If your Tappan microwave is not working, stopped working, or has power but is not turning on, start with the line fuse, the most likely cause. A blown line fuse prevents the microwave from starting, but the underlying electrical problem must also be corrected or the replacement fuse may blow. Next, inspect the switch holder behind the control panel. If it is damaged or misaligned, the door switches may not engage when the door closes. A defective main control board can also stop the microwave, although it is less common and should be considered only after testing the other components. Check the thermostat and thermal fuse for continuity because either can open when the microwave overheats, then verify that the wall outlet has power and that the circuit breaker or home fuse has not tripped. Before checking the Tappan microwave fuse location, replacing a fuse, or opening the outer cabinet, unplug the unit and understand that its high-voltage capacitor can store a lethal charge even after unplugging. Proper capacitor discharge is required, so interior repairs may require a qualified technician. Enter your model number to find the exact replacement part for your Tappan microwave.
01 - Tappan 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.)
Enter model number to search for the required part specific to your product
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.
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.)
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.
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 - Tappan 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.)
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.)