[AC Adaptor] High pitch or whining noise occur from AC Adaptor

I hear small noise (similar to vibration or whining noise) coming from AC Adaptor.Is this AC Adaptor defective?

There is a case where small vibration noise can be heard from AC adaptor while in use.
This symptom is not due to fault.

Most power conversion devices such as AC Adaptors contain a transformer which vibrate when power is induced.
This kind of vibrating noise occurs from not only Panasonic PC's AC Adaptors but also from AC Adaptors for other manufacturer's various products.
*The volume of type of noise heard will vary depending on individual and usage environment.

You can try followings if you can hear the noise;
- When not using AC Adaptor, remove plug from outlet.
- When connecting AC Adaptor to PC, put AC Adaptor away from the user.

[Notice for usage]
- Since AC Adaptor generates and releases heat from its surface, do not cover AC Adaptor.
- Put AC Adaptor on a stable place during use.
- Do not force AC Cord to bend or forcefully bind together. This may cause damage to AC Adaptor.