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    Sony KDL 32L4000 Troubleshooting

    I have this LCD TV and am told it was working fine, but just went dead. Plug it in and I hear a click, but no lights other than the optical audio out.

    Attached are three pictures, one a wide picture of the back, the second of the power board and the third of the main board. I couldn't quickly figure out how to remove the shielding for the main board and will need to investigate further if necessary; however, i am trying to figure out if I need to go there.

    To start with let me set the understanding that my knowledge is very high level and my terminology may be rather inexact. I would be interested in a component level fix if possible, but a board level fix may be sufficient.

    I tested the voltages with the power supply plugged in, but CN201 and CN202 unplugged. CN201 has two connectors -- one going to the main board and the other going to the inverter board. CN202 has a PS On, Power Err Det three grounds and three 4 VSB markings. With nothing plugged in the PS On shows 4.17 V and three 4 VSB posts change voltages over the range of about 4.03 to 4.20 (continually changing readings). Nothing on Power Err Det. No voltages detected on CN201.

    If I plug all the connectors in two of the 4 VSBs have a connection and both read 4.17V; zero volts on Power Err Det. and PS On shows .08V. CN201 has 24V and ground on the top connector which goes to the inverter and the lower connector (middle one of the three) shows 1.13V on the Pwr 6V connections, .44V on the Pwr Panel connections, .87V on the 15V connections and .01V on the 30V connections.

    These readings would lead me to believe the power supply is bad. As previously stated, pushing the power button on the top of the TV does nothing (i.e., TV seems dead), though i do notice that the optical audio light is on. My understanding is that the main board waits to be energized by the power button being pressed and then turns on the set. So i am suspecting that the fact i am getting 4.17V on PS On when nothing is connected means the power supply is good and that the main board is not energizing the TV when the button is pushed. Which I am guessing would then generate the voltages shown with CN201

    I am not sure if that is a correct understanding and would appreciate corrections to my thinking if necessary. I also suppose that the power button could be malfunctioning, but I do not suspect this because I am told the TV was working and just turned off and would not turn back on.

    I can check other things and get other/better pictures, but first would like to know if the above understanding is correct.
    Attached Files

    #2
    Re: Sony KDL 32L4000 Troubleshooting

    It makes for easier reading if you could give the voltages at the connectors when in standby and out of standby in a similar format as shown.
    Attached Files
    Willing to help but I'm no expert.

    Comment


      #3
      Re: Sony KDL 32L4000 Troubleshooting

      Am i correct in understanding standby to mean plugged in, but power button not pressed? If this is correct then not sure what you want for out of standby since I have mentioned that nothing happens when the power button is pressed.

      Comment


        #4
        Re: Sony KDL 32L4000 Troubleshooting

        Originally posted by Eaglecrest View Post
        Am i correct in understanding standby to mean plugged in, but power button not pressed? If this is correct then not sure what you want for out of standby since I have mentioned that nothing happens when the power button is pressed.
        We are looking to see if any of the control signals change state at all when TV is in standby and when power switch is activated, that is what we NEED right now.
        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


          #5
          Re: Sony KDL 32L4000 Troubleshooting

          I read the LCD TV link and put together the voltage chart attached. This is the same information I shared originally. To make sure my terminology makes sense. Standby means the measurement with all connectors attached and the plug connect to household current. Powered means that the measurement was taken while the power button on the top of the TV is being pressed. Please note there is no difference in the readings and nothing happens when the power button is pressed. Lastly if i read the pins on 202 with the connector removed I get the power readings noted and the Relay RL1 continuously clicks.

          If I understand the LCD tutorial the readings on the power board indicate that power is generated and sent to the main board; however, the main board is not generating the voltages needed to start up the set. Is this a correct understanding?
          Attached Files

          Comment


            #6
            Re: Sony KDL 32L4000 Troubleshooting

            "Lastly if i read the pins on 202 with the connector removed I get the power readings noted and the Relay RL1 continuously clicks."
            Which connector removed, the CN202?
            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


              #7
              Re: Sony KDL 32L4000 Troubleshooting

              Which connector removed, the CN202?
              Yes. Remove the connector, plug in the TV and test the pins to which the connector attaches.

              Comment


                #8
                Re: Sony KDL 32L4000 Troubleshooting

                But in your PDF you indicated '202 ONLY PLUGGED IN' and that causes the relay clicking. I just want to make sure we get the correct DATA.
                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


                  #9
                  Re: Sony KDL 32L4000 Troubleshooting

                  If you do not have any connectors connected to the power supply board except the AC power cord, is the RL1 still clicking when you plug the power cord into the AC outlet?
                  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


                    #10
                    Re: Sony KDL 32L4000 Troubleshooting

                    If you do not have any connectors connected to the power supply board except the AC power cord, is the RL1 still clicking when you plug the power cord into the AC outlet?
                    Yes. With 201, 202 and 203 disconnected the relay clicks slowly.

