One of the most common issues that many microwave owners have to deal with is a bad capacitor. When the capacitor of your microwave becomes faulty, then this useful kitchen appliance will stop working as intended.
Once the capacitor of your microwave stops working, then one thing that you are going to notice is that the microwave will stop heating food evenly. Apart from not heating food properly, your microwave may in other instances produce sparks.
However, it is important to note that you do not always have to get a new microwave, as you can easily have the capacitor of your microwave fixed. All you are going to need is a couple of bucks to get things going.
That being said, in this post, we are going to first look at the microwave capacitor, what it looks like and the telltale signs of a microwave capacitor that has gone bad.
What is a Capacitor?
A capacitor is an electrical component found in electronic circuits whose main purpose is to store electrical energy. Capacitors comprise two electric plates, separated by a dielectric material.
When voltage is applied to the capacitor, the capacitor is going to first store the energy within the plates and then release it later on. The amount of energy stored in capacitors is normally measured in Farads (F).
That being said, capacitors come in different sizes and types. However, the most common types of capacitors found in microwave ovens include ceramic capacitors, tantalum capacitors and metal oxide semiconductor capacitors.
While MOS capacitors are mostly used in high-frequency circuits, ceramic capacitors are normally used in power supply circuits. Finally, tantalum capacitors are used mostly in low-voltage circuits.
What are the Symptoms of a Bad Microwave Capacitor?
When the capacitor of a microwave fails or stops working, then the microwave will stop working correctly. That being said, here are the most common telltale signs of a bad microwave capacitor.
1. Microwave Not Heating Food Properly
One of the most common signs of a microwave with a bad capacitor is a microwave that stops heating food properly. When the microwave capacitor stops functioning properly, then it is going to affect the overall ability of the microwave to generate the voltage required to heat up food.
That being said, if your microwave is running but not heating food properly, then chances are that the capacitor is failing or has ceased to work.
2. Sparks and Smoke
Apart from not heating food properly, another common symptom of a bad microwave capacitor is sparks and smoke. Whenever a capacitor fails, it is going to cause an arc of electric current to jump across the plates, which will ultimately lead to sparks.
There are several things such as placing a magnet on a microwave or running a microwave empty that are going to make the microwave behave similarly.
If you happen to see either sparks or smoke coming from your microwave, then this is a clear sign that the capacitor of your microwave is faulty. In such a scenario, it is important to exercise safety.
Switch off your microwave immediately and then unplug your microwave from the wall before taking it to an experienced professional to have a look at it.
3. Loud Humming or Buzzing Noise
Buzzing noise or loud humming is another symptom of a bad microwave capacitor. When the capacitor of a microwave is failing or has gone bad, it’s going to fail to store enough electric current charge needed to maintain a stable output.
The noise produced by a microwave with a failing microwave capacitor is going to be loud when you first turn on the microwave.
4. Microwave Runs and then Stops Working
If your microwave oven begins to run for a short period and then suddenly stops working, then chances are that the issue is being caused by a failing capacitor.
In such instances, the capacitor of your microwave may not be storing enough charge to keep your microwave oven running for long enough. This, in turn, will cause your microwave to stop mid-cycle after being used for a short period.
5. Dim Lights or Flickering Display
Apart from your microwave stopping mid-cycle, another common symptom of a bad or failing microwave capacitor is dim lights or a flickering display. If you begin to notice that the lights of your microwave are either dimming or flickering, then your microwave capacitor is failing.
When the capacitor fails to provide enough power to maintain a steady voltage to the lights or display, then the result will be dim lights or a flickering display.
6. Microwave Not Turning On
Another common symptom of a bad microwave capacitor is a microwave that fails to turn on. If your microwave oven is failing to turn on, then the chances are that the microwave capacitor has gone bad.
On other occasions, you may begin to hear a humming sound, especially when you turn on the microwave. Despite producing the humming noise, your microwave oven will still fail to turn on.
That being said, several reasons could have led to the microwave capacitor going bad. Some of the most common causes of a bad microwave capacitor include running the microwave empty or connecting your microwave oven to an unstable power source.
7. Burning Smell
If you begin to notice a burning smell coming from your microwave oven, then chances are that the microwave capacitor has gone bad.
Nonetheless, it is important to note that a burning smell can also be caused by other things such as a malfunctioning motor, control board, inadequate ventilation and food residues.
