Sharp R-8380 Service Manual

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R-8380

SHARP SERVICE MANUAL

SX707R8380J//

CONVECTION

MICROWAVE OVEN

MODEL R-8380.

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

condition and only parts identica!to those specified should be used.

(RD16101 U)

TABLE OF CONTENTS

Page

FOREWORD ....................................................................................................................................................... 1

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

PRODUCT DESCRIPTION ............................................................................................................................... 2

OPERATING INSTRUCTIONS ......................................................................................................................... 3

OPERATION .......................................................................................................................................................

SERVICING ..................................................................................................................................................... 11

TOUCH CONTROL PANEL ASSEMBLY ..................................................................................................... 21

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ..................................................... 30

MICROWAVE MEASUREMENT PROCEDURE .......................................................................................... 35

PICTORIAL DIAGRAM .................................................................................................................................. 36

CONTROL PANEL CIRCUIT ......................................................................................................................... 37

PRINTED WIRING BOARD .......................................................................................................................... 38

PARTS LIST ....................................................................................................................................................

PACKING AND ACCESSORIES

................................................................................................................... 48

SHARPCORPORATlON

SERVICE MANUAL

SHARP

CONVECTION MICROWAVE OVEN

R-8380

FOREWORD

This Manual has been prepared to provide Sharp Corp. Service

Personnel with complete Operation and Service Information for

the SHARP CONVECTION MICROWAVE oven, R-8380.

It is recommended that service personnel carefully study the entire text of this manual so they will be qualified to render satisfactory customer service.

Check interlock switches and door seal carefully. Special attention should be given to avoid electrical shock and microwave radiation hazard.

(RD361 OZU)

CAUTION

MICROWAVE RADIATION

Personnel should not be exposed to the microwave energywhich may radiate from the magnetron or other microwave generating devices if it is improperly used or connected. All input and output microwave connections, waveguidesflanges 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.

Note( Parts List) : The parts marked m*n are used in voltage

more than 250V.

(RD36202U)

SHARPCORPORATlON

OSAKA, JAPAN

(RD37201 I

PRODUCT DESCRIPTION

WIRING DIAGRAM

R-8380

PRODUCT DESCRIPTION

SPECIFICATION

beI vvelgnt 1 Approx. L4 Kg

(RD4410

ITEM

Power Requirements

240 Volts 50 Hertz

DESCRIPTION

Single phase, 3 wire earthed

Power Consumption

Microwave cooking

1.3 kW

Convection cooking

1.6 kW

Power Output

650 watts nominal of RF microwave energy (2 liter water load) Operating frequency of 2450M Hz

Convection Heater Power Output

1.5kW

Case Dimensions

Width 520 mm

Height 336 ,mm including foot Depth 466 mm

Cooking Cavity Dimensions

Width 340 mm

Height 215 mm Depth 350 mm

Turntable diameter

Control Complement

m .I, I

330mm Touch Control System

Clock( (I:00 - 12:59) )

Timer (0 - 99min.99 sec. )

Microwave Cooking Control

Repetition Rate;

HIGH . . . . . . . . . . . . . . . . . . . . . . . .

Full power throughout the cooking time

MED HIGH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

approx. 70% of Full Power

MED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

approx. 50% of Full Power

MED LOW, DEFROST

. . . . . . . . . . . . . . . . . approx. 30% of Full Power

LOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

approx. 10% of Full Power

Convection Temperature Control Range;

40 “C, 70 “C to 250 “C SENSOR COOK pad COMPU COOK pad CONVECTION COOKING FUNCTION pads NUMBER AND TEMPERATURE pads

VARIABLE COOKING CONTROL pads

STOP/CLEAR pad ONE TOUCH REHEAT pad EASY DEFROST pad INSTANT COOK pad MORE/LESS pads AUTO START/CLOCK pad

TIMER/HOLD pad

START pad

1 e.1 I

NOTE: Numbers and letters shown after sentences such as “RD44101 U” are for factory use only.

R-8380

OPERATING INSTRUCTIONS

Auto-TouchTM Control Panel

Touch to select sensor cook mode

1 -Fresh vegetables

1 -Roast beef

Touch to enter cooking times, clock time, convec-

2 -Frozen veaetables

2 -Roast lamb

tion temperature or to select the Sensor or Compu

3 --Baked potatoes 4 -Frozen dinners 5 --Bacon 6 -Chlcken pees 7 -Fish fillets 6 -Rice 8 Pasta 9 -Cake 0 -Corned meats

3 -Roast pork 4 -Roast chicken 5 -Roast turkey 6 -Roast dinner 7 -Mixed gnll 6 -Grilled chlcken 9 -Cake layers 0 --Biscuits

Cook categories.

CONVECTION COOKING FUNCTION PADS

Touch to cook for each function

VARIABLE COOKING CONTROL PADS

Touch to select microwave power setting. If not

touched, HIGH is automatically selected.

1 minute at HIGH or increase

TIMER/HOLD PAD

Touch to set minute timer or HOLD function

@AUTO START/CLOCK PAD

Touch to set clock or auto start time

II STOP/CLEAR PAD

Touch to erase during programming. Touch once to stop operation of oven during cook- ing; touch twice to cancel cooking programme.

@MORE(A), LESS(r) pads

Touch to increase/decrease the time in one minute increments during cooking or to increase/decrease the time whilst programming the One Touch Reheat, Sensor Cook, Compu Cook or Easy Defrost modes.

@START PAD

Touch to start oven after setting programme.

OPERATION

DESCRIPTION OF OPERATING SEQUENCE

The following is a description of component functions during oven operation.

