LG LTM9000 Microwave Oven "repair sound bar shows" Questions

...sound like Inverter Power Supply. DO NOT try to repair or re-adjust preset volume on the board. It is very dangerous to repair or adjust without sufficient test equipment because this circuit handles ...

...sound of internal cooling fan when door is opened - in 99% cases it is upper door switch - it's actuator - dark brown tab which comes out when the door is opened is failing to come out fully. You may ...