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Samsung PS-42D4S plasma. Has sound, no picture. Please help!

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    Samsung PS-42D4S plasma. Has sound, no picture. Please help!

    Hello,

    Finally after 10 years of service my beloved 42" Samsung PS-42D4S plasma stopped working today. It powers ON using remote, it has sound, but no picture at all, screen is completely dark. Blind remote commands work OK. It's based on Samsung S42SD-YD05 plasma module. Internally looks quite impressive, very clean, no visibly burnt components or bad caps.

    Factory plasma module voltages are:

    Va: 70V
    Vsc: -70V
    Vs: 175V
    Ve: 165V
    Vset: 165V


    My TV when switched ON gives following voltages:

    Va: 70.1V (OK)
    Vscan: -70.2V (OK)
    Vs: 6.5V (wrong)
    Ve: floating 0V-6V (wrong)
    Vset: 0.26V (wrong)



    Other voltages are:

    VG: 15.13V (don't know if OK)
    VT: 32.1V (don't know if OK)

    A6V: 6.11V (OK)
    A12V: 12.94V (OK)
    18VAMP: 18.7V (OK)
    D3.3V: 3.25V (OK)
    D5V: 5.18V (OK)
    D6V: 6.16V (OK)
    D12V: 12.94V (OK)
    STD 5V: 5.05V (OK)

    PS ON: 0.25V (??!)
    VS ON: 2.9V (??!)


    When YSUS and ZSUS are disconnected - no difference in voltages. When TV is switched ON, no buzzing sound or hiss from PSU. YSUS and ZSUS are completely cold. ICs on video board gets warm. Some heat sinks on PSU get warm, some are cold. I checked some fuses - OK. There are lot of other fuses soldered on PCBs which I cannot measure without taking boards out and measure on bottom side. Will do after some discussion here...

    I noticed that there is no video output on monitor composite video out. I connected small LCD TV to check if plasma gives picture to monitor out. Also I remember every time when I press a button on remote (volume, program, menu...) front LED would blink. Now it does not blink when remote buttons are pressed, but commands work (volume up/down, input change, audio eq).

    Please take a look at pictures.

    I have service manual but it's from Philips TV with same plasma module. So PSU and video board are different than mine. Service manual is attached.

    I would really like to repair this TV. I have MP4 set top box connected to DVI input, Playstation to SCART RGB, Commodore 128D (yeah!) to S-Video and DVD player to component video inputs - picture is great, better than brand new fancy 46" Sony LED LCD TV from my parents.

    So, what should I check first? Shouldn't VS ON and PS ON voltages be much higher? Looks like half of PSU does not work at all.

    Any suggestion and advice is more than welcome!

    Thanks and cheers!

    Suad
    Attached Files
    Last edited by scokljat; 08-19-2015, 06:40 PM.

    #2
    Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

    Still no response... Please guys, I really need some help on this one. My wife is getting nervous not being able to watch her beloved series. You know what I mean...

    Cheers,

    Suad

    Comment


      #3
      Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

      Looks like I found PSU schematics. PSU model is: BN96-01217A Samsung Electro-Mechanics, model name V3V, REV 1.1. There is lot of info on web, looks like very common plasma PSU.

      Service manual attached.

      Cheers!

      S
      Attached Files

      Comment


        #4
        Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

        Va: 70V
        Vsc: -70V
        Vs: 175V
        Ve: 165V
        Vset: 165V

        Va: 70.1V (OK)
        Vscan: -70.2V (OK)
        Vs: 6.5V (wrong)
        Ve: floating 0V-6V (wrong)
        Vset: 0.26V (wrong)

        If you have no Vs then you would not have Vsc generated by the Y-Main Bd. Ve is generated by the X-Main Bd and is derived from the Vs voltage, also. Va and Vs are generated from the Pwr Bd. These voltages just does not make sense to me. Please check them again. check you DMM battery.

        Comment


          #5
          Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

          Originally posted by Andrew F. Ali View Post
          Va: 70V

          If you have no Vs then you would not have Vsc generated by the Y-Main Bd. Ve is generated by the X-Main Bd and is derived from the Vs voltage, also. Va and Vs are generated from the Pwr Bd. These voltages just does not make sense to me. Please check them again. check you DMM battery.
          Well, Andrew, first thank you for your response and breaking the ice ;-)

          But, what you say does not make sense to me. Look at the schematics for my PSU. It's clearly visible that Vs is generated by PSU (page 2) and Vset and Ve are derived directly from VS also by PSU (page 4). Vs should be present if both YSUS and X/ZSUS are disconnected. Right?

          Va is generated separately and Vscan is derived from Va (page 4).

          So, in my case there is no Vs and normally no Vset and Ve. As I see IC directly responsible for Vs is IC1 ML4824 (page 2). Question - is maybe some other malfunction prevents further failure and shuts down Vs with PFC IC? Anyways, my first suspect is PFC IC1 ML4824.

