Microwave trips the circuit breaker - LG LMV1630ST Microwave Oven

The circuit breakers may both be functioning properly. What might be happening is that both circuits have other current drawing appliances on them. The circuit breakers react to the sum of all of the currents drawn by all of the devices on that circuit. So, if you have a 15 amp microwave and an 8 amp refrigerator on the same circuit, you would overload a 20 amp circuit by 3 amps.

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There must be a fairly major issue with your microwave to trip a 20 amp breaker. I would recommend taking it to your local repair shop or replacing it.

Generally microwaves should be on their own breaker. Hard wired ones are required to be by code.

If yours has a plug - make sure the plug is original with the unit, not added later or spliced onto hard-wired power leads.

Plug into and outlet rated 15A as the only thing on a 15A branch circuit and try again. If it still trips, try a 20A line and circuit. If it trips that, trash the microwave and buy a new one. Nothing is meant to be repaired inside.

Answered earlier, another tips is to disconnect the power to the board and see if the circuit breaker holds, if not check the main line circuit.

The magnetron probably has a partial short pulling more current than normal as it runs, the other two items that give trouble is the high voltage diode, "sometimes cracks" to the high voltage capacitor, "usually shorts"

I have a hard time believing that the home's main breaker is tripping instead of the branch circuit breaker that feeds the microwave. I suspect it is really just a difference in terms. You should disconnect it and try using in another outlet - preferably one on a different circuit if possible. If the breaker continues to trip; this appliance should be disconnected and either be discarded, repaired or replaced before using again.

If the microwave works as expected (on a different circuit), it may indicate the original circuit is overloaded. Microwave overs are supposed to be installed on a dedicated circuit. This means only one outlet is on the circuit - no other loads (lights, appliances, etc.) are permitted on this circuit. A microwave typically requires 10 Amps or more when on "high" and will require a significant portion of the power supplied by a 15 or 20 amp circuit breaker. There is little unused to power much of anything else. If other appliances go out when the microwave trips the circuit breaker, you should contact an electrician to have a dedicated outlet installed for the microwave.

I hope this helps!

If a fuse inside had blown, that would definitely reduce the current flow rather than trip the breaker.
I have replaced several breakers over the years; they no longer last forever.
Try your Amana on a different circuit, not in the kitchen; if that other circuit likes the oven, the breaker is bad. If the alternate circuit breaker also trips, then you have not a blown fuse in the Amana but rather a shorted component inside and repairing the oven will likely cost about the same as replacing it.

Chek the high voltage capacitor and the diode . If one of them are short there is a chance for tripping the breaker

Microwaves that are either built in, a part of the oven, or over the range are on a dedicated circuit by law. This means nothing else could have tripped that breaker but the microwave.
If it has a problem severe enough to trip a 20 amp breaker several times, it is only getting worse each time you reset the breaker and turn it on.
There is a possible chance of fire. I recommend you turn the circuit breaker off and replace the microwave. Is it a plug in, or over the range type?

Check what other appliances are on your circuit. What goes off when the breaker is tripped. You may need to relocate the microwave to a different circuit. Try to stay away from the refrigerator or AC circuits.