Power supply does not start: plug in power supply, large capacitance has 300 v voltage, unplug power supply again measure large capacitance 2 terminal or 300 v voltage does not drop. After discharging the capacitor, replace the starting resistor. Starting resistance in the power input part, resistance value 150 k, power 2 w.
The power plug of motorized bicycle do not start: 2 terminal capacitor 300V voltage, unplug the power, slowly decrease capacitor voltage, the circuit board all check sealing off phenomenon, welding is completed, the 3842 will be replaced with a new, power test machine.
Flash lamp: first reweld the circuit board, try the machine again, if it is still flash, check the output sample resistor .0.1 o.3w power. Connect to the negative extreme of the output line, replace this resistor.
The output voltage is high, electrify, the voltage is more than 70 v. charge does not turn the lamp, first will circuit board reweld, try the machine again, if the voltage is still high, please replace the photo coupler, try again, or output is high. Replace the 431 reference voltage stabilizer and test the machine again.
If the charger is seriously hot, replace the fan with a new one. The output voltage is unstable. First, the circuit board is rewelded, then the output capacitor is replaced by 63v470uf capacitor.