42" Magnavox trouble

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  • Larry1988
    Member
    • Dec 2014
    • 17
    • USA

    #1

    42" Magnavox trouble

    Hello guys this will be my first post so plz be gentle lol. im working on amagnavox 42mf439b/f7 the issue is it powers on i get a solid green light and then the standby light flashs once every 15 to 30 secs ive tryed checking the screen with a flashlight as no backlighting comes on but no dice. ive checked all the caps and to the eye no bulging or bad caps. the set is unresponsive to the power button will only shut down if i ulplug the main board or the cba board. ive replaced the digital main board just out the go since it was pretty cheap. next thoughts were t con or inverter board ? im somewhat dmm friendly and can solder so fire away any help appreciated!
  • nomoresonys
    Badcaps Legend
    • Jan 2013
    • 12145
    • U.S.

    #2
    Re: 42" Magnavox trouble

    maybe check the fuse on the tcon board, the label will start with an F for fuse.

    Comment

    • nomoresonys
      Badcaps Legend
      • Jan 2013
      • 12145
      • U.S.

      #3
      Re: 42" Magnavox trouble

      careful when working with the power supply board, HIGH VOLTAGE on primary side.

      Comment

      • Larry1988
        Member
        • Dec 2014
        • 17
        • USA

        #4
        Re: 42" Magnavox trouble

        what would be the voltage for it i found one i think im not at the set currently but i got 24volts on both side if i remember correctly

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: 42" Magnavox trouble

          Well, start with this so we can see what we are dealing with.
          https://www.badcaps.net/forum/showthread.php?t=39740

          Also read this:
          Basic LCD TV and Monitor troubleshooting guides.
          The link is under my signature.
          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

          • Larry1988
            Member
            • Dec 2014
            • 17
            • USA

            #6
            Re: 42" Magnavox trouble

            i do apologize for any blurry pics im taking them and have to get to a location to upload as internet at home is slower than 56k lol any blurry pics i will retake and try again and theres a few i left out i need to retake as well
            Attached Files

            Comment

            • Larry1988
              Member
              • Dec 2014
              • 17
              • USA

              #7
              Re: 42" Magnavox trouble

              a few extras
              Attached Files

              Comment

              • Larry1988
                Member
                • Dec 2014
                • 17
                • USA

                #8
                Re: 42" Magnavox trouble

                thanks for taking the time budm and nomoresonys im very new to this have one repair tv wise under my belt but really enjoy working on electronics and learning from those who have more experience than me. most of my electronic back ground other than tvs is just building my own pc's.

                Comment

                • Larry1988
                  Member
                  • Dec 2014
                  • 17
                  • USA

                  #9
                  Re: 42" Magnavox trouble

                  i quick i know probably newb question but on the inverter board where it is labeled high voltage it has a small copper like space..is this a testing point for voltage ?

                  Comment

                  • Larry1988
                    Member
                    • Dec 2014
                    • 17
                    • USA

                    #10
                    Re: 42" Magnavox trouble

                    loved the pdf's for lcd repair budm

                    Comment

                    • ibgm
                      Senior Member
                      • Oct 2013
                      • 63
                      • usa

                      #11
                      Re: 42" Magnavox trouble

                      On pic 121643 we can see 2 fuses in the inverter board, 8A/160V. I would check those first. Good luck!
                      They are near the connectors.

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: 42" Magnavox trouble

                        So you replaced the big brown board on the right?
                        This one of those FUNAI/SYLVANIA/EMERSON/PHILIPS/MAGANAVOX TV.
                        Is there a chassis number printed on the model number sticker?
                        For example:
                        42MF438BF7_LC8.14LA
                        "LC8.14LA" is the chassis number.
                        Last edited by budm; 01-02-2015, 08:07 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

                        • Larry1988
                          Member
                          • Dec 2014
                          • 17
                          • USA

                          #13
                          Re: 42" Magnavox trouble

                          Yes both fuses on inverter board Check out at 24v and I get voltage at the caps on the inverter board but past the caps those transformer things lol dunno what there called there is no voltage. Both sets of connectors the red wires are all 24v.

                          Comment

                          • Larry1988
                            Member
                            • Dec 2014
                            • 17
                            • USA

                            #14
                            Re: 42" Magnavox trouble

                            ok so budm this is the board that i replaced the digital main and then the sec picture is of the other connector on the inverter. all the red wires as i said read out 24v but the 4 blue wires voltage are all very low im not near the set to take the readings again but i will tonight .... and i will also try and get that model number you were asking for.
                            Attached Files

                            Comment

                            • Larry1988
                              Member
                              • Dec 2014
                              • 17
                              • USA

                              #15
                              Re: 42" Magnavox trouble

                              ok budm the only thing i see on the model number sticker other than 42mf439b/f7 is is off to the side in a white box that says S fl9.2

                              Comment

                              • nomoresonys
                                Badcaps Legend
                                • Jan 2013
                                • 12145
                                • U.S.

                                #16
                                Re: 42" Magnavox trouble

                                Originally posted by Larry1988
                                what would be the voltage for it i found one i think im not at the set currently but i got 24volts on both side if i remember correctly
                                I check fuses in diode mode, one probe on each end, if no reaction or stays ol, then its probably bad, if reading is close to 000 then its prob. good.

                                Comment

                                • nomoresonys
                                  Badcaps Legend
                                  • Jan 2013
                                  • 12145
                                  • U.S.

                                  #17
                                  Re: 42" Magnavox trouble

                                  maybe check expected voltages coming from power supply, a lot of them have legends by the connectors, that show expected voltages 3.3 ,5 ,12 ,24, etc.

                                  Comment

                                  • Larry1988
                                    Member
                                    • Dec 2014
                                    • 17
                                    • USA

                                    #18
                                    Re: 42" Magnavox trouble

                                    ok on this inverter board i get 24v across the red wires the vbl then the rest as follows

                                    status 0v
                                    E-pwm 0.7
                                    I-pwm 0v
                                    On/off 1.7v

                                    and sony i will have to try testing those in diode and let you know what i get
                                    Attached Files

                                    Comment

                                    • Larry1988
                                      Member
                                      • Dec 2014
                                      • 17
                                      • USA

                                      #19
                                      Re: 42" Magnavox trouble

                                      fuses on inverter board read out 000

                                      Comment

                                      • Larry1988
                                        Member
                                        • Dec 2014
                                        • 17
                                        • USA

                                        #20
                                        Re: 42" Magnavox trouble

                                        Found this on my search of the internet thought i would share it !!
                                        Attached Files

                                        Comment

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