Sharp R-380A User manual

R-380A

R-380A
1
SERVICE MANUAL
MICROWAVE OVEN
R-380A
GENERAL IMPORTANT INFORMATION
ThisManualhasbeenpreparedtoprovideSharpCorp.Service
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
satisfactory customer service.
CAUTION
MICROWAVE RADIATION
DO NOT BECOME EXPOSED TO RADIATION FROM
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
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
load attached. Never look into an open waveguide or
antenna while the device is energized.
WARNING
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.
(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.
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.
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
PRODUCT SPECIFICATIONS
APPEARANCE VIEW
OPERATING SEQUENCE
FUNCTION OF IMPORTANT
COMPONENTS
SERVICING AND
TROUBLESHOOTING CHART
TEST PROCEDURE
TOUCH CONTROL PANEL
ASSEMBLY
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
MICROWAVE MEASUREMENT
WIRING DIAGRAM
PARTS LIST

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ITEM DESCRIPTION
Power Requirements 230 - 240 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
HELP pad
SENSOR INSTANT REHEAT pads
SENSOR COOK pad
SLOW COOK pad
EASY DEFROST pad
MEMORY pad
MORE, LESS pads
NUMBER pads
POWER LEVEL pad
CLOCK pad
TIMER pad
STOP/CLEAR pad
INSTANT COOK/START pad
Set Weight Approx. 17 kg
PRODUCT SPECIFICATIONS
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

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APPEARANCEVIEW
1. Ventilation openings
2. Oven lamp
3. Door hinges
4. Door safety latches
5. See through door
6. Door seals and sealing
surfaces
7. Coupling
8. Door open button
9. Touch control panel
10.Digital readout
11.Wave guide cover
12.Power supply cord
13.Rating label
14.Turntable tray
15.Turntable support
8
11 13
7
2
6
3
5
49
12
10
1
14
15
TOUCH CONTROL PANEL

Info Display
HELP
DINNER
PLATE
CASSEROLE SOUP
PIZZA
VEGETABLES
MEAT
SLOW
COOK
POWER
LEVEL
STOP
CLEAR
INSTANT COOK
START
CLOCK TIMER
MEMORY
EASY
DEFROST
RICE/PASTA
DESSERTS
RICE PIE
Sensor Instant Reheat
Sensor Cook
LESS MORE
12345
6789O
COOK SENSOR KG DEF HELP
POWER LEVEL PAD
Press to select microwave power
setting. If not pressed, HIGH is au-
tomatically selected.

STOP/CLEAR PAD
Press to clear during programming.
Press once to stop operation of oven
during cooking; press twice to can-
cel cooking programme.
TIMER / CLOCK PAD
Press to set Timer.

INSTANT COOK/START PAD
Press once to cook for 1 minute on
HIGH or increase by 1 minute multi-
ples each time this pad is pressed
during cooking. Press to start the
oven after setting programmes.
Indicator
HELP PAD
Press to select auto start, informa-
tion guide on/off, child lock, dem-
onstration modes or info on pads.
Press to get cooking information.
SENSOR INSTANT REHEAT PADS
Press once to reheat 1 or 6 popular
menus.
SLOW COOK PADS
Press to cook slowly and for a long-
er time.
SENSOR COOK PADS
Press to select Sensor Cook menus.
EASY DEFROST PAD
Press to defrost frozen food by
entering quantity.
MORE( ), LESS ( ) PADS
Press to increase/ decrease the time
in one minute increments during
cooking or to after the cooking result
for the Sensor Instant Reheat, Sen-
sor Cook or Easy Defrost modes
NUMBER PADS
Press to enter cooking times, clock
time, weight or quantity of food.
MEMORY PAD
Press to enter a frequently used cook-
ing program. Press to recall the
memorized program.
CLOCK PAD
Press to set Clock.

