Announcement

Collapse
No announcement yet.

Vizio SV420M Power Supply 0500-0407-0890 No 12V output

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Vizio SV420M Power Supply 0500-0407-0890 No 12V output

    I'm looking for some assistance with troubleshooting a Vizio SV420M. It has the same symptoms as some of the other post here, Light operates normally, but no picture or sound..
    All voltages except the 12V are working fine. The 12V pins read 1.9V. in my attempts to troubleshoot the fault i found that the Power supply is in fact producing the 12V at D908, but once it gets to the pins it's at 1.9V
    Ive traced the 12V to pins 1 & 3 of Q910 but the pin 2 is showing 1.9V and that leads directly to the Connector pins.. any help would be great, I'm stuck. The images are stock images from shop jimmy Picture 1 shows the voltage points i have so far. My actual board will be posted when i get in. Thank YOu!!




    Attached Files
    Craigslist Picks & Fixes

    2 ea - Samsung 52"
    Samsung 60"

    #2
    Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

    Is PS-ON present when power switched is activated?
    >360VDC on the main filter cap legs when power switch is activate?
    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


      #3
      Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

      Originally posted by budm View Post
      Is PS-ON present when power switched is activated?
      >360VDC on the main filter cap legs when power switch is activate?
      Yes it's there.. and all voltages at the connector are present except for that 12V. I really dont underserved what's going on.
      Craigslist Picks & Fixes

      2 ea - Samsung 52"
      Samsung 60"

      Comment


        #4
        Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

        That Q90 is P-CH MOSFET being used as a switch, since the Gate is stuck at 12V which means it is not being turned on, the Gate Voltage has to be about 4V less than the Source so that is why I ask if you do have 360VDC on the two legs of the main filter cap or not.
        BTW, what is the DCV for the PS-ON you are getting?
        Last edited by budm; 02-23-2015, 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


          #5
          Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

          Originally posted by budm View Post
          That Q90 is P-CH MOSFET being used as a switch, since the Gate is stuck at 12V which means it is not being turned on, the Gate Voltage has to be about 4V less than the Source so that is why I ask if you do have 360VDC on the two legs of the main filter cap or not.
          BTW, what is the DCV for the PS-ON you are getting?
          I apologize.. I read that symbol wrong. I am getting 172V at the filter cap when it's on or off.. attached are pics of my actual board. I took the board out of the TV and ran a jumper from the 5V STBY to the PS_ON so it's at 5V. I removed Q910 to test it. I did think that it was odd that i got the 12V at 2 pins.
          Attached Files
          Craigslist Picks & Fixes

          2 ea - Samsung 52"
          Samsung 60"

          Comment


            #6
            Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

            The PS-ON signal is not turning on the PFC Voltage booster right now because you are only getting 170VDC in stead of >360V.
            There is nothing wrong with that MOSFET. You need to get the PFC Voltage booster working first, the PS-ON is also used to turn on that MOSFET, but right now you need to find out why the PFC Voltage is not working, the PS-ON signal may not be getting to the circuits.
            BTW, I only one end of the wire attached to one pin of the connector, the other end is just floating.
            Last edited by budm; 02-24-2015, 12:16 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


              #7
              Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

              Wow.. thank you! now where do I start? I'm clueless with the PFC voltage booster, does that look like a regular MOSFET. I'm tired of throwing these power supplies away, I have to learn this,
              Craigslist Picks & Fixes

              2 ea - Samsung 52"
              Samsung 60"

              Comment


                #8
                Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                So did you jump the PS-ON and leave the wire on or you just touch the pin and remove?
                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


                  #9
                  Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                  It's was soldered on to test it. but I disconnected it for the picture. I read on another post that I was supposed to use a resistor, but I didn't since it worked without one..
                  Craigslist Picks & Fixes

                  2 ea - Samsung 52"
                  Samsung 60"

                  Comment


                    #10
                    Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                    You need to get the P/N as printed on PFC Controller IC 801 to the spec sheet and the pin out to locate the VCC and see if if it is getting the VCC to run or not.
                    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


                      #11
                      Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                      IC801 results below I used the the GND on the IC to measure the voltages..

