Sharp Carousel R-3S56 User manual

R-3S56
SHARP CORPORATION
SERVICE MANUAL
In interests of user-safety the oven should be restored to its original
condition and only parts identical to those specified should be used.
MODEL R-3S56
S9510R3S56PX/
MICROWAVE OVEN
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
CONTROL PANEL CIRCUIT ...............................................................................................................................27
PRINTED WIRING BOARD .................................................................................................................................28
PARTS LIST ....................................................................................................................................................... 29

R-3S56

R-3S56
1
SERVICE MANUAL
PRODUCT SPECIFICATIONS
SHARP CORPORATION
OSAKA, JAPAN
TEST PROCEDURE
SERVICING AND
TROUBLESHOOTING CHART
FUNCTION OF IMPORTANT
COMPONENTS
OPERATING SEQUENCE
APPEARANCE VIEW
MICROWAVE MEASUREMENT
WIRING DIAGRAM
PARTS LIST
TOUCH CONTROL PANEL
ASSEMBLY
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
MICROWAVE OVEN
R-3S56
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.
Serviceengineersshouldnotbeexposedtothemicrowave
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
microwave exposure, by themselves, or when they are dam-
aged, loosened or removed.

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ITEM DESCRIPTION
Power Requirements 220 Volts
50 Hertz
Single phase, 3 wire earthed
Power Consumption 1.06 kW, Approx. 4.9A
Power Output 700 watts nominal of RF microwave energy (IEC 705)
Operating fequency 2450 MHz
Case Dimensions Width 450 mm
Height 295 mm including foot
Depth 361 mm
Cooking Cavity Dimensions Width 285 mm
Height 178 mm
Depth 313 mm
Turntable diameter 272mm
Control Complement Touch Control System
Timer (0 - 99 minutes 90 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
TIME pads
AUTO COOK pad
STOP/CLEAR pad
SERVES/POWER LEVEL pad
START/INSTANT COOK pad
AUTO COOK MENUS
Set Weight (Approx.) 14 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 opening
2. Oven lamp
3. Door hinges
4. Door safety latches
5. See through door
6. Coupling
7. Door open button
8. Touch control panel
9. Digital read-out
10.Wave guide cover
11.Power supply cord
12. Earth wire
TOUCH CONTROL PANEL
a. TIME PADS
Press to enter cooking time.
b. AUTO COOK PAD
Press to select AUTO COOK menu.
c. POWER LEVEL/SERVES PAD
Press to select microwave power setting. If not
pressed, 100% is automatically selected.
Press to enter serves after selecting AUTO COOK
menu.
d. STOP / CLEAR PAD
Press to clear during programming.
Pressoncetostopoperationofovenduringcooking:
press twice to cancel cooking programme.
e. INSTANT COOK / START PAD
Pressoncetocookfor1minuteat100%orincrease
by1 minutemultipleseach timethispadispressed
during cooking.
Press to start oven after setting programmes.
f. AUTO COOK MENUS
32110
9
8
7
456411
1
12
a
b
c
d
e
f

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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
When the oven door is closed, the monitor switch contacts
(COM-NC) must be open.
When the microwave oven is plugged in a wall outlet, rated
voltage is supplied to the point A3+A5 in the control unit.
Figure O-1 on page 25
1. The display shows " 0".
NOTE: When the oven door is opened, the oven lamp
comes on at this time.
MICROWAVE COOKING CONDITION
HIGH COOKING
EnteradesiredcookingtimewiththetouchingTimekeyand
start the oven with touching START key.
Function sequence
Figure O-2 on page 25
CONNECTED COMPONENTS RELAY
Oven lamp, Fan motor, Turntable motor RY1
Power transformer RY2
1. Rated voltage is supplied to the primary winding of the
powertransformer.Thevoltageisconvertedtoabout3.3
volts A.C. output on the filament winding and high
voltageofapproximately2000voltsA.C.onthesecondary
winding.
2. The filament winding voltage (3.3 volts) heats the
magnetron filament and the high voltage (2000 volts) is
senttothevoltagedoublingcircuit,whereitisdoubledto
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
energy is channelled through the waveguide (transport
channel)intotheovencavity,wherethefoodisplacedto
be cooked.
4. When the cooking time is up, a signal tone is heard and
therelaysRY1+RY2gobacktotheirhomeposition.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 switches 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, and stop 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 the
remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by oven
door,andmonitorstheoperationofthe1stand2nd.latch
switches.
6-1 Whentheoven door isopenedduringorafter the cycle
of a cooking program, the 1st. latch and 2nd. latch
switch must open their contacts first.
Afterthat thecontacts(COM-NC) ofthemonitor switch
can be closed.
6-2. Whentheoven dooris closed,the contacts(COM-NC)
of the monitor switch must be opened. After that the
contactsofthe1st.latch,2nd.latchandstopswitchare
closed and the contacts (COM-NO) of the stop switch
can be opened.
6-3. When the oven door is opened and the contacts of the
1st and 2nd latch switches remain closed. The fuse
M6.3A 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, rated voltage is supplied to the power transformer
intermittently within a 32-second time base through the
relaycontactwhichiscoupledwiththecurrent-limitingrelay.
The following levels of microwave power 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.

