How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

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  • Robb
    Senior Member
    • Sep 2013
    • 159
    • USA

    #21
    Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

    Yup. Boards are labeled X-SUS & Y-SUS. On the XSUS, I measured where the ribbon connects to the YSUS board & at few other spots on the output side of the board (they all looked about the same). On the YSUS I measured at the TPs that I mentioned earlier, TP80, TP80E, TP85, TP85E, etc.

    Comment

    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK

      #22
      Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

      Need to figure out the actual sustain board output, probably one of those wide (6+ pins) traces on buffer board. Try one or the other.
      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

      Comment

      • Robb
        Senior Member
        • Sep 2013
        • 159
        • USA

        #23
        Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

        Correction: On the XSUS, I measured where the ribbon connects to the XSUS board & at few other spots on the output side of the board (they all looked about the same).

        On the YSUS, I've tested at the YSUS to Y-buffer connection, traces leading to the ICs on the Y-buffer and where the Y-buffers connect to each other and they all produce the same wave as pictured below.
        Attached Files

        Comment

        • tom66
          EVs Rule
          • Apr 2011
          • 32560
          • UK

          #24
          Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

          Zoom in on that spike at the beginning of each pulse if possible and adjust the FOCUS control of the scope.
          Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
          For service manual, schematic, boardview (board view), datasheet, cad - use our search.

          Comment

          • Robb
            Senior Member
            • Sep 2013
            • 159
            • USA

            #25
            Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

            Thank you for this invaluable hands on lesson. I lowered the TIME/DIV to 5mS and the position of the vertical scale (maybe a little too much), pulled out the vertical 5X Magnify knob and turned it down, adjusted the FOCUS and partially pushed down on the camera's button before taking the photo below.
            Attached Files
            Last edited by Robb; 11-03-2013, 11:45 AM.

            Comment

            • Robb
              Senior Member
              • Sep 2013
              • 159
              • USA

              #26
              Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

              Is it normal for the ABUS Test Point signals to vary? The YSUS and XSUS were fairly similar when testing different points but the ABUS produced a variety of signals as shown below. Both the Upper ABUS and the Lower ABUS boards had similar variations.

              Oscope Settings: 20mV/Div, 5mSecs/Div & 10X probe
              Attached Files
              Last edited by Robb; 11-03-2013, 01:12 PM.

              Comment

              • tom66
                EVs Rule
                • Apr 2011
                • 32560
                • UK

                #27
                Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

                It looks to me like your SUS waveforms are both more-or-less correct; at least, the major parts are there.

                Next step, check your Va voltage is holding steady. I don't know what each of your test points on the ABUS should measure, because Hitachi provide really minimal documentation...
                Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                Comment

                • Robb
                  Senior Member
                  • Sep 2013
                  • 159
                  • USA

                  #28
                  Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

                  The Va signal on the oscilloscope was a DC horizontal line that jumped up and then quickly returned to where it started from. The Va reading from a DMM was 67.0V and held for a little while before slowly diminishing I guess due to the capacitors. The panel says the Va should be 66.8V.

                  Other voltages:
                  When off;
                  STBY = 5.05V
                  AC CLOCK = 1.1V-1.5V

                  When on;
                  Vs = peaks @ 184V
                  Va = peaks @ 68V
                  Vcc = peaks @ 5.1V
                  AUDIO 17V = stays @ 17.2V
                  +5.6V = stays @ 5.5V
                  +5.6V = stays @ 5.5V
                  AC CLOCK = varies from 1.72V-1.27V
                  STBY = stays @ 5.6V
                  POWER 1 = stays @ 4.3V
                  POWER 2 = stays @ 3.2V

                  Vcc 5.1V = 5.1V
                  Vra = 1.7V
                  Vrs = 1.42V
                  Vcego = 3.0V
                  Vsago = 3.0V
                  AC OFF = 0V

                  (Va) = 67V
                  Va = 67V
                  Vcc 5.1V = 5.1V
                  Vs = 184V
                  Vs = 184V
                  Panel says Va = 66.8V & Vs = 184.1V

                  The service manual say:
                  *) Power-On control signals for Power Supply Unit
                  (1) AC power : Supplied
                  PSU outputs STBY+5V.
                  (2) Power Switch: ON : or Remote Power button : ON
                  PoWER_1 rises up.
                  (3) PoWER_1 : High PSU outputs +5.6V.
                  and STBY+5V changes from 5.1V to 5.6V.
                  (4) PoWER_2 : High PSU outputs +17V and Audio+17V.
                  (5) Vcego : High PSU outputs Vcc+5.1V for PDP Module.
                  (6) Vsago : High PSU outputs Va and Vs for PDP Module.
                  (The voltage values of Va and Vs are indicated to the sticker on the PDP Module.)


