Sharp R-380a User manual

R-380A

SERVICE MANUAL

MICROWAVE OVEN

R-380A

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.

Service engineers should not be exposed to the 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-380A

ITEM DESCRIPTION

Power Requirements 230 - 240 Volts

50 Hertz

Single phase, 3 wire earthed

Power Consumption 1.5kW

Power Output 1000 watts nominal of RF microwave energy (IEC 705)

Operating fequency 2450 MHz

Case Dimensions Width 520 mm

Height 302 mm including foot

Depth 403 mm

Cooking Cavity Dimensions Width 348 mm

Height 212 mm

Depth 379 mm

Turntable diameter 335mm

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

HELP pad

SENSOR INSTANT REHEAT pads

SENSOR COOK pad

SLOW COOK pad

EASY DEFROST pad

MEMORY pad

MORE, LESS pads

NUMBER pads

POWER LEVEL pad

CLOCK pad

TIMER pad

STOP/CLEAR pad

INSTANT COOK/START pad

Set Weight Approx. 17 kg

PRODUCT SPECIFICATIONS

GENERAL INFORMATION

WARNING

THIS APPLIANCE MUST BE EARTHED

IMPOTANT

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

GREEN-AND-YELLOW : EARTH

BLUE : NEUTRAL

BROWN : LIVE

R-380A

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 open button

9. Touch control panel

10.Digital readout

11.Wave guide cover

12.Power supply cord

13.Rating label

14.Turntable tray

15.Turntable support

11 13

TOUCH CONTROL PANEL



Info Display

HELP

DINNER

PLATE

CASSEROLE

SOUP

PIZZA

VEGETABLES

MEAT

SLOW

COOK

POWER

LEVEL

STOP

CLEAR

INSTANT COOK

START

CLOCK TIMER

MEMORY

EASY

DEFROST

RICE/PASTA

DESSERTS

RICE PIE

Sensor Instant Reheat

Sensor Cook

LESS MORE

12345

6789O

COOK SENSOR KG DEF HELP

POWER LEVEL PAD

Press to select microwave power

setting. If not pressed, HIGH is au-

tomatically selected.



STOP/CLEAR PAD

Press to clear during programming.

Press once to stop operation of oven

during cooking; press twice to can-

cel cooking programme.

TIMER / CLOCK PAD

Press to set Timer.



INSTANT COOK/START PAD

Press once to cook for 1 minute on

HIGH or increase by 1 minute multi-

ples each time this pad is pressed

during cooking. Press to start the

oven after setting programmes.

Indicator

HELP PAD

Press to select auto start, informa-

tion guide on/off, child lock, dem-

onstration modes or info on pads.

Press to get cooking information.

SENSOR INSTANT REHEAT PADS

Press once to reheat 1 or 6 popular

menus.

SLOW COOK PADS

Press to cook slowly and for a long-

er time.

SENSOR COOK PADS

Press to select Sensor Cook menus.

EASY DEFROST PAD

Press to defrost frozen food by

entering quantity.

MORE( ), LESS ( ) PADS

Press to increase/ decrease the time

in one minute increments during

cooking or to after the cooking result

for the Sensor Instant Reheat, Sen-

sor Cook or Easy Defrost modes

NUMBER PADS

Press to enter cooking times, clock

time, weight or quantity of food.

MEMORY PAD

Press to enter a frequently used cook-

ing program. Press to recall the

memorized program.

CLOCK PAD

Press to set Clock.

R-380A

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 point A3+A5 in the control unit.

Figure O-1 on page 28

1. The display shows SHARP , MICRO- , WAVE

and 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 28

CONNECTED COMPONENTS RELAY

Oven lamp, Fan motor, Turntable motor RY1

Power transformer RY2

1. Ratedvoltage is supplied to theprimary winding of 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

sent to the voltage doubling circuit, where it is doubled

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

energyischanneled throughthewaveguide (transport

channel)into theoven cavity, wherethe foodis 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.latch switch,andstop switchare madeopen.The

oven lamp remains on even if the oven door is opened

after the cooking cycle has been interrupted, because

therelayRY1 staysclosed.Shown inthedisplay isthe

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.

latchswitchand stopswitchmustopen theircontacts

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 of the 1st. latchswitch, 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.

