Sharp R-350d User manual

R-350D

SHARP CORPORATION

SERVICE MANUAL

S7005R350DPJ/

MICROWAVEOVEN

MODEL R-350D

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 .............................................................................................................................14

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ........................................................... 18

MICROWAVE MEASUREMENT .................................................................................................................... 24

WIRING DIAGRAM ......................................................................................................................................... 25

PICTORIAL DIAGRAM ................................................................................................................................... 26

POWER UNIT CIRCUIT ..................................................................................................................................27

CPU UNIT CIRCUIT ........................................................................................................................................28

PRINTED WIRING BOARD .............................................................................................................................29

PARTS LIST ................................................................................................................................................... 30

DINNER

PLATE

PASTA MEAL

FROZEN DINNER

CASSEROLE

SOUP

PIE

PIZZA

POWER

LEVEL

LESS MORE

STOP

CLEAR

INSTANT COOK

START

CLOCK

TIMER

EASY

DEFROST

EXPRESS

DEFROST

BEVERAGE

MEAT

VEGETABLES

RICE/

PASTA

CONVENIENCE MEALS

REHEAT MENU

INFORMATION COOK

1234

6789

DEFROST COOK

HELP

Info Display

R-350D

SERVICEMANUAL

MICROWAVE OVEN

R-350D

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.

Serviceengineersshouldnot beexposed tothe microwave

energy which may radiate from the magnetron or other

microwave generating devices if it is improperly used or

connected. All input and output microwave connections,

waveguides, flanges and gaskets must be secured. Never

operate the device without a microwave energy absorbing

load attached. Never look into an open waveguide or

antenna while the device is energized.

WARNING

Never operate the oven until the following points are ensured.

(A) The door is tightly closed.

(B) The door brackets and hinges are not defective.

(D) The door is not deformed or warped.

(E) There is not any other visible damage with the oven.

Servicing and repair work must be carried out only by trained

service engineers.

All the parts marked "*" on parts list are used at voltages more

than 250V.

Removal of the outer wrap gives access to potentials above

250V.

All the parts marked "∆" on parts list may cause undue micro-

wave exposure, by themselves, or when they are damaged,

loosened or removed.

SHARP CORPORATION

OSAKA, JAPAN

PRODUCT SPECIFICATIONS

APPEARANCE VIEW

OPERATING SEQUENCE

FUNCTION OF IMPORTANT

COMPONENTS

SERVICING AND

TROUBLESHOOTING CHART

TEST PROCEDURE

TOUCH CONTROL PANEL

ASSEMBLY

COMPONENT REPLACEMENT

AND ADJUSTMENT PROCEDURE

MICROWAVE MEASUREMENT

WIRING DIAGRAM

PARTS LIST

R-350D

ITEM DESCRIPTION

Power Requirements 230 - 240 Volts

50 Hertz

Single phase, 3 wire earthed

Power Consumption 1.6kW

Power Output 1100 watts nominal of RF microwave energy (IEC Test Procedure)

Operating frequency 2450 MHz

Case Dimensions Width 520 mm

Height 302 mm including foot

Depth 436 mm

Cooking Cavity Dimensions Width 374 mm

Height 227 mm

Depth 399 mm

Turntable diameter 335 mm

Control Complement Touch Control System

Clock ( 1:00 - 12:59)

Timer (0 - 99 minutes 99 seconds)

Microwave Power for Variable Cooking

Repetition Rate;

HIGH ...............................................Full power throughout the cooking time

MEDIUM HIGH ..................................................approx. 70% of Full Power

MEDIUM .............................................................approx. 50% of Full Power

MEDIUM LOW ....................................................approx. 30% of Full Power

LOW ....................................................................approx. 10% of Full Power

INSTANT ACTION pads

EXPRESS DEFROST pad

EASY DEFROST pad

NUMBER pads

POWER LEVEL pad

TIMER/CLOCK pad

STOP/CLEAR pad

INSTANT COOK/START pad

Set Weight Approx. 17 kg

PRODUCT SPECIFICATIONS

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

R-350D

APPEARANCEVIEW

1. Ventilation openings

2. Oven lamp

3. Door hinges

4. Door safety latches

5. See through door

6. Door seals and sealing surfaces

7. Coupling

8. Door handle

9. Touch control panel

10.Digital readout

11.Waveguide cover

12.Power supply cord

13.Rating label

14.Turntable tray

15.Turntable support

TOUCH CONTROL PANEL

NOTE:

The directed feature is disabled after three minutes when the oven is not in use. This feature is automatically

enabled when the door is opened and closed or the STOP/ CLEAR pad is pressed.

