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Samsung LNT4069FX/XAA no picture with sound

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    #41
    Re: Samsung LNT4069FX/XAA no picture with sound

    The P/N of the adjustable regulator is:
    37302WU
    0735

    I'll have to find some scrap resistors to complete the test.

    Comment

      #42
      Re: Samsung LNT4069FX/XAA no picture with sound

      Just use two 100 Ohms resistors since the regulator needs minimum 10mA load current.
      One resistor between output pin and the adj pin, another resistor between adj pin and Ground, this setup should make the output voltage to be about 2.5V.
      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

        #43
        Re: Samsung LNT4069FX/XAA no picture with sound

        Originally posted by ceconomon View Post
        I cleaned the back of the mainboard with alcohol. I've examined that area throughly with a magnifying glass and I can't determine the source of that mess. It looks like flux to me. Here are the new pictures.

        All of the ferrite beads tested good.
        Looks okay now, although there is quite a bit of heat discoloration from those linear regulators. I hope it's not a BGA issue. I'll wait until you confirm with the others that all of the regulators are good.

        Comment

          #44
          Re: Samsung LNT4069FX/XAA no picture with sound

          Originally posted by momaka View Post
          The last thing I can think of is if some of those caps next to those voltage regulators have gone bad due to the excessive heat. But for that you'll need to have an ESR meter to check them with.
          That might be C104. It might just be easier to replace it and retest.
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          Comment

            #45
            Re: Samsung LNT4069FX/XAA no picture with sound

            I got the resistors today and wired the test up. The results are below:

            pin1 2.99
            pin2 2.99
            pin3 0 GND
            pin4 2.461
            pin5 1.235

            Comment

              #46
              Re: Samsung LNT4069FX/XAA no picture with sound

              You only using 3V power supply to feed this LDO? I am surprised it works pretty good since the input and out difference is only about 0.5V, they usually require the input voltage to be ~1.5 to 1.75V above the required output voltage.
              But any how, this regulator is good, use 5V power supply next time for testing.
              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

                #47
                Re: Samsung LNT4069FX/XAA no picture with sound

                Originally posted by budm View Post
                You only using 3V power supply to feed this LDO?
                When the LDO is "on board", the input voltage is only 3.415V so I suggested using 2 AA in series (as per post #22).
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                Comment

                  #48
                  Re: Samsung LNT4069FX/XAA no picture with sound

                  What is the DC voltage across C104? Black probe on negative and red probe on positive.
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                  Comment

                    #49
                    Re: Samsung LNT4069FX/XAA no picture with sound

                    C104 measures 1.836V

                    Comment

                      #50
                      Re: Samsung LNT4069FX/XAA no picture with sound

                      I checked for voltage on every capacitor on this board(negative to ground and positive on each cap). I have voltage on all but two caps. The ones right next to the regulator that I replaced (C188 and C192).

                      Location C188
                      V1011
                      100
                      16J

                      Location C192
                      7e (glad I have a 20x magnifying glass)
                      22
                      16J

                      Comment

                        #51
                        Re: Samsung LNT4069FX/XAA no picture with sound

                        Originally posted by ceconomon View Post
                        C104 measures 1.836V
                        C104 could be bad. Unless you have an ESR meter and a multimeter than can measure capacitance, I suggest replacing it.
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                        Comment

                          #52
                          Re: Samsung LNT4069FX/XAA no picture with sound

                          I don't have an ESR meter, so I'll replace it.

                          Is this a 22uf and a 100uf 16V capacitor? I'll order both so my order is more than the shipping.

                          Location - C104
                          V1011
                          100
                          16J
                          looks like 6.6mm x 6.6mm
                          http://www.digikey.com/product-detai...0-1-ND/2533877


                          Location C188
                          7e
                          22
                          16j
                          looks like 5.3mm x 5.3mm
                          http://www.digikey.com/product-detai...8-1-ND/3438962

                          Comment

                            #53
                            Re: Samsung LNT4069FX/XAA no picture with sound

                            Originally posted by ceconomon View Post

                            Location - C104
                            V1011
                            100
                            16J
                            looks like 6.6mm x 6.6mm
                            http://www.digikey.com/product-detai...0-1-ND/2533877


                            Location C188
                            7e
                            22
                            16j
                            looks like 5.3mm x 5.3mm
                            http://www.digikey.com/product-detai...8-1-ND/3438962
                            Those look correct. Normally, when these caps go bad, they blow the top dramatically.
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                            If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                            We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                            Please do not post inline and offsite as they slow down the loading of pages.

                            --- end sig file ---

                            Comment

                              #54
                              Re: Samsung LNT4069FX/XAA no picture with sound

                              To bring everyone up to speed on this repair...

                              I tried replacing the cap and there was no change. I was still lacking any voltage on C188 and C192.

                              I was able to pick up a used board on ebay for $26. I would have like to fixed it at the component level, but sometimes it's not worth the battle.

                              Thanks for everyone's help.


                              3 TV's repaired and I'm looking for more.....I've caught the bug.

                              Comment

                                #55
                                Re: Samsung LNT4069FX/XAA no picture with sound

                                Well, you may not have fixed the original board, but I'm glad that you got the TV running.
                                Congrats!

                                Comment

                                  #56
                                  Re: Samsung LNT4069FX/XAA no picture with sound

                                  My Television is doing the exact same thing. Samsung sent a rep out and they put a new power board in the TV. I started getting the grey splotches and then the white screen. The tech told me I had a bad main board so I ordered one from Shop Jimmy, no change. So I thought it might be the T-Conn board and replaced that as well. I still get the solid white screen and sound on the TV. I can tell when the TV goes to commercials that the screen is changing as there is a little blink to it. The power light has a slow steady flash to it and never turns green. Any help would be greatly appreciated. Of course Samsung won't even respond to my requests any more. I don't believe the LCD panel is bad. HELP PLEASE!!!

                                  Comment

                                    #57
                                    Re: Samsung LNT4069FX/XAA no picture with sound

                                    I replaced the LCD Controller Logic Board to resolve this issue. You can search for these on Ebay. I see two out there for <= $25 shipped.

                                    LCD Controller Logic Board BN96-06669A, BN41-00944A

                                    Comment

                                      #58
                                      Re: Samsung LNT4069FX/XAA no picture with sound

                                      OK thanks so much .... I had already replaced the main board and of course the power board. I even repaired the original power board thinking that it might be the cause. I don't have the skills to do all the testing listed in this post but swapping boards is easy enough.

                                      Comment

                                        #59
                                        Re: Samsung LNT4069FX/XAA no picture with sound

                                        Thanks again.... I have one on the way and I'll let you know if it solves my problem too!

                                        Comment

                                          #60
                                          Re: Samsung LNT4069FX/XAA no picture with sound

                                          Problem is: screen is white and gray with sound. I replaced power supply board, t-con, logic control, main board but still not working. The power/standby led is red and blinking continuously. What could be the problem? I spent too much already trying to fix this TV. Any help will be greatly appreciated. Thanks!

                                          Comment

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