Introduce the common obstacles and maintenance methods of lithium-ion battery chargers

1. The fuse is blown: carefully check the various components on the circuit board to see if the appearance of these components is burnt or there is electrolyte overflow, smell-smell whether there is any peculiar smell; then measure the resistance value of the power input terminal to see the local short circuit phenomenon; Then measure whether the power filter capacitor can perform normal charging and discharging, whether the switching power tube is broken down, whether the UC3842 and surrounding components are broken down, burned out, etc., if the components are damaged, replace them. 2. There is no DC voltage output or the voltage output remains unchanged: First, use a multimeter to measure whether the various components of the high-frequency pulse transformer are damaged, and remove the high-frequency rectifier diode breakdown and load short-circuit environment; then measure the DC voltage of each output terminal See if the power supply control circuit is obstructed; then use a multimeter to statically measure whether the rectifier diode and low-voltage filter capacitor in the high-frequency filter circuit are damaged. If the above-mentioned components are damaged, replace them with new ones. 3. There is no DC voltage output, but the fuse wire is intact: first determine whether the charger's variable control chip UC3842 is in the state of working or has been damaged. If these pins are not broken down, and the charger cannot start normally as usual, it also indicates that the UC3842 is damaged and should be replaced directly. 4. The cooling fan does not turn: first use a multimeter to measure-whether the transistor of the lower control fan is damaged. If the tube is not damaged, then the fan may be damaged by itself. You can unplug the fan from the circuit board and connect others. The last 12V direct current (note the positive and negative), see if it moves, and also see if there are foreign objects stuck; if you swing the wire of the fan, the fan will move, it means that there is a broken wire inside the wire or the discussion is bad. Follow the above environment to replace the components. 5. The power supply does not start: plug in the power supply, the large capacitor has a voltage of 300V, unplug the power supply, and measure the voltage at the terminal 2 of the large capacitor again. The voltage does not drop at 300V. After discharging the capacitor, replace the starting resistor. The starting resistance is in the power input department, with a resistance of 150K and a power of 2W. 6. The power supply does not start: plug in, the large capacitor has a voltage of 300V at 2 terminals, unplug the power supply, the large capacitor voltage will gradually decrease, check all the circuit boards for any unsoldering phenomenon, after the repair soldering is completed, replace the 3842 with a new one , Just power on and test the machine. 7. Flashing light: first repair the circuit board and test the machine again. If the light flashes as usual, please check the sampling resistance of the output terminal. 0.1 Euro. 3W power. Connect it to the negative pole of the output line and replace this resistor with a new one. 8. The output voltage is high, power on, the voltage is higher than 70V, charging does not turn the lamp, first repair the circuit board, and try again, if the voltage is still high, please change the photoelectric coupler, try again, and the output is high. , Change the 431 reference regulator and try the machine again. 9. The output voltage does not change: first repair the circuit board, then test the machine, and then replace the output capacitor 63V470UF with a new test machine. 10. Charging does not turn the lights: Test the data with a tester, and then replace the 358 and 324 with a new test machine. 11. The charging is not the same, sometimes it can be charged, sometimes it can't be charged. Use the tester to check the data, and then replace the input and output power cords with new ones, repair the circuit board and test the machine. 12. Power on and burn insurance: first check whether the power tube is broken down, if not, replace all 4 rectifier diodes with new ones, and test the machine. 13. No output when power on: power on and test the machine, the large capacitor 2 has a voltage of 300V, which will gradually decrease. First, check whether the large diode at the output terminal has broken down, repair the welding, and try the machine again. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: How to detect the consumption of 18650 lithium ion battery pack?