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Model
R-8000GK
Pages
44
Size
1.16 MB
Type
PDF
Document
Service Manual
Brand
Device
Home Appliance / Microwave Oven
File
r-8000gk.pdf
Date

Sharp R-8000GK Service Manual ▷ View online

R-8000GK
2
GENERAL INFORMATION
WARNING
THIS APPLIANCE MUST BE EARTHED
IMPORTANT
THE WIRES IN THIS MAINS LEAD ARE COLOURED IN ACCORDANCE WITH THE FOLLOWING CODE:
GREEN-AND-YELLOW
: EARTH
BLUE
: NEUTRAL
BROWN
: LIVE
PRODUCT DESCRIPTION
SPECIFICATION
ITEM
DESCRIPTION
Power Requirements
230 - 240 Volts / 50 Hertz / Single phase, 3 wire earthed
Power Consumption
Microwave cooking
1.65 kW Approx. 7.2 A
Oven cooking
2.7 kW Approx. 11.3 A
Speed cooking
2.8 kW Approx. 11.7 A
Power Output
900 W nominal of RF microwave energy (measured by method of IEC 60705)
Operating fequency 2450 MHz
Top heating element Power Output
1500 W
Side heating element Power Output
1000 W
Case Dimensions
Width 550 mm
Height 420 mm (including foot)
Depth 640 mm
Cooking Cavity Dimensions
Width  408 mm
Height 214 mm
Depth 345 mm
Turntable diameter
330 mm
Control Complement
Touch Control System
Timer (0 - 99 minutes 99 sec.)
Microwave Power for Variable Cooking
 Repetition Rate;
100 PERCENT ........................................ Full power throughout the cooking time
90 PERCENT ........................................................... approx.  90% of Full Power
80 PERCENT ........................................................... approx.  80% of Full Power
70 PERCENT ........................................................... approx.  70% of Full Power
60 PERCENT ........................................................... approx.  60% of Full Power
50 PERCENT ........................................................... approx.  50% of Full Power
40 PERCENT ............................................................ approx. 40% of Full Power
30 PERCENT ............................................................ approx. 30% of Full Power
20 PERCENT ........................................................... approx.  20% of Full Power
10 PERCENT ............................................................ approx. 10% of Full Power
0 PERCENT ......................................... No power throughout the cooking time
Convection temperature control range:
   250˚C, 230˚C, 220˚C, 200˚C, 190˚C, 180˚C, 160˚C, 130˚C, 100˚C and 40˚C
SPEED GRILL key, LESS/MORE keys, SPEED CONVECTION key
NUMBER keys, HOLD key, OVEN (˚C) key, MICROWAVE key
MANUAL/REPEAT key, PAUSE key, STOP/CLEAR key
SET key, CHECK key, START key
Set Weight
Approx. 39.5 kg
NOTE: Internal capacity is calculated by measuring
maximum width, depth and height.
Actual capacity for holding food is less.
R-8000GK
3
APPEARANCE VIEW
OVEN
DEGITAL DISPLAY INDICATORS:
1. Indicators
   : SPEED
CONVECTION
MICRO
MORE(   )/LESS(   )
CHECK
PAUSE
150˚C
: HOLD 150
°C
COOK
OPERATING KEYS:
2. SPEED GRILL
Press to select speed grill mode.
3. SPEED CONVECTION
Press to select speed convection mode.
4. MORE(   )/LESS(   )
Press to set more or less mode.
1. Control panel
2. Waveguide cover
3. Oven lamp
4. Oven cavity
5. Coupling
6. Door latches
7. Door opening handle
(To open the door, pull the handle down
and forward. Never hold the door handle
when moving the oven.)
8. Door seals and sealing surfaces
9. Ventilation cover
10. Outer cabinet
11. SET
Press to select the oven sound and set
or clear memory programmes.
Press to change the holding time of
HOLD 150
°C.
12. CHECK
Press to check memory banks.
13. START
Press to start oven after setting
programmes.
Press to extend the cooking time by 1
minute multiples using the last
sequence after the cooking.
14. STOP/CLEAR
Press to clear during programming.
Press once to stop operation of oven
during cooking, press twice to cancel
cooking programme.
CONTROL PANEL
15. Turntable support
16. Low rack
17. High rack
18. Splash guard
12
13
9
10
11
12
16
17
18
14
15
6
8
7
3
5
1
2
3
4
2
3
4
1
7
8
10
11
9
12
13
14
6
5
11. Power cord
12. Air-vent openings
13. Oven lamp access cover
14. Turntable
5. NUMBER
Press to select memory number.
Press to enter cooking time.
6. HOLD 150
°C
Press to set or cancel HOLD150
°C
mode.
7. OVEN (
°C)
Press to select convection temperature.
8. MICROWAVE
Press to select microwave power
setting.
9. MANUAL/REPEAT
Press to set manual cooking or select
the repeat cooking mode.
10. PAUSE
Press to set a pause when setting a
sequence programme.
