Sharp R-820BK, Service Manual

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7
R-820BK
R-820BW
TOP AND BOTTOM HEATER MODE
In this mode, the food is cooked by both the top heaters and
bottom heater. Press the GRILL pad and number "1" pad
and then enter the cooking time by pressing the number
pads. When the START pad is pressed, the following
operations occur (Figure O-3a):
1. The relays(RY3, RY4, RY5 and RY6) are energized.
2. The numbers of the digital read-out start the count down
to zero.
3. Then the top heaters, bottom heater, turntable motor,
oven lamp and fan motor are energized.
4. Now, the food is grilled by the top heaters and the bottom
heater.
5. Upon completion of the selected cooking time, audible
signal sounds and the contacts of relays(RY3, RY4 and
RY6) are opened, then the top heating elements, bottom
heating element, turntable motor and oven lamp are de-
energized. But the relay(RY5) stays closed and the fan
motor operates for 5 minutes. But if the cooking time is
less than 2 minutes the relay(RY5) will not stay closed.
NOTE: If the total grill cooking time is beyond 35 minutes,
the relay(RY1) is energized and the convection
motor is energized.
TOP
HEATER
MODE
In this mode, the food is cooked by the top heaters. Press the
GRILL pad and number "2" pad and then enter the cooking
time by pressing the number pads. When the START pad is
pressed, the following operations occur (Figure O-3b):
1. The relays(RY3, RY5 and RY6) are energized.
2. The numbers of the digital read-out start the count down
to zero.
3. Then the top heaters, turntable motor, oven lamp and fan
motor are energized.
4. Now, the food is grilled by the top heaters.
5. Upon completion of the selected cooking time, audible
signal sounds and the contacts of relays(RY3 and RY6)
are opened, then the top heaters, turntable motor and
oven lamp are de-energized. But the relay(RY5) stays
closed and the fan motor operates for 5 minutes. But if
the cooking time is less than 2 minutes the relay(RY5)
will not stay close.
NOTE: If the total grill cooking time is beyond 35 minutes,
the relay(RY1) is energized and the convection
motor is energized.
CONVECTION COOKING CONDITION WITH PREHEAT
Touch the CONVEC pad and select the convection with
preheat mode by touching the number "1" pad.
1. Program desired convection temperature by touching
the Temperature pad. Enter the cooking time by touching
the number pads. When the START pad is touched, the
following operations occur:
PREHEATING CONDITION
2. The coil of shut-off relays (RY5 and RY6) are energized,
the oven lamp, cooling fan motor and turntable motor are
turned on.
3. The coil of relays(RY3 and RY4) are energized by the
control unit, and the top heaters and the bottom heater
work with 100% power. The relay(RY1) and the
convection motor are not energized at this preheating
condition.
NOTE: If the cavity temperature is lower than 100˚F(38C) at
4 minutes and 15 seconds after the preheat is
started, the control unit judges that the thermistor is
opened. And the oven is stopped.
4. When the oven temperature reaches the selected preheat
temperature, the following operations occur:
4-1 The relays(RY3 and RY4) are de-energized by the
control unit temperature circuit and thermistor,
opening the circuit to the heating element.
4-2. The oven will continue to function for 30 minutes,
turning the top heaters and the bottom heater on
and off, as needed to maintain the selected preheat
temperature. The oven will shutdown completely
after 30 minutes
CONVECTION TIME COOKING CONDITION
5. When the preheat temperature is reached, a beep signal
will sound indicating that the holding temperature has
been reached in the oven cavity. Open the door and
place the food to be cooked in the oven. When the
START pad is touched, the following operations occur:
6. The numbers on the digital read-out start to count down
to zero.
7. The relays(RY1, RY5 and RY6) are energized and the
oven lamp, turntable motor, cooling fan motor and
convection motor are energized.
8. The relays(RY3 and RY4) are energized (if the cavity
temperature is lower than the selected temperature) and
the main supply voltage is applied to the heating element
to return to the selected cooking temperature. The top
heaters and the bottom heater work in accordance with
the following table while the heaters are energized.
Selected Temp- Top Heaters Bottom Heaters
erature (˚F) Power (%) Power (%)
100 20 10(after 3min. 0%)
150 20 10
275 40 40
300 40 50
325 50 50
350 50 60
375 60 60
400 60 70
425 70 70
450 70 80
9. 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 250˚F(120˚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 220˚F(104˚C), at which time the relay will be de-
energized, turning off the fan motor. Relay RY1 will
however, open as soon as the convection cycle has
ended, turning off the convection fan motor.