(RD71101U)

OFF CONDITION

Closing the door activates all door interlock switcnes : Upper latch switch, lower latch switch and stop switch

(In this condiction, the monitor switch contacts are opened.) When oven is plugged in, 240 volts A.C. is supplied to control unit. (Figure O-l )

1. The display will show flashing “88:88”. To set any program or set the clock, you must first touch the STOP/CLEAR pad. The display will clear, and 1:OO will appear and count up every minute.

Note: When the door is opened, the oven lamp comes

2. A sigal is input to the control unit, energizing the coil of shut-off relay (RYl).

RYl contacts close, completing a circuit to the

damper motor.

The damper motor now operates moving the damper

to the open position, thereby closing the contacts of the damper switch inputs a signal to the control

unit. The coil of relay RYl is de-energized, opening its contacts, thereby turning off the damper motor.

COOKING CONDITION

HIGH COOKING

Program desired cooking time and Variable Cooking Control by touching the NUMBER pads and HIGH pad of the Variable Cooking Control. When the START pad is touched, the following operations occur:

1. The contacts of relays are closed and components connected to the relays are turned on as follows.

(For details, refer to Figure O-2)

RELAY CONNECTED$.COMPONENTS

RY-1 damper motor RY-2

fan motor

RY-3 convectidn motor

RY-A

oven lame / turntable motor MICRO RELAY Dower transformer HEATER RELAY convection heater

2. 240 volts A.C. is supplied to the primary winding of the power transformer and is converted to about 3 volts A.C. output on the filament winding, and approximately 2150 volts A.C. on the high voltage winding.

3. The filament winding voltage heats the magnetron filament and the H.V. winding voltage is sent to a voltage doubler circuit.

4. The microwave energy produced by the magnetron

is channeled through the waveguide into the cavity

feed-box, and then into the cavity where the food

is placed to be cooked.

5. Upon completion of the cooking time, the power transformer, oven lamp, etc. are turned off, and the

generation of microwave energy is stopped. The oven will revert to the OFF condition.

6. When the door is opened during a cook cycle, upper latch switch, lower latch switch and stop switch are

activated with the following results. The circuits to the turntable motor, the cooling fan motor, and the high voltage components are deenergized, the oven

lamp remains on, and the digital readout displays

the time still remaining in the cook cycle when the door was opened.

7. The monitor switch is electrically monitoring the

operation of the upper latch switch and lower latch switch and is mechanically associated with the door so that it will function in the following sequence.

(1)

(2)

When the door opens from a closed position, the lower latch switch opens its contacts, and then the monitor switch and upper latch switch contacts close. When the door is closed from the open position, the monitor switch and upper latch switch contacts first open, and then the contacts of the

lower latch switch close. If the upper latch switch and lower latch switch fail with its contacts closed when the door is opened, the closing of the monitor switch contacts will form a short circuit through the fuse, upper latch switch and lower latch switch, causing the fuse to blow.

MED HIGH, MED, MED LOW, DEFROST, LOW COOKING

When Variable Cooking Power is programed, the 240 volts A.C. is supplied to the power transformer intermittently through the contacts of MICRO RELAY 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 -

HIGH (100% power)

MED HIGH (approx. 70% power)

MED (approx. 50% power)

MED LOW, DEFROST

(aoorox. 30% power)

32 sec.

24 sec.

18 sec.

12 sec.

0 sec.

8 sec.

14 sec.

20 sec.

LOW

(approx. 10% power)

6 sec.

26 sec.

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.

EASY DEFROST COOKING

The EASY DEFROST key is a special function key to defrost meats and other food faster and better.

EASY DEFROST automatically defrosts foods. This key has 4 defrost stages. When the food weight is entered by using the number

pads, the oven will cook according to the special cooking sequence, refer to Easy Defrost Chart on Operation Manual.

R-8380

CONVECTION COOKING CONDITION

PREHEATING CONDITION (Figure O-3)

Program desired convection temperature by touching the CONVECTION pad and the temp. pad. When the START pad is touched, the following operations occur:

1. The coil of shut-off relays (RY2,RY3 and RY4) are energized, the oven lamp, cooling fan motor, turntable motor and convection motor are turned on.

2. The coil of relay (RYl) is energized by the control unit. The damper is moved to the closed position, opening the damper switch contacts. The opening of the damper switch contacts sends a signal to the LSI on the control unit de-energizing the relay (RYl) and opening the circuit to the damper motor.

3. The coil of heater relay is energized by the control unit and the mains supply voltage is added to the convection heater.

4. When the oven temperature reaches the selected preheat temperature, the following operations occur: 4-l. The heater relay is de-energized by the con-

trol unit temperature circuit and thermistor, opening the circuit to the conveqtion heater.

4-2. the oven will continue to function for 15

minutes, turning the heater on and off, as needed to maintain the selected preheat temperature. The oven will shut-down completely after 15 minutes.

CONVECTION COOKING CONDITION

When the preheat temperature is reached, a beep signal will sound indicating that the holding temperature has been. reached in the oven cavity. Open the door and place the food to be cooked in the oven. Program desired cooking time and convection temperature by touching the NUMBER pad, CONVECTION pad and Temperature pad. When the START pad is touched, the following operation occur:

1. The numbers of the digital readout start the count down to zero.

2. The oven lamp, turntable motor, cooling fan motor and convection motor are energized.

3. Heater relay is energized (if the cavity temperature is lower than the selected temperature) and the mains supply voltage is applied to the convection heater to return to the selected cooking temperature.

