Winter Check In: Microwave Magnetrons

This winter, we’re trying to stay as warm as possible. Sometimes, the best way to accomplish this is a nice, hot meal. But all of us are probably feeling a little lazy in the cold this year, so the microwave is getting a little bit more use than usual.

The primary heating component of the microwave is the magnetron. It’s the part responsible for generating the microwaves that heat the food that is placed in the microwave. Basic magnetron troubleshooting is easy - more advanced troubleshooting involves a multimeter.

If you’re not properly trained or experienced, we recommend bringing in a professional to troubleshoot or replace electronic components. However, there are a couple of simple ways to determine if your magnetron is malfunctioning. We’ll get into them below. 

What does a magnetron do?

The magnetron is the part that generates microwaves that heat the food in the microwave oven. It’s a complex part that emits electrons at high speeds, generating microwave energy that is directed through a waveguide to the oven itself. If that sounds complicated, it’s because it is. These are intricate and advanced parts with inner workings that are too involved to get into here. Essentially, what you need to know is this: the magnetron creates microwaves that heat your food. If the magnetron is not functioning properly, your food will not be heating properly. 

Troubleshooting a Magnetron

How do you know if a magnetron is going bad? It’s a complex part, but diagnosing problems is quite easy as there are a few telltale signs that the magnetron needs to be replaced. 

Problems: Little or no heat in microwave, humming or arcing sounds when microwaving

In cases where your microwave is not heating, or is only generating very low heat, the problem is most likely with an inner component of the magnetron. Commonly, the magnetron’s terminals can burn, the magnets can become cracked, the antenna caps can become melted or burned, the magnetron can have loose terminals. Some of these problems can be detected visually. 

Note: we do not recommend that those without the proper training or experience remove or inspect their magnetron. If you do not have the proper knowledge, we recommend enlisting the help of a trained professional. 

To inspect the magnetron, first disconnect it from its power source. You can investigate the terminal visually for signs of burnout or loose connections. A burned out terminal will show discoloration and burn marks. 

In cases where the microwave is not generating enough heat AND there is a loud humming or arcing sound, in some cases coupled with an electrical burning smell, the issue might involve cracked magnets. We have included a picture here to show you where to look when checking for cracked magnets. You will see visual cracks on the magnet. Check for cracks on the cylinder in the middle as well as on the curved metal layers along the outside. 

The same symptoms - little or no heat, along with an arcing sound - might point to a problem with the antenna cap. This part can become melted or burnt, which in turn will cause problems with the magnetron generating the necessary heat in the microwave. The damaged antenna cap will also cause an arcing sound. Refer to the image below to find the antenna cap on your magnetron.

These are simple components that can be diagnosed visually - although we still recommend enlisting the help of a trained professional. Other cases of magnetron malfunction can only be diagnosed using a multimeter, in which case we must insist you call on a trained professional if you have no experience/training yourself. 

Problems with any of these components will require a replacement magnetron.