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    GTX 750 HDMI output not working

    Hi

    I have an GTX750-FML-1GD5 with a non-working HDMI port and I'd like to figure out what's the cause and if it's easily repairable.

    GPU is working fine. VGA and DVI-D ports are also working just fine. But whatever monitor or TV I plug into the HDMI port, it isn't even recognized, let alone giving a display.

    I took a glance at the HDMI port and couldn't see any obviously broken parts.

    I've also read on various forums that some firmware versions have non-working hdmi, so I flashed dozen or so different VBIOS ROMs that I acquired from techpowerup database. I tested different rom versions from different brands, but still no success. It is reported flashing vbios of Strix card results in working hdmi, but since I have 1 GB non-TI version of the card I have large difficulty in finding reports of working vbios versions relevant to my card.

    I'm attaching shots of the card below. I have closer shots in case anyone is interested.
    Attached Files
    Last edited by hinisa; 12-05-2021, 08:51 AM.

    #2
    Re: GTX 750 HDMI output not working

    That last pic looks like a broken HDMI connector to me - it could just be the angle.

    Take an old HDMI cable, cut one of the plugs off it and strip the wires back. Plug it in and measure continuity from each wire to the PCB at or near the HDMI socket.
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      #3
      Re: GTX 750 HDMI output not working

      Originally posted by dicky96 View Post
      That last pic looks like a broken HDMI connector to me - it could just be the angle.

      Take an old HDMI cable, cut one of the plugs off it and strip the wires back. Plug it in and measure continuity from each wire to the PCB at or near the HDMI socket.
      Thanks

      Connector is fine (there is a symmetrical gap at the bottom of the metal part which may look deceiving) Cables plugs in without a problem and sits fairly tight.

      I measured continuity of 19 pins from cable to rear end of the connector. (I couldn't see further tracks on pcb unfortunately). All measured OK.

      -----------

      Last night I tried more vbios and different versions affect functionality of DVI port, too. So I still have a hope non-functionality of HDMI still might be a firmware issue.
      Last edited by hinisa; 12-06-2021, 05:46 PM.

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        #4
        Re: GTX 750 HDMI output not working

        Another strange thing (maybe related?) about the card is GPU-Z always shows it as having Elpida memory regardless of which vbios I install.

        Here it says there's a resistor for specifying which rams are installed on the board but I don't know

        1. where it's on this board

        2. Why would it be set to Elpida

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          #5
          Re: GTX 750 HDMI output not working

          I found boardview of the card and I'd appreciate any help on what to measure next. I'm a newbie.
          Attached Files
          Last edited by hinisa; 12-07-2021, 09:07 AM.

          Comment


            #6
            Re: GTX 750 HDMI output not working

            Pin 18 gives 4.9V which is OK I guess.
            Last edited by hinisa; 12-08-2021, 09:10 AM.

            Comment


              #7
              Re: GTX 750 HDMI output not working

              Hi, im a newby too, but maybe i can help a little, maybe you cand find a schematics of that board? The boardview is nice to have, but with a schematics it will be better.

              Another cuestion, do you have the original bios? I mean, the one you had before flashing a lot of bios, if you burn that bios, does gpu-z still says you have Elpida?

              I cant find a specific bios for your motherboard, Ill try this one

              https://www.techpowerup.com/vgabios/...50-1024-140325

              And finally, as far as I know there is a part of the board for HDMI autodetect, I think that is what you need to find and solve.


              Maybe that helps a little, try finding a schematics, if not found, maybe gtx760 schematics is almost the same.

              Have luck

              Comment


                #8
                Re: GTX 750 HDMI output not working

                Originally posted by foshland View Post
                Hi, im a newby too, but maybe i can help a little, maybe you cand find a schematics of that board? The boardview is nice to have, but with a schematics it will be better.

                Another cuestion, do you have the original bios? I mean, the one you had before flashing a lot of bios, if you burn that bios, does gpu-z still says you have Elpida?

                I cant find a specific bios for your motherboard, Ill try this one

                https://www.techpowerup.com/vgabios/...50-1024-140325

                And finally, as far as I know there is a part of the board for HDMI autodetect, I think that is what you need to find and solve.


                Maybe that helps a little, try finding a schematics, if not found, maybe gtx760 schematics is almost the same.

                Have luck

                Thanks!

                I've tried the bios at that link before, to no avail. I believe the original bios is this, and even with that still shows as Elpida RAM. Author of GPU-Z says RAM manufacturer is determined via a resistor strap on the board and firmware should not change the result.

                I'm afraid this might be a hardware issue.

                ----

                There's a schematics of a slightly different board here

                I think I should start with mHDMI page and follow the Pin 19. What can I measure there?


                I just wish there was a way to force the bios or the graphics driver to always push signal through the hdmi connector without waiting for a hotplug signal.
                Last edited by hinisa; 12-09-2021, 09:05 AM.

                Comment


                  #9
                  Re: GTX 750 HDMI output not working

                  I measured the resistors on Pin 19's path (hotplug detect pin) and they seem OK, too.

                  R4 97.5 kohm
                  R5 98.4 kohm
                  R6 00.5 ohm
                  R26 9.98 kohm

                  R6 should be 0.05 ohms but I thinks my multimeter isn't that sensitive.

                  I also checked Q5 transistor but I did it on PCB which I gather isn't very helpful.

                  Comment


                    #10
                    Re: GTX 750 HDMI output not working

                    Update:

                    I've managed to get picture from HDMI connector by forcing video output on linux nouveau driver and using a pre-loaded EDID file. So at least I know TMDS signals are going fine.

                    However, I couldn't get any data when I run i2cdump. Monitor isn't still connected i2c-wise. So either there's a problem in the DDC pins, or the VBIOS or driver isn't initializing DDC stuff without a hot-plug-detect event.

                    Comment


                      #11
                      Re: GTX 750 HDMI output not working

                      Hi
                      In case of HDMI problem important is +5V on pin 18 of this socket, when monitor and laptop (or PC) are connected . If it less then +5V (for example +3,3V like I had in laptop) HDMI is not working. I allways starts repair HDMI checking this value.
                      I don't know what exactly can be wrong with Your GTX card, but maybe this post will help somebody else.

                      Have A Good Day

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