Sharp Model r-2197 User manual

R-2197

SHARPCORPORATION

SERVICEMANUAL

S9811R2197PJ/

MICROWAVE OVEN

MODEL R-2197

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

original condition and only parts identical to those specified

should be used.

TABLE OF CONTENTS Page

CAUTION, MICROWAVE RADIATION............................................................................................................. 1

WARNING..........................................................................................................................................................1

PRODUCT SPECIFICATIONS ......................................................................................................................... 2

GENERAL INFORMATION................................................................................................................................2

APPEARANCE VIEW ....................................................................................................................................... 3

OPERATION SEQUENCE................................................................................................................................ 4

FUNCTION OF IMPORTANT COMPONENTS ................................................................................................ 5

SERVICING ...................................................................................................................................................... 6

TEST PROCEDURE ......................................................................................................................................... 8

TOUCH CONTROL PANEL ASSEMBLY ........................................................................................................14

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ........................................................... 21

MICROWAVE MEASUREMENT .................................................................................................................... 27

WIRING DIAGRAM ......................................................................................................................................... 28

PICTORIAL DIAGRAM ................................................................................................................................... 29

CONTROL PANEL CIRCUIT ...........................................................................................................................30

PRINTED WIRING BOARD .............................................................................................................................31

PARTS LIST ................................................................................................................................................... 32

1000W/ R-2197

DEF

NO.

CHECK

R-2197

SERVICEMANUAL

MICROWAVE OVEN

R-2197

GENERAL IMPORTANT INFORMATION

This Manual has been prepared to provide Sharp Corp. 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

Service engineers should not be exposed to the microwave

energy which may radiate from the magnetron or other micro-

wave generating devices if it is improperly used or connected.

Allinputandoutputmicrowaveconnections,waveguides,flanges

andgasketsmustbesecured.Neveroperatethedevicewithout

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.

Allthe partsmarked"*"onparts listareusedatvoltages morethan

250V.

Removal of the outer wrap gives access to potentials above 250V.

All the parts marked "∆" on parts list may cause undue microwave

exposure,bythemselves, orwhen they aredamaged, loosenedor

removed.

SHARP CORPORATION

OSAKA, JAPAN

PRODUCT SPECIFICATIONS

GENERAL INFORMATION

APPEARANCE VIEW

OPERATING SEQUENCE

FUNCTION OF IMPORTANT

COMPONENTS

SERVICING AND

TROUBLESHOOTING GUIDE

TEST PROCEDURE

TOUCH CONTROL PANEL

COMPONENT REPLACEMENT

AND ADJUSTMENT PROCEDURE

MICROWAVE MEASUREMENT

WIRING DIAGRAM

PARTS LIST

R-2197

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 : EARTH

BLUE : NEUTRAL

BROWN : LIVE

PRODUCT DESCRIPTION

SPECIFICATION

ITEM DESCRIPTION

Power Requirements 230 - 240 Volts

50 Hertz

Single phase, 3 wire earthed

Power Output

1000 W nominal of RF microwave energy (measured by method of IEC 705)

Operating frequency 2450 MHz

Case Dimensions Width 520 mm

Height 309 mm including foot

Depth 406 mm

Cooking Cavity Dimensions Width 351 mm

Height 211 mm

Depth 372 mm

Control Complement Touch Control System

Timer (0 - 99 minutes and 99 seconds)

Microwave Power for Variable Cooking

Repetition Rate;

P-HI...........................................Full power throughout the cooking time

P-90 .............................................................approx. 90% of Full Power

P-80 .............................................................approx. 80% of Full Power

P-70 .............................................................approx. 70% of Full Power

P-60 .............................................................approx. 60% of Full Power

P-50 .............................................................approx. 50% of Full Power

P-40 .............................................................approx. 40% of Full Power

P-30 .............................................................approx. 30% of Full Power

P-20 .............................................................approx. 20% of Full Power

P-10 .............................................................approx. 10% of Full Power

P-0 .............................................No power throughout the cooking time

