PANASONIC NN-SD377S
Service Manual

NN-SD377S

2 CAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING
Unlike many other appliances, the microwave oven is highvoltage, high-current equipment. Though it is free from danger in ordinary use, extreme care should be taken during repair.
CAUTION Servicemen should remove their watches whenever working close to or replacing the magnetron.

2.3.

When parts must be replaced, remove the power plug from the outlet. When the 15 Amp fuse is blown due to the operation of short switch:
WARNING

2.4.

2.1.

Do not operate on a 2-wire extension cord. The microwave oven is designed to be grounded when used. It is imperative, therefore, to make sure it is grounded properly before beginning repair work.

Check the grounding

2.2.

Warning about the electric charge in the high voltage capacitor

When the 15 Amp fuse is blown due to operation of the interlock monitor switch, you must replace all of the components (Primary latch switch, Door switch, Short switch and Power relay B (RY1)).

1. This is mandatory. Refer to Measurement� for these switches.

�Adjustments

and

For about 30 seconds after the oven is turned off, an electric charge remains in the high voltage capacitor.When replacing or checking parts, remove the power plug from the outlet and short the terminal of the high voltage capacitor (terminal of lead wire from diode) to chassis ground with an insulated handle screwdriver to discharge.
WARNING There is high-voltage present, with high-current capabilities in the circuits of the high voltage winding and filament winding of the high voltage transformer. It is extremely dangerous to work on or near these circuits with oven energized. DO NOT measure the voltage in the high voltage circuit including filament voltage of magnetron. WARNING Never touch any circuit wiring with your hand nor with an insulated tool during operation.

2. When replacing the fuse, confirm that it has the appropriate rating for these models. 3. When replacing faulty switches, be sure mounting tabs are not bent, broken or otherwise deficient in their ability to hold the switches.

2.5.

Avoid inserting nails, wire, etc. through any holes in the unit during operation.

Never insert a wire, nail or any other metal object through the lamp holes on the cavity or any other holes or gaps, because such objects may work as an antenna and cause microwave leakage.

2.6.

Confirm after repair

1. After repair or replacement of parts, make sure that the screws of the oven, etc. are neither loose nor missing. Microwaves might leak if screws are not properly tightened. 2. Make sure that all electrical connections are tight before inserting the plug into the wall outlet. 3. Check for microwave energy leakage. (Refer to procedure for measuring microwave evergy leakage.)
CAUTION MICROWAVE RADIATION USE CAUTION NOT TO BECOME EXPOSED TO RADIATION FROM THE MICROWAVE MAGNETRON OR OTHER PARTS CONDUCTING MICROWAVE ENERGY. IMPORTANT NOTICE 1.The following components have potentials above 2000V while the appliance is operated. * Magnetron * High voltage transformer * High voltage diode * High voltage capacitor Pay special attention to these areas. 2.When the appliance is operated with the door hinge or magnetron adjusted incorrectly, the microwave leakage can exceed more than 5mW/cm 2. After repair or exchange, it is very important to check that magnetron and the door hinge is correctly installed.

6