identity tv part

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  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #21
    Re: identity tv part

    So the resistance reading between GND pin and the 5VSB pin is showing less than 1 OHM?
    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

    • nosugartonight
      Senior Member
      • Jan 2018
      • 107
      • united states

      #22
      Re: identity tv part

      There is no short between cn201 and 5vsb. What I was doing is, in ohms' mode. Black lead to frame ground and touching red lead to legs of components " resistors, misfits ,capacitors, transforms cold side " shows grounded. That is not good right?!

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #23
        Re: identity tv part

        Originally posted by nosugartonight
        There is no short between cn201 and 5vsb. What I was doing is, in ohms' mode. Black lead to frame ground and touching red lead to legs of components " resistors, misfits ,capacitors, transforms cold side " shows grounded. That is not good right?!
        What do you mean 'shows grounded'? as I indicated, what is the resistance reading? The power supply outputs have loads connected between GND and the supply pins.
        I.E if the 5VSB pin has 1000 Ohms resistor connected between GND and the 5VSB pin, then you will see 1000 Ohms after the filter caps are charged up by the meter. So does it means that it is bad? No.
        Last edited by budm; 01-29-2018, 10:30 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

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #24
          Re: identity tv part

          Originally posted by nosugartonight
          Ok here what I have discovered. Before I removed the power board to take pics. There was no voltages on any pins . Everything on hot side shows voltages. I believe there all right. No voltages on cold side. But when I went to put the board back. I only used a couple of screw's. I rechecked the pins. To my surprise there are voltages on the pins. When I put the bottom right screw in. Lost all voltages on pins. Tracing from the 5v pins . Everything shows grounded. All the way up to pc702 which looks like a IC but only has 4 legs. . I will post a pic. I hope you understand what I'm saying
          So what are the Voltages on the pins you are getting? 5VDC at the 5VSB pin?
          The more details you give us the more help you will get in troubleshooting the problem.
          Also when you use the chassis GND as the GND ref for your meter, if the Ground pads (where the board mounting holes are) are not properly mounted then you will not get the Voltage readings; the Cold side circuit GND is connected to the mounting holes of the board to make connections to the chassis.
          Last edited by budm; 01-29-2018, 11:00 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

          • nosugartonight
            Senior Member
            • Jan 2018
            • 107
            • united states

            #25
            Re: identity tv part

            Here is a pic so you can see what I have my meter set at. This is the voltages I get on pins . All 5vsb pins. All 12v pins,and the two 24v pins. If I put all the screw's in to hold the board. I lose voltages on all pins.
            Attached Files

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #26
              Re: identity tv part

              That is only 0.315V! So you are not really getting 5V as it should. To get proper Data at this point, you should use the GND pin of the connector for your meter.
              So, whet is the resistance reading between GND pin of the connector and the 5VSB pin? We still need that data.
              We need to get 5VSB power supply working FIRST.
              Did you check the resistors that RJ suggested?
              Last edited by budm; 01-30-2018, 01:45 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

              • nosugartonight
                Senior Member
                • Jan 2018
                • 107
                • united states

                #27
                Re: identity tv part

                I'm not sure about checking resistance. That is checked in ohms,right? If so the meter does not stay constant. The reading keeps changing. Do you go by the first numbers shown. In mean time I will research how to check resistance. Thank you for your help ��

                Comment

                • budm
                  Badcaps Legend
                  • Feb 2010
                  • 40746
                  • USA

                  #28
                  Re: identity tv part

                  Set meter to Ohm mode (read your meter owner manual). Touch the two probes of the meter together, it should show < 1 Ohm, then use the meter to probe the resistor R901, R902 as RJ suggested.
                  You MUS NOT have TV plugged into the AC outlet when testing resistance.
                  Make sure to report EXACTLY as to what is shown on the meter display.
                  BTW, you have proper tools to do good soldering works especially the SMD device, right?
                  Last edited by budm; 01-30-2018, 02:31 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