4. Upon completion of the cooking time, the audible

signal will sound, and oven lamp, turntable motor, cooling fan motor and convection motor, are de-energized. At the end of the convection cycle, if the cavity air temperature is above 118 “C, the circuit to RY2 will be maintained (by the thermistor circuit) to continue operation of the cooling fan motor unit the temperature drops below 118 “C, at which time the relay will be de-energized, turning off the fan motor. Relay RY3 will however, open as soon as the convection cycle has ended, turning off the convection fan motor.

5. At the end of the convection cook cycle, shut-off

relay (RYI) is energized turning on the damper motor. The damper is returned to the open position, closing the damper switch contacts which send a

signal to the control unit, de-energizing shut-off relay (RYl).

AUTOMATIC MIX COOKING CONDITION

Program desired cooking time and temperature by touching the number pads and the LOW MIX/BAKE or HIGH MIX/ROAST pad

The LOW MIX/BAKE pad is preprogrammed for 180

“C with 10% micro wave power, while the HIGH MIX/ROAST pad is preprogrammed for 200 “C with 30% microwave power.

When the START pad is

touched, the following operations occur:

1. The numbers of the digital readout start the count

down to zero.

2. The shut-off relay (RY2, RY3 and RY4) are ener-

gized, turning on the oven lamp, turntable motor, cooling fan motor and convection motor.

3. The shut-off relay (RYl ) is energized.

The damper door is closed from the open position.

4. The heater relay is energized, adding the mains supply voltage to the convection heater.

5. Now, the oven is in the convection cooking condition.

6. When the oven Temperature reaches the selected temperature, the following operations occur: 6-l. The power supply voltages is alternated to

the convection heater and power transformer.

6-2. The convection heater operates through the

heater relay contacts and the power transformer operates through the micro relay contacts.

6-3. These are operated by the control unit to

supply alternately within a 32 second time base, convection heat and microwave en-

ergy.

The relationship between the convection and microwave power operations are as follows.

Note: The ON and OFF time ratio does not correspond

with the percentage of microwave power, because approx. 2 seconds are needed for heating of the magnetron filament.

YERowA”E POWER

--.10x

I t

I IoN

eOW”ECTloN .,yEo$Tu.E

Note: During alternate Microwave/Convection opera-

tion, the convection heater is energized only if

R-8380

the cavity temperature drops below the set temperature.

SENSOR COOKING CONDITION

Using the SENSOR COOK function, the foods are cooked without figuring time, power level or quantity. When the oven senses enough steam from the food, it

relays the information to its microprocessor which will

calculate the remaining 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 in-

creases gradually. When the resistance reaches the

value set according to the menu, supplementary cook-

ing is started.

The time of supplementary cooking is determined by

experiment with each food category and inputted into

the LSI.

An example of how sensor works:

1. Broccoli at room temperature. Vapor is emitted very&,$;wly.

, :

‘v4+

2. Heat broccoli. Moisture and humidity is emitted

rapidly. You

mlthearomaasitcooks.

SENSOR

! %q

i / % J ?!-c

j;/.;

Cooking Sequence.

Touch SENSOR COOK or ONE TOUCH REHEAT pad.

NOTE:The oven should not be operated on SEN-

SOR COOK immediately after plugging in the unit. Wait five minutes before cooking on SENSOR COOK.

Select desired Sensor setting.

Touch START pad.

The coil of shut-off relays(RY2,RY4) are energized, the oven lamp and cooling fan motor are turned

on, but the power transformer is not turned on.

After about 16 seconds, the micro relay is ener-

gized. The power transformer is turned on, microwave energy is produced and first stage is started.

The 16 seconds is the cooling time required to re-

move any vapor from the oven cavity and sensor.

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

or touch STOP/CLEAR pad. When the sensor detects the vapor emitted from the food, the display switches over to the remaining cooking time and the timer counts down to zero. At this time, the door may be opened to stir food, turn it or season, etc.

When the timer reaches zero, an audible signal sounds. The shut-off relays and micro relay are-

de-energized and the power transformer, oven lamp, etc. are turned off. 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.

COMPU COOK

Thre COMPU COOK pad is aspecial function pad to compute the oven temperature, microwave power and cooking time and roast, bake and grill foods. The

COMPU COOK has H,lGH MIX/BAKE mode, LOW MIX

/BAKE mode or convection mode.

3. Sensor detects moisture and humidity and calculates cooking time and variable power.

R-8380

A -8380

1-1

R-8380

DOOR OPEN MECHANISM

The door can be opened by pushing the open button on the control panel. When the open button is pushed, the open lever pushes the latch lever. The latch lever

pushes lower latch head on the door upward. The upper latch head is linked with the lower latch head,

so now, the door can be opened.

UPPER LATCH SWITCH

The upper latch switch is activated by the upper latch head on the door. When the door is opened, the switch interrupt the circuit to all components, except oven lamp, fan motor, damper motor and control unit. Then the cook cycle

is stopped. A cook cycle cannot be take place until the door is firmly closed and the start pad is depressed with the cooking time set.

DESCRIPTION AND FUNCTION OF COMPONENTS

MONITOR SWITCH

The monitor switch is mounted on the middle of latch

hook. It is activated (the contacts opened) by the lower latch head when the door is closed. The switch

is intended to render the oven inoperative by means of blowing the fuse when the contacts of the upper latch switch and lower latch switch fail to open when the door is opened.

Function

1. When the door is opened, the monitor switch con-

tacts close (to the ON condition) due to their being normally closed. At this time the upper latch switch, lower latch switch and stop switch are in the OFF condition (contacts open) due to their being normally open contact switches.

2. As the door goes to a closed position, the monitor

switch contacts are first opened and upper latch switch contacts are closed and then the stop switch and the lower latch switch contacts close.

(On opening the door, each of these switches op-

erate inversely.)

