Electronics > Repair

Hearing static and buzz from motherboard rear headphone jack

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I have an Aorus B450 M motherboard, and since a couple of weeks ago, I hear permanent static/crackling noise coming from the rear headphone jack, and also a buzzing sound when I move the mouse or hold down any keyboard key. Investigating, here are some of my findings:

* when I reduce mouse polling rate from 1000Hz to 250Hz, the static and buzz sound are almost completely eliminated
* changing Windows power plan to Power Saving, which greatly lowers CPU clock, also reduces noise considerably
* I can also hear the noise when touching the TRS connector onto any metallic parts like I/O shield, mobo pins and unpainted screws
* there's no noise when plugging the headphones in frontal jacks or a USB DAC (FiiO K1)
* I don't get shocked when touching any metal parts from the case or devices plugged into it
* changing outlet makes no difference
Based on these symptoms, as a layman, I'd say it's like the motherboard is not grounded and/or filtering electrical noise from parts and peripherals. Is this issue caused by mains improper grounding? Is it caused by a faulty PSU? I haven't tested another PSU yet or took the PC to another place, because I'm afraid it's a fault from the mobo, which unfortunately isn't in warranty period anymore.

If it's the mobo the culprit, is there any economically feasible repair, or I'd better buy another mobo, USB sound card or live with the noise? Is there something I can investigate with just a multimetre, or do I need a scope and other tools? Thanks in advance.

majority or all of the grounding is done through the cable from the main power supply cable between motherboard and PSU from which practically is grounded through the mains AC. Could ensure it's connected?

You mean the ATX 20+4 pins cable? The PC wouldn't even turn on without it.

Is it with headphones or speakers? If speakers, is the amplifier / active speaker grounded by its mains cable?

--- Quote from: ksio89 on January 17, 2022, 06:00:57 pm ---3. I can also hear the noise when touching the TRS connector onto any metallic parts like I/O shield, mobo pins and unpainted screws

--- End quote ---
Again, headphone, speakers? Which part of the TRS is touching?

I've only tested with headphones, but speakers might be affected as well. TRS tip is touching any metallic part like I/O shield edges, rear DVI-D jack threads, motherboard pins like S/PDIF connector, GPU screws on backplate etc. pretty much every part made from metal.


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