Well LCD monitors don't have bulbs, per say. They have two tubes called inverters that supply a backlight. They are on each side of the monitor, about 8 inches long and pencil thin. You can buy them off of the Internet on sites like NewEgg if you are experienced in electricity. Otherwise, it would probably be best bringing it to a shop or to the manufacturer to get it checked out. Reason I say that is when monitors have problems they are reverse of what you are experiencing. They start bright and dim versus start dim then bright. If the inverters are bad then you get no light at all, as opposed to dim then to light. But it is a very high quality monitor and you should not be having any problems..finally there are other little things that can cause it, for instance I have a monitor that is always dim and I have to press the keyboard arrow keys from dim to bright each time. Its a faulty keyboard not monitor..So nothing major on your monitor but it would be worth it to have someone at least ensure you it is working correctly. Good Luck. Please rate this solution.

Maybe you got some capacitors dried on your monitor