Sharp R-8R51 - Page 6

R-8R51(W)
R-8R51(B)
OPERATING SEQUENCE
OFF CONDITION
Closing the door activates all door interlock switches.
(1st latch switch, 2nd latch switch, 3rd latch switch
IMPORTANT
When the oven door is closed, the monitor switch
contacts COM-NC
must be open. -
When the microwave oven is pluged in a wall outlet
(220 -= 230 S6Hz) the tine voltage’ is supplied to the
point A5+A3 in the control unit.
Figure 0-1 on page 38
1. The display flashes ’88:88”.
2. To set any programmes or set the clock, you
must first touch the (e/ | key.
. [7:80] appears in the display and the time
counts up every minute.
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
(10) (+) (40) Co) key and start the oven with touching
key
Function sequence Figure 0-2 on page 38
CONNECTED COMPONENTS RELAY
Oven lamp and turntable motor RY1
Power transformer RY2
Fan motor RY?
1. The fine voltage is supplied to the primary winding
of the power 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
valts) is sent to the voltagedoubling 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 channeled 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+RY7 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.
CONDITION
URING DOOR OPEN
_- SWITCH... _. _ CONTACT COOKING {«NO-COOKING)
ist Latch Switch | ~ COM- NO Closed ‘Open
2nd Latch Switch COM-NO Closed. Open
Moniter Switch COM-NC OQpen Closed
3rd Latch Switch COM-NO Closed Open
Stop Switeh _ - COM-NO _— Closed Open
The circuits to the power transformer, fan motor and
turntable motor are cut off when the 1st latch
switch, 2nd latch switch, 3rd latch switch and step
switch are made open.
The oven lamp remains on even if the oven door is
opened after the cooking cycle has been inter-
rupted, because the relays RY1
stay closed. Shown in the display is the remaining
time.
6. MONITOR SWITCH CIRCUIT
The monitor switch SW4 is mechanically controlled
by oven door, and monitors the operation of the 1st
latch switch SW1.
6-1 When the oven door is opened during or after the
cycle of a cooking program, the 1st latch, 2nd
latch and stop switches SW1+SW2+SW5 must
open their contacts first. After that the contacts
(COM-NC) of the monitor switch
SW4 can be closed and then contacts of the 3rd
latch switch SWS3 can be opened.
6-2. When the oven door’ is closed, the contacts
(COM-NC ) of the monitor switch SW4 must be
opened first, and the contacts (COM-NO) of the
3rd latch switch SW3 must be closed. After that
the contacts of the stap switch SW5, 1st latch and
2nd latch switchesSW1+SW2 are closed.
6-3. When the oven door is opened and the contacts
of the 4st latch switch SW1 remain closed, the
fuseF1 F6.3A .
will biow, because the monitor switch is closed
and a short circuit is caused through the 1st latch
switch SW1, the monitor switch SW4, the monitor
resistor RL
and the fuse F1 F6.3A.