You expect a power adapter to plug in to a wall socket and operate silently forever, but some of them buzz, beep, click or make a variety of other irritating noises. There's often an easy, non-invasive fix: reversing the adapter's polarity, which sounds complicated, but actually amounts to no more than unplugging the adapter and turning it upside down before reinserting it into the socket.
Should this easy trick not work, it's time to call a professional, says TUV Rheinland, a technical inspection agency in Germany. Don't try to open electronic transformer-rectifiers to fix them yourself.
Trying to muffle the sounds by wrapping the adapter is another bad idea.
The noises are commonly caused by the alternating current of mains electricity. This leads to fluctuations in magnetic fields around live components, which may shake as a result, says TUEV.
If the adapter starts heating up or gives off an odour, then it's time to unplug it, says Ralf Diekmann, product safety expert at TUEV. Such signs might indicate a build-up of dust inside. But again, don't pry open the adapter and try to clean it.
"The devices are constructed so that home repair is no longer possible nowadays," says Diekmann. Losing an adapter is also not the end of the story. Most USB adapters, for example, can easily be replaced by just about any other USB adapter.
Just note that some older adapters convert to a higher voltage than newer devices tend to use, so check what voltage output an adapter provides before making use of it. The information is usually printed on a label on the adapter.