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Universal Microwave not working

If your Universal microwave is not working, start with the line fuse, especially if the microwave is completely dead or not turning on. Test the fuse for continuity and replace it only after finding what caused it to blow, since an unresolved electrical problem can blow the new fuse. Next, inspect the switch holder behind the control panel. A damaged or misaligned holder may prevent the door switches from engaging when the door closes, leaving the microwave not working but still showing power. A defective main control board is possible, but it is rarely the cause and should be considered only after testing the more common parts. Also check the thermostat and thermal fuse for continuity, since overheating can interrupt power, and verify that the electrical outlet has power by testing another appliance. Enter your model number to find the exact replacement line fuse, switch holder, control board, thermostat, or thermal fuse for your Universal microwave. Any repair that requires opening the outer cabinet involves a high-voltage capacitor that can store lethal charge even after unplugging. The capacitor must be properly discharged before interior work, so use a qualified technician if you are not familiar with safe capacitor discharge procedures.

01 - Universal Microwave Line Fuse

If too much current passes through the microwave circuitry, the line fuse will blow. If the line fuse blows, the microwave won’t start. To determine if the line fuse is at fault, use a multimeter to test it for continuity. If the fuse does not have continuity, replace it. In addition, you should investigate and resolve the problem that caused the fuse to blow. If you don’t resolve the underlying issue, the new fuse will blow too. (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, i...t is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the line fuse.)
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02 - Universal Microwave Switch Holder

The microwave switch holder is the component that houses the door switches behind the control panel. If the switch holder is damaged or misaligned, one of more switches may not be actuated when the microwave door is closed, resulting in the microwave not working. You will need to uninstall the control panel and inspect the switch holder to confirm it is in good condition and secured properly. Replace the switch holder with a new one if necessary.
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03 - Universal Microwave Main Control Board

The main control board might be defective. However, this is rarely the case. Control boards are often misdiagnosed—check all of the more commonly defective parts. If you have determined that all of the other components are working properly,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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04 - Universal Microwave Thermostat

If the microwave overheats, the thermostat trips to cut off voltage to the microwave. If the thermostat is shorted open, it may not allow voltage to reach the high voltage components. To determine if the thermostat is at fault, use a multimeter to test it for electrical continuity. If the thermostat does not have continuity, and it cannot be reset, replace it.
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Highly Likely

05 - Incoming Power Problem

The electrical outlet may not be getting power. To determine if the outlet is getting power, try plugging something else into the outlet. If the outlet is not getting power, check the home circuit breakers or fuses.
Highly Likely

06 - Universal Microwave Diode

The diode converts the A/C power output of the transformer to D/C, 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 working. 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 direct...ion. (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.)
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Common

07 - Universal Microwave Thermal Fuse

The thermal fuse cuts off power to the microwave if the microwave overheats. To determine if the thermal fuse has blown, use a multimeter to test it for continuity. If the fuse does not have continuity, replace it. The thermal fuse cannot be reset—if the fuse is blown, it must be replaced. (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 thermal fuse.)
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Common

Frequently Asked Questions

Why is my Universal microwave not working but has power?
How do I test or replace a microwave fuse?
Could the microwave door switch or switch holder be causing it not to turn on?
Is a Universal microwave main control board usually the problem?
How do I find the correct replacement part for my Universal microwave?

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