Sharp Aquos LC-40D68UT Blinking Red Power Light

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  • dhoff024
    Senior Member
    • Mar 2013
    • 96
    • USA

    #1

    Sharp Aquos LC-40D68UT Blinking Red Power Light

    Its been a while since I last posted anything and everyone on here is always a great help at troubleshooting these TV issues. I am by no means an expert when it comes to this stuff but I am handy enough that I can follow the directions of the more versed members on this forum. Now some people may think that I am crazy (I know my wife does haha). Yesterday I was walking my dog and I noticed one of my neighbors had a box out for the trash for a new TV. I didn't really think much of it until I was walking back and noticed their old LCD sitting out for the trash as well, so I grabbed it and figured it would be a nice free TV to work on and see if I could get it fixed and if not then it was no big deal really. The TV was slightly wet from sitting outside so I dried it off and let it sit overnight. I came home from work tonight and tore the back off the TV to see if I noticed any moisture or anything out of the ordinary or anything that jumped out. I did not so I proceeded to plug the TV in. When I plugged the TV in I got a blinking red power light. I did some searching and some people were saying there are some different button combinations that you hold down when you plug it back in so I figured I would try those first because those were the easiest things to try first. I held down the volume up and power and got a green light for a short period of time, but nothing came on the screen and it went back to flashing red. I am now at a point where I don't know what the next step should be. I don't see any bulging caps so I don't really know where to go from here. Any help is greatly appreciated. Hopefully with everyone's help I can bring this one back from the dead haha.
  • dhoff024
    Senior Member
    • Mar 2013
    • 96
    • USA

    #2
    Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

    Adding pictures of the boards on the back of the tv
    Attached Files
    Last edited by dhoff024; 12-27-2016, 10:21 PM.

    Comment

    • dhoff024
      Senior Member
      • Mar 2013
      • 96
      • USA

      #3
      Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

      Bump

      Comment

      • budwich
        Badcaps Legend
        • Jul 2015
        • 3097
        • Canada

        #4
        Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

        start by verifying / recording all the voltages that are printed on the boards (power, tcon, main) usually in and around the connectors. Go from there.

        you can try disconnecting the tcon and see what happens (probably not much). Further there are fuses on most tcons, check them.

        Comment

        • dhoff024
          Senior Member
          • Mar 2013
          • 96
          • USA

          #5
          Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

          Thank you for the reply. This may sound stupid but the other TV's that I fixed I didn't have to record any voltages or anything just replace bad caps and some other things that needed replaced. Is there any way you could tell me the proper way to record the voltages. I know how to use a multimeter just don't know the proper way to check the voltages. I also don't know all the abbreviations for the different boards or there functions. Is there anywhere you can direct me to get this information or could you tell me how to do this? Thanks again for all the help

          Comment

          • dhoff024
            Senior Member
            • Mar 2013
            • 96
            • USA

            #6
            Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

            Redirecting an old thread of mine. This tv has been sitting in my garage since I posted this. I was just able to successfully fix a tv I found thanks to everyone's help so I am focusing back on this TV to see if I can get it working or if not dispose of it. I will take as many of the voltages as I can and report back. I did disconnect the tcon as suggested before with no change still a blinking red power light. When you press the power nothing happens just still blinks.

            Comment

            • dick_barton
              Badcaps Legend
              • Aug 2015
              • 6642
              • Wales

              #7
              Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

              Set your meter to DC volts and measure the voltages on the pins of the connectors with the red probe and black probe on metal chassis.
              There should be a name alongside each pin of the connector
              eg
              CN751
              Pin number, legend, voltage
              Pin 1, P_ON, 4.3V
              Pin 2, DIM, 2.8V
              Pin 3, 5VSTB, 4.8V
              etc.
              Attached Files
              Willing to help but I'm no expert.

              Comment

              • dhoff024
                Senior Member
                • Mar 2013
                • 96
                • USA

                #8
                Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

                Originally posted by dick_barton
                Set your meter to DC volts and measure the voltages on the pins of the connectors with the red probe and black probe on metal chassis.
                There should be a name alongside each pin of the connector
                eg
                CN751
                Pin number, legend, voltage
                Pin 1, P_ON, 4.3V
                Pin 2, DIM, 2.8V
                Pin 3, 5VSTB, 4.8V
                etc.
                Thank you dick_barton when I was initially doing this TV I wasn't sure how to properly test the voltages but I learned a lot from the last TV I just fixed. Using your photo with the connectors highlighted, the connector at the top reads like this.

