Sharp R-241cwaa User manual

R-241CWAA

R-241CWAC

R-241CWAP

In interests of user-safety the oven should be restored to its original

condition and only parts identical to those specified should be used.

MODELS R-241CWAA (Argentina)

R-241CWAC (Chile)

R-241CWAP (Peru)

S7908R241CPA/

MICROWAVE OVEN

TABLE OF CONTENTS

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

SHARP CORPORATION

SERVICE MANUAL

R-241CWAA

R-241CWAC

R-241CWAP

R-241CWAA

R-241CWAC

R-241CWAP

SERVICE MANUAL

SHARP CORPORATION

OSAKA, JAPAN

MICROWAVE OVEN

R-241CWAA (Argentina)

R-241CWAC (Chile)

R-241CWAP (Peru)

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.

(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.

TEST PROCEDURE

SERVICING AND

TROUBLESHOOTING CHART

FUNCTION OF IMPORTANT

COMPONENTS

OPERATING SEQUENCE

APPEARANCE VIEW

PRODUCT SPECIFICATIONS

WIRING DIAGRAM

PARTS LIST

MICROWAVE MEASUREMENT

TOUCH CONTROL PANEL

ASSEMBLY

COMPONENT REPLACEMENT

AND ADJUSTMENT PROCEDURE

R-241CWAA

R-241CWAC

R-241CWAP

GENERAL INFORMATION

WARNING

THIS APPLIANCE MUST BE EARTHED

IMPORTANT

THE WIRES IN THIS MAINS LEAD ARE COLOURED IN ACCORDANCE WITH THE FOLLOWING CODE:

GREEN-AND-YELLOW (for R-241CWAA & R-241CWAC): EARTH

BLUE : NEUTRAL

BROWN : LIVE

ITEM DESCRIPTION

Power Requirements 220 Volts / 50 Hertz

R-241CWAA, R-241CWAC : Single phase, 3 wire earthed

220 Volts / 60 Hertz

R-241CWAP (Peru) : Single phase, 2 wire

Power Consumption 1.2 kW

Power Output 800 watts nominal of RF microwave energy (IEC 705)

Operating frequency 2450 MHz

Case Dimensions Width 460 mm

Height 290 mm including foot

Depth 372 mm

Cooking Cavity Dimensions Width 314 mm

Height 199 mm

Depth 321 mm

Turntable diameter 295mm

Control Complement Touch Control System

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

EASY DEFROST pad

INSTANT ACTION pads

Number pads

POWER LEVEL pad

TIMER/CLOCK pad

STOP/CLEAR pad

INSTANT COOK/START pad

Set Weight (Approx.) 14 kg

PRODUCT SPECIFICATIONS

R-241CWAA

R-241CWAC

R-241CWAP

APPEARANCE VIEW

TOUCH CONTROL PANEL

OVEN

8. Control panel

9. Waveguide cover

10.Power supply cord

11.Turntable

12.Roller stay

13. Earth wire [R-241CWAP]

1. Ventilation openings

2. Oven lamp

3. Door hinges

4. Door safety latches

5. See through door

6. Door seals sealing surfaces

7. Coupling

1. DIGITAL READOUT

2. INDICATOR

3. EASY DEFROST PAD

Press to select the Easy Defrost menu.

4. INSTANT ACTION PADS

Press to cook or reheat 6 popular menus.

5. NUMBER PADS

Press to enter cooking time, clock time, weight of

food.

6. POWER LEVEL PAD

Press to select microwave power setting.

If not pressed, HIGH is automatically selected.

Press to alter the cooking result for automatic

operations.

7. TIMER/CLOCK PAD

Press to set clock, timer, child lock or demonstra-

tion mode.

8. STOP/CLEAR PAD

Press to clear during programming.

Press once to stop operation of oven during cook-

ing; press twice to cancel cooking programme.

9. INSTANT COOK/START PAD

Press once to cook for 1 minute at 100% or in-

crease by 1 minute multiples each time this pad is

pressed during cooking.

Press to start oven after setting programmes.

R-241CWAA

R-241CWAC

R-241CWAP

OPERATION SEQUENCE

OFF CONDITION

Closing the door activates all door interlock switches

(1st. latch switch, 2nd. interlock relay control 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 control unit.

Figure O-1 on page 25

1. The display flashes "88:88".

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 the number

keys and start the oven with touching the 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

voltsA.C.outputonthefilamentwindingandhighvoltage

of approximately 2000 volts A.C. on the secondary

winding.

