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Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

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    #1

    Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

    I found part of an LG 42LK450 in the dumpster a while back. It was pretty much complete except for the back cover and the base. I've had it under the workbench for sometime. I recently discovered that the base from a 42LM3700 that I parted out fit this model too so that sparked a little more interest. Yesterday, I was bored so I decided to play around a bit. I determined that the PSU and inverter were good but the main board was bad. Not wanting to drop $75 on a main when I don't have the back cover seems foolish. Looking at the main from the 42LM3700 that I parted out, it looked like the board would mount to the back of this panel and most of the connectors were the same with the exception of the connector for the touchpad and IR board. The original main has a 15 pin connector. The new main, only ten. Ten of the fifteen wires were the same color. I pulled those ten out of the plug and put them into the ten pin plug that I pulled off of the other harness. The TV works now. It seems like everything works except the red LED doesn't turn blue anymore. Looking at the attached schematic, it looks like pins 11 and 12 handle that function. Pin 13 is ground. What are pins 14 and 15? I don't know what S/T_SCL or S/T_SDA mean.

    Here's a link to the original mainboard. http://assets.shopjimmy.com/media/ca...8816-top_1.jpg


    Here's a link to the 42LM3700 mainboard.
    http://assets.shopjimmy.com/media/ca...237503-top.jpg
    Attached Files
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    #2
    Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

    Here's a picture of the harness after surgery.
    Attached Files

    Comment

      #3
      Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

      SDL/SCL is I2C bus. Possibly for some kind of processor on that board.
      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

      Comment

        #4
        Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

        Interesting, I wonder why it would be on one and not the other. It looks like both lines run to the MICOM chip, IC1002. I Really have no plans for it as is. I'll probably just keep the panel in the event that I find one with a busted screen.

        Thanks!

        Comment

          #5
          Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

          The LM3700 is a 3D TV, page 59 of the service manual for the LK450 says "TI solution RF-3D OPTION"

          Is it possible that the 3D feature will still function?
          Attached Files

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            #6
            Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

            Don't know. I2C would be unusual for 3D glasses transmitter. It's not a guaranteed data bus (messages can be delayed or even lost altogether.)
            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

            Comment

              #7
              Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

              Originally posted by tom66 View Post
              Don't know. I2C would be unusual for 3D glasses transmitter. It's not a guaranteed data bus (messages can be delayed or even lost altogether.)
              Panny tough books have I2C for the GPS comunocations, so its not that high loss.
              Things I've fixed: anything from semis to crappy Chinese $2 radios, and now an IoT Dildo....

              "Dude, this is Wyoming, i hopped on and sent 'er. No fucking around." -- Me

              Excuse me while i do something dangerous


              You must have a sad, sad boring life if you hate on people harmlessly enjoying life with an animal costume.

              Sometimes you need to break shit to fix it.... Thats why my lawnmower doesn't have a deadman switch or engine brake anymore

              Follow the white rabbit.

              Comment

                #8
                Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

                Originally posted by goontron View Post
                Panny tough books have I2C for the GPS comunocations, so its not that high loss.
                It's not that, more because the timing is not deterministic. GPS modules don't need deterministic timing (you don't really care if the GPS updates 9 or 10 times a second in most cases.) 3D glasses need deterministic timing down to milliseconds which I2C struggles to provide.
                Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                Comment

                  #9
                  Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

                  Is it possible that S/T_SCL and S/T_SDA are used to turn off the red standby LED and turn on the blue power LED? The red LED doesn't flash or shut off at any point.
                  Last edited by johnboy1313; 03-09-2015, 09:20 AM.

                  Comment

                    #10
                    Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

                    Originally posted by johnboy1313 View Post
                    Is it possible that S/T_SCL and S/T_SDA are used to turn off the red standby LED and turn on the blue power LED? The red LED doesn't flash or shut off at any point.
                    Yes, possibly if there's a microcontroller on that board. But it looks like LED_R and LED_B are available on that connector, so I'm not sure.
                    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                    Comment

                      #11
                      Re: Frankensteined LG 42LK450/42LM3700: On mainboard, what is SDL and SDA?

                      Thanks guys.

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