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What is the reason why the microwave oven looks normal but doesn't heat it?
Experience of troubleshooting microwave ovens

Touching the start button on the control panel after startup is invalid.

After inspection, it was found that the key matrix circuit was in poor contact, and the fault was eliminated after replacing the control panel.

Start normal work at startup and stop automatically in 3 minutes.

After inspection, it was found that the poor performance of the thermal isolating switch led to misoperation, and the fault was eliminated after replacing the thermal isolating switch.

There is a fire in the stove when cooking.

After inspection, it was found that excessive residual oil in the furnace caused fire, and the fault was eliminated after removing the residual oil in the furnace.

The food was not cooked when the machine started.

After inspection, it was found that the aging function of magnetron decreased, and the fault was eliminated after replacing magnetron. The other two machines have the same fault. After inspection, it was found that the high voltage capacitor lost its capacity and the forward resistance of the high voltage diode increased. After replacing the high voltage capacitor and the high voltage diode respectively, the fault was eliminated.

Cooking time is too long after turning on the machine.

After inspection, it was found that the mains voltage was too low, and the fault was eliminated after being stabilized by a high-power AC regulator. The same fault occurred in another machine. After the magnetron choke coil was damaged and replaced, the fault was eliminated.

The display is normal, but there is no microwave output after startup.

After inspection, it was found that the secondary coil of the high voltage transformer was broken, and the fault was eliminated after replacing the high voltage transformer. The other two machines had the same fault, and it was found that the high-voltage capacitor was broken down and the high-voltage diode was burned. After replacing the high voltage capacitor and the high voltage diode respectively, the fault was eliminated.

Stop the machine after half an hour of normal operation.

After inspection, it was found that the cooling fan did not turn and the temperature in the box was too high. After replacing the fan, troubleshoot. The other two machines have the same fault. After inspection, it was found that the wiring was damaged, resulting in a short circuit, and the intake and exhaust pipes in the box were blocked by sticks. After the wiring was correctly connected and the blockage was cleared, the fault was eliminated.

Power-on shows normal, but food cannot be heated.

After inspection, Q4 was found to be short-circuited, so RY 1 could not be closed. After replacing the transistor of the same model 2SC 1685, troubleshoot. Another machine had the same fault, and it was found that the capacitor C23 was broken down, resulting in the overcurrent damage of Q4. Replace the capacitor of the same model, and troubleshoot after Q4.

When the microwave oven is turned on, it doesn't work and it doesn't display.

After inspection, the voltage stabilizing circuit ZD 1 was broken down, resulting in the voltage drop of ++ 18V. Q 1 does not work, and +5V has no output. After replacing ES3 Zener diode with 5.6V of the same model, the fault was eliminated.

It works normally after being turned on, but it often bakes food.

After inspection, it was found that R27 changed the value, which led to the separation of embankment. Stop? Yellow bottle? Are you happy? Scrape off the dew and burn it? Bald? Troubleshooting after 3k Ω resistance.

Set the cooking program after startup, and the microwave oven will not work.

After inspection, the steam sensor was damaged, and the fault was eliminated after replacing the steam sensor of the same model.

Can't keep warm after starting.

After inspection, it was found that the temperature sensor was faulty, and the fault was eliminated after replacing the same type of temperature sensor.

When cooking after starting the machine, ignition occurs in the furnace.

After inspection, the high-voltage line is close to the casing, and the fault is eliminated after the high-voltage line is separated. Another machine has the same trouble. After inspection, it was cooking with raw oil, which contained water and caused fire at high temperature. Troubleshooting after cooking with cooked oil.

Often burn food after turning it on.

After inspection, the temperature sensor was found to be faulty, and the fault was eliminated after replacing the temperature sensor.

After start-up, the furnace light is on, but it cannot be heated.

After inspection, the secondary winding of the high voltage transformer is open, and the fault is eliminated after replacing the high voltage transformer. The other two machines have the same fault. After inspection, the coil of relay RY 1 was burnt out, and the primary lead of leakage inductance transformer was open. After replacing the high-voltage transformer and relay of the same model respectively, the fault was eliminated.

The microwave oven stopped working after it was turned on.

After inspection, the power lead was broken, and the fault was eliminated after connecting the lead. The other two machines have the same fault. After inspection, the low-voltage coil group of transformer is burnt out and the power delay is damaged. After replacing the transformer and power delay of the same model respectively, the fault is eliminated.

When the machine is turned on, the words "88: 88" will be displayed after 10 seconds in the automatic cooking operation.