3. If the door is opeped during cooking, and the upper

latch switch and lower latch switch contacts fail to open, the fuse blows simultaneously with closing of the monitor switch contacts.

CAUTION: BEFORE REPLACING A BLOWN FUSE,

TEST THE UPPER LATCH SWITCH AND LOWER LATCH SWITCH FOR PROPER OPERATION.

LOWER LATCH SWITCH

The lower latch switch is activated by the lower latch head on the door.

(

When the door is opened, the switch interrupts the circuit to the convection heater and the power transformer. Then the cook cycle is stopped.

&=;z; TO CHAPTER “TEST PROCE-

STOP SWITCH

The stop switch is activated by the upper latch head. When the door is opened while the oven is in cook cycle, th stop switch contacts open to de-energize the

micro relay, heater relay and relays (except RYI ) circuits in the control unit and causes cook time count down to- pause.

LATCH HOOK

‘N_,

/UPPER LATCH SWITCH

‘\ UPPER

,‘I LATCH

1 HEAD

HOOK LEVER

UPPER LATCH LEVER

I-

‘lb

’ c

‘,b

STOP SWITCH

2’ 1

I LOWER

LATCH

MONITOR SWITCH

HEAD

~~LOWER LATCH SWlTCH

‘i:j ,id

I ‘If+,

-“_b “2 ~

-x9,

LATCH LEVER

@i j

DOOR OPEN LEVER

L.iTCti LEVER

OPEN BUTTON

Figure D-l. Upper Latch Switch,

Lower Latch Switch, Stop switch and Monitor Switch,

R-8380

CONVECTION COOKING SYSTEM This oven is designed with a hot air heating system where food is not directly heated up by the convection

heater, but is instead heated by forced circulation of the hot air produced by the convection heater. The air heated by the convection heater is circulated through the convection passage provided on the outer casing of the oven cavity by means of the convection fan which is driven by the convection motor. It then enters the inside of the oven through the vent holes provided on the back side of the oven. Next,the hot air heats the food on the turntable and leaves the oven cavity through the vent in the oven cavity rear wall. Without leaving the oven, this hot air is reheated by the convection heater, passes through the convection

passage and enters the inside of the oven cavity again,

in a continuing cycle.

In this way, the hot air circulates inside the oven cavity to raise its temperature and, at the same time, comes

into contact with the food being cooked.

When the temperature inside the oven cavity reaches the selected temperature, the convection heater is

de-energized. When the temperature inside the oven

cavity drops below the selected temperature, the con-

vection heater is energized again. In this way, the in-

side of the oven cavity is maintained at approximately

the selected temperature.

When the convection time reaches “0”, the convection

heater is deenergized and the convection fan stops operating and the oven shuts off. At the high temperature(more then 118 “C), the fan motor remains roataing. Automatically the fan motor will be shut down at low temperature(less than 118 “C).

CONVECTION HEATER

The convection heater is located at the rear of the oven cavity. It is intended to heat air driven by the convection fan. The heated air is kept in the oven and force-circulated and reheated by th% convection heater. THERMISTOR The thermistor is a negative temperature coefficient type. The temperature in the oven cavity is detected through the resistance of the thermistor, and then the control unit causes the heater relay to operate, thus the current to the heating element is turned ON/OFF.

own &“,I”

Convrctlori

P.**aqe

I, -~

‘,

.T’

conic< fl”r

- HearPr

iurnlablr

ROILER STAY

Motor

Figure D-2. Convection Cooking System

Figure D-3. Damper Mechanism

DAMPER OPEN-CLOSE MECHANISM Usually, the damper is in the open position except

during convection cooking.

Damper position is set automatically by damper motor, damper switch, damper cam and damper shaft. These components are operated by a signal that judges

if microwave cooking or convection cooking operation

is selected by the control unit.

Microwave Cooking:

Damper is in the open position, because a portion of

cooling air is channeled through the cavity to remove

steam and vapors given off from the heating foods.

It is then exhausted at the top of the oven cavity into

a condensation compartment.

Convection Cooking:

Damper is in the closed position, so that no hot air will

be allowed to leak out the oven cavity.

1. When power supply cord is plugged in: When power supply cord is plugged in, a signal is sensed in the control unit, and ooerates

l-l.

1-2.

1-3.

1-4.

l-5.

shut-off relay (RYl ). Contacts of shut-off relay (RYl) close, the damper motor is energized, opening the damper door. When the damper is moved to the open position by the damper cam, damper switch is closed (ON position). The signal of damper switch is re-sensed in the control unit and shut-off relay (RYI ) is turned off. The 240 volts A.C. to the damper motor is stopped and the motor turns off.

Damper Operation

2. When oven is microwave cooking: Damper is in the open position.

3. When oven is convection cookina: 3-l.

3-2.

3-3. 3-4.

Damper motor is energized-by touching the convection, temperature and START pads. Whep damper

is in the closed position

(damper switch is OFF), its signal is sensed by the control unit, and shut-off relay (RYI ) is de-energized. The damper is held in the closed position during the convection cooking operation. At the end of the convection cooking, shut-off relay (RYl) is energized, and the damper is returned to the open position.

NOTE: If the damper is not in the proper position,

closed during convection or open during microwave, the control unit will stop oven operation after 1 minute.

R-8380

SERVICING

TROUBLESHOOTING GUIDE

When troubleshooting the oven, it is helpfull to follow the Sequence of Operation in performing the checks.

Many of the possible causes of trouble will require that a specific test be performed. These tests are given a procedure letter which will be found in the “Test

Procedure”section.

IMPORTANT: If the oven becomes inoperative be-

cause of a blown fuse (M8A) in the monitor switch circuit, check the monitor switch, upper latch switch and lower latch switch before replacing the fuse (M8A).