INSTALLATION INFORMATION
When this commercial  microwave oven is installed near other commercial electrical appliances, connect a lead wire to each equivalent
potential terminal with equipotential marking between them (insert a lead wire between a washer and an earth angle, and screw them),
as shown in Fig. A-1, to make sure that they are at equivalent potential.
If any lead wire is not connected between them, when person touch them he/she will get a electric shock.
COMMERCIAL MICROWAVE OVEN
OTHER COMMERCIAL 
ELECTRICAL APPLIANCE
Lead wire
Equipotential marking
Earth angle
(Equivalent potential terminal)
Equivalent 
potential terminal
Screw
Washer
Lead wire
R-8000GK
4
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 and second-
ary interlock switch and 3rd. latch switch. (In this condition, the
monitor switch contacts are opened.)
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 (230 - 240V / 50Hz), the line
voltage is supplied to the noise filter.
Figure O-1 on page 33
1. The display will show "   .          ".
NOTE: When the door is opened, the oven lamp comes on.
MICROWAVE COOKING CONDITION
HIGH COOKING
Press the MANUAL/REPEAT key. Program desired cooking
time by touching the NUMBER keys. Then press the MICRO-
WAVE key once. When the START key 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
High voltage transformer
RY-5
Fan motor
2. The line voltage is supplied to the primary winding of the high
voltage transformer. The voltage is converted to about 3.3
volts A.C. output on the filament winding and high voltage of
approximately 2000 volts A.C. on the secondary winding.
3. The filament winding voltage (3.3 volts) heats the magnetron
filament and the high voltage (2000 volts) is sent to the
voltage doubling circuit, where it is doubled to negative
voltage of approximately 4000 volts D.C..
4. The 2450 MHz microwave energy produced in the magnetron
generates a wavelength 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, a signal tone is heard and the
relays RY1 + RY2 + RY5 go back to their home position. The
circuits to the oven lamp, high voltage transformer, fan motor
and turntable motor are cut off.
6. When the oven door is opened during a cooking cycle, the
switches come to the following condition.
Switch
Contact
          Condition
During
Oven Door
Cooking
Open(No cooking)
Secondary interlock
switch
COM-NO
Closed
Opened
Door sensing switch
COM-NO
Closed
Opened
3rd. latch switch
COM-NO
Closed
Opened
Monitor Switch
COM-NC
Opened
Closed
The circuit to the high voltage transformer is cut off when the
contacts of relay RY2, and the contacts (COM-NO) of the
secondary interlock switch are made open. The circuit to the
fan motor is cut off when the relay RY5 is made open. The
circuit to the turntable motor is cut off when the contacts
(COM-NO) of the secondary interlock 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 remaining time.
7. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by the oven
door, and monitors the operation of the secondary interlock
switch and the relay RY2.
7-1. When the oven door is opened during or after the cycle of
a cooking program, the secondary interlock switch and the
door sensing switch must open their contacts (COM-NO)
first. After that the contacts (COM-NC) of the monitor
switch can be closed and the contacts (COM-NO) of 3rd.
latch switch are made open.
7-2. When the oven door is closed, the contacts (COM-NC) of
the monitor switch must be opened and the contacts
(COM-NO) of 3rd. latch switch must be closed. After that
the contacts (COM-NO)  of the secondary interlock switch
and the door sensing switch are made closed.
7-3. When the oven door is opened and the contacts (COM-
NO) of  the secondary interlock switch remain closed, the
fuse F10A will blow. Because the relay RY2 and monitor
switch are closed  and a short circuit is caused.
POWER LEVEL P-0 to P-90 COOKING
When the microwave oven is preset for variable cooking power,
the line 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 RY2. The
following levels of microwave power are given.
NOTE: The ON/OFF time ratio does not exactly correspond
the percentage of microwave power, because
approx. 3 seconds are needed for heating of the
magnetron filament.
PREHEATING CONDITION (CONVECTION MODE)
Press the MANUAL/REPEAT key. Program desired convection
temperature by touching the OVEN(˚C) key. When the START
key 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. The contacts (COM-NO) of relay RY6
are opened.
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.
32 sec. ON
100%
30sec. ON
90%
26 sec. ON
80%
24 sec. ON
 70%
22 sec. ON
60%
18 sec. ON
50%
16 sec. ON
40%
12 sec. ON
30%
8 sec. ON
20%
6 sec. ON
10%
0 sec. ON
0%
R-8000GK
5
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
OVEN COOKING CONDITION
Press the MANUAL/REPEAT key. Enter the cooking time by
touching NUMBER key and select the temperature by touching
OVEN(˚C) key. When the START key is touched, the following
operations occur:
Figure O-3 on page 34
1. The numbers on the digital read-out start to count down to
zero.
2. The oven lamp, turntable motor, cooling fan motor and jet
motor are energized. The contacts (COM-NO) of relay RY6
are opened.
3.  The solid-state relays 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.
4. Upon completion of the cooking time, the audible signal will
sound, and oven lamp, turntable motor, cooling fan motor and
jet motor are de-energized. At the end of the oven 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 jet motor.