                  If any control signal does not rise, PSU cannot output the voltage.
                  PoWER_1/2 : not rise ----- Main board trouble
                  Vcego/Vsago : not rise ----- PDP Module (Logic board) trouble
                  However, Vcego rises when PNLRST/CPUgo (P901 [43] at Main board) is High, and
                  Vsago rises when PNLoN/PDPgo (P901 [42] at Main board) is also High.


                  Looks like POWER 1, POWER 2, Vcego and Vsago might be the problem, huh?
                  Last edited by Robb; 11-03-2013, 03:48 PM.

                  Comment

                  • Robb
                    Senior Member
                    • Sep 2013
                    • 159
                    • USA

                    #29
                    Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

                    Are we done with the oscilloscope? If so maybe we should return to the original post.

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK

                      #30
                      Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

                      I'm well past my knowledge point here, but why do you think a problem with "POWER 1, POWER 2, Vcego and Vsago" exists? Help me understand your train of thought.
                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                      Comment

                      • Robb
                        Senior Member
                        • Sep 2013
                        • 159
                        • USA

                        #31
                        Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

                        It looked like POWER 1, POWER 2, Vcego & Vsago voltages were low. Although the wording is difficult for me to understand the service manual says:

                        "(3) PoWER_1 : High PSU outputs +5.6V.
                        and STBY+5V changes from 5.1V to 5.6V.
                        (4) PoWER_2 : High PSU outputs +17V and Audio+17V.
                        (5) Vcego : High PSU outputs Vcc+5.1V for PDP Module.
                        (6) Vsago : High PSU outputs Va and Vs for PDP Module.
                        (The voltage values of Va and Vs are indicated to the sticker on the PDP Module.)

                        If any control signal does not rise, PSU cannot output the voltage.
                        PoWER_1/2 : not rise ----- Main board trouble
                        Vcego/Vsago : not rise ----- PDP Module (Logic board) trouble
                        However, Vcego rises when PNLRST/CPUgo (P901 [43] at Main board) is High, and
                        Vsago rises when PNLoN/PDPgo (P901 [42] at Main board) is also High."

                        Maybe the above highlighted voltages for are not what I should be finding when I measure with a DMM but they appear to be low. I was reading "If any control signal does not rise, PSU cannot output the voltage" as an indication that the voltages should rise to the highlighted voltages, however, they ARE rising just not to what I am expecting them to be.

                        In any event, I'm embarrased to say it but I think I fried my XSUS while measuring the voltages on it when my hand slipped and shorted Vs to an unknown point on the XSUS. Now the blue LED is blinking 2 times (instead of 5) and when the screen briefly lights up it is noticably dimmer.

                        There are no components at the point I shorted and there is no schematic in the service manual. I think this TV may have beaten me. Below are pics of the damage.

                        Oh the agony of defeat.
                        Attached Files

                        Comment

                        • Robb
                          Senior Member
                          • Sep 2013
                          • 159
                          • USA

                          #32
                          Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

                          Back to the more general topic of oscilloscopes. Is the External Trigger Input probe supposed to be connected to a separate signal of which the Ch1 or Ch2 probe is reading? I'm beginning to think that mine might work but I just don't know how to use it yet.

                          Comment

                          • tom66
                            EVs Rule
                            • Apr 2011
                            • 32560
                            • UK

                            #33
                            Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

                            EXT TRIG can be used with a 3rd signal which is not displayed to trigger off that, can be handy if you need a 3rd channel for triggering but don't care about what waveform is actually there.
                            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                            Comment

                            • Robb
                              Senior Member
                              • Sep 2013
                              • 159
                              • USA

                              #34
                              Re: How to Troubleshoot a Plasma TV (p50s602) with an Oscilloscope

                              Thank you for confirming and thank you for all the help...Hiatchis are buggers to work on.

                              Comment

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