If th fuse (M8A) is replaced, the monitor switch should be replaced at same time.

PROBLEM

POSSIBLE CAUSE I TEST PROCEDURE OR I /

CORRECTION :

Home fuse blows when power cord is plugged into wall receptacle.

13A fuse fitted in the plug blows when power cord is plugged into wall receptacle (The fuse should a BS 1362 13A A.S.T.A. fuse.)

Fuse(M8A) blows when power cord is plugged into wall receptacle.

88:88 do not appear in display when power cord is first plugged into wall outlet.

Display does not operate properly when

STOP/CLEAR pad is touched. (Buzzer should sound and time of day should appear in disotav.)

Oven lamp does not light with

No power in home.

door opened.

Open wire in power cord or wire harness.

-r

I-

! 1

[ I

OFF CONDITION

Shorted wire in power cord or wire harness.

Shorted wire in power cord or wire har- / ness.

Shorted wire in power cord or wire harness.

Defective monitor switch. No power at outlet.

Blown fuse (M8A). Blown magnetron temp. fuse. Defective fan thermal cut-out and/or oven

thermal cut-out. Open wire in power cord, wiring harness,

or wiring between control panel assembly units.

Defective control unit. Defective key unit.

defective control unit.

Defective stop switch.

Defective oven lamp. Blown fuse (M8A). Defective fan thermal cut-out and/or oven

thermal cut-out.

Blown magnetron temp. fuse. Defective control unit.

Open or loose wire connection to the above components.

Replase cord or check wiring. j

Replase power cord or check ~ and repair harness. At replac- ~ ing fuse, it should be a BS : 1362 13A A.S.T.A. fuse.

Replace power cord or check : and repair harness, replace I fuse.

Procedure F. Check home fuse.

Procedure G.

Procedure I.

Procedure J or H.

Replace or repair wiring.

Procedure 0. Check kev unit.

Procedure 0.

Procedure E.

Check wall outlet.

Replace same or repair wiring.

Replace.

Procedure G.

Procedure J or H.

Procedure I.

Procedure 0. Check wiring.

PROBLEM

POSSIBLE CAUSE

TEST PROCEDURE OR

CORRECTION

COOKING CONDITION

Oven lamp does not light in cook

Defective contacts of shut-off relay (RY4)

Procedure N. cycle. (Does light when door is on Control unit. opened)

Defective control unit.

Procedure 0.

Oven lamp does not light at all.

Burned out bulb.

Replace.

Open wiring to oven lamp socket.

Check and repair wiring.

Oven lamp lights, but turntable Defective turntable motor.

Replace.

motor does not operate.

Open or loose wiring to turntable motor

Check and repair wiring.

and lower latch switch.

Defective lower latch switch.

Procedure E. Turntable motor operates normally

Defective cooling fan motor.

Replace.

but cooling fan motor does not Defective shut-off relay (RY2) on control Procedure N. operate.

unit. Open or loose wiring to above compo-

Check and repair wiring.

nents.

MICROWAVE COOKING

1 Oven does not go into a cook cy-

Upper latch, lower latch and/or stop Procedures E or adjust them.

/ cle when START pad is touched.

switches defective or out of adjustment.

Defective micro relay.

Procedure M.

Defective control unit.

Procedure 0.

Defective key unit.

Procedure 0.

Open or loose wiring to above compo- Check and repair wiring. nents.

1 1

/ I Oven seems to be operating but Defective magnetron.

~ little or no heat is produced in j Defective micro relay.

oven load.( Food

incompletely cooked or not cooked at all at end of cookcycle)

Defective power transformer.

/ Defective high voltage rectifier assembly.

/ Procedure B.

I Procedure C.

j Defective high voltage capacitor.

,! Defective control unit.

Procedure A.

/ Procedure M.

1 Procedure D. / Procedure 0.

Open or loose wiring to above compo- / Check and repair wiring.

nents. Low voltage. Dirty oven cavity.

Oven goes into a cook cycle but

j extremely

Turntable motor does not operate.

/ Refer to preceding turntable ’

uneven

heating is

i motor problem.

: produced in oven load (food). ; I Oven does not cook properly ’ Defective micro relay.

/ Procedure M.

~ when programmed for MEDIUM Defective control unit.

levels. (Operates Defective key unit,

I Procedure 0.

etc. power

1 properly on HIGH)

1 Check key unit.

, Open or loose wiring between above Check and repair wiring. / , components.

Oven does not cook properly Oven does not cook properly

Defective EASY DEFROST function. Defective EASY DEFROST function.

! when programmed in the EASY ! when programmed in the EASY

/ Refer to EASY DEFROST / / Refer to EASY DEFROST / / section in operation manual. j / section in operation manual. j

DEFROST cooking mode. DEFROST cooking mode.

Defective micro relay. Defective micro relay.

, Procedure M. , Procedure M.

/ /

Defective control unit. Defective control unit.

j Procedure 0. j Procedure 0.

I I

Defective key unit.

1 Check key unit.

/ I

Open or loose wiring between above Check and repair wiring.

components.

R-8380

PROBLEM

POSSIBLE CAUSE

! TEST PROCEDURE OR

CORRECTION

CONVECTION COOKING

CONV indicator lights but oven Defective control unit.

~ Procedure 0.

does not go into cook cycle when Defective key unit,

Check key unit.

START pad is touched.

/ j Defective thermistor.

j Procedure L.

I Open wiring in circuit to above compo-

nents.

Check and repair wiring.

CONV indicator lights, but con- / Defective convection heater.

vection heater does not heat.

j Defective heater relay.

