1 fuse tube fuse

The fuse tube fusing shows that the internal circuit of the electric charger has short circuit or over-current fault. This is because the charger for a long time to work in high voltage, high current status, the higher the failure rate of internal components. In addition, the power grid voltage fluctuations, surge will cause the instantaneous increase in the charger and fuse fuse.

2 the DC voltage output is too high

This failure is often to voltage sampling and voltage control circuit is abnormal, in the electric vehicle charger, DC output, sampling resistor, error sampling amplifier, optical coupler, power control chip constitute a closed loop control, any problems will lead to higher voltage.

3 DC voltage output is too low

According to the maintenance experience, in addition to the voltage regulator circuit will cause output voltage is too low, there are several reasons:

(1) output voltage rectifier, filter capacitor pole Ju failure can be judged by substitution method.

(2) the performance of the switching power transistor is decreased, which makes the switch tube not normally conduction, and makes the internal resistance of the power supply increase, and the load capacity decreases.

(3) the source of the switching power tube is usually connected with a resistor with small resistance but very high power. It is used as an overcurrent protection resistor. The resistance value of this resistor is like 0.2 to O.8 omega. If the resistance changes or the welding is poor, the output voltage will be too low.

(4) the high frequency pulse transformer is bad, not only caused the output Strider pressure drops, will result in insufficient incentives to switch power tube damaged switch.

(5) high voltage DC filter capacitor is poor, resulting in poor load carrying capacity of the power supply.

(6) the contact of the power supply output line is bad, and there is a definite contact resistance, which causes the output voltage to be too low.

(7) the voltage of the network is too low. Although the charge voltage of charger can still be rated output, low in the jade, but when the grid voltage is lower than the limit value of the lowest voltage charger, also can make the output voltage is too low.

4 heat dissipation fan does not turn

The main cause of this failure is the control of the fan's triode (usually 8550 or 8050), or the fan itself is damaged or the blade is stuck with debris. But some charger applications are intelligent heat dissipation, for the use of this way to heat the charger, thermistor damage probability is very large.