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DOOR OPEN MECHANISM
The door is opened by pushing the open button on the
control panel, When the open button is pushed, the switch
leveronthelatchhookismovedupward,operatingthelatch
head. The latch head is moved upward, and released from
latch hook. Now, the door can be opened.
LATCH HOOK
1ST. LATCH SWITCH
2ND. LATCH SWITCH
MONITOR SWITCH
LATCH
HEADS
SWITCH LEVER
DOOR OPEN BUTTON
DOOR
STOP SWITCH
Figure D-1. Door Open Mechanism
1ST. LATCH SWITCH, 2ND. LATCH SWITCH AND
STOP SWITCH
1. When the oven door is closed, the contacts (COM-NO)
must be closed.
2. Whentheovendoorisopened,thecontacts.(COM-NO)
must be opened.
MONITOR SWITCH
1. When the oven door is closed, the contacts (COM-NC)
must be opened.
2. When the oven door is opened, the contacts (COM-NC)
must be closed.
3. If the oven door is opened and the contacts (COM-NO)
of the 1st latch switch and 2nd latch switch fail to open,
the fuse blows simultaneously with closing the contacts
(COM-NC) of the monitor switch.
CAUTION: BEFORE REPLACING A FUSE TEST THE
1ST LATCH SWITCH, 2ND LATCH SWITCH,
MONITOR SWITCH AND MONITOR RESIS-
TOR FOR PROPER OPERATION. (REFER
TO CHAPTER "TEST PROCEDURE")
MONITOR RESISTOR R 0.8Ω20W
The monitor resistor prevents the fuse bursting when the
fuse blows due to the operation of the monitor switch.
FUSE
1. The fuse blows when the contacts (COM-NO) of the 1st
latchswitch and 2nd latch switch remainclosedwith the
oven door open and when the monitor switch closes.
FUNCTION OF IMPORTANT COMPONENTS
2. If the wire harness or electrical components are short-
circuited, this fuse blows to prevent an electric shock or
fire hazard.
TEMPERATURE FUSE 150˚C (MG)
Thisfuseprotectsthemagnetronagainstoverheating.Ifthe
temperature goes up higher than 150˚C because the fan
motor is interrupted, the air inlet duct is blocked or the
ventilationopeningsareobstructed,thefuseblowsandcuts
off the power supplying to the power transformer.
The defective fuse must be replaced with new rated one.
TEMP. FUSE 150˚C (OVEN)
The temp. fuse located on the top of the oven cavity is
designed to prevent damage to the oven if the foods in the
oven catch fire due to over heating produced by improper
setting of cook time or failure of control unit.
Under normal operation, the temp. fuse remains closed.
However,whenabnormally high temperaturesarereached
within the oven cavity, the temp. fuse will open at 150˚C,
causing the oven to shut down. The defective fuse must be
replace with a new one.
THERMAL CUT-OUT 95˚C
Thethermalcut-outprotectthefanmotoragainstoverheat.
Ifitstemperaturegoesuphigherthan95˚Cbecausethefan
motor is locked or the ventilation openings are blocked, the
contactsofthethermalcut-outwillopenandswitchesoffthe
oven.Whentheovencoolsitselfdownto75˚C,thecontacts
of the thermal cut-out will close again.
TURNTABLE MOTOR
The turntable motor drives the roller stay to rotate the
turntable.
FAN MOTOR FM
The fan motor drives a blade which draws external cool air.
This cool air is directed through the air vanes surrounding
the magnetron and cools the magnetron. This air is chan-
nelled through the oven cavity to remove steam and va-
pours given off from the heating foods. It is then exhausted
through the exhausting air vents at the oven cavity