Defective control unit.

i Procedure K. I Procedure M. / Procedure 0.

! Upper latch switch and/or lower latch 1 Procrdure E or adjust them. i switch are defective or out of adjustment. /

/ Open or loose wire connection to the ;* Check and repair wiring. ~ above components.

~ Temperature in the oven cavity is

Defective convection heater.

i’ ~ Procedure K.

~ lower or higher than preset.

Defective control unit.

1 Procedure 0.

: Defective convection motor.

/ Replace.

I Defective thermistor.

j Procedure L.

Defective damper motor.

j Replace.

: Defective damper switch.

/ Procedure E.

Defective drive mechanism of convection Check.

fan.

Oven seems to be operating but temperature in the oven is lower than preset.

Shorted wire to thermistor. Thermistor shorted.

Check and repair wiring. Procedure L.

Open or loose wire connection to thermistor.

~ Check and repair wiring.

Oven stops after about 3 minutes since START pad is touched.

! I Thermistor opened.

Lower than preset tmperature.

j Low power supply voltage.

Cooling

fan

motor

runs Thermistor shorted.

intermitantly or all the time.

Convection cycle runs 2 mintes Thermistor open. then shuts down.

I Procedure L. j Check voltage.

Procedure L.

Convection indicator does not Stop switch is defective or out of adjust- Procedure E or adjust it.

light and oven does not go into a ment. cook cycle when START pad is Defective key unit.

Procedure 0.

touched.

Defective control unit.

/ Procedure 0.

-1

SENSOR COOKING

1 Oven is in the sensor cooking

condition but AH sensor does not end stage 1 or does not stop

~ cooking cycle or the oven stops

soon.

AH sensor ooen or short.

/ Procedure P.

Defective control unit.

1 Procedure 0.

Open or loose wire connection to the above comoonents.

Check and repair wiring.

AH sensor assembly and/or steam duct are not re-installed correctry.

?Ipen or short wire to AH sensor.

Wrong wiring to power transformer.

Check and repair them.

Check and repair wiring. Check and repair wiring. Or-

ange wire (HOT) must be connected to the upper terminal of power transformer.

TEST PROCEDURES

PROCEDURE

LElTER

COMPONENT TEST

MAGNETRON ASSEMBLY -EST

DISCHARGE THE HIGH VOLrAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING.

To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check across the magnetron filament leads should indicate less than 1 ohm.

To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament

leads and chassis ground. This test should indicate an infinite resistance. If there is little or no resistance, the magnetron is grounded and must be replaced.

Power output of the magnetron can be measured by performing a water temperature rise test. This test should only be used if above rests do not indicate a faulty magnetron and there is no defect in the following components or wiring: high voltage rectifier assembly, high voltage

capacitor, and power transformer.

MICROWAVE OUTPUT POWER

Microwave output power from the magnetron can be measured by way of substitution, i.e. it can be measured by using water load how much it can be absorbed by the water load. To measure the microwave output power in the microwave oven, the relation of calorie and watt is used. When P(W) heating works for t(second), approximately P x t/4.2 calorie is generated. On the other hand, if the temperature of the water with V(ml) rises AT ( “C) during this microwave

heating period, the calorie of the water is V x AT. The formular is as follows;

Pxt/4.2=Vx AT P (W) = 4.2 x V x AT/t

Our condition for the water load is as follows:

Water load . . .

2000 ml, Heating time . ..I 29 seconds

P=65x AT

Measuring method; s

1. Put the water load of two (2) litres on the center of ihe oven shelf. The water load should be arranged in two (2) Pyrex beakers, the size of which is one (1) litre, and be placed at right and left, side by side, on the oven shelf.

2. Measure the temperature of water before heating and also after heating during 129 seconds

by microwave, and calculate the temperature rise. The temperature rise should be the average of temperature differences measured in each beaker.

3. The output power should be calculated as follows. In case the measuring result is not satisfactory, execute the measurement several times and judge the result from the synthetic point

of view. Microwave output power should be within + 15% of the nominal one.

Calculation of output power; Microwave output power . ..P (W) = 65 x AT ( “C)

AT = ( ATL + ATR) / 2 : average temperature rise ATL = (TL2 - TLI ),

ATR = (TR2 - TRl)

TL2 : water temperature after heating in left beaker TLl : water temperature before heating in left beaker TR2 : water temperature after heating in right beaker TRI : water temperature before heating in right beaker

Measuring condition; As the microwave output is affected by several conditions, the measurement should be made carefully with following attentions.

1. Initial temperature of salt water should be 10 f 1 “C. Well and quickly stir the water and the temperature measurement should be done immediately after heating.

2. The graduation of thermometer should be scaled by 0.1 “C at minimum and an accurate mercury thermometer is recommended.

3. Water container should be one (1) litre beaker made of Pyrex glass and its diameter approxi-

mately 12 cm.

TEST PROCEDURES (CONT’D)

PROCEDURE

LETTER

COMPONENT TEST

4. Room temperature should be around 20 “C.

5. Power supply voltage should be specification voltage.

POWER TRANSFORMER TEST

DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING.

Disconnect the primary input terminals and measure the resistance of the transformer with an ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance of the primary coil should be approx. 1.5 ohm and the resistance of the high voltage coil should be approximately 87 ohms; the resistance of the filament coil should be less than 1 ohm.

(HIGH VOLTAGES ARE PRESENT TO HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO MEASURE THE FILAMENT AND HIGH VOLTAGE.)

C HIGH VOLTAGE RECTIFIER ASSEMBLY TEST

DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN C~MPONENTS OR WIRING.

