This child’s battery car to be repaired was sent for repair by the owner. When sending it for repair, it was stated: “The original car suddenly stopped moving while in use, but the power indicator screen showed that there was electricity and intermittent singing. So, where do you think it is? If the contact was not good, I disassembled the machine and checked it by myself. During the disassembly process, I accidentally broke the housing of the gearbox. A hole appeared in the cover of the front car and many screws were lost. Later, I found that the battery has been used for several years. The battery is not working, and I changed a pair of batteries, but it still doesn’t work. Instead, the singing voice disappears, the MP3 function fails, and finally there is no power."

After the owner described the fault, he visually inspected the whole car and found that the car was in a mess, the battery was also removed, the cable was also missing, the shell was damaged in many places, and there were obvious signs of prying, most of the fixing screws were missing, and the gears were missing. The box is indeed damaged, and the circuit board under the front cover has been removed, and the wire ends are broken in many places.

　　 First of all, put the battery back in its original position, and replace it with a new special fuse on the machine. Open the front car cover, weld the disconnected wires, and put all the disconnected plugs back in their original positions. Solder the speaker wire with an electric soldering iron and connect the battery terminals. Then remove the exploded capacitor and replace it according to the capacitor withstand voltage and capacity of the original car. The original car is a 16V470UF electrolytic capacitor. Check the whole car carefully again, and if there is no serious short circuit, conduct a power-on test run.

　　 It was found that the whole vehicle was not powered on. The battery voltage was measured at about 12V. After power failure, the key door switch was measured. There was a contact open circuit. After replacing the key door, retested and found that it can be powered on, but the starting sound is abnormal and intermittent, and the motor cannot start. If there is a problem with the battery, in order to judge whether the battery is normal, a simple method is adopted, which is to use a high-power DC light bulb directly connected to both ends of the battery. At this time, it is found that the light bulb is instantaneously bright, and then slowly darkens, and more and more Dark, indicating that the battery has no load capacity. Although the measured voltage is normal, the battery car cannot be driven without normal current after the circuit is switched on. (The owner did not bring the new battery)