DOUBLE QUANTITY pad

EXPRESS DEFROST pad

Number pads

SELECT TIME pad

STOP/CLEAR pad

SELECT POWER pad

START pad

SET pad

CHECK pad

SIGNAL pad

Set Weight Approx. 17 kg

R-2197

APPEARANCEVIEW

1. Digital Readout

2. DOUBLE QUANTITY pad

3. EXPRESS DEFROST pad

4. Number pads for time and memory program-

ming

5. SELECT TIME pad

6. STOP/CLEAR pad; touch to stop operation of

oven and clear remaining heating time

7. SELECAT POWER pad for setting variable

power level

8. START pad; touch to operate oven after door

is closed and time is set

9. SET pad for setting memory

10.CHECK pad for checking memory

11.SIGNAL pad for setting signal sound

OVEN

1. Oven light

2. Ceramic shelf

3. Control panel

4. Cavity face plate

5. Door latch openings

6. Door latches

7. Door hinges

8. Door seals and sealing surfaces

9. Door handle

10.Ovendoorwithsee-throughwindow

11.Air ventilation cover and openings

12.Power supply cord

13.Air intake openings

14.Outer case cabinet

TOUCH CONTROL PANEL

12 11

710

54 3

13 14

DEF

NO.

CHECK

R-2197

OPERATION SEQUENCE

OFF CONDITION

Closing the door activates the 1st. latch switch, 2nd. latch

switch and stop switch.

IMPORTANT:

When the oven door is closed, the contacts COM-NC

of the monitor switch must be open. When the mi-

crowave oven is plugged in a wall outlet (230 - 240V

50Hz), the line voltage is supplied to the noise filter

and the control unit.

Figure O-1 on page 28

1. The oven display will show . .

MICROWAVE COOKING CONDITION

ProgramdesiredcookingtimebytouchingSELECTTIME

pad and the NUMBER pads. When the START pad is

touched, the following operations occur:

Figure O-2 on page 28

RELAY CONNECTED COMPONENTS

RY-2 power transformer

RY-3 oven lamp/antenna motor/fan motor

1. The line voltage is supplied to the primary winding of

thehighvoltagetransformer. The voltageisconverted

to about 3.3 volts A.C. output on the filament winding

and high voltage of approximately 2300 volts A.C. on

the secondary winding.

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

magnetronfilamentandthehighvoltage(2000volts)is

senttothevoltagedoubling circuit, where it isdoubled

to negative voltage of approximately 4000 volts D.C..

3. The 2450 MHz microwave energy produced in the

magnetron generates a wave length of 12.24 cm. This

energyischannelledthroughthewaveguide(transport

channel)intothe oven cavity,wherethe food isplaced

to be cooked.

4. Whenthecookingtimeisup,asignaltoneisheardand

the relays RY2 + RY3 go back to their home position.

Thecircuitstotheovenlamp,highvoltagetransformer,

fan motor and antenna motor are cut off.

5. Whentheoven door isopenedduring a cookingcycle,

the switches come to the following condition.

Switch Contact Condition

During Oven Door

Cooking Open(No cooking)

1st. latch switch COM-NO Closed Opened

2nd.

latch switch COM-NO Closed Opened

Stop

switch COM-NO Closed Opened

Monitor Switch COM-NC Opened Closed

Thecircuittothehighvoltagetransformer,fanmotor,oven

lamp and antennamotor are cut off when the 1st. latch

switch, 2nd. latch switch and stop switch are made open.

Shown in the display is remaining time.

6. MONITOR SWITCH CIRCUIT

The monitor switch is mechanically controlled by the

oven door, and monitors the operation of the 1st. latch

switch, the 2nd. latch switch and the relay RY2.

6-1. When the oven door is opened during or after the

cycleofacookingprogram, the 1st. latch switch2nd.

latchswitch andstopswitchmustopentheircontacts

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

thecontactsofthe1st. latch switch, 2nd.latchswitch

and stop switch are closed.

6-3. Whentheovendoorisopenedandthecontactsofthe

1st. latch switch, 2nd. latch switch and the relay RY2

remain closed, the fuse M10A will blow, because the

monitorswitchisclosed andashortcircuitiscaused.

POWER LEVEL P-0 TO P-90 COOKING

When Variable Cooking Power is programmed, the line

voltageissupplied tothepower transformer intermittently

through the contacts of relay (RY-2) which is operated by

the control unit within a 32 second time base. Microwave

power operation is as follows:

VARI-MODE ON TIME OFF TIME

Power 10(P-HI) 32 sec. 0 sec.

(100% power)

Power 9(P-90) 30 sec. 2 sec.