14 15

7211

DINNER

PLATE

PASTA MEAL

FROZEN DINNER

CASSEROLE

SOUP

PIZZA

POWER

LEVEL

LESS MORE

STOP

CLEAR

INSTANT COOK

START

CLOCK

TIMER

EASY

DEFROST

EXPRESS

DEFROST

BEVERAGE

PIE

MEAT

VEGETABLES

RICE/

PASTA

CONVENIENCE MEALS

REHEAT MENU

INFORMATION COOK

12345

6789

STOP/CLEAR PAD

Press to clear during programming.

Press once to stop operation of oven

during cooking; press twice to can-

cel cooking programme.

POWER LEVEL PAD

Press to select microwave power

setting. If not pressed, HIGH is au-

tomatically selected.

INSTANT COOK/START PAD

Press to start the oven after setting

programmes. Press once to cook

for 1 minute on HIGH or increase in

1 minute increments each time this

pad is pressed during cooking.

(See note.)

HELP PAD

Press to select auto start, child

lock or demonstration modes.

Press to display preset menu

cooking information.

CONVENIENCE MEALS PADS

Press to select Convenience Meals

menus. INFORMATION COOK PADS

Press to select information Cook

mode.

EASY DEFROST PAD

Press to select Easy Defrost

menu.

REHEAT MENU PADS

Press to select a reheat menu.

MORE( ), LESS ( ) PADS

Press to increase/ decrease the

time in one minute increments dur-

ing cooking or to after the cooking

result for automatic operations.

NUMBER PADS

Press to enter cooking times, clock

time, weight or quantity of food.

EXPRESS DEFROST PAD

Press to select Express Defrost

menu.

TIMER PAD

Press to set Timer.

CLOCK PAD

Press to set Clock.

Indicator

Display

DEFROST COOK

HELP

Info Display

R-350D

OPERATION SEQUENCE

OFF CONDITION

Closing the door activates all door interlock switches

(1st. latch switch, 2nd. latch switch and stop switch).

IMPORTANT

Whentheovendoorisclosed,themonitorswitchcontacts

(COM-NC) must be open.

Whenthemicrowaveovenispluggedinawalloutlet,rated

voltage is supplied to the noise filter and the control unit.

Figure O-1 on page 25

1. The display shows "SHARP MICRO-WAVE OVEN".

2. To set any programmes or set the clock, you must

first touch the STOP/CLEAR pad.

3. : appears in the display.

NOTE: When the oven door is opened, the oven lamp

comes on at this time.

MICROWAVE COOKING CONDITION

HIGH COOKING

Enter a desired cooking time with the touching NUMBER

pad and start the oven with touching START pad.

Function sequence

Figure O-2 on page 25

CONNECTED COMPONENTS RELAY

Oven lamp, Fan motor, Turntable motor RY1

Power transformer RY2

1. Ratedvoltage issupplied tothe primarywindingof the

power transformer. The voltage is converted to about

3.3 volts A.C. output on the filament winding and high

voltage of approximately 2000 volts A.C. on the

secondary winding.

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

magnetronfilamentandthehighvoltage(2000volts)is

sentto thevoltage doublingcircuit, whereit 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

energyischanneledthroughthewaveguide(transport

channel)into theovencavity,where thefoodis placed

to be cooked.

4. Whenthecookingtimeisup,asignaltoneisheardand

the relays RY1+RY2 go back to their home position.

The circuits to the oven lamp, power transformer, fan

motor and turntable motor are cut off.

5. When the door is opened during a cook cycle, the

switches come to the following condition

CONDITION

DURING DOOR OPEN

SWITCH CONTACT COOKING

(NOCOOKING)

1st. latch switch COM-NO Closed Open

2nd. latch switch COM-NO Closed Open

Monitor switch COM-NC Open Closed

Stop switch COM-NO Closed Open

The circuits to the power transformer, fan motor and

turntable motor are cut off when the 1st. latch switch,

2nd.latchswitch,and stopswitcharemadeopen.The

ovenlamp remainson evenif theoven dooris opened

after the cooking cycle has been interrupted, because

therelayRY1staysclosed.Shown inthedisplayisthe

remaining time.