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, 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; 32 sec. ON

24 sec. ON

18 sec. ON

12 sec. ON

6 sec. ON

8 sec. OFF

14 sec. OFF

20 sec. OFF

26 sec. OFF

HIGH

MEDIUM HIGH

MEDIUM

MEDIUM LOW

LOW

Approx. 70%

Approx. 50%

Approx. 30%

Approx. 10%

NOTE: TheON/OFFtimeratiodoesnotexactlycorrespond

to the percentage of microwave power, because

approx. 2 seconds are needed for heating up the

magnetron filament.

SENSOR COOKING CONDITION

Using the SENSOR COOK or SENSOR INSTANT RE-

HEAT function, the foods are cooked or reheated without

figuring time, power level or quantity. When the oven

senses enough steam from the food, it relays the informa-

tiontoitsmicroprocessorwhichwillcalculatetheremaining

cooking time and power level needed for best results.

When the food is cooked, water vapor is developed. The

sensor “senses” the vapor and its resistance increases

gradually. When the resistance reaches the value set

according to the menu, supplementary cooking is started.

The time of supplementary cooking is determined by ex-

perimentwitheachfoodcategoryand inputtedintotheLSI.

R-380A

An example of how sensor works:

1. Potatoesatroomtemperature.

Vapor is emitted very slowly.

2. Heat potatoes. Moisture and

humidity is emitted rapidly.

Youcan smell the aroma asit

cooks.

3. Sensor detects moisture and

humidity and calculates

cooking time and variable

power.

Cooking Sequence.

1. Touch each SENSOR COOK or SENSOR INSTANT

REHEATfunctionpadtooperatingthesensorcooking.

NOTE: The oven should not be operated on SENSOR

COOK or SENSOR INSTANT REHEAT

immediately after plugging in the unit. Wait five

minutes before cooking on SENSOR COOK or

SENSOR INSTANT REHEAT.

2. The coil of shut-off relay (RY-1) is energized, the

turntable motor, oven lamp and cooling fan motor are

turned on, but the power transformer is not turned on.

3. After about 16 seconds, the cook relay (RY-2) is

energized. The power transformer is turned on,

microwaveenergyisproducedandfirststageisstarted.

The16 seconds isthe coolingtime required toremove

any vapor from the oven cavity and sensor.

NOTE: During this first stage, do not open the door or

touch STOP/CLEAR pad.

4. When the sensor detects the vapor emitted from the

food,thedisplayswitchesovertotheremainingcooking

time and the timer counts down to zero.

At this time, the door may be opened to stir food, turn

it or season, etc.

5. Whenthetimerreacheszero,anaudiblesignalsounds.

Theshut-offrelayandcookrelayarede-energizedand

the power transformer, oven lamp, etc. are turned off.

6. Opening the door or touching the STOP/CLEAR pad,

the time of day will reappear on the display and the

oven will revert to an OFF condition.

DOOR OPEN MECHANISM

The door is opened by pushing the open button on the

control panel, refer to the Figure D-1.

When the open button is pushed, the open button pushes

up the switch lever, and then the switch lever pushes up

thethelatchhead.Thelatchheadsaremovedupwardand

released from latch hook. Now the door will open.

Latch Hook



2nd. Latch

Switch

Monitor 

Switch

Stop 

Switch

Switch

Lever

Latch

Heads

Door

1st. Latch 

Switch

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 M8A blows simultaneously with closing the

contacts (COM-NC) of the monitor switch.

CAUTION: BEFOREREPLACINGABLOWNFUSEM8A

TEST THE 1ST. LATCH SWITCH, 2ND.

LATCH SWITCH MONITOR SWITCH AND

MONITOR RESISTOR FOR PROPER OP-

ERATION.

MONITOR RESISTOR R 0.8Ω20W

ThemonitorresistorpreventsthefuseM8Aburstingwhen

the fuse M8A blows due to the operation of the monitor

switch.

ASYMMETRIC RECTIFIER

The asymmetric rectifier is a solid state device that pre-

vents current flow in both directions. And it prevents the

temperature rise of the power transformer by blowing the

fuse M8A when the high voltage rectifier is shorted.

D2 D1

ASYMMETRIC

RECTIFIER HIGH VOLTAGE 

RECTIFIER

The rated peak reverse voltage of D1 of the asymmetric

rectifieris6KVTheratedpeakreversevoltageofD2ofthe

asymmetricrectifieris1.7KV.D1andD2ofthe asymmet-

ric rectifier or high voltage rectifier are shorted when the

each peak reverse voltage goes beyond the each rated

peak reverse voltage. (The process of blowing the fuse

M8A.)

FUNCTION OF IMPORTANT COMPONENTS

MICROWAVE

AH SENSOR

MICROWAVE

R-380A

1. The high voltage rectifier is shorted by any causes

when microwave cooking.