2. The filament winding voltage (3.3 volts) heats the

magnetron filament and the high voltage (2000 volts) is

senttothe voltagedoublingcircuit,where itisdoubledto

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+RY2goback totheirhome 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

(NO COOKING)

1st. latch switches 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

turntablemotor arecutoff whenthe1st.latchswitch and

2nd. interlock relay control 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, and monitors the operation of the 1st. latch switch

and the 2nd. interlock relay.

6-1 Whentheoven door isopenedduring or afterthe cycle

of a cooking program, the 1st. latch switch and 2nd.

interlock relay control switch must open their contacts

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 the

contactsofthe1st.latchswitch and2nd.interlockrelay

control switch are closed.

6-3. When the oven door is opened and the contacts of the

1st latch switch and 2nd. interlock relay 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, rated voltage is supplied to the power transformer

intermittentlywithina32-secondtimebasethroughtherelay

contact which is coupled with the current-limiting relay. The

following levels of microwave power are given.

SETTING;

NOTE: TheON/OFFtimeratiodoesnotexactlycorrespond

to the percentage of microwave power, because

approx. 2 seconds are needed for heating up the

magnetron filament.

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%

R-241CWAA

R-241CWAC

R-241CWAP

FUNCTION OF IMPORTANT COMPONENTS

DOOR OPEN MECHANISM

Thedoorisopenedbypullingthedoor,refertotheFigureD-

Figure D-1. Door Open Mechanism

1ST. LATCH SWITCH AND 2ND. INTERLOCK RE-

LAY CONTROL SWITCH

1. When the oven door is closed, the contacts (COM-NO)

must be closed.

2. When the oven door is opened, the contacts (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)

ofthe1stlatchswitchand2nd.interlockrelayfailtoopen,

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. INTERLOCK

RELAY(RY2), 2ND. INTERLOCK RELAY

CONTROLSWITCH,MONITORSWITCHAND

MONITOR RESISTOR FOR PROPER OP-

ERATION. (REFER TO CHAPTER "TEST

PROCEDURE".)

MONITOR RESISTOR 0.8Ω20W

The monitor resistor prevents the fuse bursting when the

fuseblowsduetotheoperationofthemonitorswitch.

FUSE

1. The fuse blows when the contacts (COM-NO) of the 1st

latch switch and 2nd. interlock relay remain closed with

theovendooropenandwhenthemonitorswitch closes.

2. If the wire harness or electrical components are short-

circuited,thefuseM8Ablowstopreventanelectricshock

of fire hazard.

HIGH VOLTAGE FUSE

The high voltage fuse blows when the high voltage rectifier

or the magnetron is shorted.

THERMAL CUT-OUT 125˚C (OVEN)

The thermal cut-out 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 thermal cut-out remains closed. However,

when abnormally high temperatures are reached within the

oven cavity, the thermal cut-out will open at 125˚C, causing

the oven to shut down. The defective thermal cut-out must

be replaced with a new one.

THERMAL CUT-OUT 95˚C (MAGNETRON )

The thermal cut-out located on the top of the oven cavity is

designed to prevent damage to the magnetron if an over

heated condition develops in the tube due to cooling fan

failure, obstructed air guide, dirty or blocked air intake, etc.

Undernormaloperation,thethermalcut-outremainsclosed.

However, when abnormally high temperatures are reached

tothethermalcut-out,itwillopenat 95˚C,causingtheoven

toshutdown. Whenthe magnetronhas cooled to75˚C,the

thermal cut-out closes and cook cycle will resume.

TURNTABLE MOTOR

The turntable motor drives the roller stay to rotate the

turntable.

FAN MOTOR

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-

nelledthroughtheovencavitytoremovesteamandvapours

givenofffromtheheatingfoods.Itisthenexhaustedthrough

the exhausting air vents at the oven cavity.

Latch Heads

Latch Hook

Door Monitor

Switch

1st. Latch

Switch

2nd. Interlock

Relay Control

Switch

R-241CWAA

R-241CWAC

R-241CWAP

SERVICING

WARNING TO SERVICE PERSONNEL

Microwaveovenscontaincircuitrycapableofproducingveryhighvoltageandcurrent,contactwithanypartofthehigh

voltagecircuitwillresultinelectrocution.Highvoltagecapacitor,Powertransformer,Magnetron,Highvoltagerectifier

assembly, High voltage fuse, 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

connecting lead of the high-voltage rectifier) against

the chassis with the use of an insulated screwdriver.