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SERVICING
WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with any part 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 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
The high-voltage capacitor remains charged about
60 seconds after the oven has been switched off.
Wait for 60 seconds and then short-circuit the con-
nection of the high-voltage capacitor (that is, of the
connectingleadof thehigh-voltagerectifier)against
thechassiswith theuseofan insulated screwdriver.
Sharp recommend that wherever possible fault-finding
is carried out with the supply disconnected. It may in,
some cases, be necessary to connect the supply after
theouter casehasbeen removed,inthis eventcarryout
3D checks and then disconnect the leads to the primary
of the power transformer. Ensure that these leads re-
main isolated from other components and the oven
chassis. (Use insulation tape if necessary.) When the
testing is completed carry out 3D checks and reconnect
the leads to the primary of the power transformer.
REMEMBER TO CHECK 4R
1) Reconnectallleadsremovedfromcomponentsduring
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
thepresenceofmicrowave energy withinacavity,place
acupofcoldwateronthe oven turntable, close the door
andset the microwavetimerfor two(2)minutes.Setthe
powerleveltoHIGHand push the START button. When
the two minutes has elapsed (timer at zero) carefully
checkthatthewaterisnowhot.Ifthewaterremainscold
carry out3D checks and re-examine the connections to
the component being tested.
Whenallserviceworkiscompleted,andtheoven isfullyassembled,themicrowavepoweroutputshouldbechecked
and microwave leakage test carried out
When troubleshooting the microwave oven, it is helpful to
follow the Sequence of Operation in performing the
checks. Many of the possible causes of trouble will require
that a specific test be performed. These tests are given a
procedure letter which will be found in the "Test
Procedure"section.
TROUBLESHOOTING GUIDE
IMPORTANT: Iftheovenbecomesinoperativebecauseof
a blown fuse M6.3A in the 1st. latch switch
-2nd.latchswitch-monitorswitch-monitor
resistor circuit, check the 1st. latch switch,
2nd.latch switch,monitorswitchand moni-
torresistorbeforereplacingthefuseM6.3A.

R-3S56
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Homefuseblowswhenpower
supply cord is plugged into
wall outlet.
FUSE M6.3A blows when
powersupplycordisplugged
into wall outlet.
" 0" does not appear in dis-
play but power supply cord is
plugged into wall outlet.
Display does not operate
properlywhenSTOP/CLEAR
pad is touched.
Oven lamp does not light at
door opened. (Display ap-
pears.)
Ovendoesnot startwhenthe
STARTpadis touched. (Dis-
play appears)
Ovenlampdoesnotlight(Dis-
play appears.)
Fan motor does not operate.
(Display appears.)
Turntable motor assembly
does not operate. (Display
appears.)
Oven or any electrical parts
does not stop when cooking
time is 0 or STOP/CLEAR
pad is touched.
Oven seems to be operating
but little or no heat is pro-
duced in oven load. (Micro-
wave power level is set at
HIGH)
Oven does not seems to be
operatingproperly when ME-
DIUM HIGH, MEDIUM, ME-
DIUM LOW or LOW is set.
(Oven operates properly at
HIGH and then the STOP/
CLEAR pad is touched the
oven stops.)
Oven goes into cook cycle
but shuts down before end of
cooking cycle.
OFF
CONDITION
PROBLEM
CONDITION
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
TEST PROCEDURE
ON
CONDITION
CK = Check / RE = Replace
ABC CKD EEEE FGGGHHI JLMRE CKCKRE CKCKCKCKCK K
MAGNETRON
POWER TRANSFORMER H.V. RECTIFIER ASSEMBLY HIGH VOLTAGE WIRE HIGH VOLTAGE CAPACITOR 1ST. LATCH SWITCH
2ND. LATCH SWITCH STOP SWITCH MONITOR SWITCH MONITOR RESISTOR TEMPERATURE FUSE 150˚C (OVEN)
THERMAL CUT-OUT 95˚C TEMPERATURE FUSE 150˚C (MAG.) FAN MOTOR TURNTABLE MOTOR FUSE M6.3A TOUCH CONTROL PANEL
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 TACT SWITCH

