Korad KAA3005P making noise

[psysc0rpi0n]

Hello.

Back in the end of 2019 I  bought a pair of this Korad KA3005P. I don't use them that much, because I'm only a hobbyist. I don't work with electronics (unfortunately).
Yesterday I connected an external fan to one of the power supplies at like 10V and 200mA and all of a sudden, the power supply started making a noise that looked like something was in contact with the internal fan. But visually, was nothing touching the fan.

So, I opened the case to see if there was anything from the inside, toughing the internal fan, but again, nothing visible.
Then I thought this also sound like when there is poor electrical contact, there are sparks and those sparks produces that clicks. So I turned all lights of the living room off but I couldn't spot any sparking either.

Then I thought, well maybe it's the internal fan doing noise inside the fan itself, so I unplugged the wires that connect the internal fan to the power supply board and tried again. weirdo af, the noise was still there. And it seems to come from the plug where the mains power cable is connected in the back.

My question is if anyone already had a similar experience with these power supplies or even with any other power supple brand/model and what to do?
My power supplies are still within warranty time and I already contacted the online shop where I bought them but probably they will only reply next Monday or so!

Any feedback is appreciated.
Thanks
Psy

[psysc0rpi0n]

Up...

Any ideas, suggestions, anything?

[Algoma]

230V 50Hz?  - is the sound at 50Hz or 25hz?  you can get an audio frequency measuring app for your phone? .. Those Korads have a few Relays back there.. might be one clicking. Put an Audio meter app on your phone and see if you can narrow down the source, instead of risking your ears anywhere close to mains voltage.

[psysc0rpi0n]

230V 50Hz?  - is the sound at 50Hz or 25hz?  you can get an audio frequency measuring app for your phone? .. Those Korads have a few Relays back there.. might be one clicking. Put an Audio meter app on your phone and see if you can narrow down the source, instead of risking your ears anywhere close to mains voltage.

I completely forgot this thread.

Well, somehow the noise stopped. I contacted the online shop and they told me to record a small video showing the noise, and after that, I couldn't hear the noise again... :s