                  • nosugartonight
                    Senior Member
                    • Jan 2018
                    • 107
                    • united states

                    #29
                    Re: identity tv part

                    Yes proper tools. Will report back asap. Thank you ��

                    Comment

                    • nosugartonight
                      Senior Member
                      • Jan 2018
                      • 107
                      • united states

                      #30
                      Re: identity tv part

                      In ohms mode with leads together read's all 0's
                      R901 read's O.L R902 read's 1.2

                      Comment

                      • R_J
                        Badcaps Legend
                        • Jun 2012
                        • 9514
                        • Canada

                        #31
                        Re: identity tv part

                        dc voltage from the main Capacitor C800 is feed through R901, through the transformer T901 and to Q901. I suspect Q901 is shorted, R901 acts like a fuse for the switching circuit
                        Last edited by R_J; 01-30-2018, 04:10 PM.

                        Comment

                        • nosugartonight
                          Senior Member
                          • Jan 2018
                          • 107
                          • united states

                          #32
                          Re: identity tv part

                          I think q901 is ok,out of circuit reads .492. That is acceptable correct?

                          Comment

                          • nosugartonight
                            Senior Member
                            • Jan 2018
                            • 107
                            • united states

                            #33
                            Re: identity tv part

                            .492

                            Comment

                            • nosugartonight
                              Senior Member
                              • Jan 2018
                              • 107
                              • united states

                              #34
                              Re: identity tv part

                              After resoldier Q901 reads .501 both measurements were in diode mode

                              Comment

                              • budm
                                Badcaps Legend
                                • Feb 2010
                                • 40746
                                • USA

                                #35
                                Re: identity tv part

                                Read the RESISTANCE between the Source pad and the Drain pad where the removed MOSFET legs were soldered to. Do the same resistance between the Source and the Drain of the removed MOSFET also.
                                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

                                • R_J
                                  Badcaps Legend
                                  • Jun 2012
                                  • 9514
                                  • Canada

                                  #36
                                  Re: identity tv part

                                  Check the parts around Q901 like zd901, d901, c901. also does R901 look like it is blown apart or does it just measure open? If the mosfet and other parts around it are ok, it is possible the resistor just went open, not likely but possible.

                                  Comment

                                  • nosugartonight
                                    Senior Member
                                    • Jan 2018
                                    • 107
                                    • united states

                                    #37
                                    Re: identity tv part

                                    Resistance between source and drain 10.02. I will take it back out to give you those measurements R901 looks ok. Actually I have looked the board over really close,front and back and see no burned,blown components. I will recheck all the above.

                                    Comment

                                    • budm
                                      Badcaps Legend
                                      • Feb 2010
                                      • 40746
                                      • USA

                                      #38
                                      Re: identity tv part

                                      "R901 read's O.L" It is blown open circuit!
                                      "Resistance between source and drain 10.02." Ohms? K Ohms? M Ohms?
                                      You still need to do this on those two solder pads on the board: my request "Read the RESISTANCE between the Source pad and the Drain pad where the removed MOSFET legs were soldered to."
                                      Last edited by budm; 01-30-2018, 09:45 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

                                      • nosugartonight
                                        Senior Member
                                        • Jan 2018
                                        • 107
                                        • united states

                                        #39
                                        Re: identity tv part

                                        Will do. And post measurements. Again I want to thank you for your help. Continue tomorrow ��

                                        Comment

                                        • nosugartonight
                                          Senior Member
                                          • Jan 2018
                                          • 107
                                          • united states

                                          #40
                                          Re: identity tv part

                                          R901 is blown rechecked after taking out of circuit. Q901 I believe is shorted now. After I took it back out,it reads OL from source to emitter and 13.30ohms source to drain. This is a PNP? If so I believe I'm checking it right. It was reading.492k in diode mode. Now in diode mode only reads .501k on drain, O.L on emitter. The resistance between pads source to drain 10.56ohms. Think I over heated Q901 or maybe static electricity from me. So what's next.

                                          Comment

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