following components, but no information on actual part numbers:
                  F7001, BD7001, D7805, Q7801, IC7801, C7817, Q8700

                  Originally posted by Donny2derby
                  There's a few components on there I'd be looking at as well. Hard to be sure as it's not perfectly legible but capacitor C7138 looks to be slightly ruptured as well?
                  Not sure I can find a C7138. Whereabouts are you looking?

                  I've attached some potentially better pics.
                  Attached Files

                  Comment

                  • Strudul
                    Member
                    • Apr 2021
                    • 18
                    • United Kingdom

                    #10
                    Re: Sharp LC-60LE741E - No Power

                    It does look like this is short too, which is Q7801.
                    Attached Files

                    Comment

                    • Donny2derby
                      Badcaps Veteran
                      • Apr 2023
                      • 228
                      • Uk

                      #11
                      Re: Sharp LC-60LE741E - No Power

                      Originally posted by Strudul
                      Where would be the incoming?

                      I can't find a schematic, but looks like like repair kits are sold for this issue which include the following components, but no information on actual part numbers:
                      F7001, BD7001, D7805, Q7801, IC7801, C7817, Q8700


                      Not sure I can find a C7138. Whereabouts are you looking?

                      I've attached some potentially better pics.
                      Your mains power incoming. Marked Ac at the top of the board. If you have continuity across live and neutral there then you're definitely chasing a short and that's what's taking the fuse out instantly.

                      On closer look at that picture it's cap C7130 and looks ok actually.

                      What test equipment do you have? A multimeter? Semi conductor analyser? ESR meter?

                      Do you know how to test diodes/caps etc? Not trying to be difficult but it helps others to know what your abilities are.

                      Comment

                      • Strudul
                        Member
                        • Apr 2021
                        • 18
                        • United Kingdom

                        #12
                        Re: Sharp LC-60LE741E - No Power

                        Originally posted by Donny2derby
                        Your mains power incoming. Marked Ac at the top of the board. If you have continuity across live and neutral there then you're definitely chasing a short and that's what's taking the fuse out instantly.

                        On closer look at that picture it's cap C7130 and looks ok actually.

                        What test equipment do you have? A multimeter? Semi conductor analyser? ESR meter?

                        Do you know how to test diodes/caps etc? Not trying to be difficult but it helps others to know what your abilities are.
                        No short between L and N attached (with fuse F7001 currently in blown state).

                        Only got a multimeter.

                        I can test diodes (check continuity in each direction: should be no short, infinite resistance one way, and some (typically around 500) the other).

                        Not sure on caps. Can measure voltage, but not sure that helps?
                        Attached Files

                        Comment

                        • Donny2derby
                          Badcaps Veteran
                          • Apr 2023
                          • 228
                          • Uk

                          #13
                          Re: Sharp LC-60LE741E - No Power

                          Having an ESR meter is best to be certain on caps but if you put your meter to ohms and test leads across the cap it should begin to climb to show that it’s charging. It’s not perfect to do it this way but gives you a good indication.

                          Try replacing the fuse with a good one and without powering up check for continuity again. But no continuity on there just now suggests there’s no dead short. Probably a faulty component giving an earth fault then. Needle in a haystack and requires testing each component individually.

                          Lovely stuff!

                          Comment

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