R-8000G
6
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions during oven
operation.
OFF CONDITION
Closing the door activates the door sensing switch, secondary
interlock switch and 3rd. latch switch. (In this condition, the monitor
switch contacts are opened.)
When oven is plugged in, 208 volts A.C. 60 Hz is supplied to the
control unit. (Figure O-1).
1. The display will show " . ".
NOTE: When the door is opened, the oven lamp comes on.
MICROWAVE COOKING CONDITION
Press the SELECTA TIME pad. Program desired cooking time by
touching the NUMBER pads and the power level pad by touching
SELECTA POWER pad. When the START pad is touched, the
following operations occur:
1. The contacts of relays are closed and components connected
to the relays are turned on as follows.
(For details, refer to Figure O-2)
RELAY
CONNECTED COMPONENTS
RY-1
Oven lamp/Turntable motor
RY-2
Power transformer
RY-5
Fan motor
2. 208 volts A.C. is supplied to the primary winding of the power
transformer and is converted to about 3.3 volts A.C. output on
the filament winding, and approximately 2300 volts A.C. on the
high voltage winding.
3. The filament winding voltage heats the magnetron filament and
the H.V. winding voltage is sent to a voltage doubler circuit.
4. The microwave energy produced by the magnetron is
channelled through the waveguide into the cavity feed-box,
and then into the cavity where the food is placed to be cooked.
5. Upon completion of the cooking time, the power transformer,
oven lamp, etc. are turned off, and the generation of microwave
energy is stopped. The oven will revert to the OFF condition.
6. When the door is opened during a cook cycle, monitor switch,
door sensing switch, relay (RY1), the primary interlock relay
(RY2) and the secondary interlock switch are activated with the
following results. The circuits to the turntable motor, the cooling
fan motor, and the high voltage components are de-energized,
the oven lamp remains on, and the digital read-out displays the
time still remaining in the cook cycle when the door was opened.
7. The monitor switch is electrically monitoring the operation of
the primary interlock relay (RY2) and the secondary interlock
switch and is mechanically associated with the door so that it
will function in the following sequence.
(1) When the door opens from a closed position, the primary
interlock relay (RY2), the secondary interlock switch and the
3rd. latch switch open their contacts. And contacts of the relay
(RY1) remain closed. Then the monitor switch contacts close.
(2) When the door is closed from the open position, the monitor
switch contacts first open and the 3rd. latch switch contacts
close, and then the contacts of the secondary interlock switch
close. And contacts of the relay (RY1) open.
If the primary interlock relay (RY2) and the secondary interlock
switch fail with their contacts closed when the door is opened, the
closing of the monitor switch contacts will form a short circuit
through the monitor fuse, relay (RY1), primary interlock relay
(RY2) and the secondary interlock switch, causing the monitor
fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
When Variable Cooking Power is programmed, the 208 volts A.C.
is supplied to the power transformer intermittently through the
contacts of relay (RY-2). RY-2 is operated by the control unit within
an varying time base. Microwave power operation is as follows:
VARI-MODE
ON TIME
OFF TIME
100 PERCENT (100% power)
32 sec.
0 sec.
90 PERCENT (approx. 90% power)
30 sec.
2 sec.
80 PERCENT (approx. 80% power)
26 sec.
6 sec.
70 PERCENT (approx. 70% power)
24 sec.
8 sec.
60 PERCENT (approx. 60% power)
22 sec.
10 sec.
50 PERCENT (approx. 50% power)
18 sec.
14 sec.
40 PERCENT (approx. 40% power)
16 sec.
16 sec.
30 PERCENT (approx. 30% power)
12 sec.
20 sec.
20 PERCENT (approx. 20% power)
8 sec.
24 sec.
10 PERCENT (approx. 10% power)
6 sec.
26 sec.
0 PERCENT (0% power)
0 sec.
32 sec.
NOTE: The ON/OFF time ratio does not correspond with the
percentage of microwave power, because approx. 3
seconds are needed for heating of the magnetron
filament.
EXPRESS DEFROST COOKING
This is the multiple sequence cooking composed of low microwave
power.
NORMAL CONVECTION COOKING CONDITION
Touch SELECTA PROGRAM pad 3 times. Then touch SET pad.
Program desired oven temperature by touching the SET pad.
Enter cooking time by touching number pads. When the START
pad is touched, the following operations occur: (Figure O-3)
1. The coil of shut-off relays (RY1, RY3 and RY5) are energized,
the oven lamp, cooling fan motor, turntable motor and jet motor
are turned on.
2. The solid-state relays are energized by the control unit and the
main supply voltage is applied to the top and side heating
elements.
3. When the oven temperature reaches the selected preheat
temperature, the following operations occur:
3-1 The solid-state relays are de-energized by the control unit
temperature circuit and thermistor, opening the circuit to
the heating elements.
3-2 The oven will continue to function for 30 minutes, turning
the heating elements on and off, as needed to maintain the
selected preheat temperature. The oven will shutdown
completely after 30 minutes
4. Open the door and place food in the oven. Close door. Touch
the START pad. (Figure O-3)
5. The numbers on the digital read-out start to count down to zero.
6. The oven lamp, turntable motor, cooling fan motor and jet
motor are energized.