(approx. 90% power)

Power 8(P-80) 26 sec. 6 sec.

(approx. 80% power)

Power 7(P-70) 24 sec. 8 sec.

(approx. 70% power)

Power 6(P-60) 22 sec. 10 sec.

(approx. 60% power)

Power 5(P-50) 18 sec. 14 sec.

(approx. 50% power)

Power 4(P-40) 16 sec. 16 sec.

(approx. 40% power)

Power 3(P-30) 12 sec. 20 sec.

(approx. 30% power)

Power 2(P-20) 8 sec. 24 sec.

(approx. 20% power)

Power 1(P-10) 6 sec. 26 sec.

(approx. 10% power)

Power 0(P-0) 0 sec. 32 sec.

(0% power)

Note: The ON/OFF time ratio does not correspond with

the percentage of microwave power, because

approx. 2 seconds are needed for heating of the

magnetron filament.

R-2197

DOOR OPEN MECHANISM

The door is opened by grasping the door handle, refer to

Figure D-1.

When the door handle is grasped, the handle lever is

pulled. And then the upper and lower latch heads are

moved upward by the handle lever, and they are re-

leased from the latch hook. Now the door will open.

Figure D-1. Door Open Mechanism

1ST. LATCHSWITCHAND2ND. LATCHSWITCH

AND STOP SWITCH

1. Whentheovendoorisclosed,thecontacts(COM-NO)

of each switch must be closed.

2. When the oven door is opened, the contacts (COM-

NO) of each switch must be opened.

MONITOR SWITCH

1. Whenthedoorisclosed,thecontacts(COM-NC)must

be opened.

2. When the door is opened, the contacts (COM-NC)

must be closed.

3. Iftheovendoorisopenedandthecontacts(COM-NO)

of the 1st. latch switch, 2nd. latch switch and relay

(RY2) fail to open, the fuse M10A blows immediately

after closing the contacts (COM-NC) of the monitor

switch.

CAUTION: BEFORE REPLACING A BLOWN FUSE

M10ATESTTHE1ST.LATCHSWITCH,2ND.

LATCH SWITCH, RELAY (RY2), MONITOR

SWITCH AND MONITOR RESISTOR FOR

PROPER OPERATION. (REFER TO CHAP-

TER “TEST PROCEDURE”).

FUSE M10A 250V

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

circuited,thisfuseblowstopreventanelectricshockor

fire hazard.

2. This fuse blows when the 1st. latch switch, 2nd. latch

switch and relay (RY2) remain closed with the oven

door open and when the contacts (COM-NC) of

monitor switch closes.

FUNCTION OF IMPORTANT COMPONENTS

HIGH VOLTAGE FUSE 0.75A

Thehighvoltagefuseblowswhenthehighvoltagerectifier

or the magnetron is shorted.

THERMAL CUT-OUT 145˚C (MAGNETRON)

Thisthermalcut-outprotectsthemagnetronagainstover-

heating. If the temperature goes up higher than 145˚C

because the fan motor is interrupted or the ventilation

openings are blocked, the thermal cut-out will open and

line voltages to the high voltage transformer will be cut off

and the operation of the magnetron will be stopped. The

thermal cut-out will not resume.

THERMAL CUT-OUT 125˚C (OVEN)

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

isdesignedtopreventdamagetotheovenifthefoodinthe

oven catches fire due to over heating produced by im-

propersettingofthecooking time or failureofcontrolunit.

Under normal operation, the oven thermal cut-out re-

mains closed. However, when abnormally high tempera-

turesarereachedwithintheovencavity,theoventhermal

cut-out will open at 125˚C causing the oven to shut down.

The thermal cut-out will not resume.

MONITOR RESISTOR

The monitor resistor prevents the fuse M10A bursting

when the fuse M10A blows due to the operation of the

monitor switch.

NOISE FILTER

The noise filter assembly prevents radio frequency inter-

ference that might flow back in the power circuit.

ANTENNA MOTOR

The antenna motor rotates the stirrer antenna located on

the bottom of the oven cavity, so that the food on the

ceramic shelf is cooked evenly during cooking. The an-

tenna motor may turn in either direction.

COOLING FAN MOTOR

The cooling fan motor drives a blade which draws exter-

nal cool air. This cool air is directed through the air vanes

surrounding the magnetron and cools the magnetron.

