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R-770B
SERVICE MANUAL
S3811R770BPHR
DOUBLE GRILL
MICROWAVE OVEN
TURNOVER ADD STAND COVER
STIR DEFROST HELP
%
KG PCS AUTO COOK
R-770B
AUTO COOK
PIZZA
AUTO GRILL CRISPY SNACK
MODEL
1 Grilled Chicken
Potato Skin
2 Grilled Lobster
Garlic Bread
3 Grilled Fish Chicken
4 Steak
Wings
Salty Peanuts
5 Fish Cake
Convenient Food
RICE COOK REHEAT
STEAM MENU
HELP
SLOW COOK
POWER LEVEL
EASY DEFROST
GRILL
GRILL MIX
DOUBLE GRILL 1 2 3 4 5
6 7 8 9 O
STOP/CLEAR
INSTANT COOK/START
In interests of user-safety the oven should be restored to its original
condition and only parts identical to those specified should be used.
TABLE OF CONTENTS
Page
CAUTION, MICROWAVE RADIATION.................................................................................................... 1
WARNING .................................................................................................................................................1
PRODUCT SPECIFICATIONS ................................................................................................................ 2
GENERAL INFORMATION....................................................................................................................... 2
APPEARANCE VIEW .............................................................................................................................. 3
OPERATION SEQUENCE....................................................................................................................... 4
FUNCTION OF IMPORTANT COMPONENTS ....................................................................................... 7
SERVICING .............................................................................................................................................. 8
TROUBLESHOOTING GUIDE ................................................................................................................. 9
TEST PROCEDURE .............................................................................................................................. 10
TOUCH CONTROL PANEL ASSEMBLY .............................................................................................. 16
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE .................................................. 21
MICROWAVE MEASUREMENT ........................................................................................................... 26
WIRING DIAGRAM ................................................................................................................................ 27
PICTORIAL DIAGRAM .......................................................................................................................... 30
POWER UNIT CIRCUIT ......................................................................................................................... 31
CONTROL PANEL CIRCUIT .................................................................................................................. 32
PRINTED WIRING BOARD .................................................................................................................... 33
PARTS LIST .......................................................................................................................................... 34
SHARP CORPORATION
R-770B
R-770B
SERVICE MANUAL PRODUCT SPECIFICATIONS
GENERAL INFORMATION
MICROWAVE OVEN WITH TOP
AND BOTTOM HEATER
APPEARANCE VIEW
R-770B
GENERAL IMPORTANT INFORMATION
OPERATING SEQUENCE
This Manual has been prepared to provide Sharp Corp. Service
engineers with Operation and Service Information.
It is recommended that service engineers carefully study the entire
FUNCTION OF IMPORTANT
text of this manual, so they will be qualified to render satisfactory COMPONENTS
customer service.
CAUTION SERVICING AND
MICROWAVE RADIATION TROUBLESHOOTING GUIDE
Service engineers should not be exposed to the microwave
energy which may radiate from the magnetron or other micro-
wave generating devices if it is improperly used or connected. TEST PROCEDURE
All input and output microwave connections, waveguides, flanges
and gaskets must be secured. Never operate the device without
a microwave energy absorbing load attached. Never look into
an open waveguide or antenna while the device is energized.
TOUCH CONTROL PANEL
WARNING
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
Never operate the oven until the following points are ensured.
(A) The door is tightly closed.
(B) The door brackets and hinges are not defective.
(C) The door packing is not damaged. MICROWAVE MEASUREMENT
(D) The door is not deformed or warped.
(E) There is not any other visible damage with the oven.
Servicing and repair work must be carried out only by trained
service engineers. WIRING DIAGRAM
All the parts marked "*" on parts list are used at voltages more than
250V.
Removal of the outer wrap gives access to potentials above 250V.
PARTS LIST
All the parts marked "" on parts list may cause undue microwave
exposure, by themselves, or when they are damaged, loosened or
removed.
Never operate the Top and/ or Bottom heater with the oven
outer cabinet removed. (Because air flow is eliminated, and the
excess heat generated on adjacent components). It can cause
permanent damage or a fire.