HIGH VOLTAGE RECTJFIER TEST Isolate the high voltage rectifier assembly from the circuit. Using the highest ohm scale of the meter, read the resistance across the high voltage rectifier terminals and observe, reverse the leads to the high voltage rectifier terminals and observe meter reading. If a short is indicated in both directions, or if an infinite resistance is read in both directions, the high voltage rectifier is probably defective and should be replaced with rectifier.

SHORT PROTECTOR TEST

Isolate the high voltage rectifier assembly from the circuit. Using the highest ohm scale of the meter, read the resistance across the short protector terminals, reverse the leads to the short protector terminals and observe meter reading. If an infinite resistance is read in both directions,

the rectifier is good.

If a short is indicated in either direction, the one is probably defective and should be replaced

with the high voltage rectifier.

HIGH VOLTAGE CAPACITOR TEST

DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRINGS.

If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads and check for short or open, between the terminals using.an ohmmeter. Checking with a high ohm scale, if-the high voltage capacitor is normal, the meter will indicate continuity for a short time and should indicate approxcmately IOM CI once the capacitor is charged. If the above is not the case, check the capacitor with an ohmmeter to see if it is shorted between the terminals. If it is shorted, replace the capacitor.

(RD82603U)

SWITCH TEST

Isolate the switch and check the contacts by using an ohmmeter using the following table If improper operation is indicated, make the necessary switch adjustment or replacement.

Table: Switch Connection

ConnAtion

j Common Terminal-Normally Open Termmal

(COM) (NO)

:Common Terminal-Normally Close Terminal

(OM) (NC)

Operation

Plunger released Open clrcuft

Close circuit

Plunger pushed 1 Closed circuit

-------

Open circuit

(RD82701 U)

=i -8380

TEST PROCEDURES (CONT’D)

PROCEDURE

LETTER

COMPONENT TEST

MONITOR SWITCH TEST

Disconnect oven from power supply. Disconnect the lead wire to the monitor switch. Connect one ohmmeter lead to NC terminal of monitor switch, and the other lead to COM terminal of monitor switch, as shown figure. When the door is opened, the meter should indicate a close circuit. When the plunger of monitor switch is pushed by a screw-driver through the latch hook hole on the front plate of the oven cavity with the door opened, the meter should indicate an open circuit. In case improper operation is indicated, replace the defective monitor switch. After testing moniter switch, re-connect the wire leads to the monitor switch.

FUSE M8A

If the fuse in the monitor switch circuit is blown when the door is opened, check the upper latch switch, lower latch switch and monitor switch according to the Test Procedure for those switches, before replacing the blown fuse.

If the fuse is blown by improper switch operation, replace the defective switch and fuse at the same time.

Replace just the fuse if the switches operate normally.

CAUTION; REPLACEMENT FUSE MUST BE THE L&TED FUSE IN PARTS LIST.

OVEN THERMAL CUT-OUT TEST

Oven thermal cut-out is thermal cut-out. A continuity check across the thermal cut-out terminals should indicaeflosed circuit unless the temperature of the oven thermal cu.+oGf%aches approximately 104 “C. The thermal cut-out closes automatically at approximatefyy,C,j If im-

proper operatjonis’indicated replace thermal cut-out. When the oven thermal cut-out opens, it indicates overheating of the heater duct. Check the convection motor and convection fan or check if the ventilation openings are not blocked.

MAGNETRON TEMP. FUSE TEST

A continuity check across the temp. fuse terminals should indicate a closed circuit.

If the temperature of the magnetron reaches 145 “C, the temp. fuse opens. If the temp. fuse has opened, replace the fuse. An open temp. fuse indicates overheating of the magnetron assembly.

Check for restricted air flow to the magnetron through the opening in the chassis, especially the fan duct. Or an open temp. fuse indicates stop of fan motor. Check for fan motor.

FAN THERMAL CUT-OUT TEST

Fan thermal cut-out is thermal cut-out. A continuity check across the thermal cut-out terminals

should indicate an closed circuit unless the temperature of the thermal cut-out reaches approxi-

mately 104 “C. The thermal cut-out closes automatically at approximately 84 “C. If improper

operation is indicated replace thermal cut-out. When the fan thermal cut-out opens, it indicates overheating of the cooling fan motor. Check the

cooling fan motor or check if the ventilation openings are not blocked.

R-8380

TEST PROCEDURES (CONT’D)

PROCEDURE

LElTER

COMPONENT TEST

CONVECTION HEATER TEST

Make sure the convection heater is fully cooled and test as follows;

a. Disconnect wire leads and measure the resistance with an ohmmeter. On the R x 1 scale, the

resistance between the heating element terminals should be as followings.

Convection Heater: 380hms

b. Disconnect wire leads and measure the insulation resistance with 500V - 1OOM R insulation

resistance meter. The insulation resistance between convection heater terminal and cavity should be more than 10M D.

L THERMISTOR TEST

Disconnect connector-E from the CPU unit. Measure the resistance of the thermistor with an

ohmmeter. Connect the ohmmeter leads to Pin No’s E-4 and E-5.

I Room Temp. / Resistance : 68 “F(20 “C) - 86 “F(30 “C) / Approx. 326k fI - 175k f2

If the meter does not indicate above resistance. reolace the thermistor.

MICRO RELAY AND HEATER RELAY TEST

Disconnect the wire IeJds from relay terminals (l),(3), (5) and (6).

CONTACTS: With 12 volts D.C. applied to the surge relay coil (1) and (6), a check of contact with an ohmmeter should indicated (3) and (5) contacts are closed. Without 12 volts D.C. applied to the relay coil (1) and (6), an ohmmeter

30-

should indicate those contacts are opened. If improper operation is

loindicated, replace the relay. If proper operation is indicated, check for loose on broken wire connections.

