Friends who have used microwave ovens must know that microwave ovens occasionally have some minor failures, such as microwave ovens do not heat, this failure may appear more, below I will give you answers to the reasons why microwave ovens do not heat and solutions.
1. When the high-voltage diode is normal, it can be tested with a multimeter Rx10k block, forward conduction (with a certain resistance), reverse cut-off (resistance infinity); If the forward and reverse resistance is not measured with other resistance blocks. Most of the broken high-voltage diodes are broken down, so the forward and reverse are open. The fault phenomena caused by the damage of the high-pressure diode are: burning high-pressure insurance, or the microwave oven does not heat, the microwave operation does not heat and the noise increases.
2. When the high-voltage transformer is normal, the resistance between the two input ports is less than 31-/, the filament winding resistance is also very small close to OQ, and the high-voltage winding resistance is larger in 9011-150f1. The damage of high-voltage transformers is mostly caused by the short-circuit between turns of high-voltage windings, and the phenomena caused by damage are: the running current increases and there is a peculiar smell, or the operation is not heated or smoked.
3. The capacity of the high-voltage capacitor is about 1 buF, and there is a 9MQ resistor in parallel. Under normal conditions, adjust the pointer multimeter to Rx 10k gear, and the two pens are connected to the two poles of the high-voltage capacitor, and there is a certain resistance value but not high at the beginning of the measurement, and then gradually rises to about 9MQ; The resistance of the two-pole chip to the case should be infinity. In actual maintenance, the failure of high-voltage capacitors is relatively low, and the common form of damage is pole piece or insulating wood ignition, and some are failure or breakdown. Phenomena caused by damage to high-voltage capacitors include burning power fuses or high-voltage fuses, microwave ovens that can run but do not heat.
4. When the mechanical timer/fire selector is normal, measure the resistance at both ends of the motor, twist the time knob clockwise, and the timing switch contact is turned on. The fire contact is on and off when the motor rotates. The timing switch contacts are damaged, causing the whole machine to not work; Damage to the contact of the fire switch causes the microwave oven to run without heating; Motor damage causes the microwave oven to run and heat non-stop, or run without heating or stopping.
5. The door switch switch contains several light touch switches. Under normal circumstances, there is a tiny contact transition sound when the switch is closed. The failure after damage is: the whole machine does not work, the operation does not heat, and the power fuse is burned when the door is opened.
6. The bidirectional diode adjusts the pointer multimeter to the Rxlok block, and the two pens are connected to the poles of the bidirectional diode, and the forward and reverse resistance should be infinity. Bidirectional diode breakdown and leakage generally cause the microwave oven not to heat up or burn out the power supply. If there is no tube during inspection, it can also be removed, and there is no effect on the work of the circuit after removal, but the opportunity loses the high-voltage overvoltage protection function.