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OPERATION SEQUENCE
OFF CONDITION
Closing the door activates all door interlock switches
(1st. latch switch, 2nd. latch switch and stop switch).
IMPORTANT
Whentheovendoorisclosed,themonitorswitchcontacts
(COM-NC) must be open.
Whenthemicrowaveovenispluggedinawalloutlet,rated
voltage is supplied to the point A3+A5 in the control unit.
Figure O-1 on page 28
1. The display shows SHARP , MICRO- , WAVE
and OVEN .
2. To set any programmes or set the clock, you must
first touch the STOP/CLEAR pad.
3. : appears in the display.
NOTE: When the oven door is opened, the oven lamp
comes on at this time.
MICROWAVE COOKING CONDITION
HIGH COOKING
Enter a desired cooking time with the touching NUMBER
pad and start the oven with touching START pad.
Function sequence
Figure O-2 on page 28
CONNECTED COMPONENTS RELAY
Oven lamp, Fan motor, Turntable motor RY1
Power transformer RY2
1. Ratedvoltage is supplied to theprimary winding of the
power 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.
2. The filament winding voltage (3.3 volts) heats the
magnetronfilamentandthehighvoltage(2000volts)is
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
magnetron generates a wave length of 12.24 cm. This
energyischanneled throughthewaveguide (transport
channel)into theoven cavity, wherethe foodis placed
to be cooked.
4. Whenthecookingtimeisup,asignaltoneisheardand
the relays RY1+RY2 go back to their home position.
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 (NOCOOKING)
1st. latch switch COM-NO Closed Open
2nd. latch switch COM-NO Closed Open
Monitor switch COM-NC Open Closed
Stop switch COM-NO Closed Open
The circuits to the power transformer, fan motor and
turntable motor are cut off when the 1st. latch switch,
2nd.latch switch,andstop switchare madeopen.The
oven lamp remains on even if the oven door is opened
after the cooking cycle has been interrupted, because
therelayRY1 staysclosed.Shown inthedisplay isthe
remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by
oven door, and monitors the operation of the 1st and
2nd. latch switches.
6-1 When the oven door is opened during or after the
cycleofacookingprogram,the1st.latchswitch,2nd.
latchswitchand stopswitchmustopen theircontacts
first.
After that the contacts (COM-NC) of the monitor
switch can be closed.
6-2. When the oven door is closed, the contacts (COM-
NC) of the monitor switch must be opened. After that
thecontacts of the 1st. latchswitch, 2nd. latch switch
and stop switch are closed.
6-3. When the oven door is opened and the contacts of
the1st. latch switch, 2nd. latch switch remain closed.
The fuse M8A will blow, because the monitor switch
is closed and a short circuit is caused.
MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING
When the microwave oven is preset for variable cooking
power, 230-240 volts A.C. power is supplied to the power
transformer intermittently within a 32-second time base
through the relay contact which is coupled with the cur-
rent-limitingrelay.Thefollowinglevelsofmicrowavepower
are given.
SETTING; 32 sec. ON
24 sec. ON
18 sec. ON
12 sec. ON
6 sec. ON
8 sec. OFF
14 sec. OFF
20 sec. OFF
26 sec. OFF
HIGH
MEDIUM HIGH
MEDIUM
MEDIUM LOW
LOW
Approx. 70%
Approx. 50%
Approx. 30%
Approx. 10%
NOTE: TheON/OFFtimeratiodoesnotexactlycorrespond
to the percentage of microwave power, because
approx. 2 seconds are needed for heating up the
magnetron filament.
SENSOR COOKING CONDITION
Using the SENSOR COOK or SENSOR INSTANT RE-
HEAT function, the foods are cooked or reheated without
figuring time, power level or quantity. When the oven
senses enough steam from the food, it relays the informa-
tiontoitsmicroprocessorwhichwillcalculatetheremaining
cooking time and power level needed for best results.
When the food is cooked, water vapor is developed. The
sensor “senses” the vapor and its resistance increases
gradually. When the resistance reaches the value set
according to the menu, supplementary cooking is started.
The time of supplementary cooking is determined by ex-
perimentwitheachfoodcategoryand inputtedintotheLSI.

