[disassembly] a visual air fryer. By the way, analyze the internal circuit

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‍ With the rise of healthy eating , Declare that there is no need for oil , One click can be used to fry chicken nuggets 、 The air fryer, which can make French fries and bake, has become a small appliance favored by foodies . A friend bought a leen a few years ago （Liven） Second generation air fryer （LR-KZ880 type , Light wave heating tube ,10 Increase volume ）, It is said that it is seldom used , Recent failures , Pressing the control panel key does not work . The maintenance personnel told me that the circuit board was broken , It costs hundreds of Yuan . Friends are not willing to send the store for repair , It's a pity to lose it , Please let me have a look , Can a dead horse be a living horse doctor , If the repair is difficult, throw it away .

Generally speaking, the oven uses the radiant heat emitted by electric heating elements to bake food , We can bake food according to different needs , The temperature of the electric oven can generally be 50-250℃ Range adjustment , Used to make roast chicken 、 Roasted Duck 、 Bake bread .

And the air fryer is essentially an oven , Just one more fan than the oven , The working principle is to use a fan to blow heat to food , Use the hot air generated by air circulation , Separate food fat , It can make the food taste closer to fried .

therefore , Simply put , The air fryer borrows the hot air function of the high-end oven , Let the oven make a more delicious kind .

A friend bought a leen a few years ago （Liven） Second generation air fryer （LR-KZ880 type , Light wave heating tube ,10 Increase volume ）, It is said that it is seldom used , Recent failures , Pressing the control panel key does not work .

The maintenance personnel told me that the circuit board was broken , It costs hundreds of Yuan . Friends are not willing to send the store for repair , It's a pity to lose it , Please let me have a look , Can a dead horse be a living horse doctor , If the repair is difficult, throw it away .

One 、 appearance

It seems that the number of use is really not much , The color is very new ：

After power on , There are indications , But press the buttons on the control panel , There was no response , It's kind of like “ Downtime ”：

The back of the machine , There is a power socket ：

Nameplate marks ：220V,1200W,10 Liter volume , model LR-KZ880, Light wave tube heat source .

Bottom , There are six silicone foot pads , Put it on the table to prevent sliding ：

Pull up the flap handle , Open the transparent cover , It can be baked in food ：

Take out the non stick pan with double-layer structure （ The outer layer is heat-resistant plastic , The inner layer is a Teflon coated metal basin , Also known as oil dripping bucket , Pick up the oil dripping from the baked food ）：

On the column , There are shaft holes that drive the grill to rotate . On the base , There are testing pans （ Drip bucket ） Whether the microswitch is placed in place ：

In the transparent cover （ Flip over ） Inner top , There is a heating system ：

Two 、 Disassembly and structure

Hold the transparent cover （ When it is tight , It is recommended to use both hands ）, Carefully rotate counterclockwise to remove ：

Structure of heating system ： Outside is a metal protective net cover , There are light wave heating pipes and fans inside .

Remove a fixing screw at the bottom of the metal protective net ：

Remove the protective net ：

Inside are annular light wave heating tubes and metal fan impellers . Because this fryer is a closed type , Lampblack has certain deposition on the inner wall and lamp tube ：

This is a 1200W Light wave tube , In fact, it is a circular halogen lamp ：

Between the leads of the light wave tube is a negative temperature coefficient resistance of metal armor （ Room temperature 27℃, resistance 93.8KΩ）, As a temperature sensor ：

Now that it's opened , Do hygiene together . First brush with strong kitchen oil cleaner ：

Then wipe it with a rag ：

Much cleaner ：

Remove the three fixing screws of the metal cover of the heater , Remove the cover ：

After removing the cover , There is an insulated space behind the aluminum plate of the heater ：

Look at it this way , A coaxial fan impeller is installed in the heat insulation space , Blow the heat out , Avoid burning the flip handle , At the same time, it also plays the role of airflow and heat dissipation for the circuit board in the flip handle ：

Remove the eight fixing screws on the flip handle ：

Remove the round cover plate at the rotating shaft ：

Then remove the fixing screws at both ends ：

Remove all fixing screws , To separate the flap handle , See the internal circuit board ：

The control circuit board installed on the upper cover of the flip handle ：

Fan motor and main circuit board installed in flip handle ：

Microswitch at the rotating shaft （ When opening and closing the flip handle , Contacts open or close ）：

Remove the cover plate at the back of the column

The internal claw pole permanent magnet synchronous motor is the driving force for the rotation of the grill ：

There is a photoelectric switch on the shaft of the motor , Its signal is used to control the continuous rotation or single-sided rotation of the grill ：

Remove the base cover 4 A set screw ：

See a microswitch inside ：

This microswitch is used to detect non stick pans （ Drip bucket ） For placement ：

3、 ... and 、 Circuit elements

The fan motor adopts single-phase shaded pole motor ,220V、4W、 speed 2200r/min

Next to the fan motor , There is a temperature fuse fixed on the iron plate , When the circuit has temperature control failure , Play the role of finally cutting off the circuit . This temperature insurance position is narrow , Not easy to replace , The temperature value is unknown ：

Remove the fixing screws of the main circuit board , Remove the main circuit board ：

Distribution of component function areas on the main circuit board ：

On the circuit board ,RX1 yes 10Ω 2W Safety resistor , Blue disc RV1 It's a varistor , yellow MC1 It's a safety capacitor ：

IC3 It is a non isolated power management chip commonly used in small household appliances PN8123：

IC4 yes 78L05, Three terminal linear regulator , Provide 5V regulated power supply ：

IC2 It is a commonly used single chip microcomputer for household appliances , model S3F9454BZZ-DK94, Lower Yellow component CY1 It's tripod 8MHz Ceramic filters ;IC1 It is a high current drive array integrated circuit ULN2003AN, It is mostly used for single chip microcomputer 、 Smart meters 、PLC、 Digital output card and other control circuits , The output can reach 500mA/50V, It can directly drive loads such as relays , Next to the black cylinder BUZ It's a buzzer .

