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Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

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    Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

    Hello, I'm new to this forum to address my issue I've had with my tv for quite a while now and its getting very frustrating when it starts happening!
    Im having like a flickering type of noise in the middle of my tv (horizontal) it happens randomly, mainly when alot of use is put into the tv at once, like if i play a game or watch a movie it happens more when the tv has been ON.

    I've had the panel, and mainboard replaced by samsung... i am now out of warranty.. my options are limited the only thing they didn't replace was the PSU"PowerSupply" and I've done some research and there was 1 person on youtube that had same issue and mentioned PSU, but i don't know. id like to get more opinions! which is why i am here... all help would be appriciated..
    also i don't know if interference can cause this as i have many electronics, including my router and modem on my one dresser where my tv hangs above.

    thanks all,

    kind regards.

    #2
    Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

    Hi there,
    I'm working on repairing the power board for this TV UN55JU7100.
    Power Board part number is BN44-00811A. I have found two diodes shorted but not sure how to order a replacement. Can you guys help me understanding this part number. I wrote it down as camera can't focus well on this smd diode.

    Something like: ZH 0H (shows written vertically)
    See pic
    Attached Files

    Comment


      #3
      Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

      I found another shorted: ZG 0F

      Thanks in advance!

      Comment


        #4
        Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

        this is a link to the smd code book it may help you find these

        Comment


          #5
          Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

          Originally posted by FallinDeep View Post
          Hello, I'm new to this forum to address my issue I've had with my tv for quite a while now and its getting very frustrating when it starts happening!
          Im having like a flickering type of noise in the middle of my tv (horizontal) it happens randomly, mainly when alot of use is put into the tv at once, like if i play a game or watch a movie it happens more when the tv has been ON.

          I've had the panel, and mainboard replaced by samsung... i am now out of warranty.. my options are limited the only thing they didn't replace was the PSU"PowerSupply" and I've done some research and there was 1 person on youtube that had same issue and mentioned PSU, but i don't know. id like to get more opinions! which is why i am here... all help would be appriciated..
          also i don't know if interference can cause this as i have many electronics, including my router and modem on my one dresser where my tv hangs above.

          thanks all,

          kind regards.
          Easy test, just unhook/turn off everything but the tv, to see if it's electronic interference.

          Comment


            #6
            Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

            Originally posted by vinceroger69 View Post
            this is a link to the smd code book it may help you find these
            Thanks....This is a very useful book to have.

            Comment


              #7
              Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

              Originally posted by Andrew F. Ali View Post
              Thanks....This is a very useful book to have.
              I also have this one if its any use
              Attached Files

              Comment


                #8
                Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                Oh yes!!...This is really good...Thank you very much for sharing....

                Comment


                  #9
                  Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                  [QUOTE=Louis82;813721]Hi there,
                  I have found two diodes shorted but not sure how to order a replacement. Can you guys help me understanding this part number. I wrote it down as camera can't focus well on this smd diode.

                  Are you sure the diodes are shorted
                  The 2 legs at the bottom are common and will show a short , the diode is between the top pin and any of the bottom pins

                  Comment


                    #10
                    Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                    Originally posted by Louis82 View Post
                    Hi there,
                    I'm working on repairing the power board for this TV UN55JU7100.
                    Power Board part number is BN44-00811A. I have found two diodes shorted but not sure how to order a replacement. Can you guys help me understanding this part number. I wrote it down as camera can't focus well on this smd diode.

                    Something like: ZH 0H (shows written vertically)
                    See pic
                    What is wrong with the power board? Pictures?
                    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


                      #11
                      Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                      Thanks for the SMD Code Book gents - Still wondering if the numbers written vertically mean anything. I been going through my scrap boards and I have found ZH diodes but they also show 1F, 1H written vertically. Thoughts?

                      @chrismurphy - Yes, It test shorted from pin top vs any of the two bottom. I removed them from circuit board an they seems to be bad.

                      @budm - Blown AC fuse. Found 2 mosfet, a transistor-diode and 2 SMD resistors shorted. Replaced all, tried again and now transistor-diode blew again plus a resistor (which it was probably bad from the beginning and I just missed it at first), and the 2 ZH diodes.

                      I will post pictures by noon. Seriously the board is very cheap, like $25 on eBay, but I already spent a good time messing with this and I want to find the problem - Challenged.

                      Comment


                        #12
                        Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                        So whcih section of the board where those parts are bad?
                        PFC, LED driver, main supply, standby supply?

                        http://www.shopjimmy.com/samsung-bn4...led-board.htm#
                        Pictures provided by shopjimmy.
                        Attached Files
                        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


                          #13
                          Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                          The blue dot is a 4.7 ohm that I found burned.
                          Red dots are the ZH and ZG diodes.
                          Yellow is a 10kohm resistir that test good but looked a little bit up so I removed it to replace it anyway.

                          Wonder if the DP807 diode I put in was bad (ordered from AliExpress) and it actually caused a worse mess.

                          As I said initially it was just the QP802, DP807, QP801 RP829, RP831 bad.
                          Attached Files

                          Comment


                            #14
                            Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                            So you had problem in the PFC Voltage booster section, more likely the PFC IC got damaged when the PFC MOSFET went bad, I always replace the IC at the same time as the MOSFET since you can damage the new MOSFET if the IC is bad.
                            BTW, the part designator with 'P' indicates part related to PFC circuit: I.E. QP802
                            Last edited by budm; 03-22-2018, 10:54 AM.
                            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


                              #15
                              Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                              So you think the PFC IC is what it damaged my diodes. Because after I replaced the MOSFETs, I plugged in the board and the Mosfets remain doing fine, no short.

                              Comment


                                #16
                                Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                                https://www.badcaps.net/forum/attach...6&d=1521736034
                                Those prts in that section are for the Gate drive circuits, they are connected between the Gate drive out of the IC and the Gate pin of the MOSFET, when MOSFET shorted out between Gate and Drain, that will dump 160VDC ~380VDC to the output of the IC via those parts so they blew up.
                                Look up the P/N of the PFC IC spec. sheet, it will have some reference circuit that shows you how it is being used.
                                Last edited by budm; 03-22-2018, 11:07 AM.
                                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: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                                  I found NT811 cracked, replaced all burned parts except PFC Ic and still the same.
                                  Last try will be the PFC IC but I can't tell the part number of it.

                                  Comment


                                    #18
                                    Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                                    Replaced PFC IC SPC1012T and the same, diode location DP807C keeps blowing.

                                    Comment


                                      #19
                                      Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                                      The two MOSFETs QP801, 802 did not blow?
                                      Did you replace that Common Cathode DP807 with the exact same type and isolated case?
                                      For that PFC Diode to blow, the Cathode must be seeing very low resistance to GND.
                                      See the diagram showing how that diode being used in the dual PFC circuit.
                                      Check the resistance between the two legs of the main filter cap CP810 or 814 to see what you get.
                                      Attached Files
                                      Last edited by budm; 03-22-2018, 09:27 PM.
                                      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


                                        #20
                                        Re: Need help with my Samsung UN55JU7500 random "flickering" in the middle of the tv

                                        Correct, MOSFETS still measuring fine. Diode is shorted. Replaced with exact part number. Wonder if this Diodes are chinese fake components.

                                        Comment

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