6. MONITOR SWITCH CIRCUIT

The monitor switch is mechanically controlled by

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

2nd. latch switches.

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

cycleofacookingprogram,the1st.latchswitch,2nd.

latchswitchandstopswitchmustopen 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

thecontacts ofthe 1st.latch switch,2nd.latch switch

and stop switch are closed.

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

the1st. latch switch, 2nd. latch switch remain closed.

ThefuseM10A willblow,becausethe monitorswitch

is closed and a short circuit is caused.

MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW

COOKING

When the microwave oven is preset for variable cooking

power, 230-240 volts A.C. power is supplied to the power

transformer intermittently within a 32-second time base

through the relay contact which is coupled with the cur-

rent-limitingrelay.Thefollowinglevelsofmicrowavepower

are given.

SETTING;

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-350D

FUNCTION OF IMPORTANT COMPONENTS

OVEN THERMAL CUT-OUT

Thethermal cut-out,located onthetop ofthe ovencavity,

is designed to prevent damage to the oven by fire. If the

foods load is overcooked, by either error in cook time or

defect in the control unit, the thermal cut-out will open.

Undernormaloperation,theoventhermalcut-outremains

closed.However,whenabnormallyhightemperaturesare

reached within the oven cavity, the oven thermal cut-out

will open at 125˚C, causing the oven to shut down. The

defective thermal cut-out must be replaced with new one.

MAGNETRON THERMAL CUT-OUT

The thermal cut-out located near the magnetron is de-

signed to prevent damage to the magnetron if an over

heated condition develops in the tube due to cooling fan

failure,obstructedairguide,dirtyorblockedairintake,etc.

Under normal operation, the thermal cut-out remains

closed.However,whenabnormallyhightemperaturesare

reached within the magnetron, the thermal cut-out will

open at 95˚C causing the oven to shut down, when the

magnetronhascooledto 75˚C,thethermalcut-outcloses

and cook cycle will resume.

TURNTABLE MOTOR

Theturntablemotordrivestheturntablerollerassemblyto

rotate the turntable.

FAN MOTOR

Thefanmotordrivesabladewhichdrawsexternalcoolair.

Thiscool airisdirected throughthe air vanessurrounding

the magnetron and cools the magnetron. This air is

channeled through the oven cavity to remove steam and

vapors given off from the heating foods. It is then ex-

hausted through the exhausting air vents at the oven

cavity

NOISE FILTER

The noise filter prevents the radio frequency interference

that might flow back in the power circuit.

DOOR OPEN MECHANISM

Thedoor isopened bypulling thedoor,refer tothe Figure

D-1.

Figure D-1. Door Open Mechanism

1ST.LATCHSWITCH,2ND.LATCHSWITCHAND

STOP SWITCH

1. Whentheovendoorisclosed,thecontacts (COM-NO)

must be closed.

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

NO) must be opened.

MONITOR SWITCH

1. Whentheovendoorisclosed,thecontacts(COM-NC)

must be opened.

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

NC) must be closed.

3. Iftheovendoorisopenedandthecontacts(COM-NO)

ofthe1st.latchswitchand2nd.latchswitchfailtoopen,

the fuse M10A blows simultaneously with closing the

contacts (COM-NC) of the monitor switch.

CAUTION: BEFORE REPLACING A BLOWN FUSE

M10ATESTTHE1ST.LATCHSWITCH, 2ND.

LATCH SWITCH MONITOR SWITCH AND

MONITOR RESISTOR FOR PROPER OP-

ERATION.

MONITOR RESISTOR 0.8Ω20W

The monitor resistor prevents the fuse M10A bursting

when the fuse M10A blows due to the operation of the

monitor switch.

HIGH VOLTAGE FUSE

Thehighvoltagefuseblowswhenthehighvoltagerectifier

or magnetron is shorted.

FUSE M10A

1. ThefuseM10Ablowswhenthecontacts(COM-NO)of

the 1st. latch switch and 2nd. latch switch remain

closed with the oven door open and when the monitor

switch closes.

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

circuited, this fuse M10A blows to prevent an electric

shock or fire hazard.

