PANASONIC NNS423
Manual de Servicio

NN-G463 / NN-S443 / NN-S423 / NN-S413 / NN-413

9 CAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING
Unlike many other appliances, the microwave oven is a high voltage, high current device. It is free from danger in ordinary use, though extreme care should be taken during repair. Caution Servicemen should remove their watches working close to or replacing the magnetron. whenever

9.1.

Check the grounding

Do not operate on a two wire extension cord. The microwave oven is designed to be grounded when used. It is imperative, therefore, to ensure the appliance is properly grounded before beginning repair work.

9.2.

Inverter warnings

Grounding of the inverter circuit board WARNING! DISCHARGE CAPACITORS THE HIGH VOLATGE

DANGER, HIGH VOLTAGE AND HIGH TEMPERATURE (HOT/LINE) OF THE INVERTER POWER SUPPLY (U) This high voltage inverter power supply handles very high voltage and current for the magnetron tube. Though it is free from danger in ordinary use, extreme care should be taken during repair. The aluminum heat sink is also energized with high voltage (HOT), so do not touch when the AC input terminals are energized. The power devices Collector is directly connected to the aluminum heat sink. The aluminum heat sink may be HOT due to heat energy, therefore, extreme care should be taken during servicing.

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.

H.V. Inverter warning WARNING FOR GROUNDING INVERTER POWER SUPPLY (U)

Discharging the high voltage capacitors 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 Never touch any circuit wiring with your hand or with an insulated tool during operation.

Check the high voltage inverter power supply circuit grounding. The high voltage inverter power supply circuit board must have a proper chassis ground, the inverter grounding bracket must be connected to the chassis. If the inverter board is not grounded it will expose the user to very high voltages and cause extreme DANGER! Be sure that the inverter circuit is properly grounded via the inverter earth bracket.

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