Sharp R-961 (W) - Page 9

OPERATION SEQUENCE
OFF CONDITION
Closing the oven door activates all door interlock switches
(monitored latch switch, monitor switch and door switch.
IMPORTANT:
When the oven door is closed, the contacts COM-NC of the
monitor switch SW2 must be open and the contacts (COM-
NO) must be closed. When the microwave oven is pluged in
a wall outlet (230V / 50Hz), 230 volts A.C. is supplied to the
point E1 + E3 in the control unit.
Figure O-1 on page 37
1. The display flashes "88:88"
2. To set any programmes or set the clock, you must first
touch the STOP key.
3. " : “appears in display.
NOTE: When the oven door is opened, the oven lamp
comes on at this time.
MICROWAVE COOKING CONDITION
HIGH COOKING
Enter a desired cooking time with the touching Time key and
start the oven with touching START key.
Function sequence Figure O-2 on page 37
CONNECTED COMPONENTS RELAY
Oven lamp, Turntable motor RY1
High voltage transformer RY1 + RY2
Fan motor RY5
1. 230 volts A.C. is supplied to the primary winding of the
high voltage transformer. 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 filament and the high voltage (2000 volts) is
sent to the voltage doubling circuit, where it is doubled to
negative voltage of approximately 4000 volts D.C..
3. The 2450 MHz microwave energy produced in the
magnetron generates 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 + RY5 go back to their home
position. The circuits to the oven lamp, high voltage
transformer, fan motor and turntable motor are cut off.
5. When the oven door is opened during a cooking cycle,
the switches come to the following condition.
witch ontact condition
During Oven Door
Cookin Open(No cookin
Monitored latch Switch COM-NO Closed Opened
Monitor Switch COM-NO Closed Opened
Monitor Switch
Stop switch
COM-NC Opened
COM-NO _ Closed
Closed
Opened
The circuit to the high voltage transformer, is cut off when the
contact of relay RY2, contacts COM-NO of the monitored
jatch switch, and contacts COM-NO of monitor switch SW2
are made open. The circuit to the fan motor is cut off when
the relay RY5 is made open. The circuit to the turntable motor
is cut off when the contacts COM-NO of the monitored latch
switch are made open. The relay RY2 and RY5 are made
open when the door is opened. The oven lamp remains on
even if the oven door is opened after the cooking cycle has
R-961 -
7
been interrupted, because the relay RY1_ stay closed.
Shown in the display is remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch SW2 is mechanically controlled by
the oven door, and monitors the operation of the
monitored latch switch SW1.
6-1.When the oven door is opened during or after the cycle
of a cooking program, the 1st latch switch SW1 must
open its contacts (COM-NO) first. After that the contacts
(COM-NC) of the monitor switch SW2 can be closed and
the contacts (COM-NO) of the door switch SW3 are
made open.
6-2.When the oven door is closed. The contacts (COM-NC)
of the monitor switch SW2 must be opened and the
contacts (COM-NO) of monitor switch SW2 must be
closed, and the contacts (COM-NO) of the door switch
SW3 must be closed. After that the contacts of the 1st
latch switch SW1 are made closed.
6-3.When the oven door is opened and the contacts of the
1st latch switch SW1 remain closed, the fuse F2 F8A will
blow. Because the monitor switch SW2 is closed anda
short circuit is caused.
MEDIUM HIGH, MEDIUM, MEDIUM LOW,
LOW COOKING
When the microwave oven is preset for variable cooking
power, the 230 volts A.C. power is supplied to the high
voltage transformer intermittently within a 32-second time
base through the relay contact which is coupled with the
current-limiting relay RY2. The following levels of microwave
power are given.
i, HIGH
32 sec. ON
24 sec. ON 8 sec. OFF
yo IT) ooo. 7
HIGH
18 sec. ON 14 sec. OFF
hy veo IIT] pr 5
12 sec. ON 20 sec. OFF
MEDIUM
Approx.
30%
LOW
; 6 sec. ON 28 sec. OFF
Ty LOW Approx. 10%
Note: The On/Off time ratio does not exactly correspond to
the percentage of microwave power, because approx.
3seconds are needed for heating up the magnetron
filament.
CONVECTION COOKING CONDITION
PREHEATING CONDITION (Figure O-3)
Program desired convection temperature by touching CON-
VECTION key. When the START key is touched, the follow-
ing operations occur:
1. The coil of shut-off relays RY1, RY6 and RY5 are
energized, andthe oven lamp, cooling fan motor, turntable
motor and convection motor are turned on.
2. Whenanoven temperature below 160°C is programmed,
the shut-off relay RY3 is energized and the convection
heating element is turned on.
When an oven temperature above 180°C is programmed,
not only the relay RY3 but also the relay RY4 is energized
and grill heating element is turned on to heat the oven
cavity faster.
3. In the case of an oven temperature below 160°C being
programmed, when the oven temperature reaches the