SHARP CORPORATION
OSAKA, JAPAN
1
R-770B
PRODUCT DESCRIPTION
SPECIFICATION
ITEM DESCRIPTION
Power Requirements 220 Volts
50 Hertz
Single phase, 3 wire earthed
Power Consumption Microwave cooking 1.6 kW
Top Heater mode 1.3 kW
Grill cooking Bottom heater mode 0.9 kW
Top and Bottom heater mode 2.1 kW
Power Output 900 W nominal of RF microwave energy (measured by method of IEC 705)
Operating frequency 2450 MHz
Grill heater Power Output (Top heater) 1200 W (600 W x 2)
Bottom heater Power Output 800 W
Case Dimensions Width 520 mm
Height 309 mm including foot
Depth 467 mm
Cooking Cavity Dimensions Width 352 mm
Height 207 mm
Depth 368 mm
Turntable diameter 325 mm
Control Complement Touch Control System
Clock (1:00 - 12:59) / Timer (0 - 90 minutes)
Microwave Power for Variable Cooking
Repetition Rate;
100% ................................................... Full power throughout the cooking time
70% ..................................................................... approx. 70% of FULL Power
50% ..................................................................... approx. 50% of FULL Power
30% ..................................................................... approx. 30% of FULL Power
10% ..................................................................... approx. 10% of FULL Power
Mix cooking
Grill Mix High with Top Heater ............ Top heater with 50% microwave power
Grill Mix Low with Top Heater ............. Top heater with 10% microwave power
Grill Mix High with Bottom Heater ....... Bottom heater with 50% microwave power
Grill Mix Low with Bottom Heater ........ Bottom heater with 10% microwave power
AUTO COOK pad, AUTO GRILL pad, PIZZA pad
CRISPY SNACK pad, RICE COOK pad, REHEAT pad
STEAM MENU pad, LESS (")/MORE (') pads
HELP pad, SLOW COOK pad, POWER LEVEL pad
EASY DEFROST pad, GRILL pad, GRILL MIX pad
Number pads, STOP/CLEAR pad, CLOCK pad
INSTANT COOK/START pad
Set Weight Approx. 19 kg
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
2
R-770B
APPEARANCE VIEW
OVEN
1. Oven lamp 4 1 2
2. Top heaters (Grill heaters) t 0
3. See through door r
4. Door hinges 0
q
5. Door safety latches 5 e
8 9
6. Door seals and sealing surfaces
7. Bottom heater 3 y
8. Oven cavity
9. Turntable motor shaft 0 7 w 0
6
10.Ventilation openings
11.Waveguide cover High rack NOTE:
12.Door opening button 1. Ensure that the bottom heater is in the lowest
13.Control panel Turntable Turntable position as shown the figure, as it is possible
support
14.Digital display to move it up and down to help with cleaning.
15.Power supply cord 2. Place the turntable support over the turnta-
16.Outer cabinet ble motor shaft on the floor of the cavity.
Low rack
3. Then place the turntable on to the turntable
Bottom Turntable support.
heater motor shaft
TOUCH CONTROL PANEL
1. TOP HEATER SYMBOL
The symbol will light when the top heater is in use. TURNOVER ADD STAND COVER STIR DEFROST HELP
2. BOTTOM HEATER SYMBOL Indicator
The symbol will light when the bottom heater is in use. 1 %
3. MICROWAVE SYMBOL 2 KG PCS AUTO COOK
The symbol will light during microwave cooking. 3
A. AUTO COOK PAD
Press to select 4 popular menus. A AUTO COOK PIZZA
C
B. AUTO GRILL PAD B AUTO GRILL CRISPY SNACK D
Press to select 5 popular grill menus.
C. PIZZA PAD 1 Grilled Chicken Potato Skin
2 Grilled Lobster Garlic Bread
Press to select 3 pizza menus. 3 Grilled Fish Chicken
Wings
D. CRISPY SNACK PAD 4 Steak Salty Peanuts
5 Fish Cake Convenient Food
Press to select 5 popular snack menus.
E. RICE COOK PAD
F
E G
Press to cook rice, congee or porridge. RICE COOK REHEAT STEAM MENU
F. REHEAT PAD
H
Press to reheat dish, soup, beverage or bread.
HELP
I
J
G. STEAM MENU PAD L
Press to steam fish, meat or dumpling. K SLOW COOK POWER LEVEL EASY DEFROST
H. LESS (")/MORE (') pads M GRILL GRILL MIX N
Press to adjust the doneness of food in one minute increments
during cooking or to increase/ decrease the time whilst pro-
1 2 3 4 5
O
gramming the automatic operations. 6 7 8 9 O
I. HELP PAD Q
Press to select auto start, child lock, language or demonstra-
tion modes. Press to get cooking information. P STOP/CLEAR
INSTANT COOK/START
R
J. SLOW COOK PAD
Press to cook slowly and longer time.