This air is channelled through the oven cavity to remove

steam and vapors given off from the heating food. It is

then exhausted through the exhausting air vents at the

oven cavity.

Latch Hook

Latch Switch

Lever A

Latch Switch

Lever B

Latch Switch

Lever C

Latch Head

Handle

Lever

Door

Handle

Latch

Lever 2nd. Latch Switch

Monitor

Switch

Stop Switch

1st . Latch Switch

R-2197

When troubleshooting the microwave oven, it is helpful to

followtheSequenceofOperationinperformingthechecks.

Many of the possible causes of trouble will require that a

specifictestbe performed.Thesetests aregivena proce-

dure letter which will be found in the “Test Procedure”

section.

IMPORTANT: If the oven becomes inoperative because

of a blown fuse M10A in the 1st. latch

switch - 2nd. latch switch - relay(RY2)-

monitor switch - monitor resistor circuit,

check the 1st. latch switch, 2nd. latch

switch, relay(RY2), monitor switch and

monitor resistor before replacing the fuse

M10A.

TROUBLESHOOTING GUIDE

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

connectingleadofthehigh-voltagerectifier)against

thechassiswiththeuseofaninsulatedscrewdriver.

Sharprecommendthatwhereverpossiblefault-findingis

carriedoutwiththesupplydisconnected.Itmayin,some

cases,benecessarytoconnectthesupplyaftertheouter

case has been removed, in this event carry out 3D

checks and then disconnect the leads to the primary of

the high voltage transformer. Ensure that these leads

remain 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 high voltage transformer.

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.

SERVICING

WARNING TO SERVICE PERSONNEL

Microwaveovenscontaincircuitrycapableofproducingveryhighvoltageandcurrent.Contactwithfollowingpartswill

result in electrocution.

Highvoltagecapacitor,Highvoltagetransformer,Magnetron,Highvoltagerectifierassembly,Highvoltagefuse,High

voltage harness.

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.

Microwaveovensshouldnotberunempty.Totestforthe

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 (100%) and set the

microwave timer for two (2) minutes. And push the start

key. 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 and re-examine the

connections to the component being tested.

R-2197

TEST PROCEDURE

CONDITION

PROBLEM

POSSIBLE CASE

AND 

DEFECTIVE PARTS

Home fuse or circuit

breaker blows when

power cord is plugged into

wall outlet.

Fuse M10A blows when

power cord is plugged into

wall receptacle.

. does not appear

in display when power

cord is first plugged into

wall outlet.

Oven lamp does not light

when door is opened.

Oven lamp lights but fan

motor and antenna motor

do not operate.

Oven does not go into

cook cycle when START

pad is touched

Oven seems to be

operating but little or no

heat is produced in oven

load. (Food incompletely

cooked or not cooked at

all at end of cook cycle.)

Oven goes into a cook

cycle but extremely

uneven heating is

produced in oven load

(food).

Oven does not cook

properly when

programmed for Cooking

Power 5 mode. (Operates

properly on Cooking

Power 10 (HIGH) mode.)

"EE9" Maximum time is

exceeded.

OFF

CONDITION

COOKING

CONDITION

ERROR MODE

MAGNETRON

HIGH VOLTAGE TRANSFORMER

H.V. RECTIFIER ASSEMBLY

HIGH VOLTAGE CAPACITOR

THERMAL CUT-OUT

1ST. LATCH SWITCH

2ND. LATCH SWITCH

FUSE M10A

HIGH VOLTAGE FUSE

NOISE FILTER

TOUCH CONTROL PANEL

KEY UNIT

EXCEED MAX. HEATING TIME

RELAY (RY3)

RELAY (RY2)

FOIL PATTERN ON P.W.B.

LOW VOLTAGE

WRONG OPERATION

DIRTY OVEN CAVITY

MISADJUSTMENT SWITCH

SHORTED IN POWER CORD

OVEN LAMP OR SOCKET

COOLING FAN MOTOR

ANTENNA MOTOR

SHORT OR OPENED WIRING

MONITOR SWITCH

STOP SWITCH

A B C D E E E E F G H I I

JK L M M N CK RE RE RECK CK CK CK

R-2197

A MAGNETRON TEST

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

CARRY OUT 3D CHECKS.

Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.

Totestfor anopencircuitfilament useanohmmeter to makeacontinuity testbetweenthemagnetron

filament terminals, the meter should show a reading of less than 1 ohm.

