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    #21
    Re: Question about jumpering P.S.-on command

    PFC Controler IC NCP1608B spec.
    Check the protection resistor R7814 which is connected the VCC pin 8 of the PFC IC to make sure is not open, it should be <10 Ohms.
    Attached Files
    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


      #22
      Re: Question about jumpering P.S.-on command

      There are no shorts except on the Gnd pin #6. VCC to gnd was
      11.72K ohms. Main filter capacitor C7800C supplies 168vdc to
      Q8700 (LLW a 3 leg transistor? ) No pdf. It is supposed to feed voltage to pin 8 of 1608B and DDA002C. No voltage. What is
      LLW?
      Attached Files

      Comment


        #23
        Re: Question about jumpering P.S.-on command

        I checked both the LLW and t2x transistors with my Sencore TF46 and both checked good. Resistor 7814 is good 10.2 ohms. I did not find any shorts to ground.
        This one is Challenging!

        Comment


          #24
          Re: Question about jumpering P.S.-on command

          Please look at the picture attached, I believed the VCC for the PFC IC should be fed from switched transistor some where on the board to the pad I show in the picture.
          The AUX winding of the standby transformer is usually used for powering the PFC, SMPS IC through a switched transistor. It's just a matter of tracing out the board.
          Attached Files
          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


            #25
            Re: Question about jumpering P.S.-on command

            I will trace it more tomorrow. I thought Q8700 LLW supplies power. It has 170vdc on E&B.? The resistors and parts check good. With the same voltage on E/B the transistor will not turn on. I was using maim filter cap gnd for reference. So far I have not found the problem. The two transistors that are obviously feeding the circuit check good. Have not found any open resistors yet. But When I do find the culprit I will tell you.

            Comment


              #26
              Re: Question about jumpering P.S.-on command

              "I thought Q8700 LLW supplies power. It has 170vdc on E&B" No, that will not be it at all, the low voltage (around 18V or so will be generated by the AUX winding of the standby power transformer, this same voltage is also splitted out for running the 5VSTBY IC once it starts running (but this voltage for the standby IC is NOT fed through the switched transistor).
              It looks like D7913 is the one that connected to the AUX winding of the STBY TRANSFORMER.
              What is the P/N of the SMPS IC for the stby power supply?
              Also please take good clear pictures of this section for me so I can see the traces better.
              Attached Files
              Last edited by budm; 09-18-2014, 05:39 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


                #27
                Re: Question about jumpering P.S.-on command

                The stdby IC is a DDA003A. D7913 checks fine. The 5vdc stdby is 5.11. Here are a few more pics. Normally I check the larger transistor and diodes . I am really trying to understand and trouble shoot the SMD parts.
                Attached Files

                Comment


                  #28
                  Re: Question about jumpering P.S.-on command

                  IC 7901 (8-PIN) is the STANDBY SMPS IC (ICE3BS3L) which drives the Power MOSFET Q7901 which drives the Standby power transformer T7901.
                  Pin 7 is the VCC pin
                  We need to find out why we are not getting the DC Voltage at the jumper J7022 (the GND ref will be the negative leg of the main filter cap).
                  Attached Files
                  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


                    #29
                    Re: Question about jumpering P.S.-on command

                    What is the resistance of R7818?
                    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


                      #30
                      Re: Question about jumpering P.S.-on command

                      R7818 markings are 30B meter reads 1.996k or 2k ohms. I made voltage checks from your drawing. D7913 Anode is 10.8vac. D7918 Anode is 16.85vdc. Q7916 is a t2x NPN out put to Pin #7 of 3BS03 is 16.21 vdc. Q1 is also a t2x NPN. both E/B have 0vdc, Collector is .910vdc. Reisistor R7934 smd code is 01A and it measures 100 ohms correctly.
                      Q1 tested fine on Fluke 87 and Sencore TF46 Super Cricket. Checked Q1 for shorts to neg of main filter caps. Only the Emitter is shorted. Makes no sense. If I have voltage on one side of resistor and no voltage on other side and the reisitor is not open when tested with meter. I used a 10X Loupe to inspect reisistor and I dont see any cracks. I will try resoldering it.

