The reasons for the charger to be burned out are as follows: 1, the charger works for a long time in the state of high voltage and high current, and the internal circuit is short circuit or overcurrent. 2, the fluctuation of the grid voltage, the surge will cause the current in the charger to increase instantaneously and make the fuse blown. 3, the power load is too heavy, the rectifier diode in the high-frequency rectifier filter circuit is broken down. Repair method: First carefully check the various components on the circuit board to see whether the appearance of these components is burned or there is electrolyte overflow, smell - smell no difference. Then measure the resistance value of the input end of the power supply, if less than 20OkΩ, it indicates that there is a local short circuit phenomenon at the back end, and then measure the positive and negative resistance value of the four rectifier diodes and the resistance value of the two current limiting resistors to see whether there is short circuit or burned out; Finally, measure whether the power filter capacitor can be charged and discharged normally, whether the switching power tube is broken down and damaged, and whether UC3842 and its surrounding components are broken down and burned out. If there is still no such situation, measure whether the input power cable and output power cable are short circuited. In general, in the fuse fuse failure, the rectifier diode, power filter capacitor, switching power tube, UC3842 are vulnerable parts, the probability of damage can reach 95% or more, to focus on checking these components it is easy to eliminate the fault.
The best way is to replace a battery car charger of the same model. The charger that has been burned out must not be used, and the cost of repair is relatively high, so the two trade-offs are better to buy a charger of the same model directly.