R-380A
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An example of how sensor works:
1. Potatoesatroomtemperature.
Vapor is emitted very slowly.
2. Heat potatoes. Moisture and
humidity is emitted rapidly.
Youcan smell the aroma asit
cooks.
3. Sensor detects moisture and
humidity and calculates
cooking time and variable
power.
Cooking Sequence.
1. Touch each SENSOR COOK or SENSOR INSTANT
REHEATfunctionpadtooperatingthesensorcooking.
NOTE: The oven should not be operated on SENSOR
COOK or SENSOR INSTANT REHEAT
immediately after plugging in the unit. Wait five
minutes before cooking on SENSOR COOK or
SENSOR INSTANT REHEAT.
2. The coil of shut-off relay (RY-1) is energized, the
turntable motor, oven lamp and cooling fan motor are
turned on, but the power transformer is not turned on.
3. After about 16 seconds, the cook relay (RY-2) is
energized. The power transformer is turned on,
microwaveenergyisproducedandfirststageisstarted.
The16 seconds isthe coolingtime required toremove
any vapor from the oven cavity and sensor.
NOTE: During this first stage, do not open the door or
touch STOP/CLEAR pad.
4. When the sensor detects the vapor emitted from the
food,thedisplayswitchesovertotheremainingcooking
time and the timer counts down to zero.
At this time, the door may be opened to stir food, turn
it or season, etc.
5. Whenthetimerreacheszero,anaudiblesignalsounds.
Theshut-offrelayandcookrelayarede-energizedand
the power transformer, oven lamp, etc. are turned off.
6. Opening the door or touching the STOP/CLEAR pad,
the time of day will reappear on the display and the
oven will revert to an OFF condition.
DOOR OPEN MECHANISM
The door is opened by pushing the open button on the
control panel, refer to the Figure D-1.
When the open button is pushed, the open button pushes
up the switch lever, and then the switch lever pushes up
thethelatchhead.Thelatchheadsaremovedupwardand
released from latch hook. Now the door will open.
Latch Hook

2nd. Latch
Switch
Monitor 
Switch
Stop 
Switch
Switch
Lever
Latch
Heads
Door
1st. Latch 
Switch
Figure D-1. Door Open Mechanism
1ST.LATCHSWITCH,2ND. LATCHSWITCHAND
STOP SWITCH
1. Whentheovendoorisclosed,thecontacts(COM-NO)
must be closed.
2. When the oven door is opened, the contacts .(COM-
NO) must be opened.
MONITOR SWITCH
1. Whentheovendoorisclosed,thecontacts(COM-NC)
must be opened.
2. When the oven door is opened, the contacts (COM-
NC) must be closed.
3. Iftheovendoorisopenedandthecontacts(COM-NO)
ofthe1st.latchswitchand2nd.latchswitchfailtoopen,
the fuse M8A blows simultaneously with closing the
contacts (COM-NC) of the monitor switch.
CAUTION: BEFOREREPLACINGABLOWNFUSEM8A
TEST THE 1ST. LATCH SWITCH, 2ND.
LATCH SWITCH MONITOR SWITCH AND
MONITOR RESISTOR FOR PROPER OP-
ERATION.
MONITOR RESISTOR R 0.8Ω20W
ThemonitorresistorpreventsthefuseM8Aburstingwhen
the fuse M8A blows due to the operation of the monitor
switch.
ASYMMETRIC RECTIFIER
The asymmetric rectifier is a solid state device that pre-
vents current flow in both directions. And it prevents the
temperature rise of the power transformer by blowing the
fuse M8A when the high voltage rectifier is shorted.
D2 D1
ASYMMETRIC
RECTIFIER HIGH VOLTAGE 
RECTIFIER
The rated peak reverse voltage of D1 of the asymmetric
rectifieris6KVTheratedpeakreversevoltageofD2ofthe
asymmetricrectifieris1.7KV.D1andD2ofthe asymmet-
ric rectifier or high voltage rectifier are shorted when the
each peak reverse voltage goes beyond the each rated
peak reverse voltage. (The process of blowing the fuse
M8A.)
FUNCTION OF IMPORTANT COMPONENTS
MICROWAVE
AH SENSOR
MICROWAVE

