I’ve got a fairly new 14tb Seagate Expansion. It works fine, and I’ve been using it for a month and a bit.

I don’t know how long it’s been doing this, but the power supply is making a very faint alarm sound. The power supply is plugged into a Belkin surge protector powered on and with the “protected” status light lit, and it is plugged into an outlet. The HDD is currently not plugged in to a computer.

It’s not a beep or electricity. It’s a distinct weewooweewoo. I couldn’t even determine the source until I pressed my ear against it.

Googling just points me towards typical “my HDD is making a sound, how long do I have until it dies”, but nothing pointed me to the alarm sound from the power supply.

I’ll check again if it makes the alarm in other conditions, but in the meanwhile, I was hoping someone here might know something.

Thanks in advance!

EDIT: The sound only happens when…

  • Power adapter is plugged into the HDD, AND the outlet
  • HDD is NOT plugged into the computer.

Plugging it into the computer stops the noise from the power adapter.

  • @SomeoneSomewhere
    3•5 months ago

    It’s not the bridge rectifier, but it’s an artifact of the operation of the switchmode power supply. Similar effects are often described as 'coil whine '.

    The switching operation varies in duty cycle and frequency depending on load, and isn’t absolutely stable so oscillates a little bit. This switching supply is often in the audio range; typically between about 5kHz and 200kHz depending on design and load.

    Changing current and magnetic field causes the physical components (particularly transformers/inductors) to change size and shape, and this vibration causes audible noise. At some conditions, it will resonate at an audible frequency and be loud. At other conditions, it might not resonate and/or the frequency is outside the audible range, so it’s silent.

    Mains transformers do the same, causing the characteristic 50/60Hz hum. You’ll also hear the same out of cellphone chargers.

    Nothing to worry about.

    • @[email protected]OP
      1•4 months ago

      Thank you for that! I’ve gotten into the habit of unplugging both cables (power + data) when I’m done with it, which is probably better anyways…but at least now I don’t have to fret if I forget one.

      (Always safely ejecting, of course!)

      Thanks!