Table of Contents
Advertisement
CHAPTER 5.
OPERATION SEQUENCE
R218L(W)
[1] OFF CONDITION
1. When the timer knob is at "0", the oven is OFF condition.
2. Closing the oven door activates the monitored latch switch and the
latch switch.
IMPORTANT
When the oven door is closed, the contacts (COM-NC) of the monitor
switch must be open.
When the microwave oven is plugged in a wall outlet, rated voltage is
supplied to the fuse holder assembly.
Figure O-1 on page 12-1
[2] MICROWAVE COOKING CONDITION
1. HIGH COOKING
Set the cooking control to HIGH and then set the timer.
Function sequence
Figure O-2 on page 12-1
1. Following components are energized.
High voltage capacitor High voltage fuse
Turntable motor
Timer motor
CONNECTED COMPONENTS
High voltage transforme
2. Rated voltage is supplied to the primary winding of the high voltage
transformer. The voltage is converted to about 3.3 volts A.C. output
volts A.C. on the secondary winding.
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..
4. 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.
5. When the cooking time is up, the timer returns to "0", the bell rings
and the contacts of the timer switch are opened. The following
High voltage capacitor
High voltage fuse
Turntable motor
Timer motor
Magnetron
Oven lamp
6. When the oven door is opened during a cook cycle, the switches
come to the following position and they are common to the other
cooking conditions too.
SWITCH
CONTACT
Monitored latch
COM-NO
switch
Latch switch
COM-NO
Monitor switch
COM-NC
The circuits to the high voltage transformer, turntable motor, timer
contacts (COM-NO) of the monitored latch switch and latch switch
are made open.
Fan motor
RELAY
RY1
Fan motor
CONDITION
DURING
DOOR OPEN
COOKING
(NO COOKING)
Closed
Open
Closed
Open
Open
Closed
The timer stops to indicate how much cooking time remains.
7. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by oven door, and
monitors the operation of the monitored latch switch and the relay
RY1.
1) When the oven door is opened during or after the cycle of a
cooking program, the monitored latch switch and latch switch
(COM-NC) of the monitor switch can be closed.
2) When the oven door is closed, the contacts (COM-NC) of the
(COM-NO) of the monitored latch switch and the latch switch
are closed.
3) When the oven door is opened and the contacts (COM-NO) of
the monitored latch switch and contacts of the timer switch and
the contact of the relay RY1 remain closed, the fuse T6.3A will
blow, because the monitor switch is closed and a short circuit 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 high voltage 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
HIGH
24 sec. ON
MEDIUM HIGH
18 sec. ON
M
E
D
U I
M
12 sec. ON
MEDIUM LOW
6 sec. ON
L
O
W
NOTE: The ON/OFF time ratio does not exactly correspond to the
percentage of microwave power, because approx. 3 seconds
[3] POWER OUTPUT REDUCTION
20 minutes the power level will automatically adjust itself to 70%
power to avoid overcooking.
2. If the oven is operated for more than 90 minutes continuously (at
any power levels), the relay RY1 opens. And the circuit to the high
5 – 1
R-20A1(S)VN
100%
8 sec. OFF
Approx. 70%
14 sec. OFF
A
p
p
o r
. x
5
0
%
20 sec. OFF
Approx. 30%
26 sec. OFF
A
p
p
o r
. x
1
0
%
Advertisement
Table of Contents
