The abnormal display of the LCD display refers to the failure of the LCD display to be confusing and unstable, black spots on the display, and abnormal text display.

1. The LCD display content is disordered and unstable

The cause of the clutter of the LCD display is generally caused by external magnetic field interference. The troubleshooting method is as follows:

First check whether there is a magnetic source around the LCD display, such as speakers, motors, etc. If there is any equipment that generates magnetic fields, turn it off or remove it. If no magnetic field source is found, you can change the LCD display and try again until you find the magnetic field source to troubleshoot.

2. Black dots on the LCD screen

The main reason for the black dots on the LCD screen is the bad dots on the LCD screen. The troubleshooting method is as follows:

Since the dead pixels cannot be repaired, if the dead pixels do not affect the use, you can continue to use them. If the dead dots affect the use, replace the LCD module.

3. LCD display text is abnormal

The reasons for the abnormal display of the LCD display text are mainly the uncleanness between the leads, the poor contact between the common electrode or the segment electrode, the asymmetry of the amplitude of the AC square wave, and the poor insulation of the conductive rubber. The maintenance method is as follows:

(1) First open the casing of the LCD display, and then check whether the lead room is clean. If it is not clean, wipe it with a dry cloth.

(2) If the leads are clean, then check whether the common electrode and the segment electrode are in poor contact. If the contact is not good, connect the segment electrode and the common electrode.

(3) If the common electrode and segment electrode are in good contact, then use an oscilloscope to measure whether the amplitude of the AC square wave output from the control circuit board is symmetrical. If the amplitude of the square wave is asymmetric, adjust the control circuit to make the square wave amplitude normal.

(4) If the square wave amplitude is normal, check whether the conductive rubber stripes are positive and parallel. If the stripes of the conductive rubber are not normal or parallel, the insulation of the conductive rubber is reduced, and it can be replaced.

(5) If the conductive rubber is normal, then check the LCD screen for moisture. If there is a description that the liquid crystal display is conductive on the wet glass surface, it is usually normal after drying.