monitor black-out

I have a Sampo Alphascan 411 that’s 4 yrs old. Recently, I’ve been experiencing problems with it. The display just blacks-out all of a sudden. Sometimes I could use it for a few hours with no problems, other times it would just black-out after a few minutes of use. What could be the problem? Is there something I could do or do I have to have it fixed in the shop?