I own a hantek scope DSO4254C. I wish to know if it’s normal that the fan keeps working continually from the moment I turn the scope ON until I turn it OFF, I’m not sure if this is a normal behaviour because I am almost sure that it didn’t do that in the past. I have bought it on AMAZON and it still on warranty this is why I ask, to know if I have to worry and send it to a authorized service and repair .