12V DC relay , model JQC-3FF, Contact load 10A 277VAC, Open the flip handle 、 Closed time , Be responsible for cutting off or connecting the light wave heating tube 、 Fan 、 Power supply of grill rotating motor ：

Below is for 1200W The light wave heating tube provides the driven bidirectional thyristor , model BTA16-600B（16A/600V）. Due to the high working current , High calorific value , Aluminum radiator has a large volume ：

Next to the radiator , There are two small power bidirectional thyristors , model BT31（1A/600V ）, They are fans 、 Drive of grill rotating motor ：

The control circuit board removed from the handle ：

On the circuit board IC1 yes LED Nixie tube drive control integrated circuit , model CT1642：

There are three on the circuit board LED（L1、L9、L12） suffer Q1（9014） drive , rest LED suffer CT1642 drive ：

Four 、 Circuit working principle and circuit diagram

1、 Circuit principle

According to the circuit board , Draw the circuit principle block diagram of the air fryer as follows ：

How the circuit works ：

Plug in the power supply , Only when dripping oil bucket （ Pan ） The position is normal , Its microswitch K Connect ,12V Switching power supply and 5V Regulated power supply can work , Power on the control system . Program self-test , When temperature 、 The position of the flip handle is normal , The buzzer emits a long “ drop ” A sound , Turn on the relay J, The nixie tube shows “000”, Get ready to start the machine . then , Set the baking program on the control panel , Press down “ start-up ” Key , The machine starts to work . During baking , When the temperature reaches the set value , The single chip microcomputer will send the command to stop the heating of the light wave tube ; When the temperature is lower than the set value , The single chip microcomputer sends out the heating command of the light wave tube , Continue alternating , Until the end of time . In the middle of baking , To open the flip , Brush the baked food with oil , You can directly lift the flip handle , The microswitch at the handle rotating shaft is disconnected , After the SCM gets the disconnection signal , Send the command to disconnect the relay , Light wave heating tube 、 Fan 、 The grill rotating motor will stop running immediately , When the flap is restored , Resume the original procedure and continue baking . In circuit , Nixie tube display time , Red LED Display the set baking mode , green LED It's a work indicator . The temperature insurance is used when the machine has a fault exceeding the maximum temperature limit or a serious short circuit fault , Cut off the power supply of the whole machine , To be sent for repair and troubleshooting 、 The normal operation can be resumed only after the temperature insurance is replaced .

2、 Circuit diagram

Compare with the real object , Draw the circuit diagram as follows . Respectively, the circuit diagram of the main circuit board 、 Control board circuit diagram . The parameters of each element are marked on the circuit diagram . There may be imperfections , For your reference during maintenance .

⑴ The circuit diagram of the circuit board is as follows ：

⑵ The circuit diagram of the control board is as follows ：

5、 ... and 、 Eliminate the problem that the control panel is not responding

1、 Failure cause analysis and inspection

The functions of panel keys are shown in the figure below ：

        Analyze with the circuit diagram . Under normal circumstances , The machine is powered on , Pass self-test , Only press first “ function ” key , After selecting the baking program , Then press the “ start-up ” key , The machine can start to work . Panel keys are not responding , First check “ function ” Is there a problem with the key ！

On the control circuit board ,“ function ” The fretting number of the key is K6. Use a multimeter to detect , Press down , no , There is a problem ！ There is no problem with other inching ：

2、 Repair faulty components

Drop anhydrous alcohol into K6 Fretting gap , Press the key repeatedly （ The circuit board must also be erected , Let the liquid inside the fretting flow downward ）, The purpose is to clean the contact surface inside the fretting ：

After the alcohol volatilizes , Then use the table to detect , Press down , Through the ！ For the sake of security , Deal with the rest of the fretting .

Restore the machine installation , Power on the machine , Panel keys respond , The fault phenomenon is eliminated ：

The baking mode is set , Press down “ start-up ” Key , The machine works normally . however , The light is strong , It looks a little dazzling ：

6、 ... and 、 Conclusion

1、 The essence of the air fryer is an electric oven with internal hot air circulation . Force out the oil inside the food by heating and baking （ Some food must be painted separately ）, Form a state of being scorched outside and tender inside , Need to fully master machine characteristics and food processing skills , To make delicious food . Practice makes perfect , Just practice more . For light wave tube heating , Although intuitive , I think light loss and light pollution are also existing problems .

2、 Micro button failure is a common problem of this kind of small household appliances . The main reason is that domestic manufacturers face fierce competition in the market , To control production costs , Do not hesitate to lower the standard of quality control , The result is that the product is not durable . During maintenance , Can go straight to key electronic components , Replace after testing .

（ This article comes from digital home , author ：goodanytime , The copyright belongs to the author ,）