How to maintain and repair the automatic hand dryer

How to maintain the automatic hand dryer
1. Regularly clean the dust and dirt outside the chassis. Wipe with a dry soft towel or wet cloth, and remember to use engine oil, banana water, etc. to scrub.
2. Regularly check the power supply line for damage. Automatic hand dryers are electrical products, so ensuring the integrity of the power supply line is a task that cannot be ignored. One is to ensure the safety of electricity consumption, and the other is to ensure that the automatic hand dryers can operate well at a distance!
3. Maintenance of the front filter screen (usually the rear cover of the chassis). It is advisable to clean the front filter screen 1-2 times a month. Remove the filter screen, pat it or blow it clean with a hairdryer, or even wash it with clean water and dry it before installing it into the panel!
4. Maintenance of formaldehyde filter screen. The maintenance of the formaldehyde filter screen is relatively special, and it does not require cleaning. The maintenance method is to regularly expose it to the sun, which can maintain the filtering function of the formaldehyde filter screen at all times.
5. Maintenance of activated carbon filter screen. Activated carbon filter screen is a disposable consumer product that requires regular replacement. If you can also take it to the sun regularly, you can appropriately extend its replacement time.
Troubleshooting 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: there is cold air blowing out, indicating that the blower motor is powered on and working, and the infrared detection and control circuit is normal. Only cold air indicates that the heater is open circuit or the wiring is loose. Upon inspection, the heater wiring is loose. After reconnecting, there is hot air blowing out, and the fault is eliminated.
Fault symptom 2: After being powered on, your hand has not yet been placed on the hot air outlet. The hot wind blew out of control.
Analysis and maintenance: Upon inspection, there is no breakdown phenomenon in the silicon controlled rectifier, and it is suspected that the photosensitive tubes inside the pins ③ and ④ of the photocoupler are subject to electric leakage and breakdown. After replacing the photocoupler, the operation returned to normal and the fault was eliminated.
Fault symptom 3: Put your hand into the hot air outlet and no hot air blows out.
Analysis and maintenance: Check that the fan and heater are normal, measure that there is no trigger voltage at the thyristor gate, and measure that there is a rectangular wave signal output at the c-pole of the control transistor VI. It is suspected that the photocoupler is defective. Use a multimeter Rxl0 to measure the forward and reverse resistances between the pins ③ and ④ of the photocoupler as infinity. Under normal conditions, the forward resistance should be several meters, and the reverse resistance should be infinite. It is determined that the internal photosensitive tube is open circuit, This causes the thyristor gate to not receive the trigger voltage and cannot conduct. After replacing the photocoupler, troubleshoot the problem.
Fault phenomenon 4: After power on, the indicator light is on, but no hot air blows out after reaching out.
Analysis shows that the possibility of simultaneous failure of the fan and heater is very small, most commonly due to relay failure or non action, while J failure may be due to V3 non conduction; The operational amplifier has no output; D6 and D5 fail; V1 and V2 do not vibrate or 7812 is damaged, resulting in no 12V voltage.
Before checking, first measure whether there is a 12V voltage. If so, reach out and test whether the level of the operational amplifier pin ⑦ has changed. If there is a change, check V3 and relay backward; No change, look forward to the operational amplifier circuit, photoelectric conversion, and oscillation circuit.
Fault symptom 5: After power on, the indicator light is on, but the sensing sensitivity is low.
In addition to abnormalities in the operational amplifier circuit, this fault is often caused by dust contamination of the red transmitter and receiver tubes, which can only be cleaned.

The above content is organized by Superb heater Company, super heater. Mainly professional production: industrial heating elements, temperature measuring elements, production equipment, accessories, and raw materials such as tubular heaters, tubular heaters, belt heaters, ceramic heaters, silicone rubber heaters, thermocouples, etc.

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