Totest forshort filamentto anodecondition, connectohmmeterbetweenoneofthefilamentterminals

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 load)

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 is measured by how much power the water load can absorb. 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 the test.

3. Temperature of the water

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

4. Selecttheinitialandfinalwatertemperaturesothatthemaximumdifferencebetweenthefinalwater

temperature and the ambient temperature is 5°C.

5. Selectstirring devicesand measuringinstrumentsinordertominimizeadditionorremovalofheat.

6. The graduation of the thermometer must be scaled by 0.1°C at minimum and be an accurate

thermometer.

7. The water load must be (1000±5) g.

8. “t”ismeasured while themicrowavegeneratoris operatingatfullpower. Magnetron filamentheat-

up time is not included.

NOTE:Theoperation timeofthe microwaveovenis“t +2”sec. (2sec.ismagnetron filamentheat-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) K.

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.

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

WHILE THE OVEN IS IN OPERATION.

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.............................. 42 sec.

P = 100 x ∆T

R-2197

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

Temperature after (42 + 2) = 44 sec ...................................................................... T2 = 21°C

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

Measured output power

The equation is “P = 100 x ∆T” ................................................ P = 100 x 10°C = 1000 Watts

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

CAUTION: 1°C CORRESPONDS TO 100 WATTS. REPEAT MEASUREMENT IF THE POWER IS

INSUFFICIENT.

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

1000g

T1˚C T2˚C

Heat up for 44 sec

B HIGH VOLTAGE TRANSFORMER TEST

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

filamentwindingofthehighvoltagetransformer.Itisverydangeroustowork

near this part when the oven is on. NEVER make any voltage measurements

of the high-voltage circuits, including the magnetron filament.

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

usinganohmmetersettoitshighestrange.ConnecttheohmmeteracrosstheterminalB+Cofthehigh

voltagerectifierandnotethe readingobtained.Reversethemeter leadsandnotethissecond reading.

The normal resistance is infinite in one direction and more than 100 kΩin the other direction.

CARRY OUT 4R CHECKS.

NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF

THEMEASURINGINSTRUMENTMUSTHAVEAVOLTAGEATLEAST6VOLTS,BECAUSE

OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.

CARRY OUT 3D CHECKS.

Disconnect the leads to the primary winding of the high voltage transformer. Disconnect the filament

and secondary winding connections from the rest of the HV circuitry. Using an ohmmeter, set on a low

range, it is possible to check the continuity of all three windings. The following readings should be

obtained:- a. Primary winding ................................ approximately 1.3 Ω

b. Secondary winding ............................ approximately 86 Ω

c. Filament winding......................................... less than 1 Ω

If the readings obtained are not stated as above, then the high voltage transformer is probably faulty

and should be replaced.

CARRY OUT 4R CHECKS.

HIGH VOLTAGE RECTIFIER

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)andthenaresistanceofabout10MΩafter

R-2197

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

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 Open circuit Short circuit

Depressed Short circuit Open circuit

COM; Common terminal,

NO; Normally open terminal

NC; Normally close terminal

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

CARRY OUT 4R CHECKS.

F THERMAL CUT-OUT TEST

CARRY OUT 3D CHECKS.

Disconnectthe leadsfromthe terminalsofthe thermalcut-out.Then usinganohmmeter, makeacontinuity

test across the two terminals as described in the below.

Table: Thermal Cut-out Test

Temperature of "ON" Temperature of "OFF" Indication of ohmmeter

Parts Name condition (closed circuit). condition (open circuit). (Whenroomtemperature

(˚C) (˚C) is approx. 20˚C.)

Thermal cut-out 125˚C This is not resetable type. Above 125˚C Closed circuit

Thermal cut-out 145˚C This is not resetable type. Above 145˚C Closed circuit

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

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.

An open circuit thermal cut-out (OVEN) indicates that the food in the oven cavity may catch fire, this

may be due to over heating produced by improper setting of the cooking timer or failure of the control

panel.

CARRY OUT 4R CHECKS.

GBLOWN FUSE M10A

CARRY OUT 3D CHECKS.

Ifthefuse M10A isblownwhen the doorisopened, check the1st.latch switch, 2nd.latchswitch, relay

RY2, monitor switch and monitor resistor.

