What Happens When a Microwave Capacitor Goes Bad?

When a microwave capacitor goes bad, it can prevent the microwave from heating up the food properly or at all. A microwave capacitor is a device that stores and releases electrical charge to power the magnetron, the component that generates the microwaves. A faulty capacitor can cause the high voltage circuit to malfunction and affect the cooking performance of the appliance. In this article, we will explain how a microwave capacitor works, how to test it, and how to replace it safely.

How a Microwave Capacitor Works

A microwave capacitor is part of the high voltage circuit that converts the 120 volts of alternating current (AC) from the outlet to nearly 5,000 volts of direct current (DC) for the magnetron. The high voltage circuit consists of a transformer, a diode, and a capacitor. The transformer steps up the voltage from 120 volts to about 2,000 volts. The diode acts as a one-way valve that allows the current to flow in only one direction. The capacitor acts as a reservoir that stores and smooths out the electrical charge.

The capacitor works with the diode to create a pulsating DC voltage that is suitable for the magnetron. The magnetron is the heart of the microwave oven, as it produces the electromagnetic waves that heat up the food. The magnetron needs a steady and high voltage to operate efficiently. The capacitor helps to regulate the power going into the magnetron and to filter out any fluctuations or spikes in the voltage.

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How to Test a Microwave Capacitor

A microwave capacitor can go bad due to age, wear and tear, power surges, or overheating. A bad capacitor can cause symptoms such as no heat, low heat, buzzing noise, or sparks inside the microwave. To test a microwave capacitor, you will need a multimeter, a screwdriver, and a pair of insulated gloves. Before you begin, make sure to unplug the microwave and discharge the capacitor to avoid electric shock. The capacitor can store a lethal amount of charge even when the microwave is unplugged.

To discharge the capacitor, you will need to short-circuit it with a metal tool that has a rubber or plastic handle. Touch one end of the tool to one terminal of the capacitor and the other end to the other terminal. You may hear a loud pop or see a spark as the charge is released. Repeat this process for the third terminal if there is one. Be careful not to touch the metal part of the tool or the capacitor terminals with your bare hands.

To test the capacitor, you will need to set your multimeter to the highest resistance setting (ohms). Touch the probes of the multimeter to the terminals of the capacitor. The reading should start low and then gradually increase to infinity. This means that the capacitor is charging and discharging normally. If the reading stays low or high, or does not change at all, the capacitor is defective and needs to be replaced.

How to Replace a Microwave Capacitor

To replace a microwave capacitor, you will need a new capacitor that matches the specifications of the old one, a screwdriver, a pair of pliers, and a pair of insulated gloves. Before you begin, make sure to unplug the microwave and discharge the capacitor as described above. Then, follow these steps:

  • Remove the screws that secure the outer cover of the microwave and lift it off.
  • Locate the capacitor inside the microwave. It is usually a cylindrical metal or plastic device with two or three wires attached to it.
  • Take a picture or make a note of how the wires are connected to the capacitor terminals. Then, use the pliers to disconnect the wires from the terminals. Be careful not to touch the wires or the terminals with your bare hands.
  • Remove the screws or clips that hold the capacitor in place and take it out of the microwave.
  • Install the new capacitor in the same position and orientation as the old one. Secure it with the screws or clips.
  • Reconnect the wires to the capacitor terminals according to the picture or note you took earlier. Make sure the connections are tight and secure.
  • Replace the outer cover of the microwave and fasten the screws.
  • Plug in the microwave and test it to see if it works properly.
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Conclusion

A microwave capacitor is an essential component of the high voltage circuit that powers the magnetron. A bad capacitor can cause the microwave to fail to heat up the food or to heat it unevenly. To diagnose a bad capacitor, you can use a multimeter to measure its resistance. To replace a bad capacitor, you will need a new capacitor that matches the old one, a screwdriver, a pair of pliers, and a pair of insulated gloves. You will also need to discharge the capacitor before testing or replacing it to avoid electric shock. By following the steps in this article, you can fix your microwave capacitor and enjoy your hot meals again.