see the next causes. God bless you
Diode
The high voltage diode converts the A/C power
output of the transformer to D/C, doubling the voltage to nearly 5,000
volts. This high voltage powers the magnetron which emits the energy
that cooks the food. If the diode burns out, a lower A/C voltage reaches
the magnetron, which is not sufficient to power the magnetron. When the
diode fails it is often visibly burned out. If it appears to be good,
it can be tested with a volt-Ohm meter capable of testing diodes. High
voltage diodes frequently fail and are one of the most common points of
failure in a microwave oven.
Door Switch
If the microwave does not heat, one of the
door switches might be defective. Microwave ovens normally have three
door switches, if any of them fail the microwave does not turn on and
does not heat. Check the switches for continuity with an Ohm meter.
Magnetron
If the microwave oven doesn't heat the
magnetron tube might have burned out. The magnetron uses high voltage,
high current DC power to generate the microwave frequency that cooks the
food. If the microwave oven is turned on when it is empty this can
cause the magnetron to burn out. Once it is burned out it has to be
replaced, it's not repairable.
High Voltage Capacitor
If the microwave doesn't heat the high
voltage capacitor might be defective. The high voltage capacitor works
with the high voltage diode to convert the output of the transformer to
DC voltage and to double the output voltage. If the capacitor is burned
out the entire high voltage circuit stops working properly. The high
voltage capacitor can be checked with a special VOM meter which has a
capacitance testing capability. Be aware that the high voltage capacitor
can retain a charge of more than 3,000 volts and can injure or kill a
person if not handled properly. Only trained technicians should perform
this type of testing.
High Voltage Transformer
If the microwave does not heat, the high
voltage transformer might be burned out. Microwave ovens produce a very
high voltage in order to power the magnetron antenna, which emits the
energy that cooks the food.
Thermal Fuse
If the microwave doesn't heat the thermal
fuse may have blown. It can be tested for continuity. Watch our fuse
testing video for more information.
Thermoprotector
If the microwave doesn't heat the
thermoprotector may have tripped. This is a safety device to prevent the
microwave from overheating. It can be tested for continuity to see if
it's blown.
Main Control Board
If the microwave doesn't heat the main
control board may be defective. This is not common. When a microwave
doesn't heat the problem is usually within the high voltage circuit;
either the high voltage capacitor, diode, transformer or magnetron.
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