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TEST PROCEDURES
PROCEDURE
LETTER
CARRY OUT 3D CHECKS.
Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.
To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron
filament terminals, the meter should show a reading of less than 1 ohm.
To test for short filament to anode condition, connect ohmmeter between one of the filament terminals
and the case of the magnetron (ground). This test should be indicated an infinite resistance. If a low or
zero resistance reading is obtained then the magnetron should be replaced.
MICROWAVE OUTPUT POWER (IEC 705)
The following test procedure should be carried out with the microwave oven in a fully assembled
condition (outer case fitted). Microwave output power from the magnetron can be measured by way of
IEC 705, i.e. it can be measured by using water load how much it can be absorbed by the water load.
Tomeasurethemicrowaveoutputpower inthemicrowaveoven, therelationof calorieandwattis used.
When P(W) heating works for t(second), approximately P x t/4.187 calorie is generated. On the other
hand, if the temperature of the water with V(ml) rises∆T (°C) during this microwave heating period, the
calorie of the water is V x ∆T.
NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL
WHILE THE OVEN IS IN OPERATION.
AMAGNETRON TEST
The formula is as follows;
P x t / 4.187 = V x ∆T P (W) = 4.187 x V x ∆T / t
Our condition for water load is as follows:
Room temperature..............around 20°C PowersupplyVoltage.........Ratedvoltage
Water load.........1000 g Initial temperature...........10±2°C Heating time.........60 sec.
P = 70 x ∆T
Measuring condition:
1. Container
The water container must be a cylindrical borosilicate glass vessel having a maximum material
thickness of 3 mm and an outside diameter of approximately 190 mm.
2. Temperature of the oven and vessel
The oven and the empty vessel are at ambient temperature prior to the start the test.
3. Temperature of the water
The initial temperature of the water is (10±2)°C.
4. Selecttheinitialandfinalwatertemperaturesothatthemaximumdifference between the final water
temperature and the ambient temperature is 5°C.
5. Select stirring devices and measuring instruments in order to minimize addition or removal of heat.
6. Thegraduation ofthethermometermustbescaledby 0.1°Cat minimumandaccurate thermometer.
7. The water load must be (1000±5) g.
8. “t” is measured while the microwave generator is operating at full power. Magnetron filament heat-
up time is not included.
NOTE:The operation time of the microwave oven is “t + 2” sec. 2 sec. is magnetron filament heat-up time.
Measuring method:
1. Measure the initial temperature of the water before the water is added to the vessel.
(Example: The initial temperature T1 = 11°C)
2. Add the 1 litre water to the vessel.
3. Place the load on the centre of the shelf.
4. Operate the microwave oven at HIGH for the temperature of the water rises by a value ∆T of
(10 ±2)°C.
5. Stir the water to equalize temperature throughout the vessel.
COMPONENT TEST

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9
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
6. Measure the final water temperature. (Example: The final temperature T2 = 21°C)
7. Calculate the microwave power output P in watts from above formula.
Initial temperature .................................................................................................. T1 = 11°C
Temperature after (60 + 2) = 62 sec. ..................................................................... T2 = 21°C
Temperature difference Cold-Warm.................................................................... ∆T1 = 10°C
Measured output power
The equation is “P = 70 x ∆T” ...................................................... P = 70 x 10°C = 700 Watts
JUDGMENT: The measured output power should be at least ±15 % of the rated output power.
CAUTION: 1°C CORRESPONDS TO 70 WATTS REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
1000g
1000g
1000g
T1˚C T2˚C
Heat up for62 sec.
B POWER TRANSFORMER TEST
WARNING: Highvoltagesandlargecurrentsarepresentatthesecondarywindingandfilament
winding of the power transformer. It is very dangerous to work near this part when
the oven is on. NEVER make any voltage measurements of the high-voltage
circuits, including the magnetron filament.
CARRY OUT 3D CHECKS.
Disconnect the leads to the primary winding of the power transformer. Disconnect the filament and
secondarywindingconnectionsfromtherestoftheHVcircuitry.Usinganohmmeter,setonalowrange,
it is possible to check the continuity of all three windings. The following readings should be obtained:
a. Primary winding ....................approx. 1.95 Ω
b. Secondary winding ...............approx. 136.6 Ω
c. Filament winding...................less than 1Ω
Ifthereadingobtainedarenotstatedasabove,thenthepowertransformerisprobablyfaultyandshould
be replaced.
CARRY OUT 4R CHECKS.
C HIGH VOLTAGE RECTIFIER ASSEMBLY TEST
CARRY OUT 3D CHECKS.
Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested
using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal A+B of the high
voltage rectifier and note the reading obtained. Reverse the meter leads and note this second reading.
The normal resistance is infinite in one direction and more than 100 kΩin the other direction.
AB
High voltage rectifier

