Why is the Magnetron of my Microwave overheating?

Hi All,

I bought GE Spacemaker XL 1800 microwave almost 12 years ago. It was working fine until last week since then it has stopped heating. I searched at the Internet and thought it was the magnetron. I ordered a new magnetron at Amazon and replaced with the previous one. After replacing the magnetron, microwave started to heat normally. In the meantime magnetron was overheating. When I used the microwave consecutively for estimated 10 minutes, microwave cut off. Then I changed Diode and capacitor as well and tried different combinations but the problem didn't go away. It is heating food but magnetron gets overheated and cuts off.

Has anyone faced the similar problem ? Should I replace my microwave or is there any solution ?

Thanks in advance.

Answer this question I have this problem too

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Same issue here. Magnetron tests well and no physical damage from what I can see after removing it. Works well but heats up to well over 120c so trips thermal shutoff. Oven is about two years old whirlpool WMH73521CH0. Any ideas? Fan is working. Hate to buy a new magnetron given this one tests well.


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Your braver or more foolish than I am as i won't work on one of this.

Door 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 fails, the microwave will not start or heat. 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 does not have continuity, replace it. (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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Door switches are irrelevant to magnetron overheating.


He also stated that he had changed magnetron, and capacitor. Stating that he is foolish is irrelevant at this point. Your answer contributes nothing to the discussion.


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There is a fan that pulls air thru the magnetron for cooling check to see if the fan/motor is still working

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Shoaib Shafiq will be eternally grateful.
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