Hi @diyaddict ,
There is usually only one fuse in a microwave oven. If it was faulty, nothing would work.
A circuit breaker operating indicates that the current flowing through it has exceeded its’ rating.
Have you proved that the problem is only when using the microwave, you didn’t say?
Does the circuit breaker also trip when using another appliance with the same or greater power consumption as the microwave when plugged into the same wall outlet?
Check the information labels on the appliances to check the power consumption figures e.g. microwave might say 1200W input and an electric kettle might say 2000W so try the kettle. If the breaker also trips when using the kettle, perhaps the problem is the breaker or the breaker circuit and not the microwave
If this occurs only with the microwave and then when the microwave is cooking then there is a problem in the operating circuit of either the turntable motor, internal fan or the magnetron circuit as these components are in use when cooking and you have checked that all the other circuits that can be in operation without the microwave actually cooking don’t cause the problem to occur.
An example could be there is a low resistance connection between a wire carrying supply voltage in the microwave when it is cooking and the frame of the microwave which is earthed (wire rubbing on frame perhaps) and therefore this trips the breaker. This is a safety feature, preventing electrocution if someone touches the metal case of the oven.
In any event there are several possible causes and the microwave would have to be opened and tested as to the cause of the problem. In electrical circuits and electronic circuits is doesn’t have to be the same fault every time that can give the same symptoms
Working on microwave ovens is extremely dangerous if you don’t know what you’re doing. There is still potentially lethal voltage (>6000V) in the microwave circuit even when it has been disconnected from the power for some time. If you don’t know what you’re doing then don’t do it! It’s not worth it, leave it to the experts.