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Modern Maid Microwave Won't Turn Off

The part(s) or condition(s) listed below for the symptom Microwave won't turn off are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.

Most Frequent Causes for Microwave won't turn off

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Cause 1Door Switch

Most microwaves have three or four door switches. When the microwave door closes, the door switches actuate in sequence to ensure that the door is closed properly. If any of the door switches fail, the microwave will not start or heat. In some rare cases a door switch may short out and allow the fan to run even when the door is opened. To determine if any of the door switches are defective, use a multimeter to test each of the switches for continuity. If any of the door switches lack continuity, replace the switch. (Caution: The microwave oven can store thousands of volts of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace a door switch.)

Parts
Cause 2User Control and Display Board

The cancel or off button on the user control and display board may not be activating. To determine if the control and display board is defective, try pressing each of the buttons on the control panel. If none of the buttons are responding correctly, replace the user control and display board.

Parts
Cause 3Touchpad and Control Panel

The cancel or off button on the control panel may not be activating when it's pressed. To determine if the touchpad and control panel are defective, try pressing each of the buttons on the control panel. If some of the buttons respond correctly while others don’t, replace the touchpad and control panel.

Parts
Cause 4Touchpad

The cancel or off button on the touchpad may not be activating. To determine if the touchpad is defective, try pressing each of the buttons on the control panel. If some of the buttons respond correctly while others don’t, replace the touchpad.

Parts
Cause 5Main Control Board

The main control board has relays that send power to several components to make the microwave work. If one or more of the relays or triacs short out, some of the components can keep running when the controls are turned off. (Caution: The microwave oven can store thousands of volts of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the main control board.)

Parts
Cause 6Control Board

The control board has relays that send power to several components to make the microwave work. If one or more of the relays or triacs short out, some of the components can keep running when the controls are turned off. While you can often replace just the control board, some microwave models sell control panels as an assembly with both the touchpad and control board included.

Parts