How to repair the chaotic display of the walkie talkie LCD screen? For a wide range of radio enthusiasts, walkie talkies with LCD display screens can clearly see the frequency, channel, and sub tone code of the walkie talkie. However, walkie talkies cannot display normal frequencies, display in disorder, or have short strokes, which troubles a wide range of radio enthusiasts. Today, Mr. Wang from Hua'an Jiexun walkie talkie company will assist us in interpreting the problem of walkie talkie LCD display frequency:

The inability of walkie talkies to display normal frequencies, as well as phenomena such as disordered or short strokes, are mostly caused by moisture or water that has not been treated in a timely manner; When conducting maintenance, the first thing to determine is whether it is a problem with the LCD screen or the CPU control part. If the display screen and display circuit board are found to be dirty or discolored, they should be cleaned with anhydrous alcohol first. If individual line segments are not visible, then check the connection between each stroke and the CPU to see if there is an open circuit. Generally, the fault can be eliminated.

First, open the chassis and remove the control display board. Weld open the four welding points on the metal cover of the LCD screen, remove the LCD display screen, and use the multimeter's meter rod wire to wrap 3-4 times around the AC wire. Then, use the meter rod head to gently swipe left and right along the top and bottom of the LCD screen to see the various display strokes of the LCD screen. If the short display strokes and fault strokes are common, it indicates that the display screen is faulty. Otherwise, the malfunction may lie in the control part of the CPU.

Based on the experience of repairing walkie talkies, the likelihood of damage to the LCD screen and CPU itself in real life is very low. The vast majority of faults are caused by moisture, oxidation, and open circuits in the conductive rubber holes of the wiring and double-sided printed circuits

During the practical repair of the walkie talkie, after careful inspection, the LCD display screen was found to be normal, the fourth pin of the CPU was supplied with 4V power normally, and the wiring of each line segment output to the LCD screen was also normal. The normal voltage of the fifth, sixth, and seventh pins of the CPU was V5=0 5V， V6=1.4V， V7=1.6V， And the actual results are all 0V. Further investigation revealed that there is no voltage at terminals R142 and C119, which happens to be connected to pin 38 of the CPU, resulting in a voltage of 0V at pin 10 of the CPU. Ultimately, it was found that the fault was caused by the conductive holes of the double-sided circuit board being exposed to moisture and resulting in an open circuit.

After carefully cleaning the printed board with anhydrous alcohol, the conductive holes that had been oxidized and opened were soldered together with wires. After testing, all displays of the walkie talkie returned to normal, and the fault was resolved.