Sharprecommend thatwhereverpossible fault-findingis

carriedoutwith thesupply disconnected.Itmay in,some

cases,benecessarytoconnectthesupplyaftertheouter

casehasbeenremoved,inthiseventcarryout3Dchecks

andthendisconnecttheleadstotheprimaryofthepower

transformer. Ensure that these leads remain isolated

from other components and the oven chassis. (Use

insulation tape if necessary.) When the testing is com-

pletedcarryout3Dchecksandreconnecttheleadstothe

primary of the power transformer.

REMEMBER TO CHECK 4R

1) Reconnect all leads removed from components dur-

ing 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 power level to HIGH. And set the microwave

timer for two (2) minutes. When the two minutes has

elapsed (timer at zero) carefully check that the water is

now hot. If the water remains cold carry out 3D checks

andre-examinetheconnectionstothecomponentbeing

tested.

When all service work is completed and the oven is fully assembled, the microwave power output should be

checked and microwave leakage test should be carried out.

IMPORTANT: Iftheovenbecomesinoperativebecauseof

a blown fuse M8A in the 1st. latch switch -

2nd. interlock relay - monitor switch - moni-

torresistorcircuit,checkthe1st.latchswitch,

2nd.interlockrelay,2nd.interlockrelaycon-

trol switch, monitor switch and monitor

resistor before replacing the fuse M8A.

When troubleshooting the microwave oven, it is helpful to

followtheSequence ofOperation inperforming thechecks.

Many of the possible causes of trouble will require that a

specific test be performed. These tests are given a proce-

dureletterwhichwillbefoundinthe"TestProcedure"section.

TROUBLESHOOTING GUIDE

R-241CWAA

R-241CWAC

R-241CWAP

MAGNETRON

POWER TRANSFORMER

H.V. RECTIFIER ASSEMBLY

HIGH VOLTAGE WIRE

HIGH VOLTAGE CAPACITOR

1ST. LATCH SWITCH

2ND. INTERLOCK RELAY CONTROL SWITCH

MONITOR SWITCH

MONITOR RESISTOR

THERMAL CUT-OUT 125˚C (OVEN)

THERMAL CUT-OUT 95˚C (MG)

FAN MOTOR

TURNTABLE MOTOR

FUSE M8A

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

KEY UNIT

H.V. FUSE

Homefuseblowswhenpower

supply cord is plugged into

wall outlet.

FUSEM8Ablowswhenpower

supply cord is plugged into

wall outlet.

"88:88"doesnotappearindis-

play but 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. (Display

appears)

Ovenlampdoesnotlight(Dis-

play appears.)

Fan motor does not operate.

(Display appears.)

Turntable motor does not op-

erate. (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

butlittleornoheatisproduced

in oven load. (Microwave

power 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/clear

pad is touched the oven

stops.)

Ovengoesintocook cycle but

shutsdownbeforeendofcook-

ing cycle.

OFF

CONDITION

PROBLEM

CONDITION

POSSIBLE CAUSE

AND

DEFECTIVE PARTS

TEST PROCEDURE

CONDITION

CK = Check / RE = Replace

ABC

CK D

EEEFGGHHIKMN

RECK CK RE CK CK CK CK CK

R-241CWAA

R-241CWAC

R-241CWAP

CARRY OUT 3D CHECKS.

Isolate the magnetron from the high voltage circuit by removing all leads connected to the 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 a short circuit 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 (1 litre water load)

Thefollowingtestprocedureshouldbecarriedoutwiththemicrowaveoveninafullyassembledcondition

(outercasefitted).MicrowaveoutputpowerfromthemagnetroncanbemeasuredbywayofIEC705,i.e.

it can be measured by using water load how much it can be absorbed by the water load. To measure the

microwave output power in the microwave oven, the relation of calorie and watt is 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.

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 of the test.

3. Temperature of the water

The initial temperature of the water is (10±2)˚C.

4. Select the initial and final water temperature so that the maximum difference 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.

The graduation of the thermometer must be scaled by 0.1˚C at minimum and an accurate 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: Theoperationtimeofthemicrowaveovenis“t+2”sec.2sec.ismagnetronfilamentheat-uptime.

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.

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.

A MAGNETRON TEST

NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL

WHILETHEOVENISINOPERATION.

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 Power supply Voltage.........Rated voltage

Water load.........1000 g Initial temperature...........10±2°C Heating time.........52 sec.

