If the display brightness is too bright, even if the brightness adjustment is "0" image is still very bright, some people will think this is the monitor's brightness caused by uncontrolled automatic control circuit, this view is not quite correct - although the control circuit is indeed out of control cause this phenomenon, but usually it does not control. 

 

Cause and Countermeasures: In most cases this failure is the video amplifier stage supply filter capacitor capacity is reduced or open (or virtual) caused by welding, so you can try before welding look, if the fault is still on replacement capacitance can be, are the most likely point of failure, as yet, as the place to settle should check whether the power supply circuit breaker places, such as normal and then all of the above suspicion automatic brightness control circuit (little possibility ). Note: Sometimes a memory failure can also cause this phenomenon, but the probability is very low.