2. The peak reverse voltage of D2 of the rectifier goes

beyond the rated peak reverse voltage 1.7 KV in the

voltage doubler circuit.

3. D2 of the rectifier is shorted.

4. Thelargeelectriccurrentsflowthroughthehighvoltage

winding of the power transformer.

5. Thelarge electriccurrents beyond8A flowthrough the

primary winding of the power transformer.

6. The fuse M8A blows by the large electric currents.

7. The power supply to all the electrical parts are cut off.

FUSE M8A

1. The fuse M8A blows when the contacts (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. The fuse M8A also blows when asymmetric rectifier,

H.V. rectifier, H.V. wire harness, H.V.capacitor,

magnetronorsecondarywindingofpowertransformer

is shorted.

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

circuited, this fuse M8A blows to prevent an electric

shock or fire hazard.

OVEN THERMAL CUT-OUT

Thethermal cut-out, located onthe top of theoven cavity,

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

magnetronhas cooledto75˚C, thethermal cut-outcloses

and cook cycle will resume.

TURNTABLE MOTOR

Theturntablemotordrivestheturntablerollerassemblyto

rotate the turntable.

FAN MOTOR

Thefanmotordrivesabladewhichdrawsexternalcoolair.

Thiscool air is directedthrough the airvanes surrounding

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.

R-380A

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 harness.

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 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 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.

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

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.

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

checked and microwave leakage test carried out

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.

IMPORTANT: If the oven becomes inoperative because

ofablownfuseM8Ainthe1st.latchswitch

-2nd.latch switch-monitor switch-moni-

tor resistor circuit, check the 1st. latch

switch, 2nd. latch switch, monitor switch

and monitor resistor before replacing the

fuse M8A.

TROUBLESHOOTING GUIDE

R-380A

Home fuse blows when power

supplycordispluggedintowall

outlet.

FUSE M8A blows when power

supplycordispluggedintowall

outlet.

Display does not show any-

thing when 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. (Dis-

play appears)

Oven lamp does not light (Dis-

play appears.)

Fan motor does not operate.

(Display appears.)

Turntablemotorassemblydoes

notoperate.(Displayappears.)

Oven or any electrical parts

does not stop when cooking

time is 0 or STOP/CLEAR pad

is touched.

Oven seems to be operating

butlittleornoheatis produced

inovenload.(Microwavepower

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/

CLEARpadistouchedtheoven

stops.)

Oven goes into cook cycle but

shutsdownbeforeendofcook-

ing cycle.

Oven stops as soon as when

the START pad is touched.

AHsensordoesnotendduring

Sensor Cooking condition.

(Oven does not shut off after a

cup of water is boiling by sen-

sor cooking.

Oven stops at 16 sec. after

starting.

TEST PROCEDURE

CK = Check / RE = Replace

POSSIBLE CAUSE

AND

DEFECTIVE PARTS

CONDITION PROBLEM

CONDITION

OFF

CONDITION

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 M8A

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

AH SENSOR

SENSOR

COOKING

CONDITION

ABC

EEEEGFHHIK LMN

RE CK CKRE CK CKCK CK CK

R-380A

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 magnetron from highvoltage circuit byremoving all leadsconnected to filament terminal.

Totestforanopencircuitfilamentuseanohmmetertomakeacontinuitytestbetweenthemagnetron

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

Totestforshortfilamenttoanodecondition,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 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 way

of IEC 705, i.e. it can be measured by using water load how much it can be absorbed by the water

load.Tomeasurethemicrowaveoutputpowerinthemicrowaveoven,therelationofcalorieandwatt

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

theotherhand, ifthetemperature ofthewater withV(ml)rises∆T(°C)duringthis microwaveheating

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

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

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. 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 accurate

thermometer.

7. The water load must be (1000±5) g.

8. “t”ismeasuredwhilethemicrowavegeneratorisoperatingatfullpower.Magnetronfilamentheat-

up time is not included.

NOTE: The operationtime ofthemicrowave ovenis “t+2” sec.2 sec.ismagnetron filamentheat-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-380A

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

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

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

Measured output power

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

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

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.

1000g

T1˚C T2˚C

Heat up for44 sec.

B POWER TRANSFORMER TEST

WARNING: Highvoltagesandlargecurrentsarepresentatthesecondarywindingandfilament

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

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

circuits, including the magnetron filament.

CARRY OUT 3D CHECKS.

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

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. 1.3 Ω

b. Secondary winding............... approx. 96 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.