P = 80 x ∆T

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

R-241CWAA

R-241CWAC

R-241CWAP

1000g

T1˚C T2˚C

Heat up for 54 sec.

B POWER TRANSFORMER TEST

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:

WARNING: High voltages and large currents are present at the secondary winding and filament

windingofthe powertransformer.Itisvery dangerous toworknearthispart whenthe

oven is on. NEVER make any voltage measurements of the high-voltage circuits,

including the magnetron filament.

Ifthe readingobtainedare notstatedasabove,then thepowertransformerisprobably faultyandshould

be replaced.

CARRY OUT 4R CHECKS.

Initial temperature .................................................................................................. T1 = 11°C

Temperature after (52 + 2) = 54 sec. ..................................................................... T2 = 21°C

Temperature difference Cold-Warm.................................................................... ∆T1 = 10°C

Measured output power

The equation is “P = 80 x ∆T” ...................................................... P = 80 x 10°C = 800 Watts

JUDGMENT: The measured output power should be at least ±15 % of the rated output power.

CAUTION: 1°C CORRESPONDS TO 80 WATTS. REPEAT MEASUREMENT IF THE POWER IS

INSUFFICIENT.

CHIGH VOLTAGE RECTIFIER ASSEMBLY TEST

HIGH VOLTAGE RECTIFIER 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 B+C 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.

CARRY OUT 4R CHECKS.

NOTE: FORMEASUREMENTOFTHERESISTANCEOFTHERECTIFIER,THEBATTERIESOFTHE

MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BECAUSE

OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

HIGH VOLTAGE RECTIFIER

R-241CWAA/241CWAC R-241CWAP (Peru)

Primary winding 1.6 ohms approximately 1.35 ohms approximately

Secondary winding 128 ohms approximately 123 ohms approximately

Filament winding less than 1 ohm

R-241CWAA

R-241CWAC

R-241CWAP

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

D HIGH VOLTAGE CAPACITOR TEST

CARRY OUT 3D CHECKS.

A. Isolate the high voltage capacitor from the circuit.

B. Continuitycheckmustbecarriedoutwithmeasuringinstrument whichisset tothehighest resistance

range.

C. Anormalcapacitor shows continuityfor a shorttime(kick) and thena resistance ofabout10MΩafter

it has 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 10MΩ

resistance.

F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.

G. Theresistanceacrossalltheterminalsandthechassismustbe infinitewhenthe capacitoris normal.

If incorrect reading are obtained, the high voltage capacitor must be replaced.

CARRY OUT 4R CHECKS.

E SWITCH TEST

Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the

following table.

CARRY OUT 3D CHECKS.

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

If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.

CARRY OUT 4R CHECKS.

FMONITOR RESISTOR TEST

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.

GTHERMAL CUT-OUT TEST

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of the thermal cut-out. Then using an ohmmeter, make a

continuity 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 Indicationofohmmeter(Whenroom

Parts Name (closed circuit). (open circuit). temperature is approx. 20˚C.)

Thermal cut-out 125˚C

This is not resetable type. Above 125˚C Closed circuit

Thermal cut-out 95˚C Below 75˚C Above 95˚C Closed circuit.

If incorrect readings are obtained, replace the thermal cut-out.

R-241CWAA

R-241CWAC

R-241CWAP

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

An open circuit thermal cut-out (MG) indicates that the magnetron has overheated, this may be due to

resistricted ventilation, cooling fan failure or a fault condition within the magnetron or HV circuit.

Anopen circuitthermal cut-out(OVEN) indicatesthat thefood inthe ovencavity maycatch fire,this may

be due to overheating produced by improper setting of the cooking time or failure of the control panel.

H MOTOR WINDING TEST

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.

I FUSE M8A

CARRY OUT 3D CHECKS.

If the fuse M8A is blown when the door is opened, check the 1st latch switch, 2nd. interlock relay, 2nd.

interlock relay control switch, monitor switch and monitor resistor.

If the fuse M8A is blown by incorrect door switching, replace the defective switch(s) and the fuse M8A.

If the fuse M8A 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.

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS.

J HIGH VOLTAGE FUSE TEST

CARRY OUT 3D CHECKS.

If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron.

Check them and replace the defective parts and the high voltage fuse.

CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE HIGH VOLTAGE FUSE WITH THE CORRECT VALUE REPLACE-

MENT.

KTOUCH 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 divided into two units, Control Unit and Key

Unit, troubleshooting by unit replacement is described according to the symptoms indicated.

1. Key Unit.

The following symptoms indicate a defective key unit. Replace the key unit.