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10
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER COMPONENT TEST
CARRY OUT 4R CHECKS.
NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF THE
MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BECAUSE
OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.
D HIGH VOLTAGE CAPACITOR TEST
CARRY OUT 3D CHECKS.
A. Isolate the high voltage capacitor from the circuit.
B. Continuity check must be carried out with measuring instrument which is set to the highest resistance
range.
C. Anormalcapacitorshowscontinuityforashorttime(kick)andthenaresistanceofabout10MΩafterithas
been charged.
D. A short-circuited capacitor shows continuity all the time.
E. An open capacitor constantly shows a resistance about 10 MΩbecause of its internal 10MΩresistance.
F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
G. The resistance across all the terminals and the chassis must be infinite when the capacitor is normal.
If incorrect reading are obtained, the high voltage capacitor must be replaced.
CARRY OUT 4R CHECKS.
ESWITCH TEST
CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the
following table. Table: Terminal Connection of Switch
Plunger Operation COM to NO COM to NC
Released O.C. S.C.
Depressed S.C. O.C.
COM; Common terminal,
NO; Normally open terminal
NC; Normally close terminal
S.C.; Short circuit
O.C.; Open circuit
FMONITOR RESISTOR TEST
If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.
CARRY OUT 4R CHECKS.
CARRY OUT 3D CHECKS.
Disconnecttheleadsfromthemonitorresist.Usinganohmmeterandsetonalowrange.Checkbetween
the terminals of the monitor resistor.
The resistance of monitor resistor is approx. 0.8 ohms.
If incorrect readings are obtained, replace the monitor resistor.
CARRY OUT 4R CHECKS.
GTEMPERATURE FUSE OR THERMAL CUT-OUT TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the temperature fuse or thermal cut-out. Then using an
ohmmeter, make a continuit test across the two terminals as described in the below.
CARRY OUT 4R CHECKS.
Table: Thermal cut-out Test
Temperature of "ON" condition Temperature of "OFF" condition Indication ofohmmeter
Parts Name (closed circuit) (˚C) (open circuit) (˚C) (When room temperature
is approx. 20˚C)
Temperature fuse 150˚C This is not resetable type. Above 150˚C Closed circuit.
Thermal cut-out 95˚C Below 75˚C Above 95˚C Closed circuit.

R-3S56
11
PROCEDURE
LETTER COMPONENT TEST
TEST PROCEDURES (CONT'D)
If incorrect readings are obtained, replace the temp. fuse or thermal cut-out.
Anopencircuittemperaturefuse(MAG.)indicatesthatthemagnetronhasoverheated, this may be due
to resistricted ventilation, cooling fan failure.
Anopencircuittemperaturefuse(OVEN)indicatesthattheovencavityhasoverheated,thismaybedue
to no load operation.
An open circuit thermal cut-out 95˚C indicates that the fan motor winding has overheated, this may be
due to resisted ventilation or locked cooling fan.
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 330 Ω
Turntable motor Approximately 12 kΩ
CARRY OUT 3D CHECKS.
Disconnect the leads from the motor.
Using an ohmmeter, check the resistance between the two terminals as described in the table below.
H MOTOR WINDING TEST
If incorrect readings are obtained, replace the motor.
CARRY OUT 4R CHECKS.
I FUSE
CARRY OUT 3D CHECKS.
Ifthefuseis blown whenthedoorisopened,check the 1st latchswitch,2ndlatchswitch, monitor switch
and monitor resistor.
If the fuse is blown by incorrect door switching replace the defective switch(s) and the fuse.
If the fuse is blown, there is a shorts or grounds in electrical parts or wire harness.
Check them and replace the defective parts or repair the wire harness.
CARRY OUT 4R CHECKS.
CAUTION: Only replace fuse with the correct value replacement.
J TOUCH CONTROL PANEL ASSEMBLY TEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter
and ohmmeter.
In this service manual, the touch control panel assembly is in one unit, and troubleshooting by unit
replacement is described according to the symptoms indicated.
1. Tact Switch.
The following symptoms indicate a defective tact switch. Replace the tact switch.
a) When touching the tact switches, a certain tact switch produces no signal at all.
b) When touching the tact switches, sometimes a tact switch produces no signal.
2. Control Panel
The following symptoms may indicate a defective control unit. Before replacing the control unit,
perform the tact switch test (Procedure K) to determine if control unit is faulty.
2-1 In connection with tact switches.
a) When touching the tact switches, a certain group of tact switches do not produce a signal.
b) When touching the tact switches, no tact switches produce a signal.
2-2 In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.

R-3S56
12
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER COMPONENT TEST
d) The corresponding segments of all digits do not light up or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
2-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Cooking is not possible.
If the display fails to clear when the STOP/CLEAR tact switch is depressed, first verify that the door
sensing switch(stop switch) operates properly; that is the contacts are closed when the door is closed
and open when the door is open. If the door sensing switch(stop switch) is good, make sure the door
sensing switch is closed (either close the door or short the door sensing switch connecter). Use the tact
switch matrix indicated on the control panel schematic and place a jumper wire between the pins that
correspond to the STOP/CLEAR tact switch making mo-
mentary contact. If the control unit responds by clearing
with a beep, the tact switch is faulty and must be replaced.
If the control unit does not respond, it is a faulty and must
bereplaced. Ifaspecificpaddoesnot respond, the above
method may be used (after clearing the control unit) to
determine if the control unit or tact switch is at fault.
K TACT SWITCH TEST
SW1 10 SW2 1 SW3 10
SW4 SW6
SW7
SW5
MIN. MIN. SEC.
AUTOCOOK STOP
CLEAR
START/
INSTANTCOOK
SERVES/
POWERLEVEL
LRELAY TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 3 and 5 of the 3 pin connector (A) on the
control unit with an A.C. voltmeter.
The meter should indicate 220 volts, if not check oven circuit.
RY1 and RY2 Relay Test
These relays are operated by D.C. voltage
CheckvoltageattherelaycoilwithaD.C.voltmeterduringthemicrowavecookingorconvectioncooking
operation.
DC. voltage indicated .................... Defective relay.
DC. voltage not indicated . ............ Check diode which is connected to the relay coil. If diode is good,
CARRY OUT 4R CHECKS.
RELAY SYMBOL OPERATIONAL
VOLTAGE CONNECTED COMPONENTS
RY1 Approx. 19.0V.D.C. Oven lamp/Turntable motor/Cooling fan motor
RY2 Approx. 18.0V.D.C. Power transformer
MPROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on
thePWB,thisfoilpatternactsasafuse.Ifthefoil pattern is open, follow the troubleshooting guide given
below for repair.
Problem: POWER ON, indicator does not light up.
CARRY OUT 3D CHECKS.