Latch Hook

Stop Switch

2nd. Latch

Switch

Latch

Heads

Door

Monitor Switch

1st. Latch

Switch

R-350D

SERVICING

WARNING TO SERVICE PERSONNEL

Microwaveovenscontaincircuitrycapableofproducingveryhighvoltageandcurrent,contactwithfollowingparts

of the high voltage circuit will result in electrocution. High voltage capacitor, Power transformer, Magnetron, High

voltage rectifier assembly, High voltage fuse, High voltage harness.

REMEMBER TO CHECK 3D

1) Disconnect the supply.

2) Door opened, and wedged open.

3) Discharge the high voltage capacitor.

WARNING: AGAINST THE CHARGE OF THE

HIGH-VOLTAGE CAPACITOR

Thehigh-voltagecapacitorremainschargedabout

60 seconds after the oven has been switched off.

Wait for 60 seconds and then short-circuit the

connectionofthehigh-voltagecapacitor(thatis,of

the connecting lead of the high-voltage rectifier)

against the chassis with the use of an insulated

screwdriver.

Sharprecommendthatwhereverpossiblefault-finding

is carried out with the supply disconnected. It may, in

some cases, be necessary to connect the supply after

the outer case has been removed, in this event carry

out 3D checks and then disconnect the leads to the

primary of the power transformer. Ensure that these

leads remain isolated from other components and the

ovenchassis.(Useinsulationtapeifnecessary.)When

the testing is completed carry out 3D checks and

reconnect the leads to the primary of the power trans-

former.

REMEMBER TO CHECK 4R

1) Reconnect all leads removed from components

during testing.

2) Replace the outer case (cabinet).

3) Reconnect the supply.

4) Run the oven. Check all functions.

Microwave ovensshould notbe runempty. Totest for

the presence of microwave energy within a cavity,

place a cup of cold water on the oven turntable, close

the door and set the microwave timer for two (2)

minutes. Set the power level to HIGH and push the

START button. When the two minutes has elapsed

(timeratzero)carefullycheckthatthewaterisnowhot.

If the water remains cold carry out 3D checks and re-

examine the connections to the component being

tested.

When troubleshooting the microwave oven, it is helpful to

follow the Sequence of Operation in performing the

checks.Manyofthepossiblecausesoftroublewillrequire

that a specific test be performed. These tests are given a

procedure letter which will be found in the "Test

Procedure"section.

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.

TROUBLESHOOTING GUIDE

IMPORTANT: If the oven becomes inoperative because

of a blown fuse M10A in the 1st. latch

switch - 2nd. latch switch - monitor switch

- monitor resistor circuit, check the 1st.

latch switch, 2nd. latch switch, monitor

switchand monitorresistorbeforereplac-

ing the fuse M10A.

R-350D

MAGNETRON

POWER TRANSFORMER

H.V. RECTIFIER ASSEMBLY

HIGH VOLTAGE CAPACITOR

1ST. LATCH SWITCH

2ND. LATCH SWITCH

STOP SWITCH

MONITOR SWITCH

MONITOR RESISTOR

THERMAL CUT-OUT 95˚C /125˚C

FAN MOTOR

TURNTABLE MOTOR

FUSE M10A

TOUCH CONTROL PANEL

KEY UNIT

RELAY (RY-1, RY-2)

FOIL PATERN ON P.W.B.

POWER SUPPLY CORD

SHORTED WIRE HARNESS

OPENED WIRE HARNESS

OVEN LAMP OR SOCKET

WALL OUTLET

MISADJUSTMENT SWITCH

HOME FUSE OR BREAKER

BLOCKED COOLING FAN

BLOCKED VENTILATION

NOISE FILTER

HIGH VOLTAGE FUSE

Homefuseblowswhenpower

supply cord is plugged into

wall outlet.

FUSE M10A blows when

power supply cord is plugged

into wall outlet.

Display does not show any-

thingwhenpowersupply cord

is plugged into wall outlet.

Display doesnotoperateprop-

erly when STOP/CLEAR pad

is touched.

Oven lamp does not light at

door opened. (Display ap-

pears.)

Oven does not start when the

START pad is touched. (Dis-

play appears)

Ovenlampdoesnotlight(Dis-

play appears.)

Fan motor does not operate.

(Display appears.)

Turntable motor assembly

does not operate. (Display

appears.)

Oven or any electrical parts

does not stop when cooking

timeis0orSTOP/CLEARpad

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.)