If the fuse M10A is blown, there could be a short or ground 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 M10A with the correct value replacement.

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. 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.

R-2197

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.

Table: Resistance of Motor

Motors Resistance

Fan motor Approximately 219 Ω

Antenna motor Approximately 11 kΩ

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS.

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

IMOTOR WINDING TEST

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of noise filter.

Usingan ohmmeter,check betweentheterminalsasdescribed

in the following table.

MEASURING POINTS INDICATION OF OHMMETER

Between N and L Approx. 680 kΩ

Between terminal N and WHITE Short circuit

Between terminal L and RED Short circuit

If incorrect readings are absorbed, replace the noise filter unit.

CARRY OUT 4R CHECKS.

HNOISE FILTER TEST

J HIGH VOLTAGE FUSE TST

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 replacement.

Thetouchcontrolpanel consists ofcircuitsincludingsemiconductors such asLSI,ICs,etc. Therefore,

unlikeconventionalmicrowaveovens,propermaintenancecannotbeperformedwithonlyavoltmeter

and ohmmeter.

Inthisservicemanual, the touchcontrolpanel assembly isdividedintotwo units, ControlUnitandKey

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

1. Key Unit Note : Check key unit ribbon connection before replacement.

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

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 Panel

The following symptoms indicate a defective control unit. Before replacing the control unit.

perform the key unit test (Procedure L) to determine if control unit is faulty.

2-1 In connection with pads

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 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 up.

d) The corresponding segments of all digits do not light up; or they continue to light up.

K CONTROL PANEL ASSEMBLY TEST

FUSE

M10A

DISCHARGE RESISTOR 680 kΩ

NOISE SUPPRESSION COIL

LINE BYPASS

CAPACITOR

0.0033µF/ AC 250V

DISCHARGE

RESISTOR 10MΩ

LINE BYPASS

CAPACITOR

0.0033µF/ AC 250V

LINE CROSS CAPACITOR 0.068µF/ AC 250V

NOISE FILTER

R-2197

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

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 troubles 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 STOP/CLEAR pad is depressed, first verify the flat ribbon cable

ismarkinggoodcontact,verifythatthedoorsensing switch(stop switch)operatesproperly;thatisthe

contactsareclosedwhenthedoorisclosedandopenwhenthedoorisopen.Ifthedoorsensingswitch

(stopswitch)isgood, disconnect theflatribboncable that connectsthekeyunit to the controlunitand

make sure the door sensing switch is closed (either close the door or short the door sensing switch

connecter). Use the Key unit matrix indicated on the control panel schematic and place a jumper wire

betweenthepinsthatcorrespond totheSTOP/CLEAR padmarkingmomentarycontact.If thecontrol

unitrespondsbyclearingwithabeepthekeyunitisfaultyandmustbereplaced.Ifthecontrolunitdoes

notrespond,itisa faulty and mustbereplaced. Ifa specific pad does notrespond,theabove method

may be used (after clearing the control unit) to determine if the control unit or key pad is at fault.

CARRY OUT 3D CHECKS.

Removetheouter case andcheckvoltage between PinNos.3 and 7ofthe 3 pinconnector(A) on the

control unit with an A.C. voltmeter.

The meter should indicate 230-240 volts, if not check oven circuit.

Relay Test

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

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

DC. voltage not indicated.... Check diode which is connected to the relay coil. If diode is good,

control unit is defective.

RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS

RY2 Approx. 12.0V D.C. High voltage transformer

RY3 Approx. 12.0V D.C. Oven lamp / Antenna motor / Fan motor

CARRY OUT 4R CHECKS.

M RELAY TEST

CARRY OUT 4R CHECKS.

11131519

12141620

SELECT

TIME

SELECT

POWER

STOP/

CLEAR

START SET

CHECK

SIGNAL

DOUBLE

QUANTITY

EXPRESS

DEFROST

G12

G11

G10

G 9

G 1 G 2 G 3 G 4 G 5 G 6 G 7 G 8

R-2197

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

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

(PWB) IS OPEN

Toprotect theelectronic circuits,this modelis providedwithafinefoilpatternaddedtotheinputcircuit

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.

CARRY OUT 3D CHECKS.

STEPS OCCURRENCE CAUSE OR CORRECTION

1The rated AC voltage is not present at Check supply voltage and oven power cord.