R-3S56
13
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER COMPONENT TEST
NOTE: At the time of these repairs, make a visual
inspectionofthevaristorforburningdamage
and examine the transformer with tester for
the presence of layer short-circuit (check
primary coil resistance). If any abnormal
condition is detected, replace the defective
parts.
CARRY OUT 4R CHECKS.
STEPS OCCURANCE CAUSE OR CORRECTION
1 The rated voltage is not applied to POWER
terminal of CPU connector (CN-A) Check supply voltage and oven main unit.
2 The rated voltage is applied to primary side of
power transformer. Power transformer or secondary circuit defective. Check and repair.
3 Only pattern at "a" is broken. *Insert jumper wire J1 and solder.
4 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".
VRS1
CN-A
(J1)
RY2
POWER 5
D82
ac
b
d

14
R-3S56
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOIUCH CONTROL PANEL
Control Unit
Control unit consists of tact switches, LSI, power source
circuit, synchronizing signal circuit, ACL circuit, buzzer
circuit and indicator circuit.
1) Tact Switches
The tact switches are composed of a matrix, signals
generatedintheLSIaresenttothetactswitchesthrough
R60-R62. When a tact switches is touched, a signal is
completedthroughthetactswitchesandpassedbackto
theLSIthroughR81-R83toperformthefunctionthatwas
requested.
2) LSI
This LSI controls the key strobe signal, relay driving
signal for oven function and indicator signal.
3) Power Source Circuit
This circuit generates voltages necessary in the control
unit.
Symbol Voltage Application
VC -5V LSI(IC1)
4) Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit. It accompanies a very small error because it
works on commercial frequency.
5) ACL Circuit
AcircuittogenerateasignalswhichresetstheLSItothe
initial state when power is supplied.
6) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
noticingsounds(keytouchsoundandcompletionsound).
7) Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
8) Relay Circuit
To drive the magnetron, fan motor, turntable motor and
light the oven lamp.
9) Indicator Circuit
Indicator element is a Light-emitting diode.
Basically,aLight-emittingdiodeistriodehavingacathode
and an anode.
The Light-emitting diode has 4-digits, 8-segments are
used for displaying figures.

15
R-3S56
DESCRIPTION OF LSI
LSI(IZA588DR):
The I/O signal of the LSI(IZA588DR) is detailed in the following table.
Pin No. Signal I/O Description
1XOUT OUT Internal clock oscillation frequency control output.
Output to control oscillation input of XOUT.
2XIN IN Internal clock oscillation frequency input setting.
Theinternalclockfrequencyissetbyinsertingthe ceramicfilteroscillationcircuitwith
respect to XIN terminal.
3 RESET IN Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is supplied. Temporarily
setto “L”levelthe momentpowerissupplied,atthistimethe LSIisset. Thereafterset
at “H” level.
4R70OUT Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay. In Low operation, the signals holds “L” level during
microwave cooking and “H” level while not cooking. In other cooking modes
(70%,50%,30%,10%)thesignalturnsto “L”leveland“H”levelin repetitionaccording
to the power level.
5R71OUT Oven lamp,turntable motor and cooling fan motor driving signal. (Square
Waveform : 50Hz)
Toturnonandoffthecontrol relay. The pulse signal (50Hz) is delivered tothecontrol
relay driving circuit and cook relay control circuit.
6R72OUT Terminal not used.
7 -10 R40 - R43OUT Digit selection signal.
Refer to the touch control panel circuit about the relation between signals and digits.
Normally,onepulseisoutputineverysynchronizedsignalperiod,andinputtothelight
emitting diode.
11-13 R50 - R52OUT Segment data signal.
Refer to the touch control panel circuit for the relationship between signals and
indicators. Normally, one pulse is output in every synchronized signal period, and
input to the anode of the light emitting diode.
14 VSS IN Connected to VC.
15 R53OUT Segment data signal.
Signal similar to R50.
16 R60OUT Segment data signal.
Signal similar to R50.
Switch strobe signal.
Signalappliedto tact switch section. A pulse signal isinputtoR81-R83terminalwhile
one of diode D91 line switches on switch matrix is touched.
17 R61OUT Segment data signal.
Signal similar to R50.
Switch strobe signal.
Signalappliedto tact switch section. A pulse signal isinputtoR81-R83terminalwhile
one of diode D92 line switches on switch matrix is touched.
18 R62OUT Segment data signal.
Signal similar to R50.
Switch strobe signal.
Signalappliedto tact switch section. A pulse signal isinputtoR81-R83terminalwhile
one of diode D93 line switches on switch matrix is touched.
19 R63OUT Segment data signal.
Signal similar to R50.
20 INT2 IN Signal synchronized with commercial source frequency(50Hz).
This is basic timing for time processing of LSI.