While the burning smell is one of the symptoms of a bad microwave capacitor, it should be coupled with other symptoms such as the microwave not turning on or flickering display.
Burning smell alone is not enough to deduce whether you have a failing microwave capacitor or not.
8. Microwave Producing Unusual Noises
Another common symptom of a bad microwave capacitor is unusual noises. On many occasions, these noises will often sound like popping or crackling sounds.
If your microwave oven was recently rained on, or water somehow managed to sip into the internal components of the microwave oven, then this may have resulted in electrical malfunction or caused significant damage to the electrical components of your microwave.
9. Microwave Oven Tripping Circuit Breaker
Faulty microwave capacitors tend to draw too much power, which in turn can cause the circuit breaker to trip. If you begin to notice that your microwave oven is tripping the circuit breaker regularly, then chances are the microwave capacitor is faulty.
How To Test Microwave Capacitors
If you suspect that your microwave capacitor is failing or has stopped working, then there are a few simple steps that you can take to determine whether the capacitor is faulty or not. That being said, here are a few steps that you should follow when testing a microwave capacitor.
1. Safety First
Before testing out a microwave capacitor, it is of utmost importance to first guarantee your safety. Like many other electrical devices, capacitors do hold electrical charge. Which in turn means that even when unplugged, they still have an electrical charge.
Thus, you should make an effort to discharge them, before you start testing them out. To discharge the microwave capacitor, start by removing the outer case of the microwave. Once you have removed the microwave case, the next step would be to locate the capacitor.
The microwave capacitor should look something like this. Once you have located the capacitor, take an insulated screwdriver that has a long handle and then shorten the two terminals of the capacitor together.
By doing this, you will be able to not only discharge the capacitor but also guarantee your safety during testing.
2. Multimeter
To test the microwave capacitor you are going to require a multimeter. Multimeters are electronic measuring devices which can measure the voltage, resistance and current of electrical devices.
If you do not own a multimeter, you can purchase one here. It is important to point out that multimeters can cost anywhere between $12 to $400.
If you are on a budget, then we highly recommend the AstrolAI multimeter tester that comes with a digital counter. Another affordable multimeter is the KAIWEETs digital multimeter that also comes with a digital counter.
That being said, apart from owning a multimeter, you should also make an effort to learn how to use the multimeter properly and record the readings as well.
When testing the microwave capacitor, begin by setting the multimeter to the respective capacitance setting. Once everything is in order, you will then place the leads of the multimeter on the capacitor terminals.
It is important to note that the readings on the multimeter should be close to the rated capacitance of the microwave capacitor.
If the readings on the multimeter happen to be lower than the rated capacitance of the microwave capacitor, then this is a clear indication that the capacitor is faulty.
In this instance, you will need to shop for a new microwave capacitor.
While the voltage of microwave capacitors will vary from one model to the other, most microwave capacitors have a voltage rating of between 2100 and 3700 volts.
To avoid the risk of injury or damaging the microwave appliance, it is important to ensure that the replacement capacitor has the same voltage or higher than the original capacitor.
NB: When replacing the capacitor of a microwave, we highly encourage our readers to consult the owner’s manual or reach out to a qualified technician for proper guidance.
3. Test For Short Circuit
To test for short circuits, begin by first setting the multimeter to the required resistance setting and then placing the probes on the terminals of the microwave capacitor.
You should then observe the readings on the multimeter. It is normal for the readings to start at a higher value and then gradually drop.
If the readings on the multimeter are zero, then the microwave capacitor has a short circuit. With short-circuiting, you have no other option than replacing the capacitor.
4. Test for Open Circuits
If the multimeter fails to show any reading, then this is a clear indication that there is an open circuit in the capacitor. To properly test for open circuits, begin by setting the microwave capacitor to the desired resistance setting and then place the probes of the multimeter on the terminals of the capacitor.
For this instance, the readings should begin low and then increase gradually. If the readings on the multimeter remain at infinity, then this is an indication that there is an open circuit and you have to get a new replacement.
5. Test for Leakage Current
To test for leakage current, begin by first setting the multimeter to the desired setting and then placing the multimeter probes on the terminals. The correct reading on the multimeter should be zero.
If the readings fail to go back to zero, then this is an indication that the capacitor is leaking. The best course of action would be to install a new capacitor.
6. Check for Physical Damage
Before conducting tests on the microwave capacitor, it is important to first check for any signs of physical damage. Check for any signs of cracking, swelling or cracking.
