Need help identifying smd

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  • caphair
    Badcaps Legend
    • Nov 2011
    • 1249

    #21
    Re: Need help identifying smd

    So the processor is the problem. Can't be corrected without replacing the processor?

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #22
      Re: Need help identifying smd

      Or the processor detects fault or what ever the exact problem is so it shutdown that control line, I do not the details of how this unit is designed to function, that is why you did see the Voltage on the Collector of Q12 did the toggle LOW and HIGH due to activity of the processor output that feeds Q33 Base.
      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

      • fzabkar
        Badcaps Veteran
        • Mar 2009
        • 772
        • Australia

        #23
        Re: Need help identifying smd

        Code:
                VCC   5V = power on
                +  0.22V = standby
                |
              .---+--.
              |   |
              .-.  .-.
              | |  | |
              | |  | |
              '-'  '-'
          display |   |
            o----+ Q12 |
              |   |
          5V = OFF \|  |
          0V = ON  |----+
               <|  |      hi = OFF
              |    \|  ___  lo = ON
              |  Q33 |--|___|---o
              |    <|     from micro
              |   |
              '---+--'
                |
                ===
                GND
        KTC3875-GR / BR3DG3875M, KEC / Blue Rocket Electronics, NPN transistor, 60V 150mA, hfe = 200-400, marking HALG or ALG:
        https://cdn.badcaps-static.com/pdfs/...ef4b37225e.pdf
        https://cdn.badcaps-static.com/pdfs/...2ec8d6d3bf.pdf

        Comment

        • caphair
          Badcaps Legend
          • Nov 2011
          • 1249

          #24
          Re: Need help identifying smd

          So just for reference, how does a processor turn an LCD display on?

          Does it first send backlights signal then once that's on it turns LCD display on?

          Doesn't make sense why if it's on it stays on but soon as it's turned off it won't come back on unless you keep trying
          Last edited by caphair; 04-19-2016, 04:55 PM.

          Comment

          • fzabkar
            Badcaps Veteran
            • Mar 2009
            • 772
            • Australia

            #25
            Re: Need help identifying smd

            Can you give us the part numbers of the major ICs and the model number of the device?

            Comment

            • caphair
              Badcaps Legend
              • Nov 2011
              • 1249

              #26
              Re: Need help identifying smd

              I'll provide part numbers of major ICs when I'm home but it's an Absolute DD-3000ABT

              Comment

              • fzabkar
                Badcaps Veteran
                • Mar 2009
                • 772
                • Australia

                #27
                Re: Need help identifying smd

                Is there a PDF manual for this thing?

                Comment

                • caphair
                  Badcaps Legend
                  • Nov 2011
                  • 1249

                  #28
                  Re: Need help identifying smd

                  I don't know I couldn't find one

                  Comment

                  • fzabkar
                    Badcaps Veteran
                    • Mar 2009
                    • 772
                    • Australia

                    #29
                    Re: Need help identifying smd

                    What about an FCC ID? Sometimes there are useful documents in the FCC database.

                    Comment

                    • caphair
                      Badcaps Legend
                      • Nov 2011
                      • 1249

                      #30
                      Re: Need help identifying smd

                      Don't see an FCC ID unfortunately

                      Comment

                      • caphair
                        Badcaps Legend
                        • Nov 2011
                        • 1249

                        #31
                        Re: Need help identifying smd

                        Where would the main processor most likely be located, the circuit board with DVD drive/psu or circuit behind the LCD assembly?

                        Comment

                        • caphair
                          Badcaps Legend
                          • Nov 2011
                          • 1249

                          #32
                          Re: Need help identifying smd

                          Ok here's the area where Q12, Q33 are. There's another transistor Q60 that feeds 1.5v to base of Q33 through R193. It's base isn't connected to anything though, how does that work?

                          It's emitter connects to R154 which goes out to a pin that I traced to a chip right under the DVD drive. I'll post a pic of that next as my phone only allows one pic per post. I'm not sure if this is power for the DVD drive or linked to power on for the LCD?
                          Attached Files

                          Comment

                          • caphair
                            Badcaps Legend
                            • Nov 2011
                            • 1249

                            #33
                            Re: Need help identifying smd

                            R154 connects to pin where I marked with a red line. There's no trace going to it on the board though?
                            Attached Files

                            Comment

                            • budm
                              Badcaps Legend
                              • Feb 2010
                              • 40746
                              • USA

                              #34
                              Re: Need help identifying smd

                              The Base of Q60 is connected to R324, another end of R324 goes to the VIA to connect to what ever, the board may be more than 2-layer board.
                              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

                              • caphair
                                Badcaps Legend
                                • Nov 2011
                                • 1249

                                #35
                                Re: Need help identifying smd

                                The end of R324 that connects to base of Q60 has 1.95v when the display doesn't turn on. The other end of R324 has 5v

                                When the display come on, base of Q60 drops to .70v 5v stays same on other end of R324. Is it normal to have that big a voltage drop across a resistor?

                                I wish I could figure out what's not switching every single time.

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA

                                  #36
                                  Re: Need help identifying smd

                                  You can esily find out if the Transistor are switching as it should or not by check the DCV between E and B, and E and C.
                                  if E and B changes state then E and C will also change state.
                                  You should look up on how Transistor operate.
                                  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

                                  • caphair
                                    Badcaps Legend
                                    • Nov 2011
                                    • 1249

                                    #37
                                    Re: Need help identifying smd

                                    Ok I have a question. When the display doesn't come up on Q60 there's 1.92v on the base and 1.25v on emitter and collector. When display comes on there's a difference of those voltages on the collector at .67v

                                    Does this show something wrong with that transistor or something else?

                                    Comment

                                    • budm
                                      Badcaps Legend
                                      • Feb 2010
                                      • 40746
                                      • USA

                                      #38
                                      Re: Need help identifying smd

                                      'Q60 there's 1.92v on the base and 1.25v on emitter and collector'
                                      You need to check the Voltage between the E pin and B pin, and between E and C pin. What are they?
                                      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

                                      • caphair
                                        Badcaps Legend
                                        • Nov 2011
                                        • 1249

                                        #39
                                        Re: Need help identifying smd

                                        B and E .65v
                                        C and E 0v

                                        Comment

                                        • budm
                                          Badcaps Legend
                                          • Feb 2010
                                          • 40746
                                          • USA

                                          #40
                                          Re: Need help identifying smd

                                          Originally posted by caphair
                                          B and E .65v
                                          C and E 0v
                                          As I explained before, as you can see, the E-B junction of the transistor is bias ON, so the Voltage between E and C will be close to 0V (Transistor is turned ON , saturated condition).
                                          https://learn.sparkfun.com/tutorials/transistors

                                          https://en.wikipedia.org/wiki/Bipola...sistor_biasing

                                          http://www.electronics-tutorials.ws/...r-biasing.html
                                          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

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