16
R-3S56
Pin No. Signal I/O Description
21 R81IN Signal coming from touch tact switch.
When either one of resistor R93line switches on switch matrix is touched, a
corresponding signal will be input into R81.
22 R82IN Signal coming from touch tact switch.
When either one of resistor R92line switches on switch matrix is touched, a
corresponding signal will be input into R82.
23 R83IN Signal coming from touch tact switch.
When either one of resistor R91line switches on switch matrix is touched, a
corresponding signal will be input into R83.
24 R90OUT Terminal not used.
25 SO OUT Signal to sound buzzer.
A: key touch sound(0.12 sec.).
B: Completion sound(2.4 sec.).
26 SCK OUT Connected to GND. (Pull up through resistor R2)
27 KEO IN Input signal which communicates the door open/close information to LSI.
Door closed; “H” level signal.
Door opened; “L” level signal.
28 VDD IN Connected to GND.

17
R-3S56
SERVICING
1. Precautions for Handling Electronic Components
This unit uses CMOS LSI in the integral part of the
circuits. When handling these parts, the following pre-
cautions should be strictly followed. CMOS LSI have
extremely high impedance at its input and output termi-
nals. For this reason, it is easily influenced by the
surroundinghighvoltagepowersource, static electricity
charge in clothes, etc, and sometimes it is not fully
protected by the built-in protection circuit.
In order to protect CMOS LSI.
1) Whenstoringandtransporting,thoroughlywrapthemin
aluminiumfoil.AlsowrapallPWboardscontainingthem
in aluminium foil.
2) When soldering, ground the technician as shown in the
figure and use grounded soldering iron and work table.
2. Shapes of Electronic Components
3. Servicing of Touch Control Panel
We describe the procedures to permit servicing of the
touch control panel of the microwave oven and the
precautions you must take when doing so. To perform
the servicing, power to the touch control panel is avail-
able either from the power line of the oven itself or from
an external power source.
(1)Servicingthetouchcontrol panelwithpowersupply
of the oven:
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF THE MI-
CROWAVE OVEN IS STILL LIVE DURING SERVIC-
ING PRESENTS A HAZARD.
Therefore, when checking the performance of the touch
control panel, put the outer cabinet on the oven to avoid
touching the high voltage transformer, or unplug the
primary terminal (connector) of the high voltage trans-
former to turn it off; the end of such connector must be
insulatedwithaninsulatingtape.Afterservicing,besure
to replace the leads to their original locations.
A. On some models, the power supply cord between the
touchcontrolpanelandtheovenitselfissoshortthatthe
two can’t be separated. For those models, check and
repair all the controls (sensor-related ones included) of
thetouchcontrolpanelwhilekeepingitconnectedto the
oven.
approx. 1M ohm
B. On some models, the power supply cord between the
touch control panel and the oven proper is long enough
that they may be separated from each other. For those
models, therefore, it is possible to check and repair the
controls of the touch control panel while keeping it apart
from the oven proper; in this case you must short both
ends of the door sensing switch (on PWB) of the touch
control panel with a jumper, which brings about an
operational state that is equivalent to the oven door
being closed. As for the sensor-related controls of the
touchcontrolpanel,checking them ispossibleifdummy
resistor(s) with resistance equal to that of the controls
are used.
(2)Servicingthetouchcontrol panelwithpowersupply
from an external power source:
Disconnect the touch control panel completely from the
oven proper,and short both ends of the door sensing
switch(onPWB)of the touchcontrolpanel,whichbrings
about an operational state that is equivalent to the oven
doorbeing closed.Connectan externalpowersource to
the power input terminal of the touch control panel, then
itispossibletocheckandrepairthecontrolsofthetouch
control panel it is also possible to check the sensor-
related controls of the touch control panel by using the
dummy resistor(s).
4. Servicing Tools
Toolsrequiredtoservicethetouchcontrolpanelassem-
bly.
1) Soldering iron: 30W
(It is recommended to use a soldering iron with a
grounding terminal.)
2) Oscilloscope:Singlebeam,frequencyrange:DC-10MHz
type or more advanced model.
3) Others: Hand tools
5. Other Precautions
1) Before turning on the power source of the control unit,
remove the aluminium foil applied for preventing static
electricity.
2) Afteraluminiumfoilisremoved,becarefulthatabnormal
voltage due to static electricity etc. is not applied to the
input or output terminals.
3) Attach connectors, electrolytic capacitors, etc. to PWB,
making sure that all connections are tight.
4) Be sure to use specified components where high preci-
sion is required.
ECB
IC
LM7905CT
3
2
1Transistor
KRA101M
KRA222M
KRA223M
KRC243M