C HIGH 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.

ASYMMETRIC RECTIFIER TEST

CARRY OUT 3D CHECKS.

Isolate the high voltage rectifier assembly from the HV circuit. The asymmetric can be tested using

an ohmmeter set to its highest range across the terminals A+B of the asymmetric rectifier and note

D2 D1

ASYMMETRIC

RECTIFIER

HIGH VOLTAGE RECTIFIER

R-380A

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

the reading obtained. Reverse the meter leads and note this second reading. If an open circuit is

indicated in both direction then the asymmetric rectifier is good. If an asymmetric rectifier is shorted

in either direction, then the asymmetric rectifier is probably faulty and must be replaced with high

voltage rectifier. When the asymmetric rectifier is defective, check whether magnetron, high voltage

rectifier, high voltage wire or filament winding of the power transformer is shorted.

CARRY OUT 4R CHECKS.

NOTE: FORMEASUREMENT OF THE RESISTANCEOF THE RECTIFIER, THEBATTERIES OF THE

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

OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.

D HIGH VOLTAGE CAPACITOR TEST

CARRY OUT 3D CHECKS.

A. Isolate the high voltage capacitor from the circuit.

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

range.

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

it has been charged.

D. A short-circuited capacitor shows continuity all the time.

E. Anopencapacitorconstantlyshowsaresistanceabout10MΩbecauseofitsinternal10MΩresistance.

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.

Anopen circuitthermalcut-out 95˚C(MG) indicatesthatthe magnetronhas overheated,thismay be

duetoresistrictedventilation,coolingfanfailureorafaultconditionwithinthemagnetronorHVcircuit.

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

FTEMPERATURE FUSE AND THERMAL CUT-OUT TEST

R-380A

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

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

control panel.

CARRY OUT 3D CHECKS.

Disconnect the leads from the monitor resist. 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.

If incorrect readings are obtained, replace the monitor resistor.

CARRY OUT 4R CHECKS.

G MONITOR RESISTOR 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 16.08 kΩ

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS

HMOTOR WINDING TEST

CARRY OUT 3D CHECKS.

1. If the fuse M8A 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. IfthefuseM8A isblownwhenthe doorisopened,checkthe 2nd.latchswitch,monitor switchand

monitor resistor.

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

M8A.

3. If the fuse M8A is blown, there could be a short in the asymmetric rectifier or there could be a

ground in wire harness. A short in the asymmetric rectifier may have occured due to short or

ground in H.V. rectifier, magnetron, power transformer or H.V. wire. Check them and replace the

defective parts or repair the wire harness.

CARRY OUT 4R CHECKS.

CAUTION: ONLY REPLACE FUSE M8A WITH THE CORRECT VALUE REPLACEMENT

IBLOWN FUSE F M8A

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

LCx L

WHT

RED

L (min) Cx ±20% Cy ±20%

600µH 0.068µF 0.0022µF

R-380A

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

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

CARRY OUT 4R CHECKS.

L 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.

If the door sensing switch (stop switch) is good, disconnect the flat ribbon that connects the key unit

tothe control unitand make surethe door sensingswitch is closed(either close thedoor or short the

doorsensingswitchconnector).Usethekeyunitmatrixindicatedonthecontrolpanelschematicand

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

contact.Ifthecontrolunitrespondsbyclearingwithabeepthekeyunitisfaultyandmustbereplaced.

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.

K 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 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.

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.

G 8

RICE

CLOCK

SOUP

TIMER

PIZZA

MEAT

HELP

POWER

LEVEL

STOP

CLEAR

DINNER

PLATE

SLOW

COOK

MEMORY

RICE /

PASTA

LESS

PIE

VEGETABLES

CASSEROLE

DESSERTS

EASY

DEFROST

G 7

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

G12 G11 G10

G 9

START

INSTANT

COOK

R-380A

CARRY OUT 3D CHECKS.

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

commonterminaloftherelayRY2onthepowerunitwithanA.C.voltmeter.Themetershouldindicate

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 or

convection 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. 24.5V D.C. Oven lamp / Turntable motor / Cooling fan motor

RY2 APPROX. 24.0V D.C. Power transformer

CARRY OUT 4R CHECKS.

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

M RELAY TEST

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

onthePWB, thisfoilpattern actsasa fuse.Ifthe foilpatternisopen, followthetroubleshooting guide

given below for repair.

Problem: POWER ON, indicator does not light up.

CARRY OUT 3D CHECKS.

