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R-340A
SERVICE MANUAL
S7717R340APHR
MICROWAVE OVEN
COOK KG DEF HELP
R-340A
INSTANT ACTION
To adjust quantity - touch pad
again
BEVERAGE
REHEAT PIE
REHEAT PIZZA
FROZEN VEGETABLES
RICE
FRESH VEGETABLES
JACKET POTATO
REHEAT PORRIDGE
MODEL
1.
SREAK / CHOPS
2.
ROAST MEAT
3.
POUL TRY
4. DEFROST
CHICKEN PIECES
1 2 3
4 5 6
7 8 9
POWER LEVEL
O TIMER/CLOCK
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 ................................................................................................ 5
SERVICING ...................................................................................................................................................... 6
TEST PROCEDURE ........................................................................................................................................ 8
TOUCH CONTROL PANEL ............................................................................................................................ 14
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ........................................................... 18
MICROWAVE MEASUREMENT .................................................................................................................... 24
WIRING DIAGRAM ........................................................................................................................................ 25
PICTORIAL DIAGRAM ................................................................................................................................... 26
POWER UNIT CIRCUIT .................................................................................................................................. 27
CPU UNIT CIRCUIT ........................................................................................................................................ 28
PRINTED WIRING BOARD ............................................................................................................................ 29
PARTS LIST .................................................................................................................................................... 30
SHARP CORPORATION
R-340A
R-340A
SERVICE MANUAL
PRODUCT SPECIFICATIONS
MICROWAVE OVEN
R-340A APPEARANCE VIEW
GENERAL IMPORTANT INFORMATION
This Manual has been prepared to provide Sharp Corp. Service OPERATING SEQUENCE
engineers with Operation and Service Information.
It is recommended that service engineers carefully study the
entire text of this manual, so they will be qualified to render FUNCTION OF IMPORTANT
satisfactory customer service. COMPONENTS
CAUTION
MICROWAVE RADIATION
SERVICING AND
DO NOT BECOME EXPOSED TO RADIATION FROM TROUBLESHOOTING CHART
THE MICROWAVE GENERATOR OR OTHER PARTS
CONDUCTING MICROWAVE ENERGY.
Service engineers should not be exposed to the microwave
energy which may radiate from the magnetron or other TEST PROCEDURE
microwave generating devices if it is improperly used or
connected. All input and output microwave connections,
waveguides, flanges and gaskets must be secured. Never
operate the device without a microwave energy absorbing TOUCH CONTROL PANEL
ASSEMBLY
load attached. Never look into an open waveguide or
antenna while the device is energized.
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WARNING
Never operate the oven until the following points are ensured.
(A) The door is tightly closed. MICROWAVE MEASUREMENT
(B) The door brackets and hinges are not defective.
(C) The door packing is not damaged.
(D) The door is not deformed or warped.
(E) There is not any other visible damage with the oven.
WIRING DIAGRAM
Servicing and repair work must be carried out only by trained
service engineers.
All the parts marked "*" on parts list are used at voltages more
than 250V. PARTS LIST
Removal of the outer wrap gives access to potentials above
250V.
All the parts marked "" on parts list may cause undue micro-
wave exposure, by themselves, or when they are damaged,
loosened or removed.
SHARP CORPORATION
OSAKA, JAPAN
1
R-340A
PRODUCT SPECIFICATIONS
ITEM DESCRIPTION
Power Requirements 220 Volts
50 Hertz
Single phase, 3 wire earthed
Power Consumption 1.5kW
Power Output 1000 watts nominal of RF microwave energy (IEC 705)
Operating fequency 2450 MHz
Case Dimensions Width 520 mm
Height 302 mm including foot
Depth 403 mm
Cooking Cavity Dimensions Width 348 mm
Height 212 mm
Depth 379 mm
Turntable diameter 335mm
Control Complement Touch Control System
Clock ( 1:00 - 12:59)
Timer (0 - 99 minutes 99 seconds)
Microwave Power for Variable Cooking
Repetition Rate;
HIGH ............................................... Full power throughout the cooking time
MEDIUM HIGH .................................................. approx. 70% of Full Power
MEDIUM ............................................................. approx. 50% of Full Power
MEDIUM LOW .................................................... approx. 30% of Full Power
LOW ................................................................... approx. 10% of Full Power
INSTANT ACTION pads
DEFROST pad
NUMBER pads
POWER LEVEL pad
TIMER / CLOCK pad
STOP/CLEAR pad
INSTANT COOK/START pad
Set Weight Approx. 17 kg
GENERAL INFORMATION
WARNING
THIS APPLIANCE MUST BE EARTHED
IMPOTANT
THE WIRES IN THIS MAINS LEAD ARE COLOURED IN ACCORDANCE WITH THE FOLLOWING CODE:
GREEN-AND-YELLOW : EARTH
BLUE : NEUTRAL
BROWN : LIVE
2
R-340A
APPEARANCE VIEW
1. Ventilation openings
2. Oven lamp 2
3 1
3. Door hinges
4. Door safety latches 10
5. See through door
6. Door seals and sealing 9 14
4
surfaces 7
7. Coupling
8. Door open button 12
9. Touch control panel 8
11 13
10.Digital readout 5 6 15
11.Wave guide cover
12.Power supply cord
13.Rating label
14.Turntable tray
15.Turntable support
TOUCH CONTROL PANEL
Indicator
COOK KG DEF HELP
INSTANT ACTION
To adjust quantity - touch pad again
BEVERAGE REHEAT PIE
REHEAT PIZZA FRESH VEGETABLES
INSTANT ACTION PADS
Press to cook or reheat 8 popular
FROZEN VEGETABLES JACKET POTATO
manus.
NUMBER PADS RICE REHEAT PORRIDGE
Press to enter cooking times, clock
time or weight of food. 1.
