Announcement

Collapse
No announcement yet.

Samsung QN75Q6DRA, No Picture, Has BL, and Sound

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Samsung QN75Q6DRA, No Picture, Has BL, and Sound

    Hello all,

    This is my first post, but long term lurker on the form learning as much as possible about these TV's. I was given this TV as due to a power outage of constant On/off of power to TV. The TV originally would just click on and off (Typical Reboot Cycle). I opened the back of the TV, and troubleshooted by taking the 96 pin LVDS off one at a time to see if I had a picture on either side. I finally fixed the reboot cycle by finding the error on the left side of the screen off connector CN 1301, and the TV would stay on. Further troubleshooting led me to the driver boards where the small ribbon jumper cables that hook each driver board in series, on the left side of the screen. After searching on the forum, I masked the driver board jumper from 4 to 17 as some had suggested on other tv's. I was hoping for a little guidance as to where to troubleshoot from here. This is my first TV to learn on, and would enjoy the education if I can fix it. Any guidance is appreciated.

    The SMPS does not have any blown caps, Power is being delivered to the main board. I can hear sounds when it boots up, and can here sounds as i move through the menu's (no picture of course)

    The TCONN is part of the Main board, where would one need to look to notice if its a TCONN issue on the Main board? What typically fails as I'm probing?

    My finger in the picture is pointing to a smd capacitor which I "thought" is bad as with the power off, and i check for continuity, the Fluke meter beeps on a few in this area. The resistance value varied from 8 ohms to 12 ohms, however testing other capacitors in different area didn't yield same result.

    After searching through the forums, i understand how poorly these samsung's are put together and the likely hood I have a bad panel, However if I can troubleshoot it, or see some life as in a picture, the education in my opinion is well worth it.

    I have taken Voltage points on both LVDS cables and can post my information but found that while if have 3.33v on FB_TRDY1 on pin 1, I do not have VGHD_30V_PW as its 0V. I do have test points on main board labeled FB_TRDY1 and FB_TRDY 3, if I solder a jumper on those points would that be best to rule out MB/ TCONN is working?

    #2
    FB_TRDY1 and FB_TRDY 3 is feedback from the motherboard and the panel, if you disconnect any lvds cable, the connection is broken and the t-con blocks the output voltages, put a jumper and connect the lvds cables one by one and see which side is faulty...

    Comment


      #3
      Lotas, Thank you! I'll report back ASAP.

      Comment


        #4
        Well I'm please to report some life. It may not look like much, but this is the first signs of anything after troubleshooting with an original boot loop. I soldered the jumper to FB_TRDY1 and FB_TRDY 3, and before putting power back on TV, i disconnected the CN1301 LVDS cable, and left CN1300 LVDS connected to see any thing first. I figured since I masked the driver board on the CN1301 side, and believing the short was gone because boot loop stopped after masking, the tv boot looped again. So i disconnected LVDS CN1300, and connected the CN1301, and the result is what is uploaded for all to see. I imagine I could mask the same spot on the CN1300 side connecting the diver boards to see if I can get a picture out of it. Please let me know if this is the wrong path to continue troublehsooting

        Thanks Lotas,

        I'm impressed with the result so far, glad to see "something".

        Comment


          #5
          Take a high-quality photo of the non-working buffer strip.

          Comment


            #6
            Thank you Lotas, I have attached the non-working buffer strip.

            Comment


              #7
              Remove all disguises and carefully disconnect this cable and check again how the image will look.
              Attached Files

              Comment


                #8
                Hey Lotas, what do you mean by "Remove all disguises". I am about to report results by disconnecting that jumper ribbon cable to driver board.

                Comment


                  #9
                  Originally posted by Dodgethis View Post
                  Hey Lotas, what do you mean by "Remove all disguises". I am about to report results by disconnecting that jumper ribbon cable to driver board.
                  In post 4 you wrote that you masked on the CN1301 side..., so I write that you remove all your masking.

                  Comment


                    #10
                    Lotas, Thanks for clarifying for me, I was reading into it and over thinking what you needed. I have attached the results from taking off masked tap on the CN1301 side. I want to mention that im blown away and confused, because originally I thought the short was on the CN1301 side, but as one can see in the photos, a picture is shown as if no issues. In addition,a had a boot loop, which again confuses me so i disconnected the jumper ribbon cable for the right side of the screen to stop it. I included my finger to point to what i mean.

                    Why is that lotas? Im thirsting for knowledge, why would it swap sides from orginally a short and masked on CN1301, to already swapping to the CN1300 side with boot loop needing a masking to fix it?

                    Also, in the picture that dark orb at top of screen, is that an indication of where a fault occurred inside the panel? TV wasn't dropped, and nothing was laid on it before brought to the shop to be worked on.

                    Comment


                      #11
                      The problem may also be in these TVS Diods, take a high-quality photo of this area.
                      Attached Files

                      Comment


                        #12
                        Lotas, let me know if this helps.

                        Comment


                          #13
                          on top E 5 is stated on them

                          Comment


                            #14
                            Originally posted by Dodgethis View Post
                            Lotas, let me know if this helps.
                            I know the markings are E5, I need a high-quality close-up photo (not a blurry photo).
                            Attached Files

                            Comment


                              #15
                              ok, no problem, here try this.

                              Comment


                                #16
                                Originally posted by Dodgethis View Post
                                ok, no problem, here try this.
                                A shadow falls here, I need to see all these upper terminals connected to the ground...
                                Attached Files

                                Comment


                                  #17
                                  Originally posted by lotas View Post

                                  A shadow falls here, I need to see all these upper terminals connected to the ground...
                                  as i remember E5 will be GND PIN No 5 at middle

                                  Comment


                                    #18
                                    Originally posted by Diah View Post

                                    as i remember E5 will be GND PIN No 5 at middle
                                    But in the photo you can see as if the entire top row is connected to the ground.

                                    Comment


                                      #19
                                      Originally posted by lotas View Post

                                      But in the photo you can see as if the entire top row is connected to the ground.
                                      pins 456 the track under the ESD you can see the contact pin close other other 123.... ESD 5 GND PIN 5 as i remember

                                      Comment


                                        #20
                                        Originally posted by Diah View Post

                                        pins 456 the track under the ESD you can see the contact pin close other other 123.... ESD 5 GND PIN 5 as i remember
                                        Here is a photo from another strip and you can see that the top row of contacts (4,5,6) are all connected to ground.
                                        Attached Files

                                        Comment

                                        Working...
                                        X