K. POWER LEVEL PAD P. STOP/CLEAR PAD
Press to select microwave power setting. If not pressed, HIGH Press to clear during programming. Press
power is automatically selected. once to stop operation of oven during cooking;
L. EASY DEFROST PAD Press twice to cancel cooking programme.
Press to defrost meat by entering weight. Q. CLOCK PAD
M. GRILL pad Press to set clock time.
Press to select GRILL mode. R. INSTANT COOK/START PAD
N. GRILL MIX PAD Press once to cook for 1 minute at 100%
Press to select grill and microwave mix cooking mode. (HIGH power) or increase by 1 minute multi-
O. NUMBER PADS ples each time this pad is pressed during
Press to enter cooking times, clock time, weight or quantity of cooking. Press to start oven after setting pro-
food. grams.
3
R-770B
OPERATION SEQUENCE
OFF CONDITION Switch Contact Condition
Closing the door activates the 1st. latch switch, 2nd. During Oven Door
Cooking Open(No cooking)
interlock relay control switch. 1st. latch switch COM-NO Closed Opened
IMPORTANT: 2nd. interlock relay COM-NO Closed Opened
control switch
When the oven door is closed, the contacts COM-NC
Monitor Switch COM-NC Opened Closed
of the monitor switch must be open. When the micro-
wave oven is plugged in a wall outlet (220V 50Hz), the The circuit to the high voltage transformer, fan motor and
line voltage is supplied to the noise filter and the turntable motor are cut off when the 1st. latch switch, 2nd.
control unit. interlock relay control switch are made open. The oven
lamp remains on even if the oven door is opened after the
Figure O-1 on page 27
cooking cycle has been interrupted, because the relay
1. The oven display will show " SHARP MICRO- WAVE RY6 stay closed. Shown in the display is remaining time.
OVEN " . 6. MONITOR SWITCH CIRCUIT
2. Press the STOP/CLEAR pad. The oven display will The monitor switch is mechanically controlled by the
show " : ". oven door, and monitors the operation of the 1st. latch
3. Set the clock as follows.
switch and the nd. interlock relay RY2.
3-1. Press the CLOCK pad once.
6-1. When the oven door is opened during or after the
3-2. Enter the time of day by perssing the number
cycle of a cooking program, the 1st. latch switch and
pads.
3-3. Start the clock by pressing the CLOCK pad. 2nd. interlock relay control switch must open their
contacts first. After that the contacts (COM-NC) of the
NOTE: monitor switch can be closed.
1. If you do not set the clock, " : " will appear on the 6-2. When the oven door is closed, the contacts (COM-
display. When the operation of the oven is finished, " : NC) of the monitor switch must be opened. After that
" will appear on the display instead of the time of day. the contacts of the 1st. latch switch and the 2nd.
2. The oven can be also used when the clock is not set. interlock relay control switch are closed.
3. When the oven door is opened, the oven lamp comes 6-3. When the oven door is opened and the contacts of the
on at this time. 1st. latch switch and 2nd. interlock relay remain
closed, the fuse M10A will blow, because the monitor
MICROWAVE COOKING CONDITION switch is closed and a short circuit is caused.
100% (HIGH) COOKING
Enter a desired cooking time by pressing the number pads 70% (MEDIUM HIGH), 50% (MEDIUM), 30% (ME-
and start the oven by pressing START pad. DIUM LOW), 10% (LOW COOKING)
Function sequence Figure O-2 on page 27 When the microwave oven is preset for variable cooking
CONNECTED COMPONENTS RELAY
power, the line voltage is supplied to the high voltage
High voltage transformer RY2
transformer intermittently within a 32-second time base
Grill heater (Top) RY3
through the relay contact which is coupled with the cur-
Bottom heater RY4
rent-limiting relay RY2. The following levels of microwave
power are given.
Fan motor, RY5
Oven lamp, Turntable motor RY6 32 sec. ON
SETTING 100% Approx. 100%
1. The line voltage is supplied to the primary winding of 24 sec. ON 8 sec. OFF
the high voltage transformer. The voltage is converted 70% Approx. 70%
18 sec. ON 14 sec. OFF
to about 3.3 volts A.C. output on the filament winding
and high voltage of approximately 2000 volts A.C. on 50% Approx. 50%
12 sec. ON 20 sec. OFF
the secondary winding.
30% Approx. 30%
2. The filament winding voltage (3.3 volts) heats the
6 sec. ON 26 sec. OFF
magnetron filament and the high voltage (2000 volts) is
10% Approx. 10%
sent to the voltage doubling circuit, where it is doubled
to negative voltage of approximately 4000 volts D.C..
3. The 2450 MHz microwave energy produced in the Note: The On/Off time ratio does not exactly correspond
magnetron generates a wave length of 12.24 cm. This to the percentage of microwave power, because
energy is channelled through the waveguide (transport approx. 2 seconds are needed for heating up the
channel) into the oven cavity, where the food is placed magnetron filament.
to be cooked.
