Chapter 5. Operation Sequence Off Condition; Microwave Cooking Condition; Power Output Reduction; Sensor Cooking Condition - Sharp R-380LS Service Manual

Microwave oven
Table of Contents

Advertisement

CHAPTER 5.
R380L(W)
OPERATION SEQUENCE
[1] OFF CONDITION
Closing the door activates all door interlock switches (1st. latch switch
and 2nd. interlock relay control switch).
MPORTANT
When the oven door is closed, the monitor switch contacts (COM-NC)
must be open. When the microwave oven is plugged in a wall outlet,
rated voltage is supplied to the noise filter and the control unit.
Figure O-1 on page 13-1
1. The display shows "MICRO-, WAVE, OVEN" repeatedly.
2. To set any programmes or set the clock, you must first touch the
STOP/CLEAR pad.
3. "
:
" appears in the display.
NOTE: When the oven door is opened, the oven lamp comes on at
this time.

[2] MICROWAVE COOKING CONDITION

1. HIGH COOKING
Enter a desired cooking time with the touching NUMBER pad and start
the oven with touching START pad.
Function sequence
Figure O-2 on page 13-1
CONNECTED COMPONENTS
Oven lamp, Fan motor, Turntable motor
Power transformer
1. Rated voltage is supplied to the primary winding of the power trans-
former. The voltage is converted to about 3.3 volts A.C. output on
the filament winding and high voltage of approximately 2000 volts
A.C. on the secondary winding.
2. The filament winding voltage (3.3 volts) heats the magnetron fila-
ment and the high voltage (2000 volts) is sent to the voltage dou-
bling circuit, where it is doubled to negative voltage of
approximately 4000 volts D.C.
3. The 2450 MHz microwave energy produced in the magnetron gen-
erates a wave length of 12.24 cm. This energy is channelled
through the waveguide (transport channel) into the oven cavity,
where the food is placed to be cooked.
4. When the cooking time is up, a signal tone is heard and the relays
(RY1+RY2) go back to their home position. The circuits to the oven
lamp, power transformer, fan motor and turntable motor are cut off.
5. When the door is opened during a cook cycle, the switches come to
the following condition
SWITCH
CONTACT
1st. latch switch
COM-NO
2nd. interlock relay
COM-NO
control switch
Monitor switch
COM-NC
The circuits to the power transformer, fan motor and turntable motor
are cut off when the 1st. latch switch and 2nd. interlock relay control
switch are made open. The oven lamp remains on even if the oven
door is opened after the cooking cycle has been interrupted, because
the relay RY1 stays closed. Shown in the display is the remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by oven door, and
monitors the operation of the 1st. latch switch and 2nd. interlock
relay.
RELAY
RY1
RY2
CONDITION
DURING
DOOR OPEN
COOKING
(NO COOKING)
Closed
Open
Closed
Open
Open
Closed
Service Manual
1) When the oven door is opened during or after the cycle of a
cooking program, the 1st. latch switch and 2nd. interlock relay
control switch must open their contacts first. After that the con-
tacts (COM-NC) of the monitor switch can be closed.
2) When the oven door is closed, the contacts (COM-NC) of the
monitor switch must be opened. After that the contacts of the
1st. latch switch and 2nd. interlock relay control switch are
closed.
3) When the oven door is opened and the contacts of the 1st. latch
switch and 2nd. interlock relay remain closed. The fuse F10A
will blow, because the monitor switch is closed and a short cir-
cuit is caused.
2. MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING
When the microwave oven is preset for variable cooking power, rated
voltage is supplied to the power transformer intermittently within a 32-
second time base through the relay contact which is coupled with the
current-limiting relay. The following levels of microwave power are
given.
SETTING;
32 sec. ON
100P
24 sec. ON
70P
18 sec. ON
50P
12 sec. ON
30P
6 sec. ON
10P
NOTE: The ON/OFF time ratio does not exactly correspond to the
percentage of microwave power, because approx. 3 seconds
are needed for heating up the magnetron filament.

[3] POWER OUTPUT REDUCTION

After 100% power cooking mode is carried out for more than 40 min-
utes, the power out-put is automatically reduced to 70%.

[4] SENSOR COOKING CONDITION

Using the SENSOR function, the food is cooked without figuring time,
power level or quantity. When the oven senses enough steam from the
food, it relays the information to its microprocessor which will calculate
the remaining cooking time and power level needed for best results.
When the food is cooked, water vapor is developed. The sensor
"senses" the vapor and its resistance increases gradually. When the
resistance reaches the value set according to the menu, supplemen-
tary cooking is started. The time of supplementary cooking is deter-
mined by experiment with each food category and inputted into the
LSI.
An example of how sensor works: (POTATOES)
1. Potatoes at room temperature. Vapor is emitted very slowly.
5 – 1
R380L(W)
100%
8 sec. OFF
Approx. 70%
14 sec. OFF
Approx. 50%
20 sec. OFF
Approx. 30%
26 sec. OFF
Approx. 10%

Hide quick links:

Advertisement

Table of Contents
loading

This manual is also suitable for:

R-380lwR-380l

Table of Contents