Ovengoesintocookcyclebut

shutsdownbeforeendofcook-

ing cycle.

TEST PROCEDURE

CK = Check / RE = Replace

ABC

EEEEGFHHILMNO

RECK CK RE CK CK CKCK CK

CONDITION PROBLEM

POSSIBLE CAUSE

AND

DEFECTIVE PARTS

CONDITION

OFF

CONDITION

R-350D

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

AMAGNETRON TEST

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

WHILE THE OVEN IS IN OPERATION.

CARRY OUT 3D CHECK.

Isolatethe magnetronfrom high voltagecircuit byremovingall leadsconnected tofilamentterminal.

Totestforanopencircuitfilamentuseanohmmetertomakeacontinuitytestbetweenthemagnetron

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

To test for short circuit filament to anode condition, connect ohmmeter between one of the filament

terminalsandthecaseofthemagnetron(ground).Thistestshouldbeindicatedaninfiniteresistance.

If a low or zero resistance reading is obtained then the magnetron should be replaced.

MICROWAVE OUTPUT POWER (1 litre water 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 IEC

testprocedure,i.e.itcanbemeasuredbyusingwaterloadhowmuchitcanbeabsorbedbythewater

load.Tomeasurethemicrowaveoutputpowerinthemicrowaveoven,therelationofcalorieandwatt

is used. When P(W) heating works for t(second), approximately P x t/4.187 calorie is generated. On

theotherhand, if thetemperatureofthe water withV(ml)rises∆T(˚C)during thismicrowaveheating

period, the calorie of the water is V x ∆T.

The formula is as follows;

P x t / 4.187 = V x ∆T+ 0.55 x mc (T2-T0)

(W) = 4.187 x V x ∆T / t + 0.55 x mc (T2-T0)/t

Our condition for water load is as follows:

Room temperature (T0) ... around 20°C Power supply Voltage..............Rated voltage

Water load..................................1000 g Initial temperature (T1) ...................... 10±1°C

Heating time.............................. 38 sec. Mass of container (mc) ......................... 330 g

T2............................ Final Temperature P = 110 x ∆T + 0.55 x mc (T2-T0)/38

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±1)˚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. Selectstirringdevicesandmeasuringinstrumentsinordertominimizeadditionorremovalofheat.

6. 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”ismeasuredwhilethemicrowavegeneratorisoperatingatfullpower.Magnetronfilamentheat-

up time is not included.

NOTE: The operation time of the microwave oven is “t + 2” sec. 2 sec. is magnetron filament heat-

up time.

Measuring method:

1. Measure the initial temperature of the water before the water is added to the vessel.

(Example: The initial temperature T1 = 11˚C)

2. Add the 1 litre water to the vessel.

3. Place the load on the centre of the shelf.

4. Operate the microwave oven at HIGH for the temperature of the water rises by a value ∆T of

(10 ±2)˚C.

5. Stir the water to equalize temperature throughout the vessel.

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.

R-350D

Room temperature .................. To = 21˚C Initial temperature................. T1 = 11°C

Temperature after (38 + 2) = 40 sec. ................................................................ T2 = 21°C

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

Measured output power

The equation is “P = 110 x ∆T” ........................................... P = 110 x 10°C = 1100 Watts

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

1000g

T1˚C T2˚C

Heat up for 40 sec.

BPOWER TRANSFORMER TEST

WARNING: Highvoltagesandlargecurrentsarepresentatthesecondarywindingandfilament

winding of the power transformer. It is very dangerous to work near this part when

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

circuits, including the magnetron filament.

CARRY OUT 3D CHECKS.

Disconnect the leads to the primary winding of the power transformer. Disconnect the filament and

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 ....................approx. 1.0 Ω

b. Secondary winding ...............approx. 87 Ω

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

If the reading obtained are not stated as above, then the power transformer is probably faulty and

should be replaced.

CARRY OUT 4R CHECKS.

CHIGH VOLTAGE RECTIFIER ASSEMBLY TEST

HIGH VOLTAGE RECTIFIER TEST

CARRY OUT 3D CHECKS.

IsolatethehighvoltagerectifierassemblyfromtheHVcircuit.Thehighvoltagerectifier canbetested

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.Thenormalresistanceisinfiniteinonedirectionandmorethan100kΩintheotherdirection.

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.