4. When the cooking time is up, a signal tone is heard and GRILL COOKING CONDITIONS
the relays RY2 + RY5 + RY6 go back to their home
position. The circuits to the oven lamp, high voltage The oven has three grill cooking condition. They are the
transformer, fan motor and turntable motor are cut off. TOPHEATER mode, BOTTOM HEATER mode and TOP
5. When the oven door is opened during a cooking cycle, AND BOTTOM HEATER mode.
the switches come to the following condition.
4
R-770B
TOP HEATER MODE GRILL MIX COOKING CONDITION
In this mode, the food is cooked by the top heaters. Press The oven will cook food by supplying grill heaters (top
the GRILL pad once and then enter the cooking time by heaters or Bottom heater) and microwave energy alter-
pressing the number pads. When the START pad is nately within a 48 seconds time base. And the oven has
pressed, the following operations occur: four programmed cooking mode.
Figure O-3(a) on page 27 GRILL MIX HIGH WITH TOP HEATER MODE AND
1. The relay RY3 + RY5 + RY6 are energized. GRILL MIX LOW WITH TOP HEATER MODE
2. The numbers of the digital read-out start the count In these modes, the food is cooked by the top heaters and
down to zero. the microwave energy. Press the GRILL MIX pad once for
3. Then the top heaters, turntable motor, oven lamp and GRILL MIX HIGH with TOP HEATER mode. Press the
fan motor are energized. GRILL MIX pad twice for GRILL MIX LOW with TOP
4. Now, the food is grilled by the top heaters. HEATER mode. And then enter the cooking time by
5. Upon completion of the selected cooking time, audible pressing the number pads. When the START pad is
signal sounds and the contacts of relays RY3 + RY6 pressed, the following operations occur:
are opened, then the top heaters, turntable motor and
oven lamp are de-energized. But the relay RY5 stays Figure O-4(a) on page 29
closed and the fan motor operates for 5 minutes. But if 1. The relay RY5 + RY6 are energized.
the cooking time is less than 2 minutes the relay RY5 2. The numbers of the digital read-out start the count
will not stay close. down to zero.
3. The turntable motor, oven lamp and fan motor are
BOTTOM HEATER MODE energized.
4. The relay RY2 + RY3 are energized alternately within
In this mode, the food is cooked by the bottom heater. a 48 seconds time base by the control unit.
Press the GRILL pad twice and then enter the cooking time 5. The top heaters operate through the relay RY3 is
by pressing the number pads. When the START pad is energized. And the high voltage transformer operates
pressed, the following operations occur: through the relay RY2 is energized.
Figure O-3(b) on page 28 6. The relationship between the top heating elements and
1. The relay RY4 + RY5 + RY6 are energized. magnetron operations are as follows.
2. The numbers of the digital read-out start the count 26 SEC. 22 SEC.
down to zero. ON
3. Then the bottom heater, turntable motor, oven lamp (MICRO.)
MICROWAVE POWER
OFF = APPROX. 50%
and fan motor are energized.
4. Now, the food is grilled by the bottom heater. ON
5. Upon completion of the selected cooking time, audible TOP
HEATERS OFF
signal sounds and the contacts of relays RY4 + RY6
are opened, then the bottom heating elements, turnta- GRILL MIX HIGH with TOP HEATER mode
ble motor and oven lamp are de-energized. But the
relay RY5 stays closed and the fan motor operates for 8 SEC. 40 SEC.
5 minutes. But if the cooking time is less than 2 minutes
ON
the relay RY5 will not stay close. (MICRO.) MICROWAVE POWER
OFF = APPROX. 10%
TOP AND BOTTOM HEATER MODE
ON
In this mode, the food is cooked by both the top heaters TOP
HEATERS
and bottom heater. Press the GRILL pad three times and OFF
then enter the cooking time by pressing the number pads. GRILL MIX LOW with TOP HEATER mode
When the START pad is pressed, the following operations Note: The On/Off time ratio does not exactly correspond
occur: to the percentage of microwave power, because
Figure O-3(c) on page 28 approx. 2 seconds are needed for heating up the
magnetron filament.
1. The relay RY3 + RY4 + RY5 + RY6 are energized.
7. Upon completion of the selected cooking time, audible
2. The numbers of the digital read-out start the count
signal sounds and the contacts of relays RY2 + RY3 +
down to zero.
