Sharp LC-40LE830M no power

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  • chewbacca78
    Member
    • May 2015
    • 23
    • singapore

    #1

    Sharp LC-40LE830M no power

    Hi, i have a Sharp LC-40LE830M LCD TV that has no power now.

    It was turning on and off by itself a few days ago. I pulled out the plug and left it there for 2 days. Then I plugged in last night and it's totally dead with no standby lights. I suspect it's the power supply and i'm trying to troubleshoot the components in the power supply and need some advice on which components to check. Thank you.
  • ammarben
    Senior Member
    • May 2013
    • 63
    • algeria

    #2
    Re: Sharp LC-40LE830M no power

    a bad capacitors on the power supply can do that
    find first the buggled capacitors

    Comment

    • chewbacca78
      Member
      • May 2015
      • 23
      • singapore

      #3
      Re: Sharp LC-40LE830M no power

      Originally posted by ammarben
      a bad capacitors on the power supply can do that
      find first the buggled capacitors
      I already did a visual check on the capacitors but don't see any bulge in any of them. I did a search and read that some bad capacitors may not have a bulge but I'm not sure which capacitor should I start checking first if I have to remove them. any idea?

      Comment

      • mmartell
        Badcaps Legend
        • Oct 2013
        • 3189
        • Canada

        #4
        Re: Sharp LC-40LE830M no power

        If they're not bulged and they're not shorted you can't really test them without a capacitance meter or better still an esr meter.

        You need to troubleshoot the supply. Make sure the fuse is not open then check the dc voltage at the large capacitor in Primary side but Be Careful as that is the deadly Hot side !

        Comment

        • mmartell
          Badcaps Legend
          • Oct 2013
          • 3189
          • Canada

          #5
          Re: Sharp LC-40LE830M no power

          Actually, scratch that last post since we're not even sure the power supply is the issue here. Check the pins at the mainboard harness from the ps for 5v standby voltage - if you have that but no lights in front then mainboard is likely the culprit.

          Comment

          • chewbacca78
            Member
            • May 2015
            • 23
            • singapore

            #6
            Re: Sharp LC-40LE830M no power

            Hi mmartell, i repair printers but i'm a noob at tvs so please pardon my questions.

            I attach pics of the PSU and mainboard. looking at the connector, do I measure the 5VDC on the metal part of BU5V? If I did it correctly, I got 0V on the meter for that.
            Attached Files

            Comment

            • vinceroger69
              Badcaps Legend
              • Mar 2012
              • 6714
              • uk

              #7
              Re: Sharp LC-40LE830M no power

              What voltage do you get at the pin marked stb?

              Comment

              • chewbacca78
                Member
                • May 2015
                • 23
                • singapore

                #8
                Re: Sharp LC-40LE830M no power

                hi vinceroger69, where do I measure stb? Please see photos.

                I also measure around the resistors and found one to be below reading. It's rated at 2M ohm but i measured around 1M ohm. Not sure if this is one of a few components that needed to be changed.
                Attached Files

                Comment

                • newtothis
                  Badcaps Legend
                  • Mar 2013
                  • 1556
                  • england

                  #9
                  Re: Sharp LC-40LE830M no power

                  Marked it with an arrow.

                  There are 2 rows of pins so it is the one on the lower row closest to the board
                  Attached Files

                  Comment

                  • chewbacca78
                    Member
                    • May 2015
                    • 23
                    • singapore

                    #10
                    Re: Sharp LC-40LE830M no power

                    i hope i'm doing it correctly. i measured the pin with the circle with my ground on the screw and i got 0VDC
                    Attached Files

                    Comment

                    • newtothis
                      Badcaps Legend
                      • Mar 2013
                      • 1556
                      • england

                      #11
                      Re: Sharp LC-40LE830M no power

                      Can you confirm voltage at the mains input?

                      Meter at 600v VAC

                      Comment

                      • chewbacca78
                        Member
                        • May 2015
                        • 23
                        • singapore

                        #12
                        Re: Sharp LC-40LE830M no power

                        I'm from Singapore so reading i got from my mains is 230VAC.

                        Comment

                        • vinceroger69
                          Badcaps Legend
                          • Mar 2012
                          • 6714
                          • uk

                          #13
                          Re: Sharp LC-40LE830M no power

                          There is a white fuse with wires on by the mains input socket does that test ok?

                          Comment

                          • chewbacca78
                            Member
                            • May 2015
                            • 23
                            • singapore

                            #14
                            Re: Sharp LC-40LE830M no power

                            you mean the one circled in red? yes, hear continuous beep on my meter. However, the resistor i circled is rated at 2M ohms but i measured around 1M ohm. is this ok?
                            Attached Files

                            Comment

                            • newtothis
                              Badcaps Legend
                              • Mar 2013
                              • 1556
                              • england

                              #15
                              Re: Sharp LC-40LE830M no power

                              It could be in parallel and read different in cct to out of cct.

                              Again VDC 600v , Can you put Red probe to + and black to - on one of the long capacitors. Careful high voltage.
                              Last edited by newtothis; 05-26-2015, 08:56 AM.

                              Comment

                              • chewbacca78
                                Member
                                • May 2015
                                • 23
                                • singapore

                                #16
                                Re: Sharp LC-40LE830M no power

                                i measured both long capacitors and got 0VAC for both...am I doing anything wrong? Why is everything 0V??

                                Comment

                                • newtothis
                                  Badcaps Legend
                                  • Mar 2013
                                  • 1556
                                  • england

                                  #17
                                  Re: Sharp LC-40LE830M no power

                                  You have voltage at both ends of the white fuse you highlighted yes?

                                  Can we have a photo of the underside of the board too so we can see the traces please
                                  Last edited by newtothis; 05-26-2015, 08:36 AM.

                                  Comment

                                  • chewbacca78
                                    Member
                                    • May 2015
                                    • 23
                                    • singapore

                                    #18
                                    Re: Sharp LC-40LE830M no power

                                    yes, i did continuity check on the fuse and it's ok. it's not blown

                                    Comment

                                    • newtothis
                                      Badcaps Legend
                                      • Mar 2013
                                      • 1556
                                      • england

                                      #19
                                      Re: Sharp LC-40LE830M no power

                                      Can you just confirm voltage there too please, Just to rule out broken solder joints

                                      Comment

                                      • chewbacca78
                                        Member
                                        • May 2015
                                        • 23
                                        • singapore

                                        #20
                                        Re: Sharp LC-40LE830M no power

                                        in ac?

                                        Comment

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