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Noisy front panel headphone connector on ASUS m5a78l-m

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    #1

    Noisy front panel headphone connector on ASUS m5a78l-m

    I have an Asus m5a78l-m socket AM3 motherboard. Typically I'll listen to music with my headphones on. I used to have a subwoofer with a headphone input, so this wasn't a problem until now.

    The rear audio output is nice and noise free. If I plug my headphones into that, there's no noise.

    However plugging my headphones into the more easily accessible front audio jack results in a constant background noise that becomes really noticeable when there's HDD activity, or a lot of data transfer to and from the USB WiFi dongle. There's always a background crackle/hum even if the computer isn't doing much.

    Now, I've googled the issue, and found a few other people with the same complaint, but no solid cause. I'm wondering if electrical noise is leaking into the front panel connector cable, and if some RF shielding would help?
    Tags: None
    #2
    Re: Noisy front panel headphone connector on ASUS m5a78l-m

    Originally posted by Mrx3750 View Post
    I'm wondering if electrical noise is leaking into the front panel connector cable, and if some RF shielding would help?
    Yes, and yes.

    Comment

      #3
      Re: Noisy front panel headphone connector on ASUS m5a78l-m

      Okay, I'm thinking of lopping off a piece of coax cable, and using the metal jacket as shielding.

      Comment

        #4
        Re: Noisy front panel headphone connector on ASUS m5a78l-m

        So I just shielded the cable with a jacket of aluminum foil, since I couldn't get any netting over those connectors, covered it with tape to prevent contact with anything.

        Shouldn't have bothered. Didn't affect the noise one bit.

        Comment

          #5
          Re: Noisy front panel headphone connector on ASUS m5a78l-m

          It won't unless you ground it. Search for Farraday cage if you don't understand what it should do.
          sigpicThe Sky Is Falling

          Comment

            #6
            Re: Noisy front panel headphone connector on ASUS m5a78l-m

            It is grounded to the casing.

            I haven't solved the issue yet, but I ran across something that might be relevant to other people.

            Apparently lots of times this noise can be caused because the USB ports on the front and the headphone and microphone connector all share the same ground. That was the case with mine, so I used my Dremel to sever the ground, then soldered on a wire and connected it to the casing.

            Didn't work for me, the noise is still there, but might work for some future reader of this thread.

            Comment

              #7
              Re: Noisy front panel headphone connector on ASUS m5a78l-m

              maybe bad design on the board causing noise pickup at the front audio header?like a ground loop.

              Comment

                #8
                Re: Noisy front panel headphone connector on ASUS m5a78l-m

                That's what I'm guessing at this point. I suppose it can't really be helped.

                Guess I'll need to find some good speakers with a headphone jack, or rig up a headphone jack to this pair I have now.

                Comment

                  #9
                  Re: Noisy front panel headphone connector on ASUS m5a78l-m

                  Originally posted by Mrx3750 View Post
                  Apparently lots of times this noise can be caused because the USB ports on the front and the headphone and microphone connector all share the same ground. That was the case with mine, so I used my Dremel to sever the ground, then soldered on a wire and connected it to the casing.

                  Didn't work for me, the noise is still there, but might work for some future reader of this thread.
                  This still is a ground loop issue, and it's fairly common with front panel audio jacks. Measure between the ground of the rear jacks and the front with a multimeter set to 2 volts AC. Don't have a DMM with a 2V AC scale, borrow one. And then buy one, you'll never regret it.

                  If you find a voltage difference, then you know what to do. Run a wire from the front panel audio ground to the rear panel audio ground. That should quiet things down.
                  Originally posted by PeteS in CA
                  Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                  A working TV? How boring!

                  Comment

                    #10
                    Re: Noisy front panel headphone connector on ASUS m5a78l-m

                    Have a multimeter, not sure where to probe for the rear panel ground, and I'm not removing the board to get at it.

                    Could i ground it to something else, say house ground and see what that does?

                    Comment

                      #11
                      Re: Noisy front panel headphone connector on ASUS m5a78l-m

                      Also try some ferrite beads or toroids on the front panel cabling, might work.

                      Comment

                        #12
                        Re: Noisy front panel headphone connector on ASUS m5a78l-m

                        Originally posted by Mrx3750 View Post
                        Have a multimeter, not sure where to probe for the rear panel ground, and I'm not removing the board to get at it.

