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Hotpoint Microwave Producing a Burning Smell

The part(s) or condition(s) listed below for the symptom Microwave producing a burning smell 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 producing a burning smell

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Cause 1Waveguide Cover

The waveguide cover might be damaged and arcing or burning. If this is the case or if the cover will not stay in place, replace it with a new one.

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Cause 2Power Supply Board

If you've confirmed the oven cavity has been cleaned of all food debris and the waveguide cover is in good condition, a defective power supply board could be one of the components producing a burning smell. You should inspect the board for any burn marks or a shorted component and replace if necessary.

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Cause 3High Voltage Capacitor

The high voltage capacitor works with the high voltage diode to convert the output of the transformer to DC voltage and to double the output voltage. A defective capacitor may overheat and produce a burning smell. Inspect the capacitor for visible damage or burn marks and replace if necessary.

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Cause 4Capacitor

The capacitor works with the high voltage diode to convert the output of the transformer to DC voltage and to double the output voltage. A defective capacitor may overheat and produce a burning smell. Inspect the capacitor for visible damage or burn marks and replace if necessary.

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Cause 5Thermostat

If you've confirmed the oven cavity has been cleaned of all food debris and the waveguide cover is in good condition, a defective thermostat could be one of the components producing a burning smell. You should inspect the component for any burn marks or damage and replace if necessary.

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Cause 6Interior Cavity not Clean

To avoid food splatter inside the microwave cavity, food should always be covered when cooking. Food that is left on the interior of the microwave can continue to cook each time the microwave is used. This can eventually cause a burning smell. Wipe up any spills or splatters after each use.

Cause 7Door 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 the door switch has burnt contacts or the terminal connections are loose it will produce a burning smell. Inspect the door switches. if the switch smells burnt or has burnt connectors replace the door 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.)

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Cause 8Diode

The diode converts the AC power output of the transformer to DC, doubling the voltage to nearly 5,000 volts. This high voltage powers the magnetron to heat the food. If the diode burns out, the magnetron won’t receive enough voltage to operate, preventing the microwave from heating. When the diode fails, it is often visibly burned out. Inspect the diode and if the diode is burned out, replace it. If inspecting the diode proves inconclusive, test it with a multimeter that uses a 9-volt battery or put a 9-volt battery in series with the diode. When the leads are reversed, the diode should only have continuity in one direction. (Warning: The microwave oven can store a lethal amount of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the high running voltage and the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the diode.)

Parts
Cause 9Relay Board

If you've confirmed the oven cavity has been cleaned of all food debris and the waveguide cover is in good condition, a defective relay board could be one of the components producing a burning smell. You should inspect the board for any burn marks or a shorted component and replace if necessary.

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Cause 10High Voltage Transformer

Microwave ovens produce a very high voltage in order to power the magnetron antenna, which emits the energy that cooks the food. When a high voltage transformer fails, it will usually arc and have a burning smell. (Warning: The microwave oven can store a lethal amount of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the high running voltage and the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the high voltage transformer.)

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Cause 11Main Control Board

The main control board may have a burnt component. Inspect the control board for burnt or melted components. If you find burnt components replace the main control board. (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.)

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Cause 12Magnetron

The magnetron uses high voltage, high current DC power to generate the microwave frequency that cooks the food. If the magnetron burns out, it can produce a burning smell and the microwave won’t heat. The magnetron is not repairable—if the magnetron is burned out, you must replace it. (Warning: The microwave oven can store a lethal amount of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the high running voltage and the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the magnetron.)

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Cause 13Control Board

The control board may have a burnt component. Inspect the control board for burnt or melted components. If you find burnt components replace the control board. (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.)

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Cause 14Micro Switch

If you've confirmed the oven cavity has been cleaned of all food debris and the waveguide cover is in good condition, a shorted micro switch could be one of the components producing a burning smell. You should inspect the component for any burn marks or damage. You can also use a multimeter to test the micro switches for electrical continuity. If one of more of the switches test negative for continuity or for a short, the switch or switches should be replaced.

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