HIGH VOLTAGE RECTIFIER

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

CAUTION: 1°C CORRESPONDS TO 110 WATTS REPEAT MEASUREMENT IF THE POWER IS

INSUFFICIENT.

R-350D

CARRY OUT 3D CHECKS.

Disconnect the leads from the monitor resistor. Using an ohmmeter and set on a low range. Check

between the terminals of the monitor resistor.

The resistance of monitor resistor is approx. 0.8 ohms.

GMONITOR RESISTOR TEST

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. Continuity check must be carried out with measuring instrument which is set to the highest

resistance range.

C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10MΩ

after 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.

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 COM; Common terminal

Released Open circuit Short circuit NO; Normally open terminal

Depressed Short circuit Open circuit NC; Normally close terminal

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

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of the temperature fuse or thermal cut-out. Then using an

ohmmeter, make a continuity test across the two terminals as described in the table below.

CARRY OUT 4R CHECKS.

Table: Temperature fuse and Thermal cut-out Test

Temperature of "ON" condition Temperature of "OFF" condition Indication ofohmmeter

Parts Name (closed circuit) (˚C) (open circuit) (˚C) (When room temperature

is approx. 20˚C)

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 temperature fuse or thermal cut-out.

Anopencircuitthermal cut-out95˚C(MG)indicatesthatthe magnetronhasoverheated,thismay be

duetoresistrictedventilation,coolingfanfailureorafaultconditionwithinthemagnetronorHVcircuit.

An open circuit thermal cut-out 125˚C (OVEN) indicates that the foods in the oven may catch fire,

this may be due to over heating produced by improper setting of the cooking time or failure of the

control panel.

F TEMPERATURE FUSE AND THERMAL CUT-OUT TEST

R-350D

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

CARRY OUT 3D CHECKS.

Disconnect the leads from the motor.

Usinganohmmeter,checktheresistancebetweenthetwoterminalsasdescribedinthetablebelow.

Table: Resistance of Motor

Motors Resistance

Fan motor Approximately 390 Ω

Turntable motor Approximately 12 kΩ

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS

HMOTOR WINDING TEST

CARRY OUT 3D CHECKS.

1. If the fuse M10A is blown, there could be shorts or ground in electrical parts or wire harness.

Check them and replace the defective parts or repair the wire harness.

2. If the fuse M10A is blown when the door is opened, check the 1st. latch switch, 2nd. latch switch,

monitor switch and monitor resistor.

Ifthe fuseM10A isblownby incorrectdoor switchingreplace the defectiveswitch(s) andthe fuse

M10A.

CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE FUSE M10A WITH THE CORRECT VALUE REPLACEMENT

IBLOWN FUSE M10A

JNOISE FILTER TEST

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of the noise

filter. Using an ohmmeter, check between the termi-

nals as described in the following table.

MEASURING POINT INDICATION OF

OHMMETER

Between N and L Open circuit

Between terminal N and WHITE Short circuit

Between terminal L and RED Short circuit

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

CARRY OUT 4R CHECKS.

LCx L

WHT

RED

L (min) Cx ±20% Cy ±20%

600µH 0.068µF 0.0022µF

CARRY OUT 3D CHECKS.

Ifthehighvoltagefuse isblown,therecouldbeashortin the highvoltage rectifierorthemagnetron.

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

CARRY OUT 4R CHECKS.

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

PLACEMENT

K HIGH VOLTAGE FUSE TEST

If incorrect readings are obtained, replace the monitor resistor.

CARRY OUT 4R CHECKS.

R-350D

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

M KEY UNIT TEST

If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable

ismakinggoodcontact,verifythatthedoorsensingswitch(stopswitch)operatesproperly;thatisthe

contacts are closed when the door is closed and open when the door is open.

Ifthedoorsensingswitch(stopswitch)isgood,disconnecttheflatribboncablethatconnectsthekey

unittothecontrolunit andmakesurethedoorsensingswitchis closed(eitherclosethedoororshort

thedoorsensing switch connector).Usethekey unit matrixindicatedonthecontrol panelschematic

and place a jumper wire between the pins that correspond to the STOP/CLEAR pad making

momentarycontact.Ifthecontrolunitrespondsbyclearingwithabeepthekeyunitisfaultyandmust

be replaced. If the control unit does not respond, it is faulty and must be replaced.

If a specific pad does 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.

CARRY OUT 3D CHECKS.

