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With the improvement of living standards, more and more household appliances enter every household, and the frequency of household appliances is relatively high. Therefore, some minor problems will inevitably occur. It is necessary to master some household appliance repair skills. The following is Everyone introduced in detail the common methods of household appliance repair, and explained the precautions such as being vigilant about after-sales phone calls, keeping the purchase invoice, understanding the details of the repair cost, keeping the repair bill, and filling out the warranty card during the warranty period and other precautions. Today, the relevant information specially compiled for you, I hope it will be helpful to you.
Common methods of household appliance repair
1. Inquiry and inspection method
The inquiry inspection method is the most basic method for repairing household appliances. In fact, this method is also most easily ignored by beginners and junior maintenance personnel. After receiving the faulty machine, they do not ask the user patiently, and then start to dismantle it drastically, and sometimes not only cannot quickly troubleshoot the fault, but also provoke the user. Not happy, and even go to court. Therefore, it is very important to ask the user cares about the fault characteristics and cause of the faulty machine before maintenance. Many maintenance tasks can get twice the result with half the effort. For example, when troubleshooting the remote control, if the user is asked to learn that the remote control has been dropped, the main check is to see if the circuit board has any component pins that are unsoldering. If there is no unsoldering, then check the crystal oscillator. For another example, when repairing the compressor of a refrigerator without stopping the fault, if the user talks about the poor cooling effect of the refrigerator, it means that the fault is caused by a leak in the refrigeration system or an abnormality of the compressor; if the temperature is too low, such as freezing in the refrigerator, It shows that the fault is caused by the contact of the thermostat that cannot be disconnected. For another example, when repairing the failure of the drying bucket of a double-tub washing machine, you should ask whether the drying bucket is leaking. If it leaks, it means that the drying motor is burned due to water leakage; if there is no water leakage, mainly check the running capacitor and Safety switch, etc.
2. Visual inspection method
The visual inspection method is the most basic method for repairing household appliances, and it can be used to make a preliminary judgment on the faulty part during repair. This maintenance method judges the fault location through one listening, two watches, three touchings, and four smelling methods.
Listening is a maintenance method to discover the fault location and the cause of the fault by listening to the ears. For example, when repairing small household appliances such as color TVs, microwave ovens, induction cookers, disinfection cabinets, etc., if you hear a "pop" discharge sound, you should check whether its high-voltage devices are discharging to the ground. For another example, when checking electric fans and range hoods, if the mechanical noise is too loud, check whether the motor is not rotating smoothly. For another example, if you listen to the compressor not running when repairing the refrigerator's non-refrigeration fault, check the compressor, starter, and its power supply circuit; if the compressor is running, the sound of refrigerant flowing in the evaporator cannot be heard, it means The refrigeration system has a leak or blockage failure.
Seeing is a method of overhauling to discover the fault location and the cause of the fault through observation. For example, when repairing the failure of home appliances without power, first check whether the fuse is blown to determine whether the load has an overcurrent phenomenon; another example, when repairing the low-voltage power supply failure of the computer board of the air conditioner, check whether the transformer of the low-voltage power supply is deformed, Discoloration is used to judge whether it is damaged; for example, when repairing the non-rotating fault of the washing machine motor, check whether the motor and capacitor are discolored to judge whether they are normal. In addition, when repairing circuit boards, check whether capacitors, transistors, and integrated circuits are broken to determine whether they are normal. For most of the faults with poor contact, the fault location can be found by checking whether the wiring and component pins are poorly connected and whether the circuit board is broken.
Touching is an overhaul method to find the fault location and the cause of the fault by touching it by hand. For example, during overhaul, you can touch the surface temperature of the motor, heater and other components to judge whether it is working normally. If the temperature is normal, it means that they are working normally. ; If there is no temperature, it means that it is not working; if it is overheated, it means that the power supply circuit is abnormal. For another example, when repairing the failure of the washing motor of a washing machine that does not run smoothly, you can judge whether there is any debris under the pulsator by turning the pulsator to see if it can rotate normally. For another example, when repairing circuit board circuit failures, you can judge whether its pins are unsoldered or have poor contact by touching a certain component and whether the connector is firm.
[Note] Since the grounding wires of many small household appliances are connected to the mains power supply line, this type of grounding method is a "hot" grounding method, so please pay attention to safety when using this method to avoid electric shock accidents, and touch heaters and other elements. There must be no scalding accidents when installing the device.
The smell is a maintenance method to find the fault location and the cause of the fault by sniffing. For example, when the motor of the washing machine does not rotate, if there is an abnormal smell, it means that the motor or its operating capacitor is damaged. For another example, when inspecting and repairing small household appliances with ultraviolet disinfection, if you can't smell the smell of ultraviolet disinfection, it means that the disinfection circuit is not working. Similarly, when repairing the ozone-type disinfection cabinet, if you cannot smell the ozone smell it emits, it means that the disinfection cabinet is not working.
3.Voltage measurement method
The voltage measurement method is one of the most commonly used maintenance methods. It is a method to determine the fault location and the cause of the fault by measuring whether the AC voltage or DC voltage at the suspected point is normal. For example, when repairing electric kettles, irons and other small appliances that are not working, you can check whether the mains socket has 220V mains voltage to confirm whether the mains power supply system is abnormal or the small household appliances are malfunctioning.