                      L6562A

                      1-INV - 1.08
                      2-COMP- 6
                      3-MUNTI - .877
                      4-CS - 0
                      5-VCC - 16.69
                      6-GD- 0
                      7-GND -
                      8-ZCD - .473

                      Attached Files
                      Last edited by 102mm; 02-24-2015, 01:03 AM.
                      Craigslist Picks & Fixes

                      2 ea - Samsung 52"
                      Samsung 60"

                      Comment


                        #12
                        Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                        So just to verify that the PS-ON is OK, the VCC should be at 0V, and then it should go up to 16.69VDC as you measured, then we know that the PS-ON does get through.
                        It is getting enough VCC (16.69V) to run, but there no Gate drive (GD) output.
                        I would put the meter on the two legs of the cap first and see if the Voltage did jump up when TV is turned on so we verify that it does try to start and then goes into shutdown or it is just dead, if there is no action then I would check the DCV at the Drain pin of the PFC MOSFET to make sure it does get 170VDC, if it does have 170VDC, then I would replace the IC.
                        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


                          #13
                          Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                          ok, The voltage on the CAP is steady at 170V during start-up. I don't get 170V on any pin of L6562. IC900 is labeled 6742MR, i get a 170V at the HV pin in standby, it drops a few on power on.
                          Craigslist Picks & Fixes

                          2 ea - Samsung 52"
                          Samsung 60"

                          Comment


                            #14
                            Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                            " I don't get 170V on any pin of L6562." I am talking about the 170V at the Drain pin of the MOSFETs Q801, Q802 for the PFC circuit.
                            IC900 is fine otherwise you will not be getting the 5VSTBY and the 12V for feeding the switched 12V MOSFET.
                            Last edited by budm; 02-24-2015, 10:59 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


                              #15
                              Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                              Just to check....

                              When checking the PFC Circuit and the main reservoir filter-cap, are you using the correct Return/Earth connection for the test-meter?

                              Needs to be connected to the Negative of the main res filter-cap, and not to the chassis or TV earth return
                              --I would expect around 170V on the res. filter-cap positive if it was measured to the wrong (TV Chassis) earth, instead of directly across the cap......
                              TELEFIX

                              How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
                              http://www.irf.com/technical-info/appnotes/an-1088.pdf
                              PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

                              Comment


                                #16
                                Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                                The voltages are below are at power on and off

                                Q801 on
                                1-.014
                                2-170
                                3-.0

                                Q802 on
                                1-.015
                                2-170
                                3-0

                                Q801 off
                                1-.0
                                2-173
                                3-.0

                                Q802 off
                                1-.0
                                2-173
                                3-0
                                Craigslist Picks & Fixes

                                2 ea - Samsung 52"
                                Samsung 60"

                                Comment


                                  #17
                                  Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                                  With reference --To What....?

                                  TV Chassis OR Mains Res. Filter Negative??
                                  TELEFIX

                                  How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
                                  http://www.irf.com/technical-info/appnotes/an-1088.pdf
                                  PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

                                  Comment


                                    #18
                                    Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                                    I'm using the filter Negative. should i be on the chassis?
                                    Craigslist Picks & Fixes

                                    2 ea - Samsung 52"
                                    Samsung 60"

                                    Comment


                                      #19
                                      Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                                      OK, the MOSFETs are getting the Voltage OK.
                                      You need to check the PFC Diode D803 next to make sure it is not shorted or leaky.
                                      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


                                        #20
                                        Re: Vizio SV420M Power Supply 0500-0407-0890 No 12V output

                                        Well Dang..... There it is, You have officially become my electronics Superhero!! D903 was short. I am going to check all the components in that area for shorts, or do you think that's my only issue.. There are three .27 ohm resistors close as well as the SMD resistors.
                                        Craigslist Picks & Fixes

                                        2 ea - Samsung 52"
                                        Samsung 60"

                                        Comment

                                        Working...
                                        X