18
R-3S56
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below before
operating the oven.
1. Door does not close firmly.
2. Door hinge, support or latch hook is damaged.
3. The door gasket or seal or damaged.
4. The door is bent or warped.
5. There are defective parts in the door interlock system.
6. There are defective parts in the microwave generating
and transmission assembly.
7. There is visible damage to the oven.
Do not operate the oven:
1. Without the RF gasket (Magnetron).
2. If the wave guide or oven cavity are not intact.
3. If the door is not closed.
4. If the outer case (cabinet) is not fitted.
1. Disconnect oven from power supply.
2. Make sure that a definite” click” can be heard when the
microwave oven door is unlatched. (Hold the door in a
closed position with one hand, then push the door open
button with the other, this causes the latch leads to rise,
it is then possible to hear a “click’ as the door switches
operate.)
3. Visuallycheckthedoorandcavityfaceplatefordamage
(dents, cracks, signs of arcing etc.).
Carry out any remedial work that is necessary before
operating the oven.
Do not operate the oven if any of the following conditions
exist;
Please refer to ‘OVEN PARTS, CABINET PARTS, DOOR PARTS’, when carrying out any of the following removal
procedures:
OUTER CASE REMOVAL
To remove the outer case proceed as follows.
1. Disconnect oven from power supply.
2. Open the oven door and wedge it open.
3. Remove the eight (8) screws from rear and along the
side edge of case.
4. Slide the entire case back about 3cm to free it from
retaining clips on the cavity face plate.
5. Lift the entire case from the unit.
6. Discharge the H.V. capacitor before carrying out any
further work.
7. Do not operate the oven with the outer case removed.
N.B.; Step 1, 2 and 7 form the basis of the 3D checks.
CAUTION: DISCHARGE HIGH VOLTAGE CAPACITOR
BEFORETOUCHINGANYOVENCOMPONENT
OR WIRING.
HIGH VOLTAGE COMPONENTS REMOVAL
(HIGH VOLTAGE CAPACITOR AND HIGH VOLTAGE RECTIFIER ASSEMBLY)
To remove the components, proceed as follows.
1. CARRY OUT 3D CHECKS.
2. Lift up the HVC cover.
3. Disconnect the H.V. wire of the H.V. rectifier assembly
from the power tramsformer.
4. Disconnect the filament lead of the power transformer
from the H.V. capacitor.
5. Remove one (1) screw holding capacitor holder to rear
cabinet.
6. Removeone(1)screwholdingearthsideterminalofhigh
voltagerectifierassembly,andremovecapacitorholder.
7. Disconnect all the leads and terminals of high voltage
rectifier assembly from high voltage capacitor.
8. Disconnect the H.V. wire A from the H.V. rectifier, assy.
CAUTION: WHEN REPLACING HIGH VOLTAGE
RECTIFIERASSEMBLY,ENSURETHATTHE
CATHODE (EARTH) CONNECTION IS
SECURELY FIXED TO THE CAPACITOR
HOLDER WITH AN EARTHING SCREW.
CAUTION: DO NOT REPLACE ONLY HIGH VOLTAGE
RECTIFIER. WHEN REPLACING IT,
REPLACE HIGH VOLTAGE RECTIFIER
ASSEMBLY.
9. Now H.V. rectifier assy. and H.V. copacitor. Should be
free.
POWER TRANSFORMER REMOVAL
5. Disconnect the lead of the power transformer from high
voltage capacitor.
6. Remove the four (4) screws holding the transformer to
bottom plate.
7. Remove the transformer.
1. CARRY OUT 3D CHECKS.
2. Disconnect the wire leads (main wire harness and H.V.
wire) from power transformer.
3. Releasethe leadofthe powertransformerfrom thewire
holder.
4. Disconnect the lead from magnetron filament.