What is the phenomenon that the switch diode of hair dryer is broken?

The phenomenon is that there is a burning smell.

Take out the broken part and find a rectifier diode as big as it or bigger. If the power is halved, it is estimated that 10A can withstand 400 volts.

Different hair dryers use different components and connecting circuits, which need to be determined according to the circuit of your hair dryer. We can't generalize. The diode of your hair dryer is burnt, so there is no heat. It may be that the heating wire is heated after half-wave voltage reduction by diode. Because the diode is burnt out, it cannot be heated naturally. Whether this is the case, you need to check the connection of the circuit to determine.

You need to use a multimeter. The forward resistance of diode is very small and the reverse resistance is very large. If the positive and negative directions are the same, the diode is broken. If it is infinite, it will be burned up.

Generally, hair dryers are prone to problems, such as lack of oil and jamming. This needs a little oil, because the internal temperature of the hair dryer is relatively high and the lubricating oil dries easily. You can twist the blades to see if there is resistance. If there is resistance, you can add some oil to turn it.

When the switch S reaches the "hot" position, the total pressure of 220V acts on the heating wires EH 1 and EH2, and the heat generated by the blower is the largest. Voltage obtained by DC fan M (provided by UR rectifier bridge)? Maximum, providing the maximum air volume.

The function of VD is to cut off the negative half cycle of 220V waveform when S is in the "cold" position, so that the voltage of heating wire and fan is halved, resulting in the discount of heat and air volume.

If VD is damaged by an open circuit, it is obvious that the blower has lost its "cold" function; In case of short circuit, both gears of the hair dryer have "hot" function.