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Sony KDL-46S4100 Components of tv psu are different from the schematic.

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    #1

    Sony KDL-46S4100 Components of tv psu are different from the schematic.

    Hello everyone, I'm trying to fix a LCD TV (Sony KDL-46S4100) that went bad years ago, it turns on but doesn't do anything (the standby doesn't give error blinks, it just turns off if I turn on the TV), there's no voltage on the cold side, only the standby (3.2v).

    I read someone fixed the same TV by replacing some 1mohm resistor (R614 in the schematic, which I got from here) and according to the schematic both R614 and R317 should be 1w 100mohm, but the ones that are on the board are 0.1 ohm and 0.47 ohm respectively, which baffles me, years ago some uncle took the board and gave it to someone to check it and I don't know if the guy replaced them.

    Also, the diodes ZD703 and ZD704 are bad (I desoldered one leg from the board and each have continuity both ways), but the schematic doesn't say what model number they are, what diode should I use to replace them?.

    Thanks beforehand for any help.

    Edit: Sorry for not putting the tv brand and model in the title!.
    Last edited by FatalityX; 02-09-2022, 08:41 PM. Reason: I didn't put the tv brand and model in the title.
    Tags: None
    #2
    Re: Components of tv psu are different from the schematic.

    Zd703 & zd704 = tzx6v2c-tap 0.1Ω = 100mΩ, R317 should be a 0.1Ω but it is only a fuse resistor so 0.47Ω will work in that location.

    The zeners have their anodes connected together and one cathode (ZD704) goes to ground and the other (ZD703) goes to ic706 pin13 (V_SNS)
    Last edited by R_J; 02-09-2022, 09:11 PM.

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      #3
      Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

      When you have it plugged in and you turn it on with power button on tv, what does the front light do, does it go green and stay green?
      Quit due to disrespect from unpaid sta,ff.

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        #4
        Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

        That's after you replace those diodes of course, the diodes might be all that's wrong, with any luck.
        Quit due to disrespect from unpaid sta,ff.

        Comment

          #5
          Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

          Originally posted by nomoresonys View Post
          When you have it plugged in and you turn it on with power button on tv, what does the front light do, does it go green and stay green?
          No, the light go off and it sounds like a relay, but it doesn't do anything else, no backlight and no voltages to the main board.

          Originally posted by nomoresonys View Post
          the diodes might be all that's wrong, with any luck.
          Well, I hope so!.

          Thanks for the feedback!.

          Comment

            #6
            Re: Components of tv psu are different from the schematic.

            Originally posted by R_J View Post
            0.1Ω = 100mΩ,
            Oh man, I facepalmed so hard!, I thought the schematic said megohm, not milliohm.

            Originally posted by R_J View Post
            Zd703 & zd704 = tzx6v2c-tap
            Ok, but just in case I don't find it (in the country where I live it's quite hard to find components), which other diode could I use to replace them?. Thank you!
            Last edited by FatalityX; 02-10-2022, 08:56 AM.

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              #7
              Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

              These are just 6.2 volt zener diodes, nothing special, they are used for spike protection in that circuit and when removed the circuit should work without them for testing.

              Comment

                #8
                Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                Originally posted by R_J View Post
                These are just 6.2 volt zener diodes, nothing special, they are used for spike protection in that circuit and when removed the circuit should work without them for testing.
                I removed them, but still, no voltage on the cold side, what else could it be?. Also something I forgot to mention, after turning off the tv, if I unplug it from the wall, the standby light stays on for a while, I'm not sure if that's normal (I don't remember how it was, I haven't watched TV in years, all I have is my PC monitor).

                Also there is a short in the Tcon, but after removing the C14 capacitor from it it seems it's gone.

                Comment

                  #9
                  Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                  Do you have another you can put in, should be ok with one the same physical size if you can find one on a scrap board if you have any.
                  Quit due to disrespect from unpaid sta,ff.

                  Comment

                    #10
                    Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                    Originally posted by nomoresonys View Post
                    Do you have another you can put in, should be ok with one the same physical size if you can find one on a scrap board if you have any.
                    No :/ I don't have any board (of any kind really) or components. What else could I test on the PSU board?

                    Comment

                      #11
                      Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                      With tv unplugged from power, unhook cable from powerboard to mainboard, leave it off, plug power cord back into powerboard, see if the backlights come on and stay on.
                      Quit due to disrespect from unpaid sta,ff.

                      Comment

                        #12
                        Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                        Originally posted by nomoresonys View Post
                        With tv unplugged from power, unhook cable from powerboard to mainboard, leave it off, plug power cord back into powerboard, see if the backlights come on and stay on.
                        Sorry if I misunderstand you (my english is not very good), you mean power on the TV without the mainboard connected to the psu?, I tried that and the backlights won't turn on.

                        Comment

                          #13
                          Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                          Ok, they should in this model, so there's a problem in the backlight circuit or the powerboard, don't know if you have other problems elsewhere but those lights should have come on.
                          Quit due to disrespect from unpaid sta,ff.

                          Comment

                            #14
                            Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                            Check the fuse on the inverter board.
                            Quit due to disrespect from unpaid sta,ff.

                            Comment

                              #15
                              Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                              Originally posted by nomoresonys View Post
                              Check the fuse on the inverter board.
                              Which is one is the fuse in the (inverter board)? . I checked it with the dmm and nothing seems to be shorted there.
                              Last edited by FatalityX; 02-10-2022, 04:30 PM.

                              Comment

                                #16
                                Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                                I don't see a fuse either, maybe ohm out the mini transformers on the inverter, different model there but similar process: https://www.youtube.com/watch?v=oE6K4xBVweA
                                Quit due to disrespect from unpaid sta,ff.

                                Comment

                                  #17
                                  Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                                  Originally posted by nomoresonys View Post
                                  I don't see a fuse either, maybe ohm out the mini transformers on the inverter, different model there but similar process: https://www.youtube.com/watch?v=oE6K4xBVweA
                                  Hi, sorry I didn't replied before, I didn't had access to internet until now, I did what is shown in the video and I got no voltages, and tried what it says on this video and everything seems to be alright except, the T1 (next to D4 in the middle of the pic) doesn't have continuity in any of the pins, should I take it out of the board and check it again?.

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                                    #18
                                    Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                                    see if d4 checks the same as d3 and d10.
                                    Quit due to disrespect from unpaid sta,ff.

                                    Comment

                                      #19
                                      Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                                      For now you need to get where the backlights are on when powerboard is unhooked from mainboard, so I would leave the cable off til then.
                                      Quit due to disrespect from unpaid sta,ff.

                                      Comment

                                        #20
                                        Re: Sony KDL-46S4100 Components of tv psu are different from the schematic.

                                        I would put those two new zeners in, zd703-4, never like testing without all my diodes in place.
                                        Quit due to disrespect from unpaid sta,ff.

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