Here I will tell you how you can check the operation of the Panasonic HV inverter on a safe and easy way.
If the microwave oven doesn't work, either the magnetron tube itself or the HV inverter is defect. First, the HV inverter has to be checked. The high voltage on the circuit board is very dangerous and therefore it is safer not to carry out measurements on the circuit board itself, if it is not strictly necessary. See here how to do it:
Make a wire loop around the transformer core and connect a diode 1N4007 and resistor of 10Ω / 1W in series. If the HV inverter works well, the voltage should be:
- 1.6V with the microwave tube connected.
- 1.9V with the microwave tube disconnected.
You can also use an oscilloscope; the signals are identical with a disconnected and connected microwave: