Sharp R-90GCH Service Manual page 10

R-90GCH
rent-limiting relay RY2. The following levels of microwave
power are given.
32 sec. ON
100% (HIGH)
24 sec. ON
70% (MEDIUM
HIGH)
18 sec. ON
50% (MEDIUM)
12 sec. ON
30% (MEDIUM
LOW)
6 sec. ON
10% (LOW)
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.
CONVECTION COOKING CONDITION
PREHEATING CONDITION
Program desired convection temperature by touching the
CONVECTION key. When the
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 convection motor are turned on. The contacts
(COM-NO) of relay RY6 are opened.
2. The coil of relay (RY4) is energized by the control unit.
The damper is moved to the closed position, closing
the damper switch SW5 contacts. The closing of the
damper switch SW5 contacts sends a signal to the LSI
on the control unit de-energizing the relay (RY4) and
opening the circuit to the damper motor.
3. The solid-state relays (SSR1+SSR2) are energized
by the control unit and the main supply voltage is
applied to the top and side heating elements.
4. When the oven temperature reaches the selected
preheat temperature, the following operations occur:
4-1. The solid-state relays (SSR1+SSR2) are de-
energized by the control unit temperature circuit
and thermistor, opening the circuit to the heating
elements.
4-2. 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
CONVECTION COOKING CONDITION
Enter the cooking time by touching TIME keys and select
the temperature by touching CONVECTION key. When
the (START)+1min key is touched, the following opera-
tions occur:
Figure O-3 on page 38
1. The numbers on the digital read-out start to count down
to zero.
2. The oven lamp, turntable motor, cooling fan motor and
convection motor are energized. The contacts (COM-
NO) of relay RY6 are opened.
3. The damper is moved to the closed position.
4. The solid-state relays (SSR1+SSR2) are energized (if
the cavity temperature is lower than the selected
temperature) and the main supply voltage is applied to
the heating elements to return to the selected cooking
temperature.
100%
8 sec. OFF
Approx. 70%
14 sec. OFF
Approx. 50%
20 sec. OFF
Approx. 30%
26 sec. OFF
Approx. 10%
(START)+1min key is
8
5. Upon completion of the cooking time, the audible signal
will sound, and oven lamp, turntable motor, cooling fan
motor and convection motor are de-energized. At the
end of the convection cycle, if the cavity air temperature
is above 111˚C, the circuit to RY5 will be maintained (by
the thermistor circuit) to continue operation of the cooling
fan motor until the temperature drops below 90˚C, at
which time the relay will be de-energized, turning off the
fan motor. Relay RY3 will however, open as soon as the
convection cycle has ended, turning off the convection
fan motor.
6. At the end of the convection cook cycle, if the cavity air
temperature is below 120˚C, shut-off relay (RY4) is
energized turning on the damper motor. The damper is
returned to the open position, closing the damper
switch SW5 contacts which send a signal to the control
unit, de-energizing shut-off relay (RY4).
GRILL COOKING
Enter cooking tim nd then touch the GRILL key. When the
(START)+1min key is touched, following operations
occur;
Figure O-4 on page 38
1. The contacts of the relays RY1, RY3 and RY5 are
closed, and the oven lamp, turntable motor, convection
motor and fan motors are energized. The contacts
(COM-NO) of relay RY6 are closed.
NOTE :The rotate direction of the convection motor is
reverse to one of the convection cooking by
the relay RY6.
2. The damper is moved to the closed position.
3. The solid-state relays (SSR1+SSR2) are energized
and the main supply voltage is applied to the top and
side heating elements.
NOTE :After cooking, the operation of the fan motors,
damper motor is the same as one of the
convection cooking.
DUAL1 COOKING
Enter cooking time and then touch DUAL1 key. When the
(START)+1min key is touched, following operations
occur;
Figure O-5 on page 39
1. The contacts of the relays RY1, RY3 and RY5 are
closed, and the oven lamp, turntable motor, convection
motor and fan motors are energized. The contacts
(COM-NO) of relay RY6 are closed.
NOTE :The rotate direction of the convection motor is
revers to one of the convection cooking.
2. The damper is moved to the closed position.
3. The solid-state relays (SSR1+SSR2) are energized
and the main supply voltage is applied to the top and
side heating elements.
4. The relay RY2 is energized and the microwave energy
is generated by magnetron.
NOTE: After cooking, the operation of the fan motors,
damper motor is the same as one of the
convection cooking.
DUAL2 COOKING
Enter cooking time and then touch DUAL2 key. When the
(START)+1min key is touched, following operations
occur;
Figure O-6 on page 39
1. The contacts of the relays RY1, RY3 and RY5 are
closed, and the oven lamp, turntable motor, convection
motor and fan motors are energized. The contacts