iPod Classic makes noises when charging

My iPod classic 7th gen makes a really weird noise when its connected to a power source. It began happening midway thru an iTunes sync, and occurs on any charger/cable/dock. it basically sounds kinda like the old dialup sounds computers used to made, but higher-pitched. It is not the hard drive, im positive on that one cuz i can hear it spin off but the noise continues.

Has anyone else had this problem? Is it serious? Can it be fixed?