Accessing and Testing Microwave Door Switches

Accessing and Testing Microwave Door Switches

Due to the danger and complexity of electronic equipment repair, the following technical tip is intended for professional reference only. Please refer to manufacturer’s recommendations as Encompass does not guarantee the accuracy, reliability or safety of this information. 

WARNING : Disconnect the microwave from any power source before moving forward.

Microwaves include three switches located behind the control panel: primary, secondary and monitor switch all actuate to keep the microwave from cooking the kitchen while the door is open.

Accessing the Switches

  • Remove the two Phillips screws that hold grill in place on top of microwave. Remove grill and lay aside.
  • Locate and remove the one Phillips screw that holds the control panel in place.
  • Lift up control panel and gently pull toward you. This will provide access to the three switches.
  • Remove all wires from control board. All wires are different from each other and will only fit on the terminal they were designed for.
  • Use needle nose pliers to remove connectors from terminals that can’t be removed by hand. Gently squeeze  connector to release it from the terminal.
  • The last wire to remove is the ground wire, which is connected to the microwave frame. Set control panel aside.
  • Remove  access cover and set aside.

How To Test the Switches

  • Set the multimeter to OHMS to test the three switches.
  • Please note that the primary and secondary switches are tested with the door open. With the door open, place the multimeter leads on the connectors on the primary switch first. When closing the door, the multimeter should produce a beep if the switch is good.
  • Test the secondary switch in the same manner.
  • Test the monitor switch with the door closed. When opening the door, the meter should beep.
  • If appropriate beeps did not sound on any or all three of these switches, replace the switch.

These three switches serve mainly to keep the microwave from operating with the door open. The switches also deliver voltage to the diode and magnetron which heat the microwave. If the switches test positive, this further confirms that magnetron has failed and needs to be replaced.

It’s time to button up the microwave. For most people, this is as far as you may wish to proceed. There is an ever increased chance of suffering a powerful electrical shock from the high voltage capacitor, which retains a residual amount of electricity. It will need to be discharged before the magnetron and high powered diode can be accessed and replaced.

Route the control panel wires back through the appropriate slots in the access cover and reattach the cover to the microwave frame. Reconnect the ground wire first and then reconnect all other wires to their compatible terminals.

Push the control panel back in place and secure with its Phillips screw. With the door open, replace grill cover. Opening the door makes it easier to replace the grill. Secure with its two Phillips screws. Do not over tighten these screws as the grill is made of plastic and it could break or crack.

Special thanks to Fred’s Appliance Academy for this helpful tip!

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