Philips 37PF7321/98 cannot turn on

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  • john_doe
    Senior Member
    • Apr 2013
    • 192
    • Malaysia

    #161
    Re: Philips 37PF7321/98 cannot turn on

    Originally posted by bammbammfran
    now recheck usual voltages at G D S and at 1305 and also check the pad to the right of the cut
    Gate is 9v
    Drain is 5v
    Source is 5v

    Pad to right of cut is 85v

    Comment

    • bammbammfran
      Badcaps Veteran
      • Apr 2014
      • 476
      • USA

      #162
      Re: Philips 37PF7321/98 cannot turn on

      looks like you are going to have to replace that transistor with the old one.
      I wish you would have mentioned the transplant !!

      85v ?? WTF
      I'll look into that in the morning

      Comment

      • john_doe
        Senior Member
        • Apr 2013
        • 192
        • Malaysia

        #163
        Re: Philips 37PF7321/98 cannot turn on

        Originally posted by bammbammfran
        looks like you are going to have to replace that transistor with the old one.
        I wish you would have mentioned the transplant !!

        85v ?? WTF
        I'll look into that in the morning
        Very sorry about that. I will put it back right away.

        Comment

        • john_doe
          Senior Member
          • Apr 2013
          • 192
          • Malaysia

          #164
          Re: Philips 37PF7321/98 cannot turn on

          Old transistor on board.

          With pin 7 out from 11 pin plug and trace cut, the voltage of Gate is about 6v, Source and Drain are 5v. All 3 pins of 1305 are 5v.

          Pad to right of cut is still 85v.

          When I jump ground to Gate, the relay clicks and the TV screen lights up. That means I can turn on and off the screen by touching ground to Gate.
          Last edited by john_doe; 06-21-2014, 12:56 AM.

          Comment

          • bammbammfran
            Badcaps Veteran
            • Apr 2014
            • 476
            • USA

            #165
            Re: Philips 37PF7321/98 cannot turn on

            now we need to try to find out where the hell 85 volts is coming from.
            may be leaking from high power side ?
            start with checking the pins on the optocoupler at 7501
            also mark anything that is showing over 14v on that quarter of the board


            basically back track from that 85v pin
            you'll see in my picture that I started tracing, but there is a couple parts like where the pin traces T-off that I am not sure if it goes that way
            if you run into a component where it changes voltages, make a not
            Last edited by bammbammfran; 06-21-2014, 06:42 AM.

            Comment

            • john_doe
              Senior Member
              • Apr 2013
              • 192
              • Malaysia

              #166
              Re: Philips 37PF7321/98 cannot turn on

              Originally posted by bammbammfran
              now we need to try to find out where the hell 85 volts is coming from.
              may be leaking from high power side ?
              start with checking the pins on the optocoupler at 7501
              also mark anything that is showing over 14v on that quarter of the board


              basically back track from that 85v pin
              you'll see in my picture that I started tracing, but there is a couple parts like where the pin traces T-off that I am not sure if it goes that way
              if you run into a component where it changes voltages, make a not
              I blown fuse 1315 twice. I am out of fuse to test further. Don't know where is the short. I will get 10 fuse tomorrow.

              Comment

              • bammbammfran
                Badcaps Veteran
                • Apr 2014
                • 476
                • USA

                #167
                Re: Philips 37PF7321/98 cannot turn on

                that is the one on the power supply ??
                did you blow it twice between today and yesterday or was one of those time when you did it a few days ago ?

                Comment

                • john_doe
                  Senior Member
                  • Apr 2013
                  • 192
                  • Malaysia

                  #168
                  Re: Philips 37PF7321/98 cannot turn on

                  Originally posted by bammbammfran
                  that is the one on the power supply ??
                  did you blow it twice between today and yesterday or was one of those time when you did it a few days ago ?
                  The other day I blown one. Just a couple of minutes ago, I blown two at 1315 fuse.

                  It was ok earlier after I put back the old transistor. I suspect I shorted the pin 7 wire of the 11 pin plug. Pin 7 wire was dangling and may accidently touch other part.

                  You think can pin 7 with 5v blow the fuse on the power supply board?

                  Comment

                  • bammbammfran
                    Badcaps Veteran
                    • Apr 2014
                    • 476
                    • USA

                    #169
                    Re: Philips 37PF7321/98 cannot turn on

                    hook that pin back up
                    I do not think the it would blow that fuse since that fuse is handling 340volts to the standby board
                    you might just have accidentally grounded the standby ?

                    Comment

                    • john_doe
                      Senior Member
                      • Apr 2013
                      • 192
                      • Malaysia

                      #170
                      Re: Philips 37PF7321/98 cannot turn on

                      Since I don't have power now, what else can I check?

                      Comment

                      • john_doe
                        Senior Member
                        • Apr 2013
                        • 192
                        • Malaysia

                        #171
                        Re: Philips 37PF7321/98 cannot turn on

                        Originally posted by bammbammfran
                        now we need to try to find out where the hell 85 volts is coming from.
                        may be leaking from high power side ?
                        start with checking the pins on the optocoupler at 7501
                        also mark anything that is showing over 14v on that quarter of the board


                        basically back track from that 85v pin
                        you'll see in my picture that I started tracing, but there is a couple parts like where the pin traces T-off that I am not sure if it goes that way
                        if you run into a component where it changes voltages, make a not
                        "Back track from that 85v pin" means I should trace from the pink or blue line of your pic?
                        Attached Files

                        Comment

                        • bammbammfran
                          Badcaps Veteran
                          • Apr 2014
                          • 476
                          • USA

                          #172
                          Re: Philips 37PF7321/98 cannot turn on

                          Originally posted by john_doe
                          "Back track from that 85v pin" means I should trace from the pink or blue line of your pic?
                          the 85 volts is showing right now at the solder pad to the right of the yellow cutout trace which starts as a light blue line and goes in two directions.

