Vizio VF552XVT Power Problem.

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  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #21
    Re: Vizio VF552XVT Power Problem.

    You can solder the wires to the caps legs on the bottom side of the board carefully connected them to the meter.
    Since the PS-ON is still present when the 12V/18V and 24V supplies go into shutdown like that, it has to be common latched shutdown circuit for both power supplies to go into shutdown like that which is unlikely, something has to be in common to both supplies (12V/18V and the 24V to cause that symptom. I can see just the 24V circuit shutdown but not the 12V/18v too.
    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

    • wadehavens
      Member
      • May 2010
      • 33

      #22
      Re: Vizio VF552XVT Power Problem.

      Originally posted by budm
      You can solder the wires to the caps legs on the bottom side of the board carefully connected them to the meter.
      Since the PS-ON is still present when the 12V/18V and 24V supplies go into shutdown like that, it has to be common latched shutdown circuit for both power supplies to go into shutdown like that which is unlikely, something has to be in common to both supplies (12V/18V and the 24V to cause that symptom. I can see just the 24V circuit shutdown but not the 12V/18v too.
      I tested the voltage at the filter cap.

      162v off

      305v on with CN3 disconnected, (half backlight)

      304v on with CN2 disconnected, (full backlight)

      305v and a quick drop to 157v when all connected. (supply shutdown)

      No leaking when on before shutdown.

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #23
        Re: Vizio VF552XVT Power Problem.

        Typical PFC Boosted Voltage is around 380 ~ 400VDC range. That low of the Voltage may be the problem.
        Can you read through the heatsink holes to see what Voltage rating of that cap is? It should be rated at 450VDC.
        BTW, your power supply board is the same one as shown at shopjimmy?
        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

        • wadehavens
          Member
          • May 2010
          • 33

          #24
          Re: Vizio VF552XVT Power Problem.

          Originally posted by budm
          Typical PFC Boosted Voltage is around 380 ~ 400VDC range. That low of the Voltage may be the problem.
          Can you read through the heatsink holes to see what Voltage rating of that cap is? It should be rated at 450VDC.
          BTW, your power supply board is the same one as shown at shopjimmy?
          Unfortunately the markings on the cap are on the side that is glued to the board. The bottom of the cap does have a 4XXv on it, but it's cut off to the point that I can't tell what it is.

          YES, that is the same board that you linked to on Shop Jimmy.

          Comment

          • wadehavens
            Member
            • May 2010
            • 33

            #25
            Re: Vizio VF552XVT Power Problem.

            Originally posted by budm
            Typical PFC Boosted Voltage is around 380 ~ 400VDC range. That low of the Voltage may be the problem.
            Can you read through the heatsink holes to see what Voltage rating of that cap is? It should be rated at 450VDC.
            BTW, your power supply board is the same one as shown at shopjimmy?
            Ok, so I did solder reflowing around the filter cap. The transistors and the ic's on the hot side seemed kinda cold. Now, it turns on and stays on. However, the voltage at the filter fluctuates between 316v and 330v depending on the video that's playing and how bright it is. I'm gonna monitor the voltage for a few hours and see what happens.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #26
              Re: Vizio VF552XVT Power Problem.

              Wells, I think you found the cause of the problem, we just need to get that boosted Voltage up to 380VDC or so, it may have bar resistor network in the feedback circuit in the PFC circuit.
              Need to locate the PFC IC and the resistor network on the bottom side of the board.
              Do not try to run the TV too long because when supply Voltage is low it will draw more current in the transformer driver circuits so more heat.
              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

              • wadehavens
                Member
                • May 2010
                • 33

                #27
                Re: Vizio VF552XVT Power Problem.

                Originally posted by budm
                Wells, I think you found the cause of the problem, we just need to get that boosted Voltage up to 380VDC or so, it may have bar resistor network in the feedback circuit in the PFC circuit.
                Need to locate the PFC IC and the resistor network on the bottom side of the board.
                Do not try to run the TV too long because when supply Voltage is low it will draw more current in the transformer driver circuits so more heat.
                I'm not quite sure exactly what I'm looking for. I see a resistor network, and a couple of IC's but not sure which one is the PFC IC.
                Attached Files

                Comment

                • wadehavens
                  Member
                  • May 2010
                  • 33

                  #28
                  Re: Vizio VF552XVT Power Problem.

                  I think I found the IC. ICE2PCS02 is it I think.
                  Attached Files

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #29
                    Re: Vizio VF552XVT Power Problem.

                    https://cdn.badcaps-static.com/pdfs/...f3ef28b014.pdf
                    As you can see, the Vsense pin is the output Voltage feedback pin so look for a bunch of resistor connected in series between + pin of the filter cap and the primary side circuit GND.
                    Last edited by budm; 08-22-2018, 09:39 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

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #30
                      Re: Vizio VF552XVT Power Problem.