STEPS OCCURRENCE CAUSE OR CORRECTION

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

Pin No. 3 of the 2-pin connector (A) and the

common terminal of the relay RY2.

2 The 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,

makea visualinspectionof thevaristor.

Checkforburned damageandexamine

the transformer with a tester for the

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.

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

(PWB) IS OPEN

RY2

HVT

(COM)

CN - A

(J1)

Checking the initial sensor cooking condition

(1) The oven should be plugged in at least two minutes before sensor cooking.

(2) Room temperature should not exceed 35˚C.

(3)Theunit shouldnotbeinstalled inanyarea whereheatandsteam aregenerated.The unitshould

not be installed, for example, next to a conventional surface unit. Refer to the "INSTALLATION

Instructions" .

(4) Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity. To

OAH SENSOR TEST

R-380A

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

permitadequateventilation,besuretoinstallsoasnottoblockthesevents.Thereshouldbesome

space for air circulation.

(5) Be sure the exterior of the cooking container and the interior of the oven are dry. Wipe off any

moisture with a dry cloth or paper towel.

(6) The Sensor works with food at normal storage temperature. For example, chicken pieces would

be at refrigerator temperature and canned soup at room temperature.

(7) Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings. The

sensor will detect the vapour given of by the spray and turn off before food is properly cooked.

(8) If the sensor has not detected the vapour of the food, ERROR will appear and the oven will shut

off.

Water load cooking test

Makesuretheovenhasbeenpluggedinatleastfiveminutesbeforecheckingsensorcookoperation.

The cabinet should be installed and screws tightened.

(1) Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.

(2) Place the container on the center of tray in the oven cavity.

(3) Close the door.

(4) Touch SOUP pad of SENSOR INSTANT REHEAT once. Now, the oven is in the sensor cooking

condition and "SOUP", "SENSOR" and "REHEAT" will appear in the display.

(5) The oven will operate for the first 16 seconds, without generating microwave energy.

NOTE: ERROR will appear if the door is opened or STOP/CLEAR pad is touched during first stage

of sensor cooking.

(6) After approximately 16 seconds, microwave energy is produced, and the display should start to

countdown theremaining cookingtime, andoven shouldturn offafter wateris boiling(bubbling).

If the oven does not turn off, replace the AH sensor or check the control unit, refer to explanation

below.

TESTING METHOD FOR AH SENSOR AND/OR CONTROL UNIT

To determine if the sensor is defective, the simplest method is to replace it with a new replacement

sensor.

(1) Disconnect oven from power supply and remove outer case.

(2) Discharge the high voltage capacitor.

(3) Remove the AH sensor.

(4) Install the new AH sensor.

(5) Re-install the outer case.

(6)Reconnecttheoventothepowersupplyandcheckthesensorcookoperationproceedasfollows:

6-1. Fill approximately 200 milliliters (7.2 oz) of tap water in a 1000 milliliter measuring cup.

6-2. Place the container on the center of tray in the oven cavity.

6-3. Close the door.

6-4. Touch SOUP pad once.

6-5. The control panel is in automatic Sensor operation.

6-6. The display will start to count down the remaining cooking time, and the oven will turn off

automatically after the water is boiling (babbling).

If new sensor dose not operate properly, the problem is with the control unit.

CHECKING CONTROL UNIT

(1) Disconnect oven from power supply and remove outer case.

(2) Discharge the high voltage capacitor.

(3) Disconnect the wire leads from the cook relay.

(4) Disconnect the sensor connector that is mounted to lower portion of control panel.

(5) Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.

(6)Reconnecttheoventothepowersupplyandcheckthesensorcookoperation,proceedasfollows:

6-1. Touch SOUP pad once.

6-2. The control panel is in the sensor cooking operation.

6-3. After approximately 20 seconds, push plunger of select switch. This condition is same as

judgement by AH sensor.

6-4.Afterapproximately3seconds,thedisplayshows"XX.XX"whichistheremainingcooking

time, and the display count down.

R-380A

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

If the above is not the case, the control unit is probably defective.

If the above is proper, the AH sensor is probably defective.

R1,R2 : 22Ω±1% 1/2W

R3 : 4.3kΩ±5% 1/4W

R4 : 1MΩ±5% 1/4W

Plunger

COM

COM NO

R3 R4

F-1

F-2

F-3

To connector (F)

on Control Unit.

CONNECTOR

Sensor Dummy Resistor Circuit

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following units.

(1) Key Unit

(2) Control Unit (The Control Unit consists of Power Unit

and CPU Unit).

The principal functions of these units and the signals

communicated among them are explained below.

