Microwave repairs are easy. With your multi tester to troubleshooting this household appliance and you can do your own microwave repairs. Although it's called a microwave oven, this appliance does not generate any heat – instead it develops a micro wave at 2400 MHz. The article inside the microwave absorbed these oscillating waves and the molecules of the food also start to oscillate at -+ 2.3 billion times per second. The vibrating movement of the food molecules creates friction heat and this heat cooks the food.
Before repairing this appliance, first check for visible defects like burn (black) marks on the power lead, at the wall plug and inside the cabin of the microwave. To get to the working parts of microwave oven you have to remove the wrapper by unscrewing the screws on the back of the cover and some models has one or two screws at the bottom of the cover.
Never work in a microwave with the power on or plug into the wall socket..
Lift the back end and pull the lid backwards out of casing. Microwave ovens consists only of a few working parts that normally goes on the blink. They are magnetron, diode and capacitor, transformer, control panel, interlock switches and power-in board
If the microwave is just dead it means that the fuse has blown and it needs to be replaced. Check where AC (alternating current) cord is coming into the microwave oven from the wall plug that is your AC board and on it there is always a fuse present. Setting your tester on ohms you should get a continuity reading across the fuse ends, if not replace fuse. If the microwave blows the fuse again go back to interlock switches. Check that the door latches is pressing the switches down and catching when it closed. Sometimes the door latches needs cleaning and lubricant to work properly again. If there is power at your control board the next thing to check is the transformer.
Check if power is going into the transformer(inverter) if no current is present go back to the interlock switches or control board. If power is going down to your transformer, then the problem could at the high voltage side. But first test the high voltage fuse (some microwaves don't have it) between the transformer and HV(High Voltage) capacitor. If this fuse is blown you need to replace the HV fuse, capacitor and diott.. First take a ohm reading between the magnetron two terminals there should be a resistance of less than 1 ohm and between each terminal and body it should give a infinity reading. If any different replace magnetron.
A magnetron requires between 4000+ volts to work. (To get to this negative DC voltage, AC current moves threw the transformer (inverter), capacitor and diott into the magnetron. You cannot measure the output of the transformer with a normal multimeter. Using an amperage clamp around one of the leads from the transformer and it's using 1amp or more. Then the inverter is working correctly. And you should look at replacing the capacitor and diott. If it still doesn't work replace the magnetron.
Disclaimer: Electricity can be hazardous to your health. Never use tools or your hands inside a microwave while it's plugged in or working. The information in this article is used on a “as is” basis; we are not on site to control the flow of information there for cannot take responsibility for any damage.