How to Check a Microwave Oven Magnetron

Written by kimberly johnson
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How to Check a Microwave Oven Magnetron
(Jupiterimages/ Images)

A key component of a microwave oven is a device called a magnetron. Magnetrons are made of magnets that conduct an electrical circuit, thus creating the energy needed to cook food in the microwave. Although magnetrons are durable, they will eventually begin to fail. If a microwave begins to lose the capacity to heat, the problem is most likely the magnetron. Testing the voltage in the magnetron is done using a device called an ohmmeter.

Skill level:

Things you need

  • Microwave
  • Insulated screwdriver
  • Ohmmeter

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  1. 1

    Unplug the microwave from the wall and turn it around so that you are facing the back of it.

  2. 2

    Remove the screws holding the back cover on using a screwdriver.

  3. 3

    Locate the high-voltage capacitor, an oval-shaped cylinder, and place the tip of an insulated screwdriver on top of one of the metal terminals protruding from the top of it. Tilt the other end of the screwdriver downward slightly until the metal part touches the other metal terminal. You may hear a popping or crackling sound, which is energy being discharged. Remove the screwdriver from the terminals.

  4. 4

    Place the tip of screwdriver back onto the first terminal and tilt the other end of the screwdriver until the metal touches the metal base that the capacitor sits on. Hold for a few seconds, during which time you may hear a popping sound. Repeat the procedure with the other terminal.

  5. 5

    Locate the magnetron, which is a square, metal box with two cylinders extending from it. Disconnect the cables that extend from the cylinders by pulling them out of the base of the magnetron.

  6. 6

    Turn on the ohmmeter and set it to the lowest setting. Place one wire lead from the ohmmeter on the left terminal of the magnetron and place the other wire lead from the ohmmeter onto the right terminal.

  7. 7

    Look at the display on the ohmmeter.The reading should be less than 1 ohm if the magnetron is still good. If the reading reaches 1 ohm or higher, the magnetron is defective.

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