SPEED GRILL COOKING (SG-1)
Press the MANUAL/REPEAT key. Enter cooking time and then
touch the SPEED GRILL key once. Select the temperature by
pressing OVEN(˚C) key. Then select the microwave power level
by pressing MICROWAVE key.  When the START key is touched,
following operations occur;
Figure O-4 on page 34
1. The contacts of the relays RY1, RY3 and RY5 are closed, and
the oven lamp, turntable motor, jet motor and fan motors are
energized. The contacts (COM-NO) of relay RY6 are closed.
NOTE : The rotate direction of the jet motor is reverse to one
of the oven cooking by the relay RY6.
2. The solid-state relays 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 is the
same as one of the oven cooking.
SPEED GRILL COOKING (SG-2, SG-3)
Press the MANUAL/REPEAT key. Enter cooking time and then
touch SPEED GRILL key twice or 3 times. Select the tempera-
ture by pressing OVEN(˚C) key. Then select the microwave
power level by pressing MICROWAVE key. When the start key
is touched, following operations occur;
Figure O-5 on page 35
1. The contacts of the relays RY1, RY3 and RY5 are closed, and
the oven lamp,  turntable motor, jet motor and fan motors are
energized. The contacts (COM-NO) of relay RY6 are closed.
NOTE : The rotate direction of the jet motor is revers to one
of the oven cooking.
2. The solid-state relays are energized and the main supply
voltage is applied to the top and side heating elements.
3. The relay RY2 is energized and the microwave energy is
generated by magnetron.
NOTE: After cooking, the operation of the fan motors is the
same as one of the oven cooking.
SPEED CONVECTION COOKING (SC-2, SC-3)
Press the MANUAL/REPEAT key. Enter cooking time and then
touch SPEED CONV. key twice or 3 times. Select the tempera-
ture by pressing OVEN(˚C) key. Then select the microwave
power level by pressing MICROWAVE key. When the start key
is touched, following operations occur;
Figure O-6 on page 35
1. The contacts of the relays RY1, RY3 and RY5 are closed, and
the oven lamp, turntable motor, jet motor and fan motors are
energized. The contacts (COM-NO) of relay RY6 are opened.
2. The solid-state relays and relay RY2 are energized, and the
main supply voltage is applied to the top and side heating
elements and the high voltage transformer alternately.
NOTE: After cooking, the operation of the fan motors is the
same as one of the oven cooking.
FIRE SENSING FEATURE (MICROWAVE MODE)
This model incorporates a sensing feature which will stop the
oven's operation if there is a fire in the oven cavity during
microwave cooking. This fire sensing feature will operate when
the microwave power level is set to 80% or more. This is
accomplished by the LSI repeatedly measuring the voltage
across the temperature measurement circuit (thermistor) during
it's 32-seconds time base comparing the obtained voltage meas-
urements. If the most recent  voltage measured is 300 mV
greater than the previous voltage measured, the LSI judges it as
a fire in the oven cavity and switches off the relays to the power
transformer, fan motor and jet motor. The LSI also stops counting
down and closes the damper door so that no fresh air will enter
the oven cavity. Please refer to the following section for a more
detailed description.
Operation
Please refer to the timing diagrams below.
1. The fire sensing will start after 5 minutes when the oven is
started.
2. The thermistor operates within a 32-seconds time base and
it is energized for three (3) seconds and off for 29 seconds.
Two (2) seconds after the thermistor is energized, the voltage
across the temperature measurement circuit is sampled by
the LSI and twenty five (25) seconds after the thermistor is cut
off the LSI turns on the convection fan for three (3) seconds.
3. The above procedure is repeated. If the difference between the
first voltage measured (in step 1) and the voltage measured
when the procedure is repeated (step 2) is greater than 300 mV
the LSI makes the judgment that there is a fire in the oven cavity
and will switch off the relays to the power transformer, fan motor
and jet motor. The LSI also stops counting down and closes the
damper door so that no fresh air will enter the oven cavity.
4. Once the fire sensor feature has shut the unit down, the
programmed cooking cycle may be resumed by  pressing the
"START" key or the unit may be reset by pressing the STOP/
CLEAR key.
JET MOTOR
THERMISTOR
Sensing 
Voltage
ON
OFF
ON
OFF
ON
OFF
0 2 3
28
31
32 (sec.)
64 (sec.)
3 sec.
Sensing the voltage across temperature measurement circuit.
3 sec.
Page of 44
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  • Here you can View online or download the Service Manual for the Sharp R-8000GK in PDF for free, which will help you to disassemble, recover, fix and repair Sharp R-8000GK Microwave Oven. Information contained in Sharp R-8000GK Service Manual (repair manual) includes:
  • Disassembly, troubleshooting, maintenance, adjustment, installation and setup instructions.
  • Schematics, Circuit, Wiring and Block diagrams.
  • Printed wiring boards (PWB) and printed circuit boards (PCB).
  • Exploded View and Parts List.