                      Comment


                        #31
                        Re: Question about jumpering P.S.-on command

                        "D7918 Anode is 16.85vdc. Q7916 is a t2x NPN out put to Pin #7 of 3BS03 is 16.21 vdc" They are correct as I expected.
                        "Checked Q1 for shorts to neg of main filter caps. Only the Emitter is shorted." That is correct, the Emitter is connected to Primary circuit ground. There should be about 0.6~0.7VDC on the Base -Emitter junction which is bias on by the resistor R7934, Q1 should be on that is why the Collector Voltage is LOW, Collector is connected pin 1 of SMPS IC7901.
                        OK, so that big copper trace is not getting the Voltage through R7818 (resistance is too high for Voltage source). I wish I have the board in front of me, we just need to find where the Voltage is being fed from.", this not correct.
                        Last edited by budm; 09-19-2014, 03:45 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


                          #32
                          Re: Question about jumpering P.S.-on command

                          Please let me see the picture of the PFC section.
                          Please tell me which one is pin 1 of the PFC IC, I cannot see the dot on the IC to show pin 1.
                          Is it the top left side per picture or bottom right (which was my first thought)? I think I have it right the first time, bottom right is pin 1.
                          Attached Files
                          Last edited by budm; 09-19-2014, 03:45 PM. Reason: Corrections
                          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


                            #33
                            Re: Question about jumpering P.S.-on command

                            On that pic the #1 pin is the lower right. Of the IC. I have 16.8vdc on the Anode of D7819, the Cathode has 0vdc. As is the voltage on Rd 924 and Base of Q1. I probed around and could no find anything with .9 vdc other than pin #1 and things attached to that trace. The other pic is one of the other area . I am at home now so can't get back until Monday
                            Attached Files

                            Comment


                              #34
                              Re: Question about jumpering P.S.-on command

                              "On that pic the #1 pin is the lower right." OK, so I do have the pin out correct, so back to where the Voltage source for that IC is.
                              Q1 is not used for supplying VCC, the Collector is connected to pin 1 of the stby SMPS, it is for something else.
                              "I have 16.8vdc on the Anode of D7819, the Cathode has 0vdc. As is the voltage on Rd 924 and Base of Q1." 0V is not right, since the Cathode is connected to high value resistor R7934, and the other end of the resistor is connected to the BASE of Q1, unless D7819 has open circuit, there is no way you can have 0V on that end of the resistor that is connected to the Cathode of D7819.
                              Last edited by budm; 09-19-2014, 06:45 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


                                #35
                                Re: Question about jumpering P.S.-on command

                                Ok. I revised the drawing just a little. Added the active voltages and placed a few notes. D7918 checks good as does R7934 and Q1. 0vdc on D7918 cathode and Q1 Base. I spent most of the day on it. See notes.
                                Attached Files

                                Comment


                                  #36
                                  Re: Question about jumpering P.S.-on command

                                  I did a diode check and got my high/low resistance and R7934
                                  resistance was 100 ohms as indicated by the 01A code. I used
                                  a 10 loupe and could not find any cracks. I even re soldered the diode and resistor. No change. This problem is making me feel
                                  Stupid.

                                  Comment


                                    #37
                                    Re: Question about jumpering P.S.-on command

                                    If you measure Cathode to Ground of the D7918, What do yo get?
                                    16.8V - 0.6 for D7918 Vf - 0.6 Vb-e of Q1 = 16.6V drops across the resistor.
                                    Last edited by budm; 09-20-2014, 10:20 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


                                      #38
                                      Re: Question about jumpering P.S.-on command

                                      I will check that Monday. Shop is 35 miles away. When checked diode it was with diode tester of Fluke 87. Then I will let you know. I did not check across the diode directly. I checked voltage with gnd lead to negative of main filter cap and positive lead to anode was 16.8 and cathode was 0. And got zero vdc on both side of resistor and at base of Q1.
                                      Last edited by Ltank; 09-20-2014, 12:14 PM.

                                      Comment


                                        #39
                                        Re: Question about jumpering P.S.-on command

                                        Check the voltage right across that 100 Ohms resistor (probe on each end of the resistor).
                                        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


                                          #40
                                          Re: Question about jumpering P.S.-on command

                                          When making the diode check on D7918 the neg lead on + of C7912 was a low .704 and with the positve lead at + of cap was OL high. This tells me that the Cathode is connected to the + of C7912 not the anaode. I made a error in my drawing. I drew D7918 backwards.
                                          Voltage across D7918 16.65vdc. Voltage Cap neg to Anode 0vdc. Voltage Cap neg to cathode 16.6vdc. Voltage Gnd to either side od R7934 is 0vdc. Voltage across RR7934

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