                GND-0
                PNL-0
                POW-0
                Bus5v- 5V
                Pson- 3V
                ACDET-0
                INV4-0
                INV3-0
                INV2-0
                INV1-0

                12V-0

                Bottom Connector:

                24V-0
                GND-0
                INV1-0
                INV2-0
                INV3-0
                INV4-0

                I also took the voltage readings of the connector from the power supply to the main board. I got a 0 reading from all pins besides the 4th pin from the left on this connector read 5V. The only other connector that I got any voltage reading on was the connector from the button panel to the main board. There are 4 pins the first pin going from left to right was 0, the next was 3.3V, and the next 2 read 3.2V. I got a 0 reading from all other connectors on the board. Any help from here is greatly appreciated.

                Comment

                • dick_barton
                  Badcaps Legend
                  • Aug 2015
                  • 6642
                  • Wales

                  #9
                  Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

                  I'm a little confused here. One connector has 14 positions with only 13 wires connected so doesn't match up with your table above. The second connector at the top of the picture also has 14 position of which 2 are not connected.

                  Connector xxxx (photo post#7 top connector)
                  Pin1
                  Pin2
                  .....etc.
                  Pin12
                  Pin13
                  Pin14

                  Connector yyyy (photo post#7 bottom connector)
                  Pin1
                  Pin2
                  ......etc.
                  Pin 13
                  Pin14
                  Last edited by dick_barton; 10-01-2017, 12:42 PM.
                  Willing to help but I'm no expert.

                  Comment

                  • dick_barton
                    Badcaps Legend
                    • Aug 2015
                    • 6642
                    • Wales

                    #10
                    Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

                    CN4771
                    Pin 1,2,3,4,5, [24V]...........0V
                    Pin 6,7,8,9,10, [GND]
                    Pin 11, [INV1]..................0V
                    Pin 12, [INV2]..................0V
                    Pin 13, [INV3]..................0V


                    CN751
                    Pin1,2, [12V]............0V
                    Pin3, [INV1].............0V
                    Pin4, [INV2].............0V
                    Pin5, [INV3].............0V
                    Pin6, [INV4].............0V
                    Pin7, [AC_DET].........0V
                    Pin8, [PS_ON]..........3V
                    Pin9, [BUS5V]..........5V
                    Pin10, [POW]...........0V
                    Pin11, [PNL]............0V
                    Pin12,13,14, [GND]



                    If you disconnect the mainboard and power up the set do the backlights come on.
                    Last edited by dick_barton; 10-01-2017, 01:14 PM.
                    Willing to help but I'm no expert.

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #11
                      Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

                      Are the Voltage readings with all the connector in place?
                      "ACDET-0" If that is true reading with all the connectors in place then it is not normal, it should be >2V if I remember it correctly, this will cause the main board not to send out the command signal to turn on the power supply because it thinks the incoming AC to the the TV is not in the operating range. The common cause of the bad AD DET is sue to bad Opto-isolator or the resistors network for the incoming AC sensing circuit.
                      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

                      • dhoff024
                        Senior Member
                        • Mar 2013
                        • 96
                        • USA

                        #12
                        Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

                        Originally posted by dick_barton
                        CN4771
                        Pin 1,2,3,4,5, [24V]...........0V
                        Pin 6,7,8,9,10, [GND]
                        Pin 11, [INV1]..................0V
                        Pin 12, [INV2]..................0V
                        Pin 13, [INV3]..................0V


                        CN751
                        Pin1,2, [12V]............0V
                        Pin3, [INV1].............0V
                        Pin4, [INV2].............0V
                        Pin5, [INV3].............0V
                        Pin6, [INV4].............0V
                        Pin7, [AC_DET].........0V
                        Pin8, [PS_ON]..........3V
                        Pin9, [BUS5V]..........5V
                        Pin10, [POW]...........0V
                        Pin11, [PNL]............0V
                        Pin12,13,14, [GND]



                        If you disconnect the mainboard and power up the set do the backlights come on.
                        Disconnecting the mainboard and powering up does nothing but shut the red blinking LED off. I get nothing else happening from the TV.

                        Comment

                        • dhoff024
                          Senior Member
                          • Mar 2013
                          • 96
                          • USA

                          #13
                          Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

                          Originally posted by budm
                          Are the Voltage readings with all the connector in place?
                          "ACDET-0" If that is true reading with all the connectors in place then it is not normal, it should be >2V if I remember it correctly, this will cause the main board not to send out the command signal to turn on the power supply because it thinks the incoming AC to the the TV is not in the operating range. The common cause of the bad AD DET is sue to bad Opto-isolator or the resistors network for the incoming AC sensing circuit.
                          I will double check all the readings again and let you know to make sure. The readings I took were with all connectors in place.

                          Comment

                          • Scollins
                            Member
                            • Sep 2018
                            • 18
                            • USA

                            #14
                            Re: Sharp Aquos LC-40D68UT Blinking Red Power Light

                            Did you do anything to figure it out?

                            Comment

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