Help Identifying Which TV Board to Replace

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • tom565
    Member
    • Jan 2014
    • 12
    • USA
    #1

    Help Identifying Which TV Board to Replace

    Hi. I have a Sharp LC-C6577UM TV that won't turn on after a lightning storm. It acts completely dead. The power button or remote won't do anything. I don't hear any clicks or see any any lights on the TV.

    I would like to diagnose the board that is causing me the issues so I can replace the whole board. I understand that it could be more than one board that is damaged. I do not see any visual issues with any of the boards, front or back.

    The main board has no voltage outputs on any terminals. The power board has no outputs on the lower left terminal pins. There are three upper left plugs that do have voltage outputs on the power board.

    #1
    Black Wire-55v
    White Wire-68v

    #2
    Black Wire-55
    White Wire-68

    #3
    Black Wire-63
    White Wire-63
    Attached Files
    Tags: None
    • vinceroger69
      Badcaps Legend
      • Mar 2012
      • 6714
      • uk
      #2
      Re: Help Identifying Which TV Board to Replace

      In picture 1 the main board is under that metal cover bottom left can you take some pictures of that board thanks

        Comment

        • R_J
          Badcaps Legend
          • Jun 2012
          • 9588
          • Canada
          #3
          Re: Help Identifying Which TV Board to Replace

          Those voltages you are measuring (#1,2,3) are from chassis ground to the HOT side of the power supply, thats why they are wrong (50-60 volts)
          You have no standby voltage.
          With no BU5V I suspect ic7905 is bad, Check the resistance of R7918, R7853 and R7914 the first two should be less than 1Ω R7914 should be 2.2Ω
          Last edited by R_J; 09-03-2018, 10:47 AM.

            Comment

            • tom565
              Member
              • Jan 2014
              • 12
              • USA
              #4
              Re: Help Identifying Which TV Board to Replace

              Vinceroger69, sorry for the wrong description on the "main board". Here is a picture of the actual main board that's under the metal cover. It has no power anywhere on it.

              R_J, the #1, #2, #3 voltages were measured from the wires to the TV frame. I will try to get some OHM measurements tonight of the components you mentioned.

              Thanks for the help so far.
              Attached Files

                Comment

                • vinceroger69
                  Badcaps Legend
                  • Mar 2012
                  • 6714
                  • uk
                  #5
                  Re: Help Identifying Which TV Board to Replace

                  link to the service manual if you dont have one
                  https://www.manualslib.com/manual/91...c-60e77un.html

                    Comment

                    • R_J
                      Badcaps Legend
                      • Jun 2012
                      • 9588
                      • Canada
                      #6
                      Re: Help Identifying Which TV Board to Replace

                      This is the standby section, You need to have BU5V, If R7914 is open, it is very liklely IC7905 is bad.
                      Attached Files

                        Comment

                        Previous template Next

                        Related Topics

                        Collapse
                        • howardc64
                          A1312 (27” iMac 2009-2011) A1407 (Thunderbolt Display) A1316 (Cinema Display) Display Black Screen Repair
                          by howardc64
                          Problem

                          This is an LG edge LED lit LCD Display. The LEDs are on the bottom edge of the display. There are 2 bars (left and right) Each bar has many LEDs and a 6 pin connector. Each pin drive several LEDs thus is the highest current flow / heat junction. The weak lead free solder gradually fails with thermal expansion/contraction cycling and increases resistance. PSU will compensate up to a point, then when the current is too high, PSU just shut down the backlight causing a dark display. I have even seen one which the connector just fell off as solder points became completely detached....
                          08-04-2024, 10:36 PM
                        • howardc64
                          TCL 55S425 few horizontal lines, potential failure on both side of panel/buffer board
                          by howardc64
                          All left and right refers to looking from rear of TV (or looking from front with TV upside down)
                          • TV came with vertical bars and no image. Found faulty TVS on left buffer board. Also replaced T-Con (may have damaged the original while hot air removing components, board has slight warp) and have full image but few horizontal lines on the screen. Some of the lines appears to be 2 pixel tall while others are 1 pixel tall.
                          • Disconnecting left and right buffer board potentially reveals problems on both sides with different signals (unless this T-Con require jumper like Samsung FB_TRDY1&3) Fault
                          ...
                          07-24-2025, 05:17 PM
                        • howardc64
                          TCL 49S405 double image
                          by howardc64
                          LCD displays a 2nd image slighty offset vertically. And multiple pairs of black lines along the bottom. Probably common as google "TCL 49S405 double image" pulls up this ifixit post ( link ) with identical ( nearly, but their fault seems to be on the other half of the panel than mine ) problem without solution.

                          This one looks to be a more difficult to diagnose because most? of TCON seems integrated ( CSOT BGA on buffer baord) into the left panel edge board ( looking from rear of TV) There are 2 buffer boards for each 1/2 of the screen. Main connects to the left buffer board...
                          06-23-2025, 03:20 PM
                        • kca
                          LG 82UN8570AUD ~ TCON or PANEL?
                          by kca
                          Hello all ~

                          Hope this finds you well. This LG 82UN8570AUD (April 2021 model) 4K UHD television has full audio capabilities but video is compromised / problematic.

                          When I picked up this large LG tv it had a full black screen upon startup. Previous owner said it just went black one day. No popping sound or anything else of note.

                          I got the display to work by taping off several traces of the right-hand side ribbon cable on the TCON that leads from TCON to PANEL. However, despite dozens and dozens of attempts to find the right combination / range of traces taped...
                          08-31-2025, 06:38 AM
                        • snipersquad100
                          Dewalt DCR020 Power Board – No Power, Need Help Identifying ICs / Possible Replacement
                          by snipersquad100
                          Hi all,

                          I’m working on a Dewalt DCR020 jobsite radio that won’t power on.
                          So far, I’ve checked the following:
                          • The mains is reaching the transformer
                          • Transformer outputs ~15-20 V AC
                          • Bridge rectifier outputs ~15-20 V DC
                          • All fuses test OK
                          • The on/off button signal reaches the PCB connector

                          Despite this, the unit does not power up at all.

                          Inside, I’ve identified some of the ICs:
                          • ST7317 (appears to be an LCD driver, not the main MCU)
                          • LM2937L (voltage regulator)Not putting out power, 0.5V on the input
                          • Markings like FS1235, unknown IC
                          • Board number:
                          ...
                          30 Photos
                          09-01-2025, 10:57 AM
                        • Loading...
                        • No more items.
                        Working...