Originally Posted by Whitey

Yeah, the little black box that goes between the mains and the laptop. If you will look in your laptop manual, it talks about changing it if you excessively use it with 220v. See 220V is double 110V and when it steps down to the 18V your laptop needs it generates a lot of heat. If in doubt, feel the black box. Well, it generates even more heat with 220V. The heat can really degrade the transformer oil.

That's why you need to change it often.

When you change it, the little black box can be hard to pop open. I really suggest you use a wood chisel to open it with. If it's hard to open just pry harder and harder. After you change the oil the first time, it will be a lot easier to open the black box in the future. If you pry it open too hard, you might break the black plastic but don't worry, just use some duct to keep it closed.