                    Comment


                      #11
                      Re: Sony KDL 32L4000 Troubleshooting

                      OK, your power supply board is Sony 1-857-108-11 Power Supply
                      http://www.shopjimmy.com/sony-1-857-...pply-unit.htm#
                      That power relay should not be turning on and off when the power supply board is running by itself.
                      I found the schematic for it:
                      Per schematic, the PS-ON signal in this case is active LO, <1VDC at PS-ON = the rest of power supply come on, you did indicated that the PS-ON pin is 0V when all connectors in place and you should notice that relay RL1 clicks on. So it does not make sense that the replay is clicking on and off when the power supply board is not connecting to anything.
                      Attached Files
                      Last edited by budm; 08-01-2018, 08:45 PM.
                      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


                        #12
                        Re: Sony KDL 32L4000 Troubleshooting

                        Thanks Budm, it is the end of my day. I will investigate this further.

                        Mike

                        Comment


                          #13
                          Re: Sony KDL 32L4000 Troubleshooting

                          Per schematic, the PS-ON signal in this case is active LO, <1VDC at PS-ON = the rest of power supply come on, you did indicated that the PS-ON pin is 0V when all connectors in place and you should notice that relay RL1 clicks on. So it does not make sense that the replay is clicking on and off when the power supply board is not connecting to anything.
                          Budm,

                          I looked over the info and don't understand where you are getting the fact that PS-ON is active low. However, it is < 1VDC when all three connectors are attached. In that state, when power cord is plugged in I hear a RL1 clicks once, but nothing comes on.

                          RL1 continuously clicks whenever connector 202 is not connected, the other two connector's status makes no difference. It clicks about once/second and about double that rate, once unplugged, until it stops (drains?). I mistakenly stated on the chart that PS-On cycles between 4 and 4.25 VDC with 202 only connected, what should have been stated is the this happens whenever 202 is NOT connected.

                          So when 202 is disconnected PS_ON is > 1VDC which would make it in active. Would that cause the relay to keep trying to energize and keep clicking on and off?

                          Comment


                            #14
                            Re: Sony KDL 32L4000 Troubleshooting

                            Originally posted by Eaglecrest View Post
                            Budm,

                            I looked over the info and don't understand where you are getting the fact that PS-ON is active low. However, it is < 1VDC when all three connectors are attached. In that state, when power cord is plugged in I hear a RL1 clicks once, but nothing comes on.

                            RL1 continuously clicks whenever connector 202 is not connected, the other two connector's status makes no difference. It clicks about once/second and about double that rate, once unplugged, until it stops (drains?). I mistakenly stated on the chart that PS-On cycles between 4 and 4.25 VDC with 202 only connected, what should have been stated is the this happens whenever 202 is NOT connected.

                            So when 202 is disconnected PS_ON is > 1VDC which would make it in active. Would that cause the relay to keep trying to energize and keep clicking on and off?
                            Well, if you look at what the PS-ON pin is connected to in the schematic, you will see that it connected to PNP Transistor then you will see why it is ACTIVE LO, that is why RL1 is turned on when all the connectors are in place, you can easily check the DC Voltage on the two legs of the relay coil.
                            Last edited by budm; 08-02-2018, 06:24 PM.
                            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


                              #15
                              Re: Sony KDL 32L4000 Troubleshooting

                              Budm,

                              Thanks, as I mentioned my knowledge level is low, but I would like to understand better. Are you willing to help walk me through a better understanding, or is that asking too much? If so better to do so through this forum or offline?

                              Comment


                                #16
                                Re: Sony KDL 32L4000 Troubleshooting

                                Well, you will need to learn the basic first such as how Transistors, MOSFET's, Diode function, knowing the Ohms laws, knowing how to read schematic symbols and diagrams. It will not be just a walk through without knowing the basic first and apply that knowledge to what you are trying fix.
                                Lots of free electronics learning out on the web.
                                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


                                  #17
                                  Re: Sony KDL 32L4000 Troubleshooting

                                  you will need to learn the basic first such as how Transistors, MOSFET's, Diode function, knowing the Ohms laws, knowing how to read schematic symbols and diagrams.
                                  I have no doubt about that and to understand all the design parameters of the electronics I am looking at will take quite a bit of learning. I am thinking that at the macro level, perhaps less depth can still be useful.