R-380A
6
1. The high voltage rectifier is shorted by any causes
when microwave cooking.
2. The peak reverse voltage of D2 of the rectifier goes
beyond the rated peak reverse voltage 1.7 KV in the
voltage doubler circuit.
3. D2 of the rectifier is shorted.
4. Thelargeelectriccurrentsflowthroughthehighvoltage
winding of the power transformer.
5. Thelarge electriccurrents beyond8A flowthrough the
primary winding of the power transformer.
6. The fuse M8A blows by the large electric currents.
7. The power supply to all the electrical parts are cut off.
FUSE M8A
1. The fuse M8A blows when the contacts (COM-NO) of
the 1st. latch switch and 2nd. latch switch remain
closed with the oven door open and when the monitor
switch closes.
2. The fuse M8A also blows when asymmetric rectifier,
H.V. rectifier, H.V. wire harness, H.V.capacitor,
magnetronorsecondarywindingofpowertransformer
is shorted.
3. If the wire harness or electrical components are short-
circuited, this fuse M8A blows to prevent an electric
shock or fire hazard.
OVEN THERMAL CUT-OUT
Thethermal cut-out, located onthe top of theoven cavity,
is designed to prevent damage to the oven by fire. If the
foods load is overcooked, by either error in cook time or
defect in the control unit, the thermal cut-out will open.
Undernormaloperation,theoventhermalcut-outremains
closed.However,whenabnormallyhightemperaturesare
reached within the oven cavity, the oven thermal cut-out
will open at 125˚C, causing the oven to shut down. The
defective thermal cut-out must be replaced with new one.
MAGNETRON THERMAL CUT-OUT
The thermal cut-out located near the magnetron is de-
signed to prevent damage to the magnetron if an over
heated condition develops in the tube due to cooling fan
failure,obstructedairguide,dirtyorblockedairintake,etc.
Under normal operation, the thermal cut-out remains
closed.However,whenabnormallyhightemperaturesare
reached within the magnetron, the thermal cut-out will
open at 95˚C causing the oven to shut down, when the
magnetronhas cooledto75˚C, thethermal cut-outcloses
and cook cycle will resume.
TURNTABLE MOTOR
Theturntablemotordrivestheturntablerollerassemblyto
rotate the turntable.
FAN MOTOR
Thefanmotordrivesabladewhichdrawsexternalcoolair.
Thiscool air is directedthrough the airvanes surrounding
the magnetron and cools the magnetron. This air is
channeled through the oven cavity to remove steam and
vapors given off from the heating foods. It is then ex-
hausted through the exhausting air vents at the oven
cavity
NOISE FILTER
The noise filter prevents the radio frequency interference
that might flow back in the power circuit.