Key Unit

Thekeyunitiscomposedofamatrix,signalsgeneratedin

the LSI are sent to the key unit through P20 - P27.

Whena keypadis touched,a signaliscompleted through

thekeyunitandpassedbacktothe LSIthroughP74-P77

to perform the function that was requested.

Control Unit

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

powersource circuit,relay circuit, buzzercircuit, synchro-

nizing signal circuit, absolute humidity sensor 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 25 segments and 4 common

electrodes using a Liquid Crystal Display.

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 -5.3V 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

LD1 - LD5).

9) Absolute Humidity Sensor Circuit

This circuit detects moisture of the cooking food to

allow its automatic cooking.

R-380A

DESCRIPTION OF LSI

LSI(IZA778DR):

The I/O signal of the LSI(IZA778DR) is detailed in the following table.

Pin No. Signal I/O Description

0.12 sec.

2.4 sec.

H : GND

L : -5V

H : GND

L : -5V

1 C1 IN Terminal not used.

2 VL1 IN Power source voltage input terminal.

Standard voltage for LCD.

3-6 AN7-AN4 IN Terminal to change cooking constant according to the Model.

ByusingtheA/DconvertercontainedintheLSI,DCvoltageinaccordancewiththe

Model in operation is applied to set up its cooking constant.

7 AN3 OUT Terminal not used.

8 AIN2 IN Toinputsignalwhichcommunicatesthedooropen/closeinformationtoLSI.

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

Door opened; "L" level signal (-5V).

9 AN1 IN AH sensor input.

This input is an analog input terminal from the AH sensor circuit, and connected

the A/D converter built into the LSI.

10 AN0 IN Usedforinitialbalancingofthebridgecircuit(absolutehumiditysensor).Thisinput

is an analog input terminal from the AH sensor circuit, and connected to the A/D

converter built into the LSI.

11-13 P57-P55 OUT Terminal not used.

14 P54 OUT Signal to sound buzzer (2.0kHz).

A: key touch sound.

B: Completion sound.

15-18 P53-P50 OUT Terminal not used.

19-23 P47-P43 OUT Used for initial balancing of the bridge circuit (absolute humidity sensor).

24 INT0 IN Signal synchronized with commercial power source frequency.

Thisisthebasictimingfortimeprocess-

ing of LSI.

25-26 P41-P40 OUT Terminal not used.

27 P77 IN Signal coming from touch key.

When either G12 line on key matrix is touched, a corresponding signal out of P20

-P27 willbe input intoP77. Whenno key istouched, thesignal isheld at "H"level.

28 P76 IN Signal similar to R77.

WheneitherG11lineonkeymatrixistouched,acorrespondingsignalwillbeinputintoR76.

29 P75 IN Signal similar to R77.

WheneitherG10lineonkeymatrixistouched,acorrespondingsignalwillbeinputintoR75.

30 P74 IN Signal similar to R77.

WheneitherG9lineonkeymatrixistouched,acorrespondingsignalwillbeinputintoR74.

31 P73 OUT Oven lamp, fan motor and turntable motor driving signal.

Toturn onandoff theshut-off relay(RY1).

Thesquare waveform voltageis delivered

to the relay RY1 driving circuit and RY2

control circuit.

32 P72 OUT Magnetron high-voltage circuit driving signal.

To turn on and off the cook relay

(RY2). The signals holds "L" level

during microwave cooking and "H"

levelwhilenotcooking.Inothercook-

ing modes (variable cooking) the sig-

nal turns to "H" level and "L" level in

repetitionaccordingtothepowerlevel.

33 P71 OUT Terminal not used.

34 P70 IN Connected to VC.

35 RESET IN Auto clear terminal.

Signal is input to reset the LSI to the initial state when power is supplied.

Temporarily set to "L" level the moment power is supplied, at this time the LSI is

reset. Thereafter set at "H" level.

20.0 msec.

H : GND

L : -5V

20.0 msec.

During cooking

H : GND

L : -5V

P-HI

H : GND

L : -5V

H : GND

L : -5V

P-70

OFF

OFF OFF

24 sec.

8 sec.

R-380A

36-37 P81-P80 OUT Terminal not used.

38 XIN IN Internal clock oscillation frequency input setting.

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

with respect to XIN terminal.

39 XOUT OUT Internal clock oscillation frequency control output.

Output to control oscillation input of XOUT.

40 VSS IN Power source voltage: -5.1V.

VC voltage of power source circuit input.

41 P27 OUT Key strobe signal.