Panasonic dimenion 4/ nna772sbbpq

Question

to robotek
the microwave seems to work but then after about 25 seconds it stops and the time resets and goes back to the clock & the food inside it has not heated it at all  you said that it could be magnotron, diodes, or power supply i have changed the magnotron but it hasn't made any difference could you tell if the diodes are on the inverter board & the supply is on the first board

ps    ill be carefull around the high voltage im a electrican i deal with 500volts every day

thanks dom