Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

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  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #1

    Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

    Another one of failed AUOPTO T-CON board with bad GAMMA Vref IC AS15.
    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
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

    Did you check gamma curve or just replace IC? You can try the spreadsheet I made which helps determine bad gamma IC for sure.

    https://www.badcaps.net/forum/showthread.php?t=35301
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

      I already installed the new IC, the TV is already donated today. I will keep that spreadheet in the future, but so far all the AUOPTO T-CON that I have replaced the AS15 solved the problem, I did 5 so far, need to get more IC.
      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

      • tom66
        EVs Rule
        • Apr 2011
        • 32560
        • UK

        #4
        Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

        It seems to be a common fault, you can almost always see it from the picture. The nearest was one which just had overly contrasted image, I believe same Samsung model but Taiwanese, which is also where AUO panels are from.

        I'm a data hoarder, I like numbers and certainty. Unfortunately haven't had a single bad gamma IC myself yet.
        Last edited by tom66; 02-15-2014, 08:47 PM.
        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

        Comment

        • tibimakai
          Badcaps Legend
          • Jan 2012
          • 3680
          • USA

          #5
          Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

          Last two weeks, I have done the same thing on the same TV, and a 46A630(AS15G).
          I have the same TV now, but it needs a new mainboard.

          Comment

          • marcmum
            New Member
            • Oct 2013
            • 4
            • USA

            #6
            Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

            I have this exact same model with the T-CON Gamma IC problem (screen too bright/white). My question is how do I get access to the T-CON board? I've removed the 5 screws holding the metal cover and it's loose, but it won't come free. It looks like the T-CON board is moving with the cover. I didn't want to force it too much for fear of doing any damage to the two connectors on the other end of the board. Can someone tell what I'm doing wrong?
            I was hoping to take some voltage measurements to confirm the bad Gamma IC (I downloaded the spreadsheet) before sending it off to get repaired.
            Thanks.

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK

              #7
              Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

              There's sometimes a thermal pad which is lightly glued to the case. You just need to lever it slightly, maybe best to remove board completely from set.
              Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
              For service manual, schematic, boardview (board view), datasheet, cad - use our search.

              Comment

              • mmartell
                Badcaps Legend
                • Oct 2013
                • 3189
                • Canada

                #8
                Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                Try rotating it back and forth in a cirxular motion that should break the seal.

                Comment

                • Dang
                  Badcaps Veteran
                  • Aug 2013
                  • 440
                  • UK

                  #9
                  Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                  The above works, seat the whole thing properly, there's sometimes some lugs to hold the T-con in place, gently hold it down where the LVDS cable enters and twist clockwise then anticlockwise, after a few turns it should come free, just make sure the T-con board can't move, a little bit of heat from a hair dryer can help here.

                  Comment

                  • marcmum
                    New Member
                    • Oct 2013
                    • 4
                    • USA

                    #10
                    Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                    Thanks for all the suggestions. I used a small screwdriver and a little force and the cover popped free. It took a little more dis-assembly to remove the cover, but I eventually got it out. I took the VGMA voltage measurements and tried the above spreadsheet. I think the gamma IC is bad, but a number of the cells in the spreadsheet didn't translate over when using Microsoft Excel.
                    One more question on removing the T-CON board, how do the two ribbon cables that go to the screen connect to the board? Do they push in from the side or the top of the board? It wasn't obvious to me and I don't want to do any damage when disconnecting.
                    Thanks.

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK

                      #11
                      Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                      Can you try posting your listing of voltages? I developed the spreadsheet in OO.org Calc so have not been able to fully test it in Excel.
                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                        @marcmum:"One more question on removing the T-CON board, how do the two ribbon cables that go to the screen connect to the board? Do they push in from the side or the top of the board? It wasn't obvious to me and I don't want to do any damage when disconnecting." The brown plastic bar flips up to release the cable, see picture #6 you can see the right one is flipped up. One thing is that it not very easy inserting those two flat cables back in place.
                        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

                        • marcmum
                          New Member
                          • Oct 2013
                          • 4
                          • USA

                          #13
                          Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                          Here are my T-CON Voltage Measurements:
                          VGMA1: 15.4
                          VGMA2: 15.33
                          VGMA3: 15.18
                          VGMA4: 12.34
                          VGMA5: 11.54
                          VGMA6: 10.59
                          VGMA7: 10.05
                          VGMA8: 9.79
                          VGMA9: 8.27
                          VGMA10: 7.92
                          VGMA11: 7.88
                          VGMA12: 0.206
                          VGMA13: 0.206
                          VGMA14: 0.206
                          VGMA15: 0.214
                          VGMA16: 0.224
                          VGMA17: 0.244
                          VGMA18: 0.251
                          VGMA19: 0.257
                          VGMA20: 0.291
                          VGMA21: 0.292
                          VGMA22: 0.297
                          VCOM: 6.37
                          AVDD: 15.61
                          VGH: 17.3 mV AC (out of limits on DC)
                          VGL: 16.2 mV AC (out of limits on DC)

                          Comment

                          • tom66
                            EVs Rule
                            • Apr 2011
                            • 32560
                            • UK

                            #14
                            Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                            I've never seen half of the readings at near zero, wow. Double check those last readings but if so, the gamma IC is definitely bad.

                            For VGH/VGL, generally not an issue on these, but you might have to use next highest DC range.
                            Last edited by tom66; 02-25-2014, 01:34 PM.
                            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                            Comment

                            • splitcrete
                              Badcaps Veteran
                              • Dec 2012
                              • 387
                              • usa

                              #15
                              Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                              What are the readings supposed to be for 12-22 my meter is on auto and I'm getting almost the same readings.

                              Comment

                              • tom66
                                EVs Rule
                                • Apr 2011
                                • 32560
                                • UK

                                #16
                                Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                                Either slow increase our decrease. But it has to be consistent. Ie only increasing or only decreasing.
                                Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                Comment

                                • splitcrete
                                  Badcaps Veteran
                                  • Dec 2012
                                  • 387
                                  • usa

                                  #17
                                  Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                                  I soldered a new as15-f in this morning . Do you think I missed a pin or two . Should I have another go at it ? That is only the second chip I have ever changed.
                                  Attached Files

                                  Comment

                                  • splitcrete
                                    Badcaps Veteran
                                    • Dec 2012
                                    • 387
                                    • usa

                                    #18
                                    Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                                    Pin one was 15.09 and slowly went down till it got to pin 13 and it dropped to 2.336 and went down from there a little at a time pin 22 000.1

                                    Comment

                                    • tom66
                                      EVs Rule
                                      • Apr 2011
                                      • 32560
                                      • UK

                                      #19
                                      Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                                      The full readings would help.
                                      Soldering looks OK.
                                      Tibimaki replaced IC, and found new IC to be bad. So do not rule out chance you got a bad IC.
                                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                      Comment

                                      • splitcrete
                                        Badcaps Veteran
                                        • Dec 2012
                                        • 387
                                        • usa

                                        #20
                                        Re: Samsung LN37A550P3F with bad Gamma AS15 AUOPTO T-CON

                                        Sorry pin 22 was 1.244

                                        Comment

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