          Btw, I checked all fuses on PSU, all OK.

          Check picture - on the PSU itself it's written exactly what voltages it should normally output.


          Cheers,

          S
          Attached Files
          Last edited by scokljat; 08-21-2015, 06:17 PM.

          Comment


            #6
            Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

            Came back from vacation. My TV is still dead, no progress so far. Please, I would really appreciate some ideas. Should I replace IC1 ML4824 PFC?

            Cheers!

            S

            Comment


              #7
              Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

              Try to change the panel in internal mode.

              Comment


                #8
                Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                Originally posted by Maklaud View Post
                Try to change the panel in internal mode.
                How do I do that?? What do I get with that? Plasma module will power up even without main video board? That would be helpful.

                Thanks.

                Suad

                Comment


                  #9
                  Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                  Originally posted by Maklaud View Post
                  Try to change the panel in internal mode.
                  OK. I see the procedure in service manual (see pic). Idea is to switch ON PSU and plasma module (without main video board) and get test patterns. However, even if I manage to make jumper cable, this does not apply to my case as I have original Samsung BN96-01217A PSU. Service manual is for Philips TV with same plasma module, all with completely different PSU's than mine.

                  Just to remind you, my TV switches ON correctly by remote, sound and blind commands works, all voltages are OK except Vs (and Vset and Ve which are derived from Vs). No change if I disconnect Y-SUS and/or Z-SUS.

                  So, my main question is: what is the reason of missing Vs. Is it pure PSU failure of Vs power supply part or VS-ON signal from control board to PSU is wrong. When TV is switched ON, VS-ON signal is 3V (measured to GND). See pics.

                  From What I can see, IC1 ML4824 PFC is crucial to get proper Vs so if VS-ON signal is OK, first thing I suspect is ML4824. Problem is it's very hard to test and measure voltages with DMM when PSU is mounted to TV chasis as I cannot reach bottom of PSU PCB. It would be great if I can operate PSU alone on the bench so I can test it properly and easily measure all points at bottom od PCB.

                  Cheers!

                  S
                  Attached Files
                  Last edited by scokljat; 09-16-2015, 05:51 AM.

                  Comment


                    #10
                    Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                    Common issue on these is a failed Polly cap on the psu causing Vs to die. I will see if I can find the video of the repair someone did.
                    Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

                    https://www.facebook.com/Telford-Tel...7894576335359/

                    Comment


                      #11
                      Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                      If you run in internal mode then I think you will get PS-ON signal is 3V.
                      Last edited by Maklaud; 09-16-2015, 06:04 AM.

                      Comment


                        #12
                        Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                        Originally posted by ReeceyBurger123 View Post
                        Common issue on these is a failed Polly cap on the psu causing Vs to die. I will see if I can find the video of the repair someone did.
                        Please, which one is the "Polly cap"? Would you highlight it on the schematics? Btw, I'm unfamiliar with term "Polly" :-) Please shed some light ;-)

                        Thanks,

                        S

                        Comment


                          #13
                          Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                          Or try using a resistor 1kOhm +3V PS ON
                          Lvds interface, disconnect.

                          Comment


                            #14
                            Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                            Originally posted by Maklaud View Post
                            If you run in internal mode then I think you will get PS-ON signal is 3V.
                            There is PS-ON and VS-ON signals. PS-ON is sent to PSU by main video board (tuner board). VS-ON is sent to PSU by control board.

                            On my TV when in standby (front red LED ON) PS-ON signal is 3.3V. When TV is switched ON with remote PS-ON is 0.25V.

                            However, when TV is in standby VS-ON signal is 0.4V, and when TV is switched ON is 2.95V.

                            Thanks,

                            S

                            Comment


                              #15
                              Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                              Have you got 390-400V there? B+_PFC
                              Last edited by Maklaud; 09-16-2015, 07:00 AM.

                              Comment


                                #16
                                Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                                Originally posted by Maklaud View Post
                                Have you got 390-400V there? B+_PFC
                                I suppose yes because all other voltages which are OK are derived from B+_PFC. I'll measure exact value. You want me to measure B+PFC to GND?

                                Thanks,

                                S

                                Comment


                                  #17
                                  Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                                  https://drive.google.com/file/d/0B1b...ew?usp=sharing

                                  Comment


                                    #18
                                    Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                                    Yes measure. Because there can be 290-300V and not 390-400V.

                                    Comment


                                      #19
                                      Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                                      Do you have a hair drier you can use it to help diagnose the issue ? ?
                                      Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

                                      https://www.facebook.com/Telford-Tel...7894576335359/

                                      Comment


                                        #20
                                        Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

                                        Originally posted by Maklaud View Post
                                        Yes measure. Because there can be 290-300V and not 390-400V.
                                        I will later today as soon I get back home.

                                        Thanks!

                                        S

                                        Comment

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