                        Could i ground it to something else, say house ground and see what that does?
                        No pain, no gain, but here's one for you if you haven't it yet figured out yourself. Just buy a 3.5mm jack from your local shack. Unscrew the housing of the jack to expose the terminals, plug it into the rear panel of your motherboard, and measure from the ground terminal to the ground of your front audio panel.
                        Originally posted by PeteS in CA
                        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                        A working TV? How boring!

                        Comment

                          #13
                          Re: Noisy front panel headphone connector on ASUS m5a78l-m

                          Oh yeah. Duh I can do that right now. Front panel headphone is grounded to the casing, so all I need to do is measure from the rear ground to the casing.

                          And I'm getting 0 ohms.

                          Comment

                            #14
                            Re: Noisy front panel headphone connector on ASUS m5a78l-m

                            One more thing to try. Connect a .01 uf ceramic disc between the front panel audio ground and the case ground. Keep the leads as short as possible.
                            Last edited by Sparkey55; 08-18-2013, 08:23 PM.

                            Comment

                              #15
                              Re: Noisy front panel headphone connector on ASUS m5a78l-m

                              Hm. Need one of those. I likely have one on one of these TV chassis boards. .01uf, would that just be numbered 01 on a disc cap?

                              Edit: Oh wait I remember now, should say 103 on it. Or is it 104? 104's I have a few of.
                              Last edited by Mrx3750; 08-18-2013, 09:38 PM.

                              Comment

                                #16
                                Re: Noisy front panel headphone connector on ASUS m5a78l-m

                                Originally posted by barainny
                                Oh, I haven't the problem. Fortunately, I have a friend who is a specialist in the field . Later, I'll ask him about your problem. And I'll reply you.
                                If your friend is a specialist, then what are we?

                                Comment

                                  #17
                                  Re: Noisy front panel headphone connector on ASUS m5a78l-m

                                  Originally posted by Sparkey55 View Post
                                  If your friend is a specialist, then what are we?
                                  Geeks, nerds, etc.
                                  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

                                    #18
                                    Re: Noisy front panel headphone connector on ASUS m5a78l-m

                                    Originally posted by Sparkey55 View Post
                                    If your friend is a specialist, then what are we?
                                    great learning curve for the likes of me, thanks fellas

                                    Comment

                                      #19
                                      Re: Noisy front panel headphone connector on ASUS m5a78l-m

                                      I have this problem with my PC. I work around it by using the headphone jack on my speakers. It only happens in the Antec 1200 case. I used to have it in a CoolerMaster Centurion 5 II, and it didn't happen there. This case has had the same problem with 2 different motherboards
                                      I love putting bad caps and flat batteries in fire and watching them explode!!

                                      No wonder it doesn't work! You installed the jumper wires backwards

                                      Main PC: Core i7 3770K 3.5GHz, Gigabyte GA-Z77M-D3H-MVP, 8GB Kingston HyperX DDR3 1600, 240GB Intel 335 Series SSD, 750GB WD HDD, Sony Optiarc DVD RW, Palit nVidia GTX660 Ti, CoolerMaster N200 Case, Delta DPS-600MB 600W PSU, Hauppauge TV Tuner, Windows 7 Home Premium

                                      Office PC: HP ProLiant ML150 G3, 2x Xeon E5335 2GHz, 4GB DDR2 RAM, 120GB Intel 530 SSD, 2x 250GB HDD, 2x 450GB 15K SAS HDD in RAID 1, 1x 2TB HDD, nVidia 8400GS, Delta DPS-650BB 650W PSU, Windows 7 Pro

                                      Comment

                                        #20
                                        Re: Noisy front panel headphone connector on ASUS m5a78l-m

                                        Originally posted by Mrx3750 View Post
                                        Oh yeah. Duh I can do that right now. Front panel headphone is grounded to the casing, so all I need to do is measure from the rear ground to the casing.

                                        And I'm getting 0 ohms.
                                        Measure voltage between the two, with your multimeter on AC 2 volts scale. 0 ohms at DC isn't always 0 ohms at AC.
                                        Originally posted by PeteS in CA
                                        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                        A working TV? How boring!

                                        Comment

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