Panasonic NN-S554WF Service Manual page 9

WARNING! DISCHARGE THE HIGH VOLATGE CAPACITORS
For about 30 seconds after the oven is turned off, an electric charge
remains in the high voltage capacitors in the inverter power supply
circuit board.
When replacing or checking parts, remove the power plug from the
outlet and short the inverter output terminal of the magnetron
filament terminals to the chassis ground with an insulated handle
screwdriver to discharge. Please be sure to touch the chassis
ground side first and then short to the output terminals.
WARNING
There is high voltage present with high current capabilities in the
circuits of the primary and secondary windings, choke coil and heat
sink of the inverter. It is extremely dangerous to work on or near
these circuits with the oven energized. DO NOT measure the
voltage in the high voltage circuit including the filament voltage of
the magnetron.
WARNING
Grounding of the inverter circuit board
Discharging the high voltage capacitors
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