VIZIO VP423 no display

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  • ajshoe
    ajshoe
    • Dec 2012
    • 477
    • usa

    #1

    VIZIO VP423 no display

    Have a VIZIO VP423 that turns on (front name plate goes from orange to white) - power clicks on, all voltages are present on PWB. on Y_SUS Vsch = 55-77 Volts, Vscan = 185-192 Volts. On X_SUS Ve = 1.9V.

    Is this a PWB problem ?
    Attached Files
  • freakaftr8
    Badcaps Legend
    • Oct 2012
    • 3743
    • USA

    #2
    Re: VIZIO VP423 no display

    I would try disconnecting the power connector to the X sustain. (Far right board) Your VE is way too low I'm suspecting an x sustain short on that board. Can you post a picture of the X sustain board
    Did I leave the soldering iron on?

    Comment

    • ajshoe
      ajshoe
      • Dec 2012
      • 477
      • usa

      #3
      Re: VIZIO VP423 no display

      X_sus board is posted above - I'll check for shorts and post some closeup pics of board.

      Comment

      • freakaftr8
        Badcaps Legend
        • Oct 2012
        • 3743
        • USA

        #4
        Re: VIZIO VP423 no display

        My apologies. Didn't see the pics before. How does f4001 test on xsus?
        Did I leave the soldering iron on?

        Comment

        • ajshoe
          ajshoe
          • Dec 2012
          • 477
          • usa

          #5
          Re: VIZIO VP423 no display

          nothing shorted. fuses F001 and F003 are good

          Comment

          • ajshoe
            ajshoe
            • Dec 2012
            • 477
            • usa

            #6
            Re: VIZIO VP423 no display

            [ATTACH]167008[/ATTACH]

            [ATTACH]167009[/ATTACH]

            [ATTACH]167010[/ATTACH]
            Last edited by ajshoe; 11-26-2017, 08:43 PM. Reason: pics

            Comment

            • ajshoe
              ajshoe
              • Dec 2012
              • 477
              • usa

              #7
              Re: VIZIO VP423 no display

              also Vsch and Vscan are fluctuating

              Comment

              • freakaftr8
                Badcaps Legend
                • Oct 2012
                • 3743
                • USA

                #8
                Re: VIZIO VP423 no display

                Then in that case why don't you try removing the buffer board connections from the ysus. Possibly a shorted buffer board loading the system down
                Did I leave the soldering iron on?

                Comment

                • ajshoe
                  ajshoe
                  • Dec 2012
                  • 477
                  • usa

                  #9
                  Re: VIZIO VP423 no display

                  probably worth giving a little history of set. was working and would shut off. only way to get it to turn on with display was to wait overnite. I got the set and plugged it in - it worked. left it on overnite and next morning sound on but black display. after a week - I can't repeat this symptom. just black display but it seems to turn on (and stays on) - voltages are good and front vizio nameplate turns white from orange. changed main board with NEW one - same symptoms. don't think bad buffers would cause this scenario.

                  Comment

                  • ajshoe
                    ajshoe
                    • Dec 2012
                    • 477
                    • usa

                    #10
                    Re: VIZIO VP423 no display

                    disconnected sustain boards & hooked up 2 100 watt light bulbs across Vs and ground. power supply comes on, bulbs come on and stay on. repeat test with X sustain plugged in - same result. All voltages are good. any ideas ???

                    Comment

                    • freakaftr8
                      Badcaps Legend
                      • Oct 2012
                      • 3743
                      • USA

                      #11
                      Re: VIZIO VP423 no display

                      What is your reading for VA?
                      Did I leave the soldering iron on?

                      Comment

                      • ajshoe
                        ajshoe
                        • Dec 2012
                        • 477
                        • usa

                        #12
                        Re: VIZIO VP423 no display

                        Va is 54 V. measured it with 2 100 watt bulbs on Vs and with y & x sustain boards plugged in

                        Comment

                        • ajshoe
                          ajshoe
                          • Dec 2012
                          • 477
                          • usa

                          #13
                          Re: VIZIO VP423 no display

                          what I meant by earlier post - Va was 54v with 2 100 watt bulbs on Vs to grd with x y sustains disconnected. ran test again with sustains connected and Vs was 54v also.

                          Comment

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