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SERVICING
WARNING TO SERVICE PERSONNEL
Microwaveovenscontaincircuitrycapableofproducingveryhighvoltageandcurrent,contactwithfollowingparts
of the high voltage circuit will result in electrocution. High voltage capacitor, Power transformer, Magnetron, High
voltage rectifier assembly, High voltage harness.
REMEMBER TO CHECK 4R
1) Reconnect all leads removed from components
during testing.
2) Replace the outer case (cabinet).
3) Reconnect the supply.
4) Run the oven. Check all functions.
Microwave ovens should not be run empty. To test for
the presence of microwave energy within a cavity,
place a cup of cold water on the oven turntable, close
the door and set the microwave timer for two (2)
minutes. Set the power level to HIGH and push the
START button. When the two minutes has elapsed
(timeratzero)carefullycheckthatthewaterisnowhot.
If the water remains cold carry out 3D checks and re-
examine the connections to the component being
tested.
REMEMBER TO CHECK 3D
1) Disconnect the supply.
2) Door opened, and wedged open.
3) Discharge high voltage capacitor.
WARNING: AGAINST THE CHARGE OF THE
HIGH-VOLTAGE CAPACITOR
Thehigh-voltagecapacitorremainschargedabout
60 seconds after the oven has been switched off.
Wait for 60 seconds and then short-circuit the
connectionofthehigh-voltagecapacitor(thatis,of
the connecting lead of the high-voltage rectifier)
against the chassis with the use of an insulated
screwdriver.
Sharprecommendthatwhereverpossiblefault-finding
is carried out with the supply disconnected. It may in,
some cases, be necessary to connect the supply after
the outer case has been removed, in this event carry
out 3D checks and then disconnect the leads to the
primary of the power transformer. Ensure that these
leads remain isolated from other components and the
ovenchassis.(Useinsulationtapeifnecessary.)When
the testing is completed carry out 3D checks and
reconnect the leads to the primary of the power trans-
former.
When all service work is completed, and the oven is fully assembled, the microwave power output should be
checked and microwave leakage test carried out
When troubleshooting the microwave oven, it is helpful to
follow the Sequence of Operation in performing the
checks.Manyofthepossiblecausesoftroublewillrequire
that a specific test be performed. These tests are given a
procedure letter which will be found in the "Test
Procedure"section.
IMPORTANT: If the oven becomes inoperative because
ofablownfuseM8Ainthe1st.latchswitch
-2nd.latch switch-monitor switch-moni-
tor resistor circuit, check the 1st. latch
switch, 2nd. latch switch, monitor switch
and monitor resistor before replacing the
fuse M8A.
TROUBLESHOOTING GUIDE

R-380A
8
Home fuse blows when power
supplycordispluggedintowall
outlet.
FUSE M8A blows when power
supplycordispluggedintowall
outlet.
Display does not show any-
thing when power supply cord
is plugged into wall outlet.
Display doesnotoperateprop-
erly when STOP/CLEAR pad
is touched.
Oven lamp does not light at
door opened. (Display ap-
pears.)
Oven does not start when the
START pad is touched. (Dis-
play appears)
Oven lamp does not light (Dis-
play appears.)
Fan motor does not operate.
(Display appears.)
Turntablemotorassemblydoes
notoperate.(Displayappears.)
Oven or any electrical parts
does not stop when cooking
time is 0 or STOP/CLEAR pad
is touched.
Oven seems to be operating
butlittleornoheatis produced
inovenload.(Microwavepower
level is set at HIGH)
Oven does not seems to be
operating properly when ME-
DIUM HIGH, MEDIUM, ME-
DIUM LOW or LOW is set.
(Oven operates properly at
HIGH and then the STOP/
CLEARpadistouchedtheoven
stops.)
Oven goes into cook cycle but
shutsdownbeforeendofcook-
ing cycle.
Oven stops as soon as when
the START pad is touched.
AHsensordoesnotendduring
Sensor Cooking condition.
(Oven does not shut off after a
cup of water is boiling by sen-
sor cooking.
Oven stops at 16 sec. after
starting.
TEST PROCEDURE
CK = Check / RE = Replace
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
CONDITION PROBLEM
ON
CONDITION
OFF
CONDITION
MAGNETRON POWER TRANSFORMER H.V. RECTIFIER ASSEMBLY HIGH VOLTAGE CAPACITOR 1ST. LATCH SWITCH
2ND. LATCH SWITCH STOP SWITCH MONITOR SWITCH MONITOR RESISTOR THERMAL CUT-OUT 95˚C /125˚C
FAN MOTOR TURNTABLE MOTOR FUSE M8A TOUCH CONTROL PANEL KEY UNIT RELAY (RY-1, RY-2)
FOIL PATERN ON P.W.B. POWER SUPPLY CORD SHORTED WIRE HARNESS OPENED WIRE HARNESS OVEN LAMP OR SOCKET
WALL OUTLET MISADJUSTMENT SWITCH HOME FUSE OR BREAKER BLOCKED COOLING FAN BLOCKED VENTILATION NOISE FILTER AH SENSOR
SENSOR
COOKING
CONDITION
ABC D EEEEGFHHIK LMN RE CK CKRE CK CKCK CK CK JO