Four, the resistance measurement method
3.1 The function of resistance measurement is one of the most important maintenance methods.
This method is to determine the fault location and the cause of the fault by measuring whether the resistance of the suspected circuit or device is normal. For example, when repairing fuse failures of electric fans and washing machines, you can determine whether the motors, capacitors, and capacitors are normal by measuring the resistance of the motor and the running capacitor, and confirm whether the fault is caused by their abnormality or caused by other reasons. . For another example, when repairing an electric rice cooker or electric frying pan that does not heat up, you can confirm whether it is open by measuring the resistance of the heating plate. When troubleshooting a circuit board, you can confirm whether it is normal by measuring the resistance of components such as resistance and inductance.
[Note] When using the resistance measurement method to measure components, it must be done when the power is off, otherwise the multimeter will be easily damaged.
[Methods and techniques] When detecting whether the circuit, fuse and other devices are open, you can use the multimeter on-off measurement file and some digital multimeters. This function is attached to the "diode" block for measurement. If the multimeter's buzzer beeps, It means the line is normal; if there is no beep, it means the line is broken; if there is no beep, it means the line is in poor contact.
3.2There are two types of classification resistance measurement methods: on-road detection and off-road detection.
The in-circuit detection method is to directly detect the resistance of the component on the circuit or on the circuit board, while non-in-circuit detection is a detection method to detect the resistance of the component separately.
[Methods and Skills] RX1Ω gear pointer multimeter or 200Ω gear and "on-off measurement" gear digital multimeter are usually used for on-road measurement.
[Note] When using the method of detecting the resistance in the circuit, the components, and devices under test cannot have parallel low-resistance devices, otherwise it will cause large errors in the detected data.
The temperature method is a method of judging the cause of the fault and the location of the fault by touching the surface of some components and determining whether the temperature of the component is too high. After a certain amount of maintenance experience, this method is easier to use when judging whether the power tube and rectifier stack of the induction cooker are working normally. After a short period of power-on, if they have a high temperature, it means that they have high power consumption or overcurrent. In addition, this method is more useful for judging whether the thermistor is normal. After heating the thermistor of a negative temperature system, if the resistance decreases sharply, it means it is normal, otherwise it means it is damaged.
[Note] Pay attention to safety when using the temperature method to avoid electric shock or burns.
The substitution method is a method to judge whether it is normal or not by substituting normal components with the same specifications for components that are not easy to judge. When repairing small household appliances circuits, the substitution method is mainly used to judge whether the capacitors, voltage regulator tubes, integrated circuits, inductive devices, transformers, coils, etc. are normal. This method can also be used to judge the poor performance of the transistor. Of course, the overall replacement method can also be used to determine the fault location during maintenance. For example, when it is suspected that the operation display board is abnormal and the computer-controlled small household appliances work abnormally, the normal operation display board can also be replaced as a whole. Can return to normal, indicating that the replaced operation display panel is abnormal.
6.Open road method
The open-circuit method is a method to judge the fault location by disconnecting a certain device. For example, when repairing a color TV power supply with a low output voltage failure, if the output voltage returns to normal after the load is disconnected, most of the load is abnormal; if the voltage is still low, the internal resistance of the power supply circuit is large, resulting in a fault with poor load capacity.
[Note] When the output voltage of the power supply is low due to some load abnormalities, it will cause the temperature of the power components of the power supply to increase. If it does not increase, the output voltage of the power supply returns to normal or close to normal after the load is disconnected, and it is mostly in the power supply. The resistance is large, resulting in poor load-carrying capacity of the power supply. Pay attention to the difference when repairing, and don't make a mistake.
The working environment of some household appliances, such as small household appliances in the kitchen and bathroom, makes it easy to enter water or be polluted by oil smoke, so that the operating circuit board and main board are damp and cause the whole machine to not work, work disorder or some control function failures. Therefore, The cleaning method is also an important method for repairing household appliances, especially for repairing malfunctions of small household turtles in kitchens and bathrooms. It is best to use absolute alcohol or water when cleaning. After cleaning, dry or dry, and then you can power on and test the machine.
8.Short circuit method
The short-circuit method is a method of short-circuiting a certain part of a circuit or a certain device of a household appliance to judge the fault location. For example, when repairing the compressor of a computer-controlled refrigerator with a non-rotating fault, after short-circuiting the c and e poles of the compressor power supply circuit drive tube, if the compressor can rotate, it means that the compressor or its starting components are normal and the fault has occurred In the compressor power supply circuit; for example, when repairing part of the remote control button uncontrolled fault, short-circuit the solder joints of the two pins of the button and if the fault disappears, it means that the button is damaged. The short circuit method can also be used to judge when the circuit board is suspected to be broken.
9.Emergency Repair Law
The emergency repair method is a method of repairing by canceling a certain part of a circuit or a certain device. For example, when repairing air conditioners, soymilk machines, and other household appliances, and finding that their varistor short circuit causes the fuse to blow, if you don’t have the component on hand, you can eliminate the fault without installing it and replacing the fuse; another example is repairing part of the drinking water. When the resettable overheat protector of small appliances such as machine and electric kettle is damaged, and there is no such overheat protector on hand, it can be replaced with a one-time fuse type overheat protector with the same temperature value.
[Reminder] Because the varistor does not work when the mains voltage is normal, and the current mains voltage in our country is relatively stable, the method of not installing a varistor can be used to troubleshoot the fault during maintenance. However, some household appliances after emergency repairs must be replaced in time after replacement components are required to avoid new failures.
10.Fault code repair method
At present, many computer-controlled household appliances have fault self-diagnosis functions in order to facilitate production and fault maintenance. When they have a fault, after they are detected by the CPU of the microprocessor circuit, the CPU will display the fault code through the indicator lamp or the display screen to remind the cause of the fault And the fault location, so the maintenance personnel can quickly find the fault location through the fault code. Mastering this method is one of the shortcuts to quickly repair such household appliances.