L TOUCH CONTROL PANEL ASSEMBLY TEST

ThetouchcontrolpanelconsistsofcircuitsincludingsemiconductorssuchasLSI,ICs,etc.Therefore,

unlike conventional microwave ovens, proper maintenance cannot be performed with only a

voltmeterandohmmeter.Inthisservicemanual,thetouchcontrolpanelassemblyisdivided intotwo

units, Control Unit and Key Unit, and also the Control Unit is divided into two units, CPU Unit and

Power Unit, and troubleshooting by unit 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 Unit.

Thefollowingsymptomsindicateadefectivecontrolunit.Beforereplacingthecontrolunit,perform

the Key unit test (Procedure M) 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.

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 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.

54321

09876

BEVERAGE

POWER

LEVEL

FROZEN

DINNER

MEAT CLOCK TIMER

HELP

LESS

DINNER

PLATE

RICE/

PASTA

MEAL

EASY

DEFROST

EXPRESS

DEFROST

STOP

CLEAR

VEGETABLES

INSTANT

COOK

START

G 8

G 9

G10

G11

G12

G13

G14

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

SOUP

CASSEROLE

PIE PIZZA

R-350D

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

onthePWB,thisfoil patternactsasafuse.Ifthefoil patternisopen,followthetroubleshootingguide

given below for repair.

Problem: POWER ON, indicator does not light up.

CARRY OUT 3D CHECKS.

STEPS OCCURRENCE CAUSE OR CORRECTION

The rated AC voltage is not present between

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

normal open terminal of the relay RY1.

2The rated AC voltage is present to 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.

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

NOTE: *At the time of making these repairs,

makeavisualinspectionofthevaristor.

Checkfor burned damageand exam-

inethetransformerwithatesterforthe

presence of layer short-circuit (check

the primary coil resistance). If any ab-

normal condition is detected, replace

the defective parts.

CARRY OUT 4R CHECKS.

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

NRELAY TEST

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

(PWB) IS OPEN

RemovetheoutercaseandcheckvoltagebetweenPinNo1ofthe2-pinconnector(A)andthenormal

open terminal of the relay RY1 on the power unit with an A.C. voltmeter. The meter should indicate

230 - 240 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.

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

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

control unit is defective.

RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS

RY1 APPROX. 24.0V D.C. Oven lamp / Turntable motor / Cooling fan motor

RY2 APPROX. 23.0V D.C. Power transformer

CARRY OUT 4R CHECKS.

RY1

VRS1

RY3

(J1)

R-350D

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following units.

(1) Key Unit

(2) Control Unit (TheControl UnitconsistsofPowerUnit

and LSI Unit).

The principal functions of these units and the signals

communicated among them are explained below.

Key Unit

The key unit is composed of a matrix, signals generated

in the LSI are sent to the key unit through P10-P17.

Whenakeypadistouched,asignaliscompletedthrough

the key unit and passed back to the LSI through AN11,

AN10, AN9, P42, P41 and AN8 to perform the function

that was requested.

Control Unit

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

powersourcecircuit,relaycircuit,buzzercircuit,synchro-

nizing signal circuit and back light circuit.

1) ACL

This circuit generates a signal which resets the LSI to

the initial state when power is supplied.

2) Indicator Circuit

This circuit consists of 40 segments and 16 common

electrodes using a Liquid Crystal Display.

The Liquid Crystal Display (LCD) is drived by LCD

driver IC3.

3) Power Source Circuit

Thiscircuitgeneratesvoltagesnecessaryinthecontrol

unit from the AC line voltage.

In addition, the synchronizing 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

A circuit to drive the magnetron, fan motor, turntable

motor and light the oven lamp.

5) Buzzer Circuit

ThebuzzerisresponsivetosignalsfromtheLSItoemit

audible sounds (key touch sound and completion

sound).

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) Door Sensing Switch

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

8) Back Light Circuit

A circuit to drive the back light (Light emitting diodes

LD10-LD19).

R-350D

1 AN10 IN Signal coming from touch key.

When either G10 line on key matrix is touched, a corresponding signal out of P10 - P17

will be input into AN10. When no key is touched, the signal is held at "H" level.

2 AN11 IN Signal similar to AN10.

When either G9 line on key matrix is touched, a corresponding signal will be input into

AN11.

3 AVSS IN Connected to VC.

4 P10 OUT Key strobe signal.