After inspection, it was found that the digital program circuit was damaged, which caused the steam sensor coil to break. After replacing the steam sensor, the fault was eliminated.

The microwave oven does not work after the automatic cooking function is set on.

After inspection, the steam sensor was damaged, and the fault was eliminated after replacing the steam sensor.

Stop working after 10 minutes of power-on, and the words "88: 88" are displayed on the display screen.

After inspection, the steam sensor was damaged, and the fault was eliminated after replacing the steam sensor of the same model.

The boot does not work, and the monitor does not display.

After inspection, the varistor VRS 1 was damaged, and the fault was eliminated after replacing the varistor of the same model.

There is no microwave output after the machine is turned on, so it is impossible to heat food.

After inspection, it was found that the high voltage diode of microwave generating circuit was broken down, and the fault was eliminated after replacing the diode of the same model.

When the machine is turned on, food often burns.

After inspection, it was found that the contact of thermal control switch was sintered, and after the oxide layer was removed with sandpaper, the fault was eliminated.

After starting, the furnace is on, but there is no microwave output.

After inspection, it is found that the contact of the locking switch is poor, and the fault is eliminated after repairing the locking switch.

The stove will light up after it is turned on, but it will take a long time to cook food.

After inspection, it was found that the heating performance of the magnetron deteriorated due to aging, and the fault was eliminated after replacing the magnetron.

Turn on the power, the microwave oven does not work, and the display screen does not display.

After inspection, it was found that the varistor VRS 1 was burnt out, resulting in a short circuit of the transformer. After replacing the varistor of the same model, the fault is eliminated.

After startup, the display screen is not bright, and there is no response when pressing the touch key.

After inspection, the B and E poles of the reset circuit Q 1 were broken down, and the fault was eliminated after replacing the A9335 tube of the same model.

As soon as the machine is turned on, there is a loud buzzing sound, and the food can't be cooked.

After inspection, it was found that the working current of leakage inductance transformer was too large due to the short circuit between magnetron filament and anode, and the fault was eliminated after replacing magnetron.

When the machine is turned on, the stove is on, but you can't cook food.

After inspection, the high-voltage diode of microwave generating circuit is open, and the fault is eliminated after replacing the high-voltage diode of the same model.

There is no microwave output after startup, and pressing the function key is invalid.

After inspection, it was found that the reset capacitor C3 was broken down, and the fault was eliminated after replacing the electrolytic capacitor of 47 μ f/ 16V.

After starting the machine, the timer, turntable and stove lamp are all normal, but the food can't be heated.

After inspection, it was found that the high-voltage diode was short-circuited by microwave. Two1N4007 (1a/1000 V) were used to replace it in series, and then the fault was eliminated.

It works normally after startup, but the buzzer doesn't ring.

After inspection, the shunt resistor R30 of buzzer circuit is short-circuited, which is the same as model 3? Troubleshooting after replacing 3kΩ resistor. The other two machines have the same fault. After inspection, it was found that the buzzer was damaged and the transistors Q30b and C were open. Replace buzzer and Q30 respectively, and troubleshoot.

The food cooked after turning on the machine is not cooked well.

After inspection, the magnetron was turned on, and the fault was eliminated after replacing the magnetron. The other two machines have the same fault. After inspection, the ignition inside the magnetron and the aging heating performance of the magnetron become worse. After replacing the magnetrons respectively, the fault was eliminated.

When the timer is adjusted after starting, the fuse will blow immediately.

After inspection, it was secondary short circuit of high voltage transformer, and the fault was eliminated after replacing the same type of high voltage transformer. Another machine had the same fault, and the fault was eliminated after replacing the capacitor with the same specification.

Turn off the oven door start switch after startup, and the fuse will blow immediately after it is turned on.

After inspection, the push rod of the monitoring switch of the oven door interlocking mechanism was broken, and the fault was eliminated after replacing the monitoring switch. Another machine has the same trouble. After inspection, replace the short-circuited turntable motor.

When the machine is turned on, food often burns.

After inspection, it was found that the thermal control switch had poor contact, and the fault was eliminated after the contact was repaired.

The microwave oven stops working before the set time after starting.

After inspection, it was found that the fan motor stopped rotating, the magnetron was overheated, and the thermal switch automatically turned off the power supply. When the temperature drops to 135℃, the thermal switch is reset and the fault is eliminated. Another machine had the same fault. After inspection, it was found that the thermal switch was damaged. After replacing the thermal switch, the fault is eliminated.