If the hair dryer is not powered, check whether the power supply is loose. It may also be that the solder joints inside are off. If it is not energized, it can be removed by hand. The general hair dryer is not powered. It may be because it is a solder joint. Shedding, check it first, if it is not, take it to the repair shop for repair. If the hair dryer suddenly does not work during use, it may be because the temperature is too high, the temperature control device automatically cuts off the power supply, and the temperature can be lowered after the temperature is lowered. The hair dryer can be faulty according to the test quad. Reason 1. Confirm that the power is connected. 2. Confirm that the switch is cut to open. 3. Smell if there is any focus. The hair dryer is composed of two parts, one is the heating part, and the other is the fan part. The current fault is that the fan does not turn without wind. So we put the hair dryer into the cold air gear position, so that the heating part is separated from the motor, in order to measure the circuit of the motor part, hit the multimeter to the resistance file, measure its resistance value, and find that the resistance is infinite, indicating that the line is not connected, the power supply is not sent. The motor has no wind. Fold the hair dryer for internal inspection. Measuring circuit, switch, found that the resistance is zero, indicating that the circuit, the switch is good, because the electric blow motor is a DC motor, its power is supplied after the rectifier bridge, the meter is hit to the diode measurement file, measurement The rectifier bridge, in which two diode resistances are found to be infinite, indicates that the diode is broken. Replace the diode and measure the rectifier bridge. Normal precautions: Take care to separate the heating part from the motor part in order to accurately measure the fault point.