Panasonic Nn St452w User Manual

© Panasonic Appliances Microwave Oven
(Shanghai) Co., Ltd. 2012.
NN-SD452W
NN-ST462M
NN-ST452W
BPQ (U.K.)
EPG (Continental Europe)
Microwave Oven
ORDER NO.PAPMOSH1201015CE 

2
NN-SD452W / NN-ST462M / NN-ST452W 

3
NN-SD452W / NN-ST462M / NN-ST452W 

 1 SCHEMATIC DIAGRAM 5
 2 DESCRIPTION OF OPERATING SEQUENCE 
6
 2.1. Variable power cooking control 
6
 2.2. Inverter power supply circuit 
6
 2.3. Turbo defrost, Auto cook 
6
 2.4. Sensor cooking 
6
 2.5. Steam sensor and digital programmer circuit 
7
 3 CAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING 
8
 3.1. Check the grounding 
8
 3.2. Inverter warnings 
8
 3.3. Part replacement. 
9
 3.4. When the 10A fuse is blown due to the malfunction of the
short switch: 
9
 3.5. Avoid inserting nails, wire etc....

1 SCHEMATIC DIAGRAM
5
NN-SD452W / NN-ST462M / NN-ST452W 

2.1. Variable power cooking
control
High Voltage Inverter Power Supply (U) controls output power
by the signal from Digital Programmer Circuit (DPC). Power
relay always stay on, but PWM (Pulse Width Modulation) signal
controls microwave output power.
NOTE:
The ON/OFF time ratio does not correspond with the
percentage of microwave power since approximately 2
seconds are required for heating of magnetron
filament.
Variable Power CookingPOWE R SETTINGOUTPUT
POWE R(%)
APPROX.MANUAL MICROWAV E
DUTY...

Explanation of the Auto Sensor Cooking process
 1. During the first 10 second period there is no microwave
activity. When calculating the T2 time by using the
formula below make sure this 10 seconds is subtracted
from the T1 time. In other words, T1 time starts at the
end of the 10 second period.
 2. T1 timeThe total amount of time it takes the microwave
oven to switch to T2 time after the 10second period.
 3. T2 timeWhen the steam escapes from the cooking
container placed in the oven, the steam sensor...

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 & rings whenever
working close to or replacing the magnetron.
3.1. 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...

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.
3.3. Part...

4.1. Magnetron
 1. Discharge the high voltage capacitor.
 2. Remove 1 screw holding air guide A on the magnetron.
 3. Remove 1 screw holding air guide A on cavity top plate.
 4. Remove 1 screws holding thermistor on the magnetron.
 5. Remove 1 screw holding air guide A on the wave guide,
then remove the air guide A.
 6. Remove 4 screws holding the magnetron.
NOTE:
After replacement of the magnetron, tighten mounting
screws properly, making sure there is no gap between
the waveguide and the magnetron to...