FX4021 subwoofer hum

Hi,

I just bought a second hand FX4021 set. The subwoofer hums loudly when plugged in for power, regardless of whether the audio cables are plugged in or not and also regardless of whether it is switched on or not.

I noticed the hum becomes very faint and undisturbing if the subwoofer is inclined at around a 45° angle to the left.

Is there a way to suppress the hum ? Is the unit defective ? Ultimately, can i just position the unit laterally (even though it doesn't seem normal), with it still working properly afterwards ?

Thanks for your replies.

I'd be inclined to open it up and check the internal wiring myself based on what you said about the noise abating on angle.

Most of the forumites around here are into vintage JBL and Altec Lansing stuff but some know their way around electronics. Maybe they'll chime in.

thanks, i'll see what i can do.