R-244M - 5
OPERATING SEQUENCE
1. When the oven door is opened, the oven lamp comes on
at this time.
MICROWAVE COOKING CONDITION
2. When the cooking time is up, a single 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.
CONNECTED COMPONENTS
RELAY
Oven lamp, Fan motor, Turntable motor
RY1
Power transformer
RY2
CONDITION
DURING
DOOR OPEN
SWITCH
CONTACT
COOKING
(NO COOKING)
Monitor switch
COM-NC
Open
Closed
Monitored latch switch
COM-NO
Closed
Open
Stop switch
COM-NO
Closed
Open
3. When the door is opened during a cook cycle, the
switches come to the following condition.
The circuits to the power transformer, fan motor and
turntable motor are cut off when the monitored latch switch
and stop 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.
HIGH, MEDIUM HIGH, MEDIUM, MEDIUM
LOW, LOW COOKING
When the microwave oven is preset for variable cooking
power, the line 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
(RY2). The following levels of microwave power are given.
SETTING
MEDIUM HIGH
MEDIUM LOW
Approx. 10% = 80 Watts
32 sec. ON
6 sec. ON
12 sec. ON
18 sec. ON
24 sec. ON
26 sec. OFF
20 sec. OFF
14 sec. OFF
8 sec. OFF
LOW
MEDIUM
HIGH
Approx. 70% = 560Watts
Approx. 50% = 400 Watts
Approx. 30% = 240 Watts
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.
Approx. 100% = 800 Watts
OFF CONDITION
DOOR OPEN MECHANISM
The door can be opened by pulling the door.
Figure D-1. Door Open Mechanism
MONITORED LATCH SWITCH AND STOP
SWITCH
1. When the oven door is closed, the contacts (COM-NO)
must be closed.
MONITOR SWITCH
1. When the oven door is closed, the contacts (COM-NC)
must be opened.
2. When the oven door is opened, the contacts (COM-
NC) must be closed.
3. If the oven door is opened and he contacts (COM-NO)
of the monitored latch switch fail to open, the fuse F1
blows immediately after closing the contacts (COM-
NC) of the monitor switch.
CAUTION: BEFORE REPLACING A BLOWN FUSE F1
TEST MONITORED LATCH SWITCH (SW1)
AND MONITOR SWITCH FOR PROPER
OPERATION. (REFER TO CHAPTER “TEST
PROCEDURE”).
FUSE
1. The fuse F1 blows when the contacts (COM-NO) of the
monitored latch switch remain closed with the oven
door open and when the contacts (COM-NC) of the
monitor switch are closed.
2. If the wire harness or electrical components are short-
circuited, the fuse F1 blows to prevent an electric shock
or fire hazard.
HVT THERMOSTAT 150˚C
The thermostat protects the high voltage transformer against
overheating. If the temperature goes up higher than 150˚C
because the fan motor is interrupted or the ventilation
openings are blocked, the thermostat will cycle, line volt-
age to the high voltage transformer will also cycle. (If
operated, check the magnetron for damage.)
Latch hook
SW3: Stop switch
Door
SW2: Monitor switch
SW1: Monitored latch switch
Latch heads
