What symptom indicates noise on the LCD?

The symptom that indicates noise on an LCD is often characterized by erratic video and sharp changes in intensity, which signifies that the signal being processed by the screen is not stable or properly formatted. Noise can manifest as random variations in brightness and color, leading to flickering or unusual artifacts that interrupt the display's normal operation.

Black spots, while they can indicate physical damage or dead pixels, do not directly denote noise in the signal. They suggest an issue with the LCD panel itself rather than interference or instability in the electronic signal being displayed. Changes in bearings relate to mechanical movement and are not associated with video display issues. Therefore, erratic video and sharp changes in intensity are the most relevant indicators of noise affecting the LCD.