A microwave oven is a fairly fail-safe device. It can cook meals in minutes without any worry of an appliance malfunction. But even the most reliable of cooking contraptions can sometimes go on the fritz. Perhaps your microwave keeps losing power or won't turn on at all. Or maybe the appliance cooks slowly or unevenly. In most cases, you can figure out on your own if the unit can be fixed or needs to be replaced.
If the microwave won't run at all, there are several small components that could be faulty, but the most common is a blown fuse. Before doing any investigative work on the microwave, make sure it is unplugged and follow your owner's manual.
First, check to make sure that there are no issues with the power cord. Next, check the fuse. To do this, you will need to remove the microwave cabinet. This can be done by taking out all of the screws from the back and the bottom of the microwave. After doing this, the cabinet should be able to slide back and off.
In most models, the fuse will be found in the back of the microwave near the electrical cord. The fuse can be removed by using a fuse puller or by carefully using a screwdriver. The fuse can be replaced or tested with a multimeter, which tests for electrical charges and will be able to tell if the fuse still works or if it needs to be replaced.
What if the microwave keeps blowing fuses? This can be a symptom of a larger problem, such as a faulty capacitor, diode or magnetron. The capacitor and the diode take household AC power and turn it into high-voltage DC power used by the magnetron. With this in mind, investigate these components with caution. Never touch the capacitor with your hands. It can actually still hold power after the microwave has been unplugged.
Use your manufacturer directions to locate the capacitor. On most models, it will be in the back of the machine. Use a screwdriver to remove the leads from the capacitor. Then connect the probes from your multimeter to see if the component is faulty. The diode will be connected to the capacitor. Disconnect the diode from the capacitor and connect your multimeter to find out if there is a charge.
If both the capacitor and diode seem to be in working order, your problem will most likely be with the magnetron, which is best left for a professional to replace.
The magnetron can also be responsible for slow and uneven cooking. This can also happen if your microwave turntable is not working. Checking and fixing the turntable is a much simpler task than dealing with the magnetron.
First, turn the microwave upside down and locate the motor housing. Unscrew the motor housing to reveal a circular turntable motor. There should be two leads connected to the motor. Remove one and connect your multimeter probes. If your multimeter reveals an infinity symbol, the motor will need to be replaced.