Table: Resistance of Motor

Resistance

Motors R-241CWAA/241CWAC R-241CWAP (Peru)

Fan motor Approximately 390 ohms Approximately 166 ohms

Turntable motor Approximately 12 kohms Approximately 12 kohms

R-241CWAA

R-241CWAC

R-241CWAP

M RELAY TEST

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

a) When touching the pads, a certain pad produces no signal at all.

b) When touching a number pad, two figures or more are displayed.

c) When touching the pads, sometimes a pad produces no signal.

2. Control Unit.

The following symptoms indicate a defective control unit. Replace the control unit.

2-1 Programming problems.

a) When touching the pads, a certain group of pads do not produce a signal.

b) When touching the pads, no pads produce a signal.

2-2 Display problems.

a) For a certain digit, all or some segments do not light up.

b) For a certain digit, brightness is low.

c) Only one indicator does not light up.

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) Clock does not operate properly.

c) Cooking is not possible.

LKEY UNIT TEST

If the display fails to clear when the Detención/Cancelación pad is depressed, first verify the flat ribbon

cableismakinggoodcontact,verifythat2ndinterlockrelaycontrolswitch(doorsensingswitch) operates

properly; that is the contacts are closed when the door is closed and open when the door is open. If 2nd

interlockrelaycontrolswitch(doorsensingswitch)isgood,disconnecttheflatribboncablethatconnects

the key unit to the control unit and make sure the door sensing switch is closed (either close the door or

shortthedoorsensingswitchconnecter).UsetheKeyunitmatrixindicatedonthecontrolpanelschematic

and place a jumper wire between the pins that correspond to the Detención/Cancelación pad making

momentary contact. If the control unit responds by clearing with a beep, the key unit is faulty and must

bereplaced.Ifthecontrolunitdoesnotrespond,itis afaultyand mustbereplaced. Ifaspecific paddoes

not respond, the above method may be used (after clearing the control unit) to determine if the control

unit or key pad is at fault.

Remove the outer case and check voltage between Pin No 3 of the 2 pin connector (A) and common

terminal (lower terminal) of the relay (RY2) 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

Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.

345

Plato

Principal

Nivel de

Potencia

Verdura

Congelada



Papa

Asada

Bebida

Verdure

Fresca



Cronómetro

Reloj

Arroz/

Pasta

G 6 G 5 G 4 G 3 G 2 G 1

G 7

G 8

G 9

G10

Comienzo

Minuto Extra

Detención

Cancelación

DESCONGELACION

AUTOMATICA



R-241CWAA

R-241CWAC

R-241CWAP

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

N PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD

(PWB) IS OPEN

NOTE: At the time of making these repairs,

makeavisual inspectionof the varistor.

Checkforburneddamageandexamine

the transformer with tester for the pres-

ence of layer short-circuit (check pri-

mary coil resistance). If any abnormal

conditionisdetected,replacethedefec-

tive parts.

DC. voltage indicated.......... Defective relay.

DC. voltage not indicated .... Checkdiodewhichisconnectedtotherelaycoil.Ifdiodeisgood,control

unit is defective.

RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS

RY1 Approx. 15.0V D.C. Oven lamp / Turntable motor / Cooling fan motor

RY2 Approx. 14.0V D.C. Power transformer

To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on

the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide given

below for repair.

Problem: POWER ON, indicator does not light up.

STEPS OCCURANCE CAUSE OR CORRECTION

The rated voltage is not applied between Pin

1 No. 3 of the 2 pin connector (A) and the. Check supply voltage and oven power cord.

common terminal of the relay RY2.

2The rated voltage is applied to primary side Low voltage transformer or secondary circuit defective.

of low voltage transformer. 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".

b c

AC (N) FM TTM OL RY1

VRS1

T1 RY2

(J1)

R-241CWAA

R-241CWAC

R-241CWAP

The touch control section consists of the following units as

shown in the touch control panel circuit.

(1) Key Unit

(2) Control Unit

The principal functions of these units and their related

signals are explained below.

Key Unit

The key unit is composed of a matrix, signals generated in

theLSIaresenttothekeyunitthroughR81,R82,R83,R90,

R91 and R92.

When a key pad is touched, a signal is completed through

the key unit and passed back to the LSI through R60, R61,

R62, R63 to perform the function that was requested.

Control Unit

Control unit consists of LSI, ACL circuit, indicator circuit,

power source circuit, relay circuit, buzzer circuit and syn-

chronizing signal circuit.