                      So PFC IS is IC800 (ICE2PCS02). IC801 is LM293.
                      Pictures provided by shopjimmy
                      Vizio 0500-0507-0670 (DPS-450RP A)
                      Attached Files
                      Last edited by budm; 08-22-2018, 09:52 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

                      • wadehavens
                        Member
                        • May 2010
                        • 33

                        #31
                        Re: Vizio VF552XVT Power Problem.

                        Originally posted by budm
                        So PFC IS is IC800 (ICE2PCS02). IC801 is LM293.
                        Pictures provided by shopjimmy
                        Vizio 0500-0507-0670 (DPS-450RP A)
                        c819 is the filter cap. There is a small transistor and then a block of resistors that is connected from the positive side of the filter cap and then to pin 6 of IC800 after the resistors.

                        I'm not sure what to do from here.

                        Are you saying that the IC is bad? Or that I may have a bad resistor in that block?
                        Last edited by wadehavens; 08-22-2018, 10:19 PM.

                        Comment

                        • budm
                          Badcaps Legend
                          • Feb 2010
                          • 40746
                          • USA

                          #32
                          Re: Vizio VF552XVT Power Problem.

                          I suspect the resistors have drifted in value, the IC is working otherwise you will not have that 300V, it is just too low than what it should be.
                          You are going to have to test the value of each one of those resistors.
                          At this point, the problem is in your power supply board.
                          I cannot really do much from long distant to be able to trace out the board connections using pictures.
                          There should be a resistor between pin 6 and GND, if that resistor goes up in value then the output Voltage will be less.
                          You may want to check the filter cap on the VCC pin of that PFC IC too to make sure it is good, or monitor the VCC pin to see how steady the Voltage is.That darn heatsink is also in the way to see if there are any small lytics caps under that heatsink.
                          Last edited by budm; 08-22-2018, 10:29 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

                          • wadehavens
                            Member
                            • May 2010
                            • 33

                            #33
                            Re: Vizio VF552XVT Power Problem.

                            Originally posted by budm
                            I suspect the resistors have drifted in value, the IC is working otherwise you will not have that 300V, it is just too low than what it should be.
                            You are going to have to test the value of each one of those resistors.
                            At this point, the problem is in your power supply board.
                            I cannot really do much from long distant to be able to trace out the board connections using pictures.
                            ok thank you very much for your help. I'll post the findings when I have them.

                            Comment

                            • wadehavens
                              Member
                              • May 2010
                              • 33

                              #34
                              Re: Vizio VF552XVT Power Problem.

                              Originally posted by budm
                              I suspect the resistors have drifted in value, the IC is working otherwise you will not have that 300V, it is just too low than what it should be.
                              You are going to have to test the value of each one of those resistors.
                              At this point, the problem is in your power supply board.
                              I cannot really do much from long distant to be able to trace out the board connections using pictures.
                              There should be a resistor between pin 6 and GND, if that resistor goes up in value then the output Voltage will be less.
                              You may want to check the filter cap on the VCC pin of that PFC IC too to make sure it is good, or monitor the VCC pin to see how steady the Voltage is.That darn heatsink is also in the way to see if there are any small lytics caps under that heatsink.
                              I checked all the resistors in the area. If anything they've drifted down a bit, but nothing has gone up in value. The ones closest to the IC are spot on.

                              Do you think it could just be a bad filter cap at this point?

                              Comment

                              • budm
                                Badcaps Legend
                                • Feb 2010
                                • 40746
                                • USA

                                #35
                                Re: Vizio VF552XVT Power Problem.

                                If the top strings (the string connected to the cap +) go down in value then the output will be less..
                                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

                                • wadehavens
                                  Member
                                  • May 2010
                                  • 33

                                  #36
                                  Re: Vizio VF552XVT Power Problem.

                                  Originally posted by budm
                                  If the top strings (the string connected to the cap +) go down in value then the output will be less..
                                  Unfortunately they are all fine. It's the string after the transistor connected to the cap + that is lower than they should be. By about 20%.

                                  Comment

                                  • budm
                                    Badcaps Legend
                                    • Feb 2010
                                    • 40746
                                    • USA

                                    #37
                                    Re: Vizio VF552XVT Power Problem.

                                    20% is a BIG number. Those resistors are at most 5% tolerance for that circuit but more likely to be 1%.
                                    See application circuit here: page 8

                                    Getting 305V instead of 380V that means the output Voltage is only 80% of what the Voltage should be.
                                    Attached Files
                                    Last edited by budm; 08-23-2018, 12:37 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

                                    • wadehavens
                                      Member
                                      • May 2010
                                      • 33

                                      #38
                                      Re: Vizio VF552XVT Power Problem.

                                      Originally posted by budm
                                      20% is a BIG number. Those resistors are at most 5% tolerance for that circuit.
                                      Getting 305V instead of 380V that means the output Voltage is only 80% of what the Voltage should be.
                                      ok...I'll replace those resistors and see what that does.

                                      Comment

                                      • budm
                                        Badcaps Legend
                                        • Feb 2010
                                        • 40746
                                        • USA

                                        #39
                                        Re: Vizio VF552XVT Power Problem.

                                        See my update post 37 with application circuit.
                                        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

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