How to Discharge a Microwave Capacitor

Upgraded Home Team
by Upgraded Home Team

When your microwave just doesn’t seem to heat up your food anymore, a simple fix might get it back in working order. Any microwave repair begins with discharging the capacitor. Even unplugged, a charged capacitor makes microwave repairs dangerous.

To discharge a microwave capacity, you will need to complete a circuit through the capacitor. Use a metal tool with rubber or plastic insulated handlers to span the prongs sticking out of the capacitor body.

Repairing a microwave can be very dangerous. Between the capacitor, megatron, and other components, you can potentially and critically injure yourself. Read on to learn more about microwave capacitors and microwave safety.

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What is a Microwave Capacitor?

At a basic level, a microwave capacitor helps to amplify your house’s electrical voltage into microwaves. This is a multistage process. The capacitor holds charge like a battery. It helps to filter the voltage when converting from AC to DC to make sure the rest of the appliance has reliable power.

The capacitor also helps to regulate power going into the megatron. The megatron converts residential 120V power into high voltage. To do this, it needs a steady power source. The capacitor provides this steady power in conjunction with the outlet’s power.

Discharging a Microwave Capacitor Safely

To discharge a microwave capacitor, you have to complete the circuit for current to flow. Even when no current flows through the capacitor, it will continue to hold a charge. After it’s been unplugged from the outlet, the capacitor cannot be recharged. Remove the cover from your microwave and locate the capacitor.

Find a metal tool, such as a pair of pliers or screwdriver, that has good rubber handlers. The rubber handles will insulate your hands from the metal. This should prevent you from getting shocked as you discharge the capacitor. You should even consider wearing gloves for extra protection.

First touch the screwdriver to one prong of the capacitor, then the second. If there is a third prong, touch that one as well. As you touch the second (or third) prong, you may hear a pop or spark. If it doesn’t, that’s OK.

The pop or spark can be dangerous. If you are trying to repair your own microwave, make sure that you are working in a safe, open place. If the cord sparks, you don’t want it to catch something on fire.

Discharging the capacitor should be instantaneous.

Reach Out to a Professional

Repairing a microwave should be trusted to a professional. We even mentioned this in our furnace post. Replacing a capacitor should be done by someone with experience working with electronic equipment.

Our method of discharging a capacitor short circuits the capacitor. This could also potentially fry other electronic components in your microwave.

Microwave repair professions charge around $70 an hour. Fixing your microwave could be a quick replacement of a failed part. On average, most repairs cost between $100-200. The cost may be worth it for high end or build in microwave units.

Why Discharge a Capacitor?

Even while unplugged, the capacitor will continue to hold the charge until it’s discharged. Since your microwave operates at very high voltage to heat food, the capacitor can hold a lot of dangerous charge.

When repairing your microwave, you may touch components in the microwave that could complete a circuit. If this happens, you could have a lot of voltage running through your body. To prevent this from happening, you should discharge the capacitor.

How Much Power is in a Microwave Capacitor?

Even while unplugged, the capacitor will continue to hold the charge until it’s discharged. The voltage in your home is typically 120V. The output voltage on your microwave is around 2100-3000 V.

Capacitors are rated in Farads. Farads measure how much charge the capacitor can hold. A larger number is a higher rating and holds more charge. A microwave capacitor may have around 0.95-1.00 microFarad capacitance.

Additionally, inside the microwave is a transformer. A transformer converts one level of voltage to another. This transformer is what takes the 120 volts from the power outlet and steps it up to the 2100-3000 volts that is needed to heat your food.

However, it’s the magnetron that takes the electricity and converts it to microwaves. All these components work together in a circuit.

Can a Microwave Capacitor Kill You?

Electricity can kill or critically injure people. While high voltage sounds dangerous, high electrical current is the most fatal. A current of 0.01 amps can be painful, but a current of just 0.10 amps can be fatal.

A current of 1-10 amps or more can cause muscular contractions that prevent someone from moving away from a shock, heart attacks, or unconsciousness. To calculate current from voltage, you divide the voltage by resistance. Resistance is measured in Ohms. It indicates how easy or hard it is for current to flow through an object.

Damp or sweaty hands can increase the risk or death due to electric shock. Wet hands may have a resistance of just 500 Ohms from fingers to toes. Dry hands may give you a resistance of up to 50,000 ohms.

With a high voltage around 2100 V and a deadly current of 10 amps, you just need a resistance of 210 ohms to avoid the deadliest of shocks. However, a dangerous and sometimes fatal 1-amp current needs 2100 ohms of resistance. If you are working on your microwave with sweaty hands, you are in extreme danger.

Testing your Microwave Capacitor

If your microwave is not heating well, or at all, you may test to make sure the capacitor is able to hold a charge. To do this, you may need a multimeter that is able to measure capacitance. If you have one that doesn’t, you can measure the voltage difference across the prongs.

Take your multimeter probes and touch one prong with the red lead and the second prong with the black lead. If the difference in the voltage measures more than 10 volts, the capacitor is likely working. If it measures less than 10 volts, it may not be able to hold a substantial charge.

A multimeter that measures capacitance should tell you if your capacitor works at its rating. The capacitor should be labeled with its rated capacitance. If the reading on the multimeter is less than the rating, the capacitor may be going bad.

Replacing a Microwave Capacitor

Since replacement capacitors for microwaves only cost around $10, replacing it yourself can be very intriguing.

If you decide to replace a failed microwave capacitor, remember a few things:

  • Refer to your microwave’s manual for reference on how the components are installed.
  • It’s best to buy the same part number as used in your microwave from the same manufacturer.
  • Make sure that the replacement capacitor you buy is listed for use in a microwave and is the same size to the original one.
  • Install the capacitor in the correct way. Incorrectly installed capacitors can explode or start fires!

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Final Words

It may seem really easy for you to discharge a microwave capacitor and troubleshoot your microwave repairs.

However, unless you have experience with repairing high voltage appliances, it’s best to leave it to professionals. Repairing a microwave can be frugal and sustainable, reducing electronic waste. Always use precaution when working on any appliance.

Upgraded Home Team
Upgraded Home Team

We are a team of passionate homeowners, home improvement pros, and DIY enthusiasts who enjoy sharing home improvement, housekeeping, decorating, and more with other homeowners! Whether you're looking for a step-by-step guide on fixing an appliance or the cost of installing a fence, we've here to help.

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