Coby TFTV4028 Blue Light Special

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  • CraigR
    Badcaps Veteran
    • Dec 2013
    • 959
    • USA
    #1

    Coby TFTV4028 Blue Light Special

    Been a while since posting but I ran into this in the shop and I see on the site a few threads with no real answers and most were started by the same person over and over. ANYWAY Coby 42" TFTV4028 Sometimes the TV will not come on and only the blue light on the bottom. I say this because at times it will work just fine hit or miss. I can unplug for a couple hours and plug back in then maybe it will work and never skip a beat all night. shut it off and next day will not turn on. Never the same thing to get it to work again. When the set will not work I have checked and I do have good voltages from the power board. No signs of bulging caps on the any of the boards. I did see mentioned to replace the 1000Uf caps on the main board for this so I did and it did not help at all.
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    • ReeceyBurger123
      Never Give Up !
      • May 2014
      • 7325
      • Britain
      #2
      Re: Coby TFTV4028 Blue Light Special

      Checked Psu and Bl on signal coming off Mb ?
      Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

      https://www.facebook.com/Telford-Tel...7894576335359/

        Comment

        • CraigR
          Badcaps Veteran
          • Dec 2013
          • 959
          • USA
          #3
          Re: Coby TFTV4028 Blue Light Special

          Not seeing any markings for Backlight-on on the main board. Getting 24v over at the inverter board.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: Coby TFTV4028 Blue Light Special

              https://www.badcaps.net/forum/attach...0&d=1465839357
              There are labels for the pins of those 3 connectors that go to the main board and the main board, give the list of those names for each connectors, look at the bottom side of the board too.
              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

                • budm
                  Badcaps Legend
                  • Feb 2010
                  • 40746
                  • USA
                  #5
                  Re: Coby TFTV4028 Blue Light Special

                  https://www.badcaps.net/forum/attach...8&d=1465839357

                  Also the connector on the Inverter board, the wire are separated into two set, one goes to the power supply board for the 24V and GND, then the other set of wire goes to the main board, this the set of wire that should have BL-ON and Dimming control wires, look at the connector on the main board to see if they are labeled with names.
                  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

                    • hmendez86
                      Badcaps Veteran
                      • Jun 2015
                      • 344
                      • united states
                      #6
                      Re: Coby TFTV4028 Blue Light Special

                      What I did I buy a board on ebay for tftv4028 there's 3 diferente boards but you might think it won't fit because of serial. Mine had 2810 on the serial number and I buy the 2813 serial #, what I did is change the old eeprom to the new board you going to install, it is just swapping the eeproms...and it work..so easy fix..

                        Comment

                        • hmendez86
                          Badcaps Veteran
                          • Jun 2015
                          • 344
                          • united states
                          #7
                          Re: Coby TFTV4028 Blue Light Special

                          When you change the eeprom be sure to install it, how it was be careful not to install it backwards. The most important eeprom is the one on the old board of your tv......

                            Comment

                            • CraigR
                              Badcaps Veteran
                              • Dec 2013
                              • 959
                              • USA
                              #8
                              Re: Coby TFTV4028 Blue Light Special

                              Ended up scraping the Tv as a used board was more than the TV is worth working.

                                Comment

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