Power terminal of CPU connector (CN-A).

2The rated AC voltage is present at primary Low voltage transformer or secondary circuit defective.

side of low voltage transformer. Check and repair.

3 Only pattern at "a" is broken. *Insert jumper wire J1 and solder.

(CARRY OUT 3D CHECKS BEFORE REPAIR)

4 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".

(CARRY OUT 3D CHECKS BEFORE REPAIR)

NOTE: *At the time of these repairs, make a

visual inspection of the varistor for

burning damage and examine the

transformer with tester for the pres-

ence of layer short circuit (check pri-

mary coil resistance).

If any abnormal condition is detected,

replace the defective parts.

CARRY OUT 4R CHECKS.

(17)

(CT1)

(J1)

(J7)

(TB1)

VRS1

(VRS2)

POWER

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11) Relay Driving Circuit

This is a circuit for driving output relay by IC1 output.

12) Door Sensing Switch Circuit

This is a circuit for driving IC1 to detect door opening/

closing.

2. Key Unit

The key unit is composed of a matrix circuit in which

when a key it touched, one of signals P30--P34

generated by the LSI, is passed through the key and

returned to the LSI as one of signals P24--P27.

This model has 20 Memory pads.

Whenthe ovenis shipped,Memorypad1to10areset

as follows: fig.1.

Memory No. Cook Time Output Power

1 10 sec. 100%

2 20 sec. 100%

3 30 sec. 100%

4 45 sec. 100%

5 1 min. 100%

6 1 min. 15 sec. 100%

7 1 min. 30 sec. 100%

8 2 min. 100%

9 2 min. 30 sec. 100%

0 3 min. 100%

(fig. 1)

This model has a double quantity pad. When the oven

is shipped, Magnification "1.7" is preset in the double

quantity pad.

This model has an express defrost pad. When the

oven is shipped, express defrost is set as follows:

fig.2.

1 STAGE 2 STAGE 3 STAGE

FORMULA P = 0.2T P = 0.15T P = 0.65T

POWER 60 % 40 % 20 %

T : Total cooling time (fig. 2)

When 1/2 total cooking time is passed, the signal

will sound and "CHECK" indicator will flash

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

Thetouchcontrolsectionconsistsofthefollowingunitsas

shown in the touch control panel circuit.

(1) Control Unit

(2) Key Unit

The principal functions of these units and the signals

communicated among them are explained below.

1. Control Unit

Signal of key touch and oven function control are all

processed by one microcomputer.

1) Power Supply Circuit

This circuit changes output voltage at the secondary

side of the low voltage (T1) transformer to voltages

required at each part by full wave rectifying circuit,

constant voltage circuit, etc..

2) ACL Circuit

This is an Auto-clear Circuit, i.e., a reset circuit, which

enables IC1 to be activated from initial state.

3) Power SYNC Signal Generating Circuit

This is a circuit for generating power SYNC signal by

virtue of the secondary side output of transformer T1.

This signal is used for a basic frequency to time

processing and so on.

4) Clock Circuit

Thisisacircuitforcontrollingclockfrequencyrequired

for operating IC1.

5) IC1 (Main Processor)

This is a one-chip microcomputer, responsible for

controlling the entire control unit.

6) IC2 (Memory Processor)

Thisisa memoryIC,responsibleformemory function.

7) IC3

This is a IC for driving light emitting diode.

8) Display Circuit

This is a circuit for driving light emitting diode by IC1

output.

9) Key Input Circuit

Thisisacircuitfortransmittingkeyinputinformationto

IC1.

10) Sound-body Driving Circuit

This is a circuit for driving sound body by IC1 output.

DESCRIPTION OF LSI

LSI(IZA897DR)

The I/O signal of the LSI(IZA897DR) is detailed in the following table.

Pin No. Signal I/O Description

1 VCC IN Power source voltage: +5V.

VC voltage of power source circuit input.

2/3 VEE/AVSS IN Connected to GND

4 VREF IN Connected to VC. (+5V)

5-6 AN7-AN6 IN Terminal not used.

R-2197

7-8 AN5-AN4 IN Terminal to change functions according to the model.

Signal in accordance with the model in operation is applied to set up its function.

9-10 AN3-AN2 IN Terminal not used.

11 AN1 IN Input signal which communicates the door open/close information to LSI.

Door closed; "L" level signal (0V).