If your microwave capacitor shows any of these signs, then it might be high time to replace the capacitor. That being said, it is important to note that you cannot conduct repairs on capacitors with signs of physical damage.
As discussed earlier, faulty microwave capacitors can end up causing various problems to your microwave oven.
If you happen to suspect that the capacitor of your microwave is failing, then it is important to check out for signs of physical damage. In addition, you should also conduct various tests whether necessary.
By following the steps discussed above, you will be able to establish whether the capacitor is functioning correctly or a replacement is needed.
That being said, you should always exercise safety and caution especially when you are working with electronic appliances. Where possible seek professional assistance, especially when you are not sure about something.
How To Safely Discharge a Microwave Capacitor
Microwave capacitors store electrical energy; thus, handling them without ensuring that they are fully discharged can be extremely dangerous. So, how does one safely discharge a capacitor?
To safely discharge a capacitor you will need a set of pliers with insulated handles or two screwdrivers.
Word of caution: Before trying to access the internal parts of a microwave, it is extremely important to ensure that you have unplugged your microwave oven from a power source. Failure to do this will result in electrical shock or fire.
Doing this ensures that if there is any electrical charge left inside the microwave capacitor, will be discharged. Here are the steps to safely discharge a microwave capacitor.
- Ensure that the microwave oven is disconnected from the power source
- Apply slight pressure on the handles, to open the jaws of the pliers.
- Place one of the jaws on one of the terminal leads and the other jaw on the other terminal lead
- Hold the jaws in place for about 30 seconds.
- Test using an electrical meter to establish whether the microwave oven capacitor has discharged fully.
How Much Does It Cost to Replace a Microwave Capacitor
The cost of replacing a microwave capacitor can range anywhere from $10 to $100. Again, while most microwave capacitors on the market will work with most microwaves, the size of the metal insert tends to vary.
Thus, you should always make an effort to ensure whether you need a microwave capacitor with a large metal insert or a small metal insert. Kindly refer to the previous image.
Doing this will go a long way in ensuring that you can repair your microwave in turn and avoid unnecessary returns.
Furthermore, you should also make an effort to go through the reviews especially if you are shopping on a marketplace that allows users to place reviews.
Many of the capacitors in the market are poorly made and thus may not last for long.
That being said, we highly encourage our readers to always settle for microwave capacitors made in North America first. If you are not able to find one made in North America, then you can settle for either Korean or Japanese-made capacitors as your second option.
Always choose Chinese-made microwave capacitors as your last resort.
What are Single-Layer Capacitors in Microwaves?
Because of their reliability, superb performance and consistency, single-layer capacitors are commonly found in microwave circuits. They mainly consist of ceramic materials which tend to have high dielectric materials and feature metalization on the bottom and top parts of the ceramic.
In addition, single-layered capacitors tend to be small in size with a rather low profile. This in turn makes them suitable for high frequency applications such as microwave circuits.
In microwaves, single-layered capacitors are mainly used for various functions such as tuning, filtering, coupling and decoupling. Simply put, single-layered capacitors are used to not only store but also release energy as well, which makes them an essential component of the microwave circuit.
As mentioned earlier, single-layer capacitors feature two metal plates that are separated by a ceramic dielectric material. The ceramic dielectric material is highly insulating and has a high dielectric constant.
This in turn allows the capacitor to store a large amount of charge within a rather confined space.
To ensure superb conductivity and eliminate chances of corrosion, the metallic plates are usually designed from silver. Nonetheless, this does not have to be the case as there are other capacitors which come with plates made from zirconium titanate, alumina and barium titanate.
It is important to point out that single-layered capacitors can have various capacitance values that range from a few picofarads to several microfarads. On top of that, they are also available in a variety of shapes and sizes including square, circular or rectangular to suit different applications.
Wrap-Up
That being said, if your microwave begins to show any of the symptoms discussed above then chances are that there is an issue with the microwave capacitor. However, it is important to note that any of these symptoms do not guarantee that there is an issue with the capacitor.
Thus, it is important to perform tests to ensure that there is an issue with the capacitor or any other electrical component in your microwave.
If you are familiar with electrical components in your microwave, then you can always perform repairs on your own.
However, if you have zero technical skills or simply you are not sure of what you are doing then we highly encourage you to reach out to an experienced technician.
Replacing components within your microwave without taking the necessary precautions can result in electrocution and other cases fire. Exercise caution at all times.
