L42A403 Hitachi NO POWER - Fuse Good - Caps Good

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  • barryra
    Senior Member
    • Aug 2013
    • 107
    • USA

    #1

    L42A403 Hitachi NO POWER - Fuse Good - Caps Good

    I'm stumped on what would be the issue with no power, lights & no clicks with a Hitachi L42A403. I tested fuse & caps look good. Thanks
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

    Good clear Pictures of the back side of the TV, the boards? Any voltage testing?
    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

    • barryra
      Senior Member
      • Aug 2013
      • 107
      • USA

      #3
      Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

      Hello, thanks for the response. There are 2 +12 V that measured 2.2.. the 2 24V measured .4

      I sent you a PM.... thanks again
      Attached Files

      Comment

      • barryra
        Senior Member
        • Aug 2013
        • 107
        • USA

        #4
        Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

        Where it's listed 5V it measures 4.98. I didn't get anything on the 12 or 24 v this time. Maybe I did it wrong the last time.

        Comment

        • barryra
          Senior Member
          • Aug 2013
          • 107
          • USA

          #5
          Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

          Where it's listed 5V it measures 4.98. I didn't get anything on the 12 or 24 v this time. Maybe I did it wrong the last time.

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

            OK, the 12v, 24, and the PFC voltage booster are turn on by the main board, so lets see if we do have the PS_ON siganl and the PFC voltage is working or not first by checking the dc voltage right at the two legs of the big 450vdc caps laying on the side. When the TV is off, the voltage should be about 160~170vdc, and it should go up to about 370~390vdc when TV is switched on.
            Please also post the voltage label of the connectors on the power supply board.
            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

            • barryra
              Senior Member
              • Aug 2013
              • 107
              • USA

              #7
              Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

              The 450v caps measured .2 on & off. Where are the measurements listed on the power board? Thank you

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                That cannot be the correct reading since the 5VDC power supply is also connected to those two caps, if those two caps has no voltage, you will not have the 5V either. What meter setting are you using?
                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

                • barryra
                  Senior Member
                  • Aug 2013
                  • 107
                  • USA

                  #9
                  Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                  I measured the 450v caps at .2 each on & off I attached a picture of the power board voltages.
                  Attached Files

                  Comment

                  • barryra
                    Senior Member
                    • Aug 2013
                    • 107
                    • USA

                    #10
                    Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                    I'm using 200 v dc reading

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #11
                      Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                      Can I see the bottom side of the board?
                      Last edited by budm; 10-06-2013, 09:08 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

                      • barryra
                        Senior Member
                        • Aug 2013
                        • 107
                        • USA

                        #12
                        Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                        Sure... I don't see any burnt spots. Hopefully you see something I don't. Thanks
                        Attached Files

                        Comment

                        • budm
                          Badcaps Legend
                          • Feb 2010
                          • 40746
                          • USA

                          #13
                          Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                          Well I cannot see why you are not getting the 160vdc on the cap at all, from tracing the bottom side of the board, the 5VDC power supply is transformer is connected to those two cap positive legs of the two caps which it is using the power from after the AC is rectified by the bridge.
                          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

                          • barryra
                            Senior Member
                            • Aug 2013
                            • 107
                            • USA

                            #14
                            Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                            When will you be on here again? I better get some sleep. I'll check it again afte work tomorrow. I really appreciate you helping me with this.

                            Comment

                            • barryra
                              Senior Member
                              • Aug 2013
                              • 107
                              • USA

                              #15
                              Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                              I found out the tv repair shop had this tv before I did.. He thinks it has a bad main board. Wouldn't there be something lit up? It's dead.. no power light etc..

                              Comment

                              • barryra
                                Senior Member
                                • Aug 2013
                                • 107
                                • USA

                                #16
                                Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                                Correction.. I searched the board number the repair shop thought was bad & it came up with the power board.

                                Hope to see you on tonight Budm

                                Comment

                                • barryra
                                  Senior Member
                                  • Aug 2013
                                  • 107
                                  • USA

                                  #17
                                  Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                                  Hi Budm.. I'm ready to do more testing if you are.

                                  Comment

                                  • barryra
                                    Senior Member
                                    • Aug 2013
                                    • 107
                                    • USA

                                    #18
                                    Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

                                    Budm.. would you have some time tonight to help me with this? Thanks

                                    Comment

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