Topic: Humming sound from tv speakers when playing nes

Hi. I am new to this forum and I have a problem with my nes (it's a Swedish model).
When I turn it on so comes a loud humming sound through the speakers. It doesn't matter if I use the antenna or the audio and video ports on the side of the nes.
I have tried it on two different tvs. First on my flatscreen tv where I have other things hooked up to and the on my old crt tv. No difference between them when it comes to the sound.
I have searched on google for an answer but the only thing I can find is about some kind of interference.
But I think it must be some other problem with it.

Are you using an original Nintendo power supply? A buzzing noise can be caused by a mismatched PSU.

I think you might have a mosquito stuck in there.

I don't have a original nes adapter. Will test to buy one when I get money.
I couldn't find the original one so I use one who is near enough powerfull.

If that woun't help so must it be something internal.

Thanks for the help. I post how it goes.

EDIT

I am using a switshable adapter at the moment and when I increased the voltage from 9 to 12 volts so did the humming dissapear.
So it is the adapter. Will buy a original one in about two weeks.

Thanks for the help.