How to Test a Microwave Magnetron with a Multimeter

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Science has made everybody’s lives much simpler with advanced inventions such as the microwave. There’s no denying that a microwave oven is one of the most widely utilized and highly sought appliances in your kitchen.

Every modern household today has a microwave oven. Throughout the years, it has become a necessity for modern cooking. A microwave oven is a dependable kitchen appliance. However, there are times when the appliance itself gives up. 

One of the typical problems of your microwave is not heating or giving uneven heating. 

What Causes No Heat or Uneven Heating in Your Microwave? 

Have you ever tried cooking your frozen foods in your microwave but ended up with a half-hot-half-cold dish after? Not generating sufficient heat is another typical microwave issue that takes place when the magnetron is failing.

If you disregard the issue and keep trying to run your appliance while it is empty, you will just burn out the magnetron.

If you burn out the magnetron, you need to have an expert replace the part with a brand new one. After the magnetron burns out, it cannot be repaired. Always keep that in mind. 

Now, you may be wondering what a magnetron is? 

What is a Microwave Magnetron, by the way? 

Does your microwave not heat properly? You may have an issue with the magnetron. In case you didn’t know, this component is a part of the high voltage circuit and offers the microwaves the heat it generates. Keep in mind that if your magnetron is defective, the entire unit might blow a fuse. 

To explain further, a magnetron is a device that utilizes the interaction of an electron stream, guided by a magnetic field, along with cavities in a block of copper to generate microwave radiation.

The frequency range of the radiation varies on the cavities’ size. The devices are utilized in microwave ovens and radar. The radiation causes the molecules in food—especially water molecules—to vibrate, resulting in a fast increase in temperature that is enough to cook the food. 

How Does a Microwave Magnetron Work?

A magnetron is composed of a short copper cylinder with a set of cavities opening into a central vacuum chamber that is composed of a metal cathode. A stable magnet offers a magnetic field going parallel to the cylinder’s axis. 

The cathode is heated with a high voltage direct current, which causes it to generate electrons flowing out near the cylinder wall at a ninety-degree angle into the magnetic field. Further, the electrons are redirected by the field into curved directions, which causes them to create circular currents in the cavities. Such currents generate microwave radiation at frequencies, which are connected to the cavities’ size.  

The microwaves should be directed to when they’re required. That’s done by a metal structure we called a waveguide, where the waves travel. It extends outside the main body from one of the cavities, securing the microwaves and guiding them to their length.

Concerning the magnetron utilized for radar, the waveguide will connect to the antenna transmitting the waves. Inside a microwave oven, it will then direct the waves into the oven chamber to be utilized for cooking.

What are the Practical Uses of a Magnetron?

Keep in mind that magnetrons are utilized to produce microwaves for radar. That’s because they can obtain the needed power output. A shortcoming with a magnetron varies with the range, even though the cavities’ size determines that range of frequencies generated. That happens because of fluctuations in the current and changes in the temperature.

That’s not an issue when the energy generated is utilized for heating. However, it impacts the radar images’ accuracy. That could be fixed by using adjustable conducting materials plugged into the cavities to tune the radiation as needed. 

The most common use of magnetrons is, of course, in microwave ovens. It directs the waves into a tiny cooking chamber where the food could be cooked right away. Some molecules in foods are polar, meaning they have a negative charge at one side and a positive charge at the other.

When flooded with electromagnetic radiation in the microwave range, such molecules align themselves to alternating magnetic and electric fields created by the waves. That causes them to vibrate quickly, resulting in fast healing. One such molecule is water that is present in huge amounts in many foods. 

How Can You Test a Microwave Magnetron Using a Digital Multimeter?

As stated earlier, having a defective microwave magnetron might result in your unit blowing a fuse. You may still have other functions running normally, but you must test it right away. 

Here are the simple steps you need to do to determine whether your microwave magnetron is bad and needs to be replaced immediately. 

  1. Take note that access to your microwave magnetron will need the removal of the cabinet. Disconnect the power and discharge the high voltage capacitor to avoid any potential electrical shock. 
  1. You can then find the magnetron and disconnect the two connected wires.
  1. Connect the leads from your digital multimeter to the magnetron terminals and check for continuity. There should be two to three ohms of resistance between those terminals. What does it mean if there’s no continuity? It simply suggests your magnetron will need to be replaced.
  1. Check for continuity between the grounded other case of the terminals of the magnetron. Is there any continuity between either of the ground and terminals? Your magnetron will need to be replaced right away. 
  1. Do the continuity checks not reveal any defects? If that’s the case, a live voltage test might be necessary and should be referred to a qualified electrician. 

Final Thoughts

There you have it! We hope you find our step-by-step guide on testing your microwave magnetron really helpful. After diagnosing the issue, kindly talk to your preferred electrician or repair service provider for a replacement that fits your appliance.

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