                                  I assume the tutorial, "LCD Flat panel TV troubleshooting guide by Bud Martin" is your work piece. At the macro level it states that the power supply board creates the voltages for running the various boards and supplies them as needed. The main board controls the logic and drives the actions of the other boards. The inverter and TCon control translation of the video signal into the visual representation on the LCD panel.

                                  An LCD TV is always powered with a standby voltage that allows to TV to sense a turn on command either from the power button or from the remote control. Once this signal occurs the TV is energized to turn on the rest of the circuits to allow it to accomplish its task of displaying video inputs.

                                  All the boards are, obviously, tied together and if one is out or malfunctioning then the final output will be inferior at best. If the TV is dead it could be because the power board is bad or because the circuit that reacts to the "turn on signal" is bad. What I am trying to understand is how this works at the macro level.

                                  On this set there are no status lights on, no picture, no sound. Power is making it to the connector 202 pins, but no other pins have power. I recall reading somewhere that the other voltages don't get generated until the power on operation is completed so I am assuming that the 201 and 203 voltages are absent for that reason and not necessarily because the power board is bad.

                                  The tutorial states "The power supply has Standby 5vdc ... which is always on the minute the TV is plugged into the AC outlet". This TV does not have 5 VDC, but does have 4 VDC which I am assuming is the standby voltage. If that is correct then I have a standby voltage, but the TV is not turning on when signaled to do so. Assuming this understanding is correct the following questions come to my mind:
                                  1. [1]Voltage reads 4.16 VDC is this acceptable for a 4 VSB requirement or is this an over voltage?
                                    [2]Is the monitoring of the power on signal done on the main board?
                                    [3]Is it a correct understanding that either pin 3 or 7 on 202 is feeding the "signal on" monitoring circuit?
                                    [4]What does the other 4 VSB pin do?
                                    [5]The tutorial states "the Processor will send the turn on signal (3.3~5vdc) to the power supply module (PSON pin)" Since the voltage reading for PS-ON is .08 it appears that the turn on voltage is not being sent by the microprocessor. Correct?

                                  Comment


                                    #18
                                    Re: Sony KDL 32L4000 Troubleshooting

                                    [1]Voltage reads 4.16 VDC is this acceptable for a 4 VSB requirement or is this an over voltage? 4.16V is fine, it is <5% off, the higher reading can also be due to your meter calibration.

                                    [2]Is the monitoring of the power on signal done on the main board? The main board send out PS-ON steady signal. most TV's use active high (>2vdc = on <1V = OFF, but your TV uses active low.

                                    [3]Is it a correct understanding that either pin 3 or 7 on 202 is feeding the "signal on" monitoring circuit? cn 202 Pin 1 is an input pin for PS-ON pin, pin 2 is for the output pin for Power supply error signal to tell the main board the condition of the power supply. Pin 3, 7, and 8 are output pins for 4V Standby Voltage to run the main board.

                                    [4]What does the other 4 VSB pin do? If you look at the traces you will see that 4VSB pins are all tied together.

                                    [5]The tutorial states "the Processor will send the turn on signal (3.3~5vdc) to the power supply module (PSON pin)" Since the voltage reading for PS-ON is .08 it appears that the turn on voltage is not being sent by the microprocessor. Correct? Your TV uses active LO, you can easily verify that by check the DC Voltage on the two pins of the relay coil when all the boards are connected together and the PS-ON pin showing 0 V.

                                    Sony 1-857-108-11
                                    Pictures provided by shopjimmy.
                                    Attached Files
                                    Last edited by budm; 08-03-2018, 09:49 AM.
                                    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


                                      #19
                                      Re: Sony KDL 32L4000 Troubleshooting

                                      As you have mentioned my TV is active low. So if I understand that, a low voltage from the microprocessor turns on the switch to energize the TV. It is has .08 VDC on PS_ON which should turn on the TV, but it doesn't so, therefore, the assumption would be the Power board is bad.

                                      Is this a correct understanding?

                                      Comment


                                        #20
                                        Re: Sony KDL 32L4000 Troubleshooting

                                        Originally posted by Eaglecrest View Post
                                        As you have mentioned my TV is active low. So if I understand that, a low voltage from the microprocessor turns on the switch to energize the TV. It is has .08 VDC on PS_ON which should turn on the TV, but it doesn't so, therefore, the assumption would be the Power board is bad.

                                        Is this a correct understanding?
                                        It is turning on the power supply because the relay RL1 is on based on your report that the relay clicks on (as I already indicate as how you can tell by checking the DCV of the relay coil) but the rest of the power supply did not come on as you can see that the 6V,15V, 24V, and 30V did not come on.
                                        So right now the power needs to be fixed first to get all those Volages.
                                        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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