Panasonic NN-K584SF, Service Manual

Page: 37 / 65

8.1. Variable power cooking
control
High Voltage Inverter Power supply (U) controls output power
by the signal from Digital Programmer Circuit (DPC). Power
relay stays ON for P4 to P10 and For P1 to P3, both inverter
drive signal and power relay to control 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 Cooking
POWER SETTING OUTPUT
POWER(%)
APPROX.
ON-OFF TIME OF
POWER RELAY (RY1)
ON(SEC) OFF(SEC)
HIGH P10 100% 22 0
P9 90% 22 0
P8 80% 22 0
MEDIUM-HIGH P7 70% 22 0
MEDIUM P6 60% 22 0
P5 50% 22 0
P4 40% 22 0
MEDIUM-LOW P3 30% 22 0
P2 20% 15 7
P1 10% 8 14
DEFROST P3 30% 22 0
8.2. Inverter power supply circuit
NEW H.V.
This Inverter Power Supply Circuit supplies 4,000V DC to the
magnetron tube from the line voltage, 120V 60Hz AC input.
functions as the H.V. transformer, the H.V.capacitor and
H.V.Diode.
1. The AC input voltage 120V 60Hz is rectified to DC voltage
immediately.
2. DC voltage will be supplied to the switching devices called
IGBT. These devices will be switched ON-OFF by the 20 to
40 kHz PWM. (pulse width modulation) signal from the
microcomputer in the DPC.
3. This drives the High voltage transformer to increase up to
2,000V AC and approximately 3V AC by means of
transformer.
4. Then the half-wave doubler voltage rectifier circuit,
consisting of the H.V. diodes and Capacitors, generates the
necessary 4,000V DC needed for the magnetron.
5. Output power of the magnetron tube is always monitored by
the signal output from the current transformer built into the
inverter circuit.
6. Then this signal will be fed back to the microcomputer in the
DPC to determine operating conditions and output
necessary to control PWM signal to the inverter Power
Supply to control output power.
8.3. Inverter turbo defrost
When this Auto Control feature is selected and the Start Pad is
tapped:
1. The digital programer circuit determines the power level and
cooking time to complete cooking and indicates the
operating state in the display window. Table shows the
corresponding cooking times for respective serving by
categories.
2. When cooking time the display window has elapsed, the
oven turns off automatically by a control signal from the
digital programmer circuit.
Inverter Turbo Defrost
SELECTED WEIGHT COOKING TIME
1.0 oz 5 min.20 sec.
8.4. Sensor cooking (Only for
sensor models)
Auto sensor cooking is a revolutionary way to cook by
microwave without setting a power level or selecting a time.
All that is necessary is to select an Auto Sensor Program
before starting to cook.
Understanding Auto Sensor Cooking
As the food cooks, a certain amount of steam is produced. If
the food is covered, this steam builds up and eventually
escapes from the container. In Auto Sensor Cooking, a
carefully
designed instrument, called the steam sensor
element, senses this escape of steam. Then, based upon the
Auto Sensor Program Selected, the unit will automatically
determine the correct power level and the proper length of time
it will take to cook the food.
NOTE:
Auto Sensor Cooking is successful with the foods and
recipes found in the Auto Sensor Cooking Guide.
Because of the vast differences in food composition,
items not mentioned in the Cooking Guide should be
prepared in the microwave oven using power select
and time features. Please consult variable Power
Microwave cookbook for procedures.
8 DESCRIPTION OF OPERATING SEQUENCE
12
NN-G463 / NN-S443 / NN-S423 / NN-S413 / NN-413