Common Faults Of Hand Dryers

Fault phenomenon 1: Put your hand into the hot air outlet, no hot air blows out, only cold air blows out.
Analysis and maintenance: If cold air blows out, it means that the hair dryer motor is powered and working, and the infrared detection and control circuits are normal. If there is only cold air, it means that the heater is broken or the wiring is loose. After inspection, it is found that the heater wiring is loose. After reconnection, hot air blows out and the fault is eliminated.
Fault phenomenon 2: After power on. The hand is not placed on the hot air outlet. The hot air blows out uncontrollably.
Analysis and maintenance: After inspection, the thyristor has no breakdown phenomenon. It is suspected that the photosensitive tube inside the ③ and ④ pins of the photoelectric coupler is leaking and breaking down. After replacing the photoelectric coupler, the work returns to normal and the fault is eliminated.
Fault phenomenon 3: Put your hand into the hot air outlet, no hot air blows out.
Analysis and repair: Check that the fan and heater are normal, the gate of the thyristor has no trigger voltage, and the c pole of the control transistor VI has a rectangular wave signal output. It is suspected that the photoelectric coupler is bad. The forward and reverse resistances between the ③ and ④ pins of the photoelectric coupler are infinite when the multimeter Rxl0 block is used. The forward resistance should be several m in normal conditions, and the reverse resistance is infinite. It is determined that the internal photosensitive tube is open, resulting in the thyristor gate not getting the trigger voltage and failing to conduct. After replacing the photoelectric coupler, the fault is eliminated.