1) ACL

ThiscircuitgeneratesasignalwhichresetstheLSItothe

initial state when power is supplied.

2) Indicator Circuit

This circuit consists of 4-digits, 12-segments and 3-

common electrodes using a Liquid Crystal Display.

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

3) Power Source Circuit

This circuit generates voltage necessary in the control

unitfromtheAClinevoltage.Inaddition,thesynchroniz-

ing signal is available in order to compose a basic

standard time in the clock circuit.

Symbol Voltage Application

VC -5V LSI(IC1)

4) Relay Circuit

To drive the magnetron, fan motor, turntable motor and

light the oven lamp.

5) Buzzer Circuit

The buzzer is responsive to signals from the LSI to emit

audiblesounds(keytouchsoundandcompletionsound).

6) 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.

7) 2nd. Interlock Relay Control Switch (Door Sensing

Switch)

A switch to “tell” the LSI if the door is open or closed.

R-241CWAA

R-241CWAC

R-241CWAP

1-12 SEG0-SEG11 OUT Segment data signal.

Connected to LCD.

The relation between signals are as follows:

LSI signal (Pin No.) LCD (Pin No.) LSI signal (Pin No.) LCD (Pin No.)

SEG 0 (1) ..............................S12 SEG 6 (7)................................. S6

SEG 1 (2) ..............................S11 SEG 7 (8)................................. S5

SEG 2 (3) ..............................S10 SEG 8 (9)................................. S4

SEG 3 (4) ................................S9 SEG 9 (10)............................... S3

SEG 4 (5) ................................S8 SEG 10 (11)............................. S2

SEG 5 (6) ................................S7 SEG 11 (12)............................. S1

13 R60 IN Signal coming from touch key.

Wheneither G10lineon keymatrixistouched,a correspondingsignaloutofR81 -R83

and R90 - R92 will be input into R60. When no key is touched, the signal is held at “H”

level.

14 R61 IN Signal similar to R60.

WheneitherG9lineonkeymatrixistouched,acorrespondingsignalwillbeinputintoR60.

15 R62 IN

Signal similar to R60.

WheneitherG8lineonkeymatrixistouched,acorrespondingsignalwillbeinputintoR60.

16 R63 IN Signal similar to R60.

WheneitherG7 lineon keymatrix istouched,a correspondingsignal willbeinput intoR60.

17 AIN0 IN To input signal which communicates the door open/close information to LSI.

Door close “H” level signal (0V). Door open “L” level (-5V).

18-20 AIN1-AIN3 IN Terminal to change functions according to the Model.

By using the A/D converter contained in the LSI, DC voltage in accordance with the

Model in operation is applied to set up its function.

21 VSS IN Power source voltage: -5V.

VSS voltage of power source circuit input.

22 R70 OUT Magnetron high-voltage circuit driving signal.

Toturnonandoffthecookrelay(RY2). Thesignals

holds “L” level during microwave cooking and “H”

level while not cooking. In other cooking modes

(variable cooking) the signal turns to “H” level and

“L” level in repetition according to the power level.

23 PULSE OUT Signal to sound buzzer (2.0 kHz).

A: key touch sound.

B: Completion sound.

R-241CWAA/ R-241CWAC R-241CWAP (Peru)

24 R72 OUT Oven lamp, fan motor and turntable motor driving signal.

Toturnonandoffshutoffrelay(RY1).Thesquarewaveformvoltageisdeliveredtothe

RY1 driving circuit and RY2 control circuit.

R-241CWAA/ R-241CWAC R-241CWAP (Peru)

DESCRIPTION OF LSI

LSI(IZA906DR)

The I/O signal of the LSI(IZA906DR) are detailed in the following table.

Pin No. Signal I/O Description

H : GND

L : -5V

OFF

OFF OFF

H : GND

L : -5V

P-HI

P-70 24 sec. 8 sec.

0.12 sec.

2.4 sec.

H : GND

L : -5V

H : GND

L : -5V

During cooking L : -5V

H : GND

20.0 msec.

0.1 sec.

2.0 sec.

H : GND

L : -5V

H : GND

L : -5V

During cooking L : -5V

H : GND

16.7 msec.

R-241CWAA

R-241CWAC

R-241CWAP

25 R73 OUT Terminal not used.

26 INT2 IN Signal synchronized with commercial power source frequency.

This is the basic timing for time processing of LSI.

R-241CWAA/R-241CWAC R-241CWAP (Peru)

27 R81 OUT Key strobe signal.