                          It can partly be traced with an ohm meter, but I think it would be easier to track it with the 85volts active
                          so without a fuse, that won't be doable

                          the orange rectangular fuse at 1500 on the standby could have been stolen for temporary use but it is probably not rated high enough in amps ???

                          Comment

                          • john_doe
                            Senior Member
                            • Apr 2013
                            • 192
                            • Malaysia

                            #173
                            Re: Philips 37PF7321/98 cannot turn on

                            Originally posted by bammbammfran
                            the 85 volts is showing right now at the solder pad to the right of the yellow cutout trace which starts as a light blue line and goes in two directions.

                            It can partly be traced with an ohm meter, but I think it would be easier to track it with the 85volts active
                            so without a fuse, that won't be doable

                            the orange rectangular fuse at 1500 on the standby could have been stolen for temporary use but it is probably not rated high enough in amps ???
                            Being a noob like me, I think I better get the proper fuse.

                            Comment

                            • bammbammfran
                              Badcaps Veteran
                              • Apr 2014
                              • 476
                              • USA

                              #174
                              Re: Philips 37PF7321/98 cannot turn on

                              on the standby board near the large transformer and on the low voltage side: there is a diode at 6140 that looks like it leads to the positive pin of capacitor at 2140 that might be worth checking voltage at
                              see what that voltage at that cap is and what that cap is rated for voltage wise

                              Comment

                              • bammbammfran
                                Badcaps Veteran
                                • Apr 2014
                                • 476
                                • USA

                                #175
                                Re: Philips 37PF7321/98 cannot turn on

                                I started retracing from a different part of the board and it looks like the last picture that I posted is incorrect at the pink T
                                this one should be more correct
                                Still tough to see some stuff and I am not 100% sure if the T in the pink line At the pink circle marked with a pink B is correct
                                green is ground
                                red is 5volt
                                pink appears to go to or from the transistor gate
                                I lose track on the right side at that one diode at white A
                                Attached Files

                                Comment

                                • john_doe
                                  Senior Member
                                  • Apr 2013
                                  • 192
                                  • Malaysia

                                  #176
                                  Re: Philips 37PF7321/98 cannot turn on

                                  Originally posted by bammbammfran
                                  I started retracing from a different part of the board and it looks like the last picture that I posted is incorrect at the pink T
                                  this one should be more correct
                                  Still tough to see some stuff and I am not 100% sure if the T in the pink line At the pink circle marked with a pink B is correct
                                  green is ground
                                  red is 5volt
                                  pink appears to go to or from the transistor gate
                                  I lose track on the right side at that one diode at white A
                                  I added some tracing at white A.

                                  The thinner pink line at the pink circle is not touching the thicker pink line.
                                  Attached Files

                                  Comment

                                  • john_doe
                                    Senior Member
                                    • Apr 2013
                                    • 192
                                    • Malaysia

                                    #177
                                    Re: Philips 37PF7321/98 cannot turn on

                                    Put in new fuse at 1315 and switch on main power from wall. Fuse blown sky high.

                                    Check the hot section of the standby board and found it has shorted.

                                    There is continuity from pin 1 and pin 2 of 1306. Also from pin 1 of 1306 to as far as all pins on hot side of transformer. Even the transistor 7102 has continuity to 1306.

                                    Is the board fried?
                                    Attached Files

                                    Comment

                                    • bammbammfran
                                      Badcaps Veteran
                                      • Apr 2014
                                      • 476
                                      • USA

                                      #178
                                      Re: Philips 37PF7321/98 cannot turn on

                                      take out one end of 5104 and recheck 1806 power plug pins
                                      then check resistance at all 3 pins to each other on 7102

                                      Comment

                                      • bammbammfran
                                        Badcaps Veteran
                                        • Apr 2014
                                        • 476
                                        • USA

                                        #179
                                        Re: Philips 37PF7321/98 cannot turn on

                                        Originally posted by john_doe
                                        I added some tracing at white A.

                                        The thinner pink line at the pink circle is not touching the thicker pink line.
                                        ok on the thin pink which means there ia a direct line from the capacitor by the main transformer all the way to the gate. only thing in the way is a diode that should be blocking that voltage. so that diode need to be check to see if it only allows resistance in one direction

                                        so , at the transistor that I marked with the white A the trace that goes under that transistor is from the single pin side up to the 471 resistors right side ?
                                        If that is the case, then we have to figure out where the top left pin of that transistor goes. the 253x white numbers cover the traces

                                        FYI: At the diode at 6149- the top K pin goes to 5 volts at the 9065 jumper
                                        and the jumper below that goes to the 0 resistor and also gets 5 volts and that feeds 5 volts to the 1 and 2 pins at the 1305 plug

                                        Comment

                                        • bammbammfran
                                          Badcaps Veteran
                                          • Apr 2014
                                          • 476
                                          • USA

                                          #180
                                          Re: Philips 37PF7321/98 cannot turn on

                                          is 8105 cooked by the 7106

                                          Comment

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