Sharp R-2S56 User manual

R-2S56
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-2S56
S7402R2S56PJZ
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 .......................................................................................................................................................... 7
TEST PROCEDURE ............................................................................................................................................ 9
TOUCH CONTROL PANEL ................................................................................................................................ 16
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE............................................................... 19
MICROWAVE MEASUREMENT ........................................................................................................................ 25
WIRING DIAGRAM ............................................................................................................................................. 26
PICTORIAL DIAGRAM....................................................................................................................................... 28
CONTROL PANEL CIRCUIT .............................................................................................................................. 30
PRINTED WIRING BOARD ................................................................................................................................ 31
PARTS LIST........................................................................................................................................................ 32

R-2S56

R-2S56
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-2S56
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 240 Volts (for Australia) / 230 - 240 Volts (for New Zealand)
50 Hertz
Single phase, 3 wire earthed
Power Consumption 1.06 kW, Approx. 4.5 A
Power Output 700 watts nominal of RF microwave energy (IEC 705)
600 watts (2 litre water load)
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/DEFROST pad
STOP/CLEAR pad
POWER LEVEL/SERVES pad
INSTANT COOK/START pad
AUTO COOK/DEFROST 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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APPEARANCE VIEW
32110
9
8
7
456412 11
1
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.Rating label
TOUCH CONTROL PANEL
a. TIME PADS
Press to enter cooking time.
b. AUTO COOK/DEFROST PAD
Press to select AUTO COOK/DEFROST menu.
c. POWER LEVEL/SERVES PAD
Press to select microwave power setting. If not
pressed, 100% is automatically selected.
PresstoenterservesafterselectingAUTOCOOK/
DEFROST menu.
d. STOP / CLEAR PAD
Press to clear during programming.
Pressoncetostopoperationofovenduringcooking:
press twice to cancel cooking programme.
e. INSTANT COOK / START PAD
Pressoncetocookfor1minuteat100%orincrease
by1minutemultipleseachtimethispadispressed
during cooking.
Press to start oven after setting programmes.
f. AUTO COOK/DEFROST MENUS
10 1 10
MIN MIN SEC
AUTO
COOK/DEFROST
STOP
CLEAR POWER
LEVEL
SERVES
INSTANT
COOK
START
1
2
3
4
5
Reheat Dinner Plate 1 Serve
Defrost Meat 100g
Fresh Vegetables 150g
Jacket Potato 1 piece
Frozen Vegetables 150g
b
d
f
a
c
e

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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 26
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 27
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 isopened duringor after thecycle
of a cooking program, the 1st. latch and 2nd. latch
switch must open their contacts first.
Afterthatthecontacts(COM-NC)ofthemonitorswitch
can be closed.
6-2. Whentheoven door isclosed, thecontacts (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, 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 current-
limiting relay. 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.
ASYMMETRIC RECTIFIER
Theasymmetricrectifierisasolidstatedevicethatprevents
currentflow inbothdirections. Andit preventsthetempera-
turerise of thepowertransformerby blowingthe fusewhen
FUNCTION OF IMPORTANT COMPONENTS
the high voltage rectifier is shorted.
D2 D1
ASYMMETRIC
RECTIFIER
HIGH VOLTAGE RECTIFIER
AB
C
The rated peak reverse voltage of D1 of the asymmetric
rectifier is 6 KV The rated peak reverse voltage of D2 of the
asymmetricrectifieris1.7KV.D1andD2oftheasymmetric
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.)
1. Thehighvoltagerectifierisshortedbyanycauseswhen
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. The large electric currents flow through the high voltage
winding of the power transformer.
5. The large electric currents beyond M6.3A flow through
the primary winding of the power transformer.
6. The fuse blows by the large electric currents.
7. The power supply to the all electrical parts are cut off.
FUSE
1. The fuse blows when the contacts (COM-NO) of the 1st
latchswitch and2nd latch switchremain closedwiththe
oven door open and when the monitor switch closes.
2. The fuse also blows when asymmetric rectifier, H.V.
rectifier,H.V.wireharness,H.V.capacitor,magnetronor
secondary winding of power transformer is shorted.
3. 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 temperaturesare reached
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.

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THERMAL CUT-OUT 95˚C
Thethermal cut-out protectthefan motor againstoverheat.
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
NOISE FILTER (for New Zealand)
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
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
connectingleadofthe high-voltage rectifier)against
thechassiswiththe use ofan 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
theoutercasehasbeenremoved,inthiseventcarryout
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
thepresenceof microwaveenergy within acavity, place
acup ofcold wateronthe oventurntable,close the door
andset themicrowavetimerfortwo(2)minutes.Setthe
powerlevel to HIGHand pushthe STARTbutton.When
the two minutes has elapsed (timer at zero) carefully
checkthatthewaterisnowhot.Ifthewaterremainscold
carry out 3D checks and re-examine the connections to
the component being tested.
Whenallserviceworkiscompleted,and the oven is fully assembled,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.latchswitch,monitorswitchand moni-
torresistorbeforereplacingthefuseM6.3A.

R-2S56
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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
NOISE FILTER (FOR N.Z.) TACT SWITCH
Home fuse blows when power
supply cord is plugged into wall
outlet.
FUSE M6.3A blows when power
supply cord is plugged into wall
outlet.
"88:88"doesnotappearindisplay
but power supply cord is plugged
into wall outlet.
Display does not operate prop-
erly when STOP/CLEAR pad is
touched.
Oven lamp does not light at door
opened. (Display appears.)
Oven does not start when the
START pad is touched. (Display
appears)
Ovenlampdoesnot light(Display
appears.)
Fanmotordoesnotoperate.(Dis-
play appears.)
Turntable motor assembly does
not operate. (Display appears.)
Oven or any electrical parts does
notstopwhen cookingtimeis0or
STOP/CLEAR pad is touched.
Oven seems to be operating but
little or no heat is produced in
ovenload.(Microwavepowerlevel
is set at HIGH)
Oven does not seems to be oper-
ating properly when MEDIUM
HIGH, MEDIUM, MEDIUM LOW
or LOW is set. (Oven operates
properly at HIGH and then the
STOP/CLEARpad is touched the
oven stops.)
Oven goes into cook cycle but
shutsdownbeforeendofcooking
cycle.
Oven stops as soon as when the
START pad is touched.
OFF
CONDITION
PROBLEM
CONDITION
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
TEST PROCEDURE
ON
CONDITION
CK = Check / RE = Replace
ABC CK D EEEE FGGGHH IJ LMRECKCKRECKCKCKCKCK NK