Door opened; "H" level signal (+5V).

12 AN0 IN Terminal not used.

13 P55 OUT Magnetron high-voltage circuit driving signal.

To turn on and off the cook relay. In 100% power level operation, "H" level during

cooking; "L" level otherwise. In other power level operation

(90,80,70,60,50,40,30,20,10or0%),"H"and"L"levelisrepeatedaccordingtopower

level.

Power level ON OFF Power level ON OFF

100% 32sec. 0sec. 40% 16sec. 16sec.

90% 30sec. 2sec. 30% 12sec. 20sec.

80% 26sec. 6sec. 20% 8sec. 24sec.

70% 24sec. 8sec. 10% 6sec. 26sec.

60% 22sec. 10sec. 0% 0sec. 32sec.

50% 18sec. 14sec.

14-15 P54-P53 OUT Terminal not used.

16-18 P52-P50 IN Terminal not used.

19 P47 OUT Signal to sound buzzer.

This signal is to control the 2.5kHz con-

tinuous signal through IC3.

A: key touch sound.

B: Guidance sound.

C: Completion sound.

20 P46 OUT Oven lamp, Fan motor and Antenna motor driving signal. (Square Waveform :

50Hz)

To turn on and off the shut-off relay (RY3). The

Square waveform voltage is delivered to the

RY3drivingcircuit andrelays(RY2,COOK RE-

LAY) control circuit.

21 P45 OUT Digit selection signal.

Therelationbetweendigitsignalanddigitare

as follows:

Digit signal Digit

P42..................... 1st.

P43....................2nd.

P44.....................3rd.

P45..................... 4th.

Normally, one pulse is output in every ß

period, and input to the grid of the light-

emitting diode.

22-24 P44-P42 OUT Digit selection signal.

Signal similar to P45.

25 INT1 IN Signal synchronized with commercial power source frequency.

This is basic timing for all time processing of LSI.

26 P40 IN Connected to GND through resistor.

Pin No. Signal I/O Description

+5V

GND

32 sec.

OFF

0.12 sec

2.4 sec

1.2 sec

+5V

GND T

200µsec.

1.2 sec

B+5V

GND

C+5V

GND

20 msec

During cooking

+5V

ß(50Hz)

P42

P43

P44

P45

GND

H : +5V

L : GND

20 msec

R-2197

27 RESET IN Auto clear terminal.

SignalisinputtoresettheLSItotheinitialstatewhenpowerissupplied.Temporarily

setto"L"levelthe momentpowerissupplied,atthistimetheLSIisreset.Thereafter

set at "H" level.

28 P71 OUT Memory (EEPROM) clock output.

29 P70 IN/OUT Memory (EEPROM) data input/output.

30 XIN IN Internal clock oscillation frequency setting input.

The internal clock frequency is set by inserting the ceramic filter oscillation circuit

with respect to XOUT terminal.

31 XOUT OUT Internal clock oscillation frequency control output.

Output to control oscillation input of XIN.

32 VSS IN Connected to GND.

33 P27 IN Signal coming from touch key.

When either one of G-12 line keys on key matrix is touched, a corresponding signal

out of P30, P31, P32, P33, P34 will be input into P27. When no key is touched, the

signal is held at "L" level.

34 P26 IN Signal similar to P27.

When either one of G-11 line keys on key matrix is touched, a corresponding signal

will be input into P26.

35 P25 IN Signal similar to P27.

When either one of G-10 line keys on key matrix is touched, a corresponding signal

will be input into P25.

36 P24 IN Signal similar to P27.

When either one of G-9 line keys on key matrix is touched, a corresponding signal

will be input into P24.

37-38 P23-P22 OUT Terminal not used.

39-40 P21-P20 OUT Segment data signals.

The relation between signals and indicators are as follows:

Signal Segment Signal Segment

P21,P20 ..........1 P05,P04 .............7

P17.P16 ..........2 P03,P02 .............8

P15,P14 ..........3 P01,P00 .............9

P13,P12 ..........4

P11,P10 ..........5

P07,P06 ..........6

41-48 P17-P10 OUT Segment data signal.

Signal similar to P21.

49-56 P07-P00 OUT Segment data signal.

Signal similar to P21.

57-59 P37-P35 OUT Terminal not used.

60 P34 OUT Key strobe signal.