RY6 are opened, then the top heaters, high voltage
3. Then the top heaters, bottom heater, turntable motor,
transformer, turntable motor and oven lamp are de-
oven lamp and fan motor are energized.
energized. But the relay RY5 stays closed and the fan
4. Now, the food is grilled by the top heaters and the
motor operates for 5 minutes. But if the cooking time is
bottom heater.
less than 2 minutes the relay RY5 will not stay close.
5. Upon completion of the selected cooking time, audible
signal sounds and the contacts of relays RY3 + RY4 + GRILL MIX HIGH WITH BOTTOM HEATER MODE AND
RY6 are opened, then the top heating elements, bot- GRILL MIX LOW WITH BOTTOM HEATER MODE
tom heating element, turntable motor and oven lamp
are de-energized. But the relay RY5 stays closed and IIn these modes, the food is cooked by the bottom heater
the fan motor operates for 5 minutes. But if the cooking and the microwave energy. Press the GRILL MIX pad
time is less than 2 minutes the relay RY5 will not stay three (3) times for GRILL MIX HIGH with BOTTOM
closed. HEATER mode. Press the GRILL MIX pad four (4) times
for GRILL MIXLOW with BOTTOM HEATER mode. And
then enter the cooking time by pressing the number pads.
5
R-770B
When the START pad is pressed, the following operations protect the oven door against temperature rising.
occur: Specified cooking Limited power Time base
Figure O-4(b) on page 29 Cooking mode time (minutes) output (%) (seconds)
1. The relay RY5 + RY6 are energized. Microwave 20 70 32
100% Power
2. The numbers of the digital read-out start the count
down to zero. Top heaters 30 50 48
3. The turntable motor, oven lamp and fan motor are Bottom heater 15 50 48
energized. Top browner and 10 (Top) 50 48
Bottom browner
4. The relay RY2 + RY4 are energized alternately within or Oven cooking 10 (Bottom) 50 48
a 48 seconds time base by the control unit.
5. The bottom heater operate through the relay RY4 is NOTE:
energized. And the high voltage transformer operates 1. In case of Automatic operations, the limitations of
through the relay RY2 is energized. power output are not carried out.
6. The relationship between the top heating elements and 2. In case that the STOP/CLEAR pad is pressed or the
magnetron operations are as follows. oven door is opened during cooking, the limitations of
power output are carried out after the total cooking time
26 SEC. 22 SEC.
beyond the specified cooking time.
ON
3. In case of the two or more same cooking modes are
MICROWAVE POWER
(MICRO.) OFF = APPROX. 50% carried out, the limitations of power output are carried
out after the total cooking time beyond the specified
ON cooking time.
BOTTOM
HEATER OFF 4. In case of the two or more different cooking modes are
carried out, the specified cooking time is started to
GRILL MIX HIGH with BOTTOM HEATER mode count from the point when the cooking mode is changed.
5. If the cooking mode has the power level display, the
8 SEC. 40 SEC. power level is also displayed when the limitations of
ON power output are carried out.
(MICRO.) MICROWAVE POWER
OFF = APPROX. 10%
ON
BOTTOM
HEATER
OFF
GRILL MIX LOW with BOTTOM HEATER mode
Note: The On/Off time ratio does not exactly correspond
to the percentage of microwave power, because
approx. 2 seconds are needed for heating up the
magnetron filament.
7. Upon completion of the selected cooking time, audible
signal sounds and the contacts of relays RY2 + RY4 +
RY6 are opened, then the bottom heater, high voltage
transformer, 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.
AUTOMATIC OPERATIONS
This oven has the following automatic operations;
PIZZA
CRISPY SNACK
AUTO COOK
AUTO GRILL
REHEAT
STEAM MENU
RICE COOK
EASY DEFROST
Thease will automatically compute the cooking mode and
the cooking time. And the oven will cook or defrost the food
according to the special cooking sequence.
LIMITATIONS OF POWER OUTPUT IN MANUAL
OPERATION
After the same cooking mode is carried out for more than
the specified cooking time, the power output is automati-
cally reduced by turning the control relays on and off
intermittently, as shown in the table below. This is to
6
R-770B
FUNCTION OF IMPORTANT COMPONENTS
DOOR OPEN MECHANISM HIGH VOLTAGE FUSE 0.75A
The door can be opened by pushing the open button on the The high voltage fuse blows when the high voltage rectifier
control panel. When the open button is pushed, the switch or the magnetron is shorted.
lever is moved upward, operating the latch head. The latch
head is moved upward and released from the latch hook. THERMAL CUT-OUT 125◦ Jabse Service Manual Search 2024 ◦ Jabse Pravopis ◦ onTap.bg ◦ Other service manual resources online : Fixya ◦ eServiceinfo