Panasonic NN-CS894S, Service Manual

Page: 6 / 33

2.6. Grill cooking control
Grill cooking is accomplished by upper heaters only. One grill
cooking cycle is 33 seconds.
1. During grill cooking, the digital programmer circuit controls
power relay RY3´s ON-OFF time. In all three grill cooking
categories, power relay RY1 always stay ON, but RY3´s
ON-OFF time are shown in Figure.
GRILL
CATEGORY
GRILL (RY3) MICROWAVE (DUTY)
ON (sec.) OFF (sec.) ON (sec.) OFF (sec.)
1 33 0 0 33
2 24 9
3 18 15
2.7. Convection cooking control
The digital programmer circuit controls the ON-OFF time of the
heater in order to control oven cavity temperature.
1. After selecting desired oven cavity temperature of oven (the
range of selected oven temp is 100°C-230°C) and pressing
[Start] pad, a high level signal comes out of the micro
computer and applies to power relays, RY5 & RY3.
2. When RY5 & RY3 are switched to ON, power source
voltage is applied to the upper heater & lower heater, and
the heaters turn on.
3. The digital programmer circuit senses the oven cavity
temperature through oven temp sensor (thermistor). When
the oven temperature reaches the set temperature, DPC
stops supplying high level signal to the power relays, and
the heaters turn off.
4. After the upper heater and lower heater turn off, the oven
temperature will continue increasing for a while and then
decrease as shown in Figure.
When the oven temperature drops below the set
temperature, the digital programmer circuit senses the
signal and starts supplying a high level signal to RY5 & RY3
again.
NOTE:
If cooking by convection without preheating, upper
heater will not turn on.
2.8. Steam function
2.8.1. Water Supply
Water in water tank will be pumped out and supply to the steam
generation heater located left side of oven cavity.
2.8.2. Operation
When pressing [start] pad, oven preheat will start and then
water supply begins. When preheat is completed, it will turn
into actual cooking process. During heating, the temperature
sensor (Thermistor) located on steam heater will monitor steam
heater temperature and when it exceeds a certain level, the
additional water will be supplied to maintain moisture/steam
within oven cavity.
7
NN-CS894S