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My computer speakers have started to emit a buzz, which "behaves" as following: It is loud when I power the speakers on, and then it fades quickly to a much lower volume level and remains constant and little audible thereafter. It is independent of the level the volume button is set. That is, if there's no audio at all, the buzz is the same at all volume levels. It has nothing to do with the computer and its sound card since its "behavior" is the same when I have the speakers disconnected.

Can it be caused by the adaptor, which has got a problem? Is it a question of grounding? In any of these cases, can it be fixed and how?

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  • "volume button"? Are you talking about digital controls inside the OS? Your speakers don't have an analogue volume control know at all? What model of speakers? Connected to the computer with an analogue plug (like classic headphones use), not USB or something? With the plug disconnected, does touching all three metal parts with your fingers (to ground them to each other instead of floating picking up noise) change anything? It's not a ground loop since it happens with the speakers only connected to their own power supply, not also to your computer. Dec 6, 2023 at 5:01
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    @Peter Cordes, I mean the volume regulator on one of the the speakers of course, since I'm talking about a buzz emitted with the speakers disconnected from the PC. It's old an model (YAMAHA YST-M45D). And right, it's not a grounding issue as I've learned in the meantime.
    – Apostolos
    Dec 7, 2023 at 8:34

1 Answer 1

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You've performed good testing! By unplugging the speakers from everything but the power supply (AKA power adapter and wall wart), and checking that the buzzing continues even with low volume, the only source of the AC hum is that power supply.

If the supply is operating at normal temperature, likely, a capacitor in the output is failing. If it's running very warm, likely a diode has shorted.

Either way, it can easily be replaced with another supply of the same voltage rating, and the same or greater current rating, and the correct connectors for the PC and AC mains. There are "universal" power supplies with multiple output voltage settings, and with multiple plugs for the output, such as this, but make sure it meets the current (amps) needs.

If you are comfortable repairing electronics, it is possible to break open the power supply and replace a component, but it would be difficult to reassemble safely.

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  • Thank you @DrMoishe. I hope it is indeed a question of the adapter or the speakers themselves, since they can be both replaced. Otherwise, I have no idea about how to deal with grounding! 🙂
    – Apostolos
    Dec 5, 2023 at 21:23
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    @Apostolos, unlikely it's a ground loop issue, since you unplugged the speaker from the PC and the buzz was still there. If you can borrow a similar power adapter, it would be a quick test to prove the point. Dec 5, 2023 at 23:52
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    Another quick test is to use batteries to briefly power the speakers. If the speakers don't take batteries directly, a DC power lead and a set of normal batteries will do. 12V is eight 1.5V batteries or three lithium batteries. I keep a couple of plastic battery holders around just for this kind of thing. This assumes the wall adapter is putting out DC, not low-voltage AC.
    – Criggie
    Dec 6, 2023 at 2:58
  • @DrMoishe: Yes, this is what I have in mind to do. Even maybe change speakers, since the ones I use are quite old and the panning doesn't work quite well.
    – Apostolos
    Dec 6, 2023 at 18:12
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    Thanks, @Criggie. I can try that as a test. I'm not sure though if I can do it correctly. The speakers work with DC-15V. The adaptor is also 15V, of course, and it also says 1.2A.
    – Apostolos
    Dec 6, 2023 at 18:32

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