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Sony KDL-55EX620, no stand-by volts from one bad resistor?

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    #81
    Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

    When the conditions of ac detect of ic6501 are met pin 26 logic is HIGH. Since VCC of that ic is ~18 volts I would believe +18 on pin 26 would be considered HIGH,
    PH6302 (led) is off, transistor between 3 & 4 open, Q6402 off (open) +3.3 applied through R6403 and R6404 to AC_DET_OFF = 3.3 volts.
    If you are getting 0 volts on AC_DET_OFF, Q6402 could be shorted.
    Last edited by R_J; 12-06-2018, 04:46 PM.

    Comment

      #82
      Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

      Ok here's what I see when looking at my board:

      Q6301 is the one that looks crispy. I think it is on the primary side of the board.
      They call me......."threadkiller"

      Comment

        #83
        Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

        Q6301 is the switch controlled by the power on opto, you could diode check it or check the voltage on the base and the collector
        Its collector connects to pin 28 of IC6501
        Mode select input
        GND connection: Normal sequence
        VCC connection: Standby mode
        Last edited by R_J; 12-06-2018, 04:53 PM.

        Comment

          #84
          Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

          Originally posted by R_J View Post
          So +18 volts on pin#2 of the opto = +18 on pin 26 which is not low but high
          So AC_OFF_DET should be 3.3 volts?
          Yep, that is what should happen.
          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

            #85
            Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

            Originally posted by r_j View Post
            when the conditions of ac detect of ic6501 are met pin 26 logic is high. Since vcc of that ic is ~18 volts i would believe +18 on pin 26 would be considered high,
            ph6302 (led) is off, transistor between 3 & 4 open, q6402 off (open) +3.3 applied through r6403 and r6404 to ac_det_off = 3.3 volts.
            If you are getting 0 volts on ac_det_off, q6402 could be shorted.
            +1
            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

              #86
              Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

              Ok I looked at the board. It looks like I can test collector voltage at one side of R6307, on top of the board. I see no way to test base voltage from the top of the board.

              The board needs to be screwed down so it is grounded, correct? If so how am I going to test base voltage?

              Thanks for hanging in there R_J
              They call me......."threadkiller"

              Comment

                #87
                Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                Originally posted by budm View Post
                +1
                I was so busy typing and looking at the schematic I didn't see you jump in there. Thanks budm
                They call me......."threadkiller"

                Comment

                  #88
                  Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                  So are we transitioning away from Q6301 and more towards Q6401?

                  When testing Q6401 is that in diode mode and which probes on the meter go to which pin?
                  Last edited by DXseekerMO; 12-06-2018, 05:14 PM.
                  They call me......."threadkiller"

                  Comment

                    #89
                    Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                    You can check the base voltage on pin 3 of opto PH6301, I'm more interested in the collector voltage and the condition of this crispy transistor.

                    Comment

                      #90
                      Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                      Q6401??????????????


                      Q6301 is the switch controlled by the power on opto, you could diode check it or check the voltage on the base and the collector
                      Its collector connects to pin 28 of IC6501
                      Last edited by R_J; 12-06-2018, 05:25 PM.

                      Comment

                        #91
                        Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                        Originally posted by R_J View Post
                        You can check the base voltage on pin 3 of opto PH6301, I'm more interested in the collector voltage and the condition of this crispy transistor.
                        Pin 3 of opto PH6301, base voltage is zero volts, measured against hot ground
                        Resistor R6307, collector volts is 18.67 volts measured against hot ground

                        Originally posted by R_J View Post
                        Q6401??????????????
                        Thank you for issuing correction, I meant Q6402. I asked if we were transitioning away from Q6301 and more towards Q6402 because budm gave a +1 on the possibility of it being shorted
                        Last edited by DXseekerMO; 12-06-2018, 05:28 PM.
                        They call me......."threadkiller"

                        Comment

                          #92
                          Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                          Ok so that crispy Q6302 transistor is likely ok, it has 18 volts on the collector which means the power supply is in standby mode. (not on)

                          So just to refresh, what is the voltage on CN6101 pin 7 (AC_OFF_DET)?
                          Last edited by R_J; 12-06-2018, 05:34 PM.

                          Comment

                            #93
                            Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                            Originally posted by R_J View Post
                            Ok so that crispy Q6302 transistor is likely ok, it has 18 volts on the collector which means the power supply is in standby mode. (not on)

                            So just to refresh, what is the voltage on CN6101 pin 7 (AC_DET_OFF)?
                            Voltage at pin 7 of CN6101 is .47V
                            They call me......."threadkiller"

                            Comment

                              #94
                              Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                              Unplug CN6102 and check it again.

                              Comment

                                #95
                                Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                                Originally posted by R_J View Post
                                Unplug CN6102 and check it again.
                                No change in voltage. Maybe you were thinking something on that board was pulling down the AC_OFF_DET volts?
                                They call me......."threadkiller"

                                Comment

                                  #96
                                  Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                                  Yes I was, but its not so Re check the voltage on PH6302 pin 3, it should be 0 volts

                                  Comment

                                    #97
                                    Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                                    Yes it is zero volts
                                    They call me......."threadkiller"

                                    Comment

                                      #98
                                      Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                                      Check Q6402, It must be shorted e-c

                                      Comment

                                        #99
                                        Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                                        with the red probe on C and black on E it tests open
                                        Reverse the probes and the reading is 1.297

                                        Diode check mode used. Confirmed I tested the right transistor
                                        They call me......."threadkiller"

                                        Comment

                                          #100
                                          Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

                                          If you disconnect CN6101 from the main board, does the voltage come up to 3.3 volts? Somethings killing it

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