onn. (Element/Walmart) 32" LED add missing PC audio jack?

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  • bluto
    Badcaps Veteran
    • Oct 2007
    • 560

    #1

    onn. (Element/Walmart) 32" LED add missing PC audio jack?

    I picked this up yesterday at Walmart, a 32" LED TV (model #100002458) for just under $100 to use in my shop. A few months ago, the older models used the 'Element' brand name but apparently now they go by 'onn'. Either way it looks like they are all made by Tsinghau TongFang (THTF) Global. The main board is MS35533-ZC01-01.



    Unfortunately it looks like on this one they had to leave off the PC audio 3.5mm input jack to save a few cents per unit. The older models all had this included. I took the cover off and there is clearly an unused location to receive the 3.5mm connector. I tried soldering a cable with a 3.5mm plug to the three pads (the center pin at the back of the solder pads is ground) to see if it would play audio through the speakers but it did not work. There are some other components missing like Q500, Q501, R76, C323, etc. near the connector. Other than those, I think I can trace the one channel back to the main CPU. Does anyone know the best approach to figure out what components are needed and add them back? Maybe even a small perf board with regular through hole components for the transistor, resistor, capacitor, etc. could be used and then all one would have to do is solder the two audio wires to traces leading to the CPU.

    I did play around with the setup menus and the audio screen appears to be active on the PC/VGA input the same as on the Component video input, so I am hoping that the audio is not muted in the firmware for this input. I looked in the service menu and could not find any settings that might change this. So if I could figure out the circuit, I think there is a good chance the PC audio input would work.
    Attached Files
    Last edited by bluto; 01-13-2020, 08:23 PM.
  • R_J
    Badcaps Legend
    • Jun 2012
    • 9535
    • Canada

    #2
    Re: onn. (Element/Walmart) 32" LED add missing PC audio jack?

    Get a VGA to HDMI converter, That would be the easiest
    here is just one example https://www.amazon.ca/FOINNEX-Conver...129WR1Z5PAAFT4
    This one is made by ONTEN, It takes the VGA and audio and converts it to hdmi, it uses a usb port for 5 volt power
    Last edited by R_J; 01-14-2020, 11:01 AM.

    Comment

    • bluto
      Badcaps Veteran
      • Oct 2007
      • 560

      #3
      Re: onn. (Element/Walmart) 32" LED add missing PC audio jack?

      I dug into this a little more and I think the main SOC is a TSUMV59XUS. It is amazing that all of the inputs (HDMI, analog audio & video, USB, etc.) get fed directly into the chip where it does all the signal processing and outputs the LVDS signal directly to the panel. I found a service manual of another TV that uses the same chip and it showed all of the circuits for its inputs and outputs including the PC audio input. If it is to believed, then all I need to feed into the SOC's audio input pins is two resistors and a capacitor for each audio channel coming off of a 3.5mm connector. I am going to give it a try and see if it works.



      Attached Files
      Last edited by bluto; 01-14-2020, 07:58 PM.

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      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: onn. (Element/Walmart) 32" LED add missing PC audio jack?

        I would try feeding one of the Analog line (L or R) and see if the sound will come through or not before putting lots of parts.
        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

        • bluto
          Badcaps Veteran
          • Oct 2007
          • 560

          #5
          Re: onn. (Element/Walmart) 32" LED add missing PC audio jack?

          So here is what I tried (be sure to zoom in to see the annotations):



          I did the same wiring for both channels but only one channel is fully visible in the photo. I removed CD61 (the top of it and the pad to the left were grounded). I added a bridge to the pad to the left of the removed capacitor. Now I had continuity all the way to the SOC. I noted that both channels had a 30k resistor and capacitor pull down to ground on each trace leading to the SOC. I left those alone. I added a 10k resistor for each channel in the input plug holes. So now the input will go through a 10k resistor, then straight to the SOC with the existing resistors and capacitors (pull downs?) going to ground as noted above. Everything looks good in my estimation as it matches pretty closely the circuit in the service manual schematic.

          But when I hooked up an audio signal to the three input pins, I got nothing. Not even one little crackle or a pop. Any thoughts before I give up on this?
          Attached Files
          Last edited by bluto; 01-15-2020, 12:45 AM.

          Comment

          • R_J
            Badcaps Legend
            • Jun 2012
            • 9535
            • Canada

            #6
            Re: onn. (Element/Walmart) 32" LED add missing PC audio jack?

            Did you have a vga signal going to the vga jack? sometimes the video must be present before you will get audio.

            Comment

            • bluto
              Badcaps Veteran
              • Oct 2007
              • 560

              #7
              Re: onn. (Element/Walmart) 32" LED add missing PC audio jack?

              Originally posted by R_J
              Did you have a vga signal going to the vga jack? sometimes the video must be present before you will get audio.
              Yes sir, I did try it while displaying a picture on the vga input. I can adjust the volume, toggle the mute, etc while on this input which makes me believe that it wants to work. So I was hoping for some comments about how my circuit was wrong. If not I suppose that it is still possible that this audio input is disabled by the firmware on some other level.

              Comment

              • R_J
                Badcaps Legend
                • Jun 2012
                • 9535
                • Canada

                #8
                Re: onn. (Element/Walmart) 32" LED add missing PC audio jack?

                You may need to try and get into the service menu somehow. I'm not sure ok this but worth a try:
                Try MENU-1-1-4-7

                Comment

                • bluto
                  Badcaps Veteran
                  • Oct 2007
                  • 560

                  #9
                  Re: onn. (Element/Walmart) 32" LED add missing PC audio jack?

                  Yep MENU+1147 works to get into the service menu. Also MENU+0000 does the same thing. I looked all around in there but did not see any settings for audio inputs. Oh well it was worth a try but I give up now

                  Comment

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