SREAK / CHOPS
2.
ROAST MEAT
3. DEFROST PAD
POULTRY DEFROST
POWER LEVEL PAD 4. Press to select the Defrost menu.
Press to select microwave power CHICKEN PIECES
setting. If not pressed, 100% is au-
tomatically selected. 1 2 3
Press to alter the cooking result for TIMER / CLOCK PAD
automatic operations.
4 5 6 Press to set Clock, timer, child
lock or demonstration mode.
7 8 9 INSTANT COOK/START PAD
Press to start oven after setting
STOP/CLEAR PAD
Press to clear during programming.
POWER LEVEL O TIMER/CLOCK programmes. Press once to cook
for 1 minute on HIGH or increase
Press once to stop operation of oven in 1 minute increments each time
during cooking; press twice to can- STOP/CLEAR INSTANT COOK /START this pad is pressed during cook-
cel cooking programme. ing.
3
R-340A
OPERATION SEQUENCE
OFF CONDITION opened after the cooking cycle has been interrupted,
Closing the door activates all door interlock switches (1st. because the relay RY1 stays closed. Shown in the
latch switch and 2nd. interlock relay control switch). display is the remaining time.
IMPORTANT 6. MONITOR SWITCH CIRCUIT
When the oven door is closed, the monitor switch contacts The monitor switch is mechanically controlled by
(COM-NC) must be open. oven door, and monitors the operation of the 1st latch
When the microwave oven is plugged in a wall outlet, rated switch and 2nd. interlock relay.
voltage is supplied to the control unit. 6-1 When the oven door is opened during or after the
Figure O-1 on page 25 cycle of a cooking program, the 1st. latch switch and
2nd. interlock relay control switch must open their
1. The display will show flashing "88:88".
contacts first.
2. To set any programmes or set the clock, you must first
After that the contacts (COM-NC) of the monitor
touch the STOP/CLEAR pad.
switch can be closed.
3. " : " appears in the display.
6-2. When the oven door is closed, the contacts (COM-
NOTE: When the oven door is opened, the oven lamp NC) of the monitor switch must be opened. After that
comes on at this time. the contacts of the 1st. latch switch and 2nd. interlock
relay control switch are closed.
MICROWAVE COOKING CONDITION 6-3. When the oven door is opened and the contacts of the
HIGH COOKING 1st. latch switch and 2nd. interlock relay remain
Enter a desired cooking time with the touching NUMBER closed. The fuse M10A will blow, because the monitor
pad and start the oven with touching START pad. switch is closed and a short circuit is caused.
Function sequence
MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
Figure O-2 on page 25 COOKING
CONNECTED COMPONENTS RELAY When the microwave oven is preset for variable cooking
Oven lamp, Fan motor, Turntable motor RY1 power, rated voltage is supplied to the power transformer
Power transformer RY2 intermittently within a 32-second time base through the
relay contact which is coupled with the current-limiting
1. Rated voltage. is supplied to the primary winding of the relay. The following levels of microwave power are given.
power transformer. The voltage is converted to about
32 sec. ON
3.3 volts A.C. output on the filament winding and high SETTING; HIGH
voltage of approximately 2000 volts A.C. on the
24 sec. ON 8 sec. OFF
secondary winding. MEDIUM HIGH Approx. 70%
2. The filament winding voltage (3.3 volts) heats the 18 sec. ON 14 sec. OFF
magnetron filament and the high voltage (2000 volts) is MEDIUM Approx. 50%
sent to the voltage doubling circuit, where it is doubled 12 sec. ON 20 sec. OFF
MEDIUM LOW Approx. 30%
to negative voltage of approximately 4000 volts D.C..
6 sec. ON 26 sec. OFF
3. The 2450 MHz microwave energy produced in the LOW Approx. 10%
magnetron generates a wave length of 12.24 cm. This
energy is channelled through the waveguide (transport
channel) into the oven cavity, where the food is placed NOTE: TheON/OFF time ratio does not exactly correspond
to be cooked. to the percentage of microwave power, because
4. When the cooking time is up, a signal tone is heard and approx. 2 seconds are needed for heating up the
the relays RY1+RY2 go back to their home position. magnetron filament.
The circuits to the oven lamp, power transformer, fan
motor and turntable motor are cut off.
5. When the door is opened during a cook cycle, the
switches come to the following condition
CONDITION
DURING DOOR OPEN
SWITCH CONTACT COOKING (NO COOK-
ING)
1st. latch switch COM-NO Closed Open
2nd. interlock relay
control switch COM-NO Closed Open
Monitor switch COM-NC Open Closed
The circuits to the power transformer, fan motor and
turntable motor are cut off when the 1st. latch switch
and 2nd. interlock relay control switch are made open.
The oven lamp remains on even if the oven door is
4
R-340A
FUNCTION OF IMPORTANT COMPONENTS
DOOR OPEN MECHANISM HIGH VOLTAGE FUSE 0.75A
The door is opened by pushing the open button on the The high voltage fuse blows when the high voltage rectifier
control panel, refer to the Figure D-1. or the magnetron is shorted.
When the open button is pushed, the open button pushes
up the switch lever, and then the switch lever pushes up OVEN THERMAL CUT-OUT
the the latch head. The latch heads are moved upward and The thermal cut-out, located on the top of the oven cavity,
released from latch hook. Now the door will open. is designed to prevent damage to the oven by fire. If the
Door foods load is overcooked, by either error in cook time or
Latch Hook defect in the control unit, the thermal cut-out will open.
Under normal operation, the oven thermal cut-out remains
Latch closed. However, when abnormally high temperatures are
Heads reached within the oven cavity, the oven thermal cut-out
2nd. Interlock
Relay Control will open at 125