jvc 32c670 smart no backlight

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  • jimbofz
    Badcaps Veteran
    • Apr 2013
    • 537
    • uk
    #1

    jvc 32c670 smart no backlight

    hi tv respnds to remote and psu starts up 12v 24v ,boost voltage to backlight comes up to 85v then fades .backlight doesnt come on at all.
    theres no sound or trace of image even with flashlight test ,
    the backlights are ok with my led tester ,so i checked the volts on the main board theres a switched 5v and a 3.3v supply on v94 reg

    the psu is vestel 17ips62 ,ive downloaded two versions of this psu both have different led control ics my board has mp3398a
    the main board is type 17mb110p
    any ideas please
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    • nomoresonys
      Badcaps Legend
      • Jan 2013
      • 12093
      • U.S.
      #2
      Re: jvc 32c670 smart no backlight

      Maybe start with testing the voltages at the connector on the powerboard with the cables all hooked up, it's the connector that the cable from powerboard to mainboard hooks into, most times there's a legend/map nearby that gives the expected voltages, you measure them with your mutimeter, set meter to 20 vdc then report them, put neg probe on chassis metal ground, pos probe on pin of connector, measure in standby take note, leave probes where they are then power on tv and again take note of voltages, report them here, example pin 1-ps-on-0 volts standby-power on-3.3 volts. A lot of the vestels aren't marked very well so it might be tough.

        Comment

        • nomoresonys
          Badcaps Legend
          • Jan 2013
          • 12093
          • U.S.
          #3
          Re: jvc 32c670 smart no backlight

          Video demo: https://www.youtube.com/watch?v=4v8DcqCNG4A

            Comment

            • jimbofz
              Badcaps Veteran
              • Apr 2013
              • 537
              • uk
              #4
              Re: jvc 32c670 smart no backlight

              as you say its very difficult ,as both boards are joined together
              i have soldered a wire to the back of the print to see if theres any volts on the inner row of the plug n skt ,ive established 5v ,5v switched 12v
              does anyone have a cct that uses the MP3398A led controller ?
              this would help to see why boost volts is turned off

                Comment

                • jimbofz
                  Badcaps Veteran
                  • Apr 2013
                  • 537
                  • uk
                  #5
                  Re: jvc 32c670 smart no backlight

                  Originally posted by nomoresonys
                  Video demo: https://www.youtube.com/watch?v=4v8DcqCNG4A
                  yes in the ideal world this would be possible but not on this vestel

                    Comment

                    • zwarder
                      Member
                      • Oct 2013
                      • 45
                      • United Kingdom
                      #6
                      Re: jvc 32c670 smart no backlight

                      Check smd diode D42 i believe a RA159 1A 400-1000v
                      I have these syptoms & believe this diode is short

                        Comment

                        • sintv
                          Member
                          • Feb 2015
                          • 37
                          • scotland
                          #7
                          Re: jvc 32c670 smart no backlight

                          Have you checked continuity on board that strips plug into. Ive had that fault on a few 32in sets

                            Comment

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