COIL:

A continuity check of the relay coil should indicate approximately 160

Q. If the motor does not imdicate above ohms, replace the relay.

lFi2iik5

COIL 5

RELAY TEST

Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 3-pin connector (A)

on the control unit with an A.C. voltmeter.

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

Shut-off,Cook and Heater 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 or convection

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 / CONNECTED COMPONENTS

VOLTAGE

RYl ; Approx. 12 V.D.C. /

Damper motor

RY2

1 Approx. 12 V.D.C. I

Cooling fan motor

RY3

I Approx. 12 V.D.C. :

ConvectIon motor

RY4

i Approx. 12 V.D.C.

Turntable motor and Oven lamp

MICRO RELAY

~ Approx. 12 V.D.C. T

Power transformer

------+-

HEATER RELAY

~ Approx. 12 V.D.C.

Heating element

(RD82ROEwI

TEST PROCEDURES (CONT’D)

PROCEDURE

LETTER

COMPONENT TEST

TOUCH CONTROL PANEL ASSEMBLY TEST

The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and ohmmeter. In this service manual, the touch control panel assembly is divided into two units Control Unit and Key Unit and troubleshooting by unit replacement is described according to the symptoms indicated.

1. Key Unit. The following symptoms indicate a defective key unit. Replace the key unit. a) When touching the pads, a certain pad produces no signal at all.

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

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

2. Control Unit

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

2-l 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. 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. d) Proper temperature measurement is not obtained.

Note:- When defective components, the Control Unit or Key Unit are replaced, the defective part

or parts must be properly packed for return in the shipping carton, with its cushion material, in which the new replacement part was shipped to you.

(RD82SOl U)

TEST PROCEDURES (CONT’D)

PROCEDURE

LElTER

COMPONENT TEST

P AH SENSOR TEST

Checking the initial sensor cooking condition

(1) The oven should be plugged in at least five minutes before sensor cooking. (2) Room temperature should not exceed 95 “F(35 “C). (3) The unit should not be installed in any area where heat and steam are generated. The unit

should 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 permit adequate ventilation, be sure to install so as not to block these vents. There should be some 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 vapor given of by the spray and turn off before food is properly cooked.

<’

(8) After 30 minutes if the sensor has not detected the vapor of the food, ERROR will appear

and the oven will shut off.

Water load cooking test

Make sure the oven has b&en plugged in at least five minutes before checking sensor cook operation. 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 SENSOR COOK pad and number pad 2. Now, the oven is in the sensor cooking

condition and SC-2 will appear in the display.

(5) Touch Start pad.The oven will operate for the first 16 seconds, without generating micro-

wave energy.

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

stage of sensor cooking.

(6) After approximately 16 seconds, microwave energy is produced, oven should turn off when

water is boiling (bubling).

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) Reconnect the oven to the power supply and check the sensor cook operation proceed as

follows: 6-l. 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 SENSOR COOK pad and number 2 pad. 6-5. Touch Start pad. The control panel is in automatic Sensor operation. 6-6. The oven will turn off automatically when the water is boiling (bubling).

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

R-8380

TEST PROCEDURES (CONT’D)

PROCEDURE

LETTER

COMPONENT TEST

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 :onnector. (5) Then connect the duml .y resistor circuit (see fig.) to the sensor connector of control panel. (6) Reconnect the oven to the power supply and check the sensor cook operation proceed as

follows: 6-l. Touch SENSOR COOK pad and number 2 pad. 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. After approximately 3 seconds, cooking operation turns off, an audible signal will sound, and the display will then revert to the time of day.

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

T, Conncc1or NC’

07 Con,,0 ““8’

C3W~EC’O~

COM

Rl.R2 10011 f ? 1% 1 ‘2W

R3 10kli t 5% 1 ‘4W

12klZ I 5%

1 4w

Sensor Dummy Resistor Circuit

CRD82Q09U)

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

BOARD(PWB) IS OPEN.

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

primary on the PWB, and this fine pattern service as a substitute coil. If the foil pattern is open,

follow the troubleshooting guide given below for repair.

Problem: POWER ON, indicator does not light up.

STEPS /

OCCURANCE

’ The rated voltage is not applied to POWER terminal / Check supply voltage and oven main unit.

/ of CPU connector (CN-A)

~ The rated voltage is applied to primary side of power / Power transformer or secondary circuit defective. /

I transformer.

/ Check and reoair.

1 Only pattern at “a” is broken.

/ ‘Insert jumper wire 1 and solder.

~ 4

1 Pattern at “a” and “b” are broken.

j ‘Insert the coil RCILF2003YAZZ between “c” and / / “d”

NOTE:’ At the time of these repairs, make visual in-

spection of the varistor for burning damage

and examine the transformer with tester for the presence of layer short-circuit (check primary coil resistance). If any abnormal condition is detected, replace

the defective parts.

(04U)

R-8380

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following units as

shown in the touch control panel circuit.

(1) Key unit (2) Control unit

The principal functions of these units and signal 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 PO1 - PO3, PCK,

PO6 and PlO.

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

key unit and passed back to the LSI through RO - R3 to perform the function that was requested.

Control Unit

Control unit consists of LSI (IZAQIDR),

power source

circuit,

synchronizing signal circuit, ACL circuit, buzzer circuit, temperature measurement circuit, indicator circuit and absolute humidity sensor circuit.

1) LSI This LSI controls the temperature measurement signal, key strobe signal relay driving signal for oven function and indicator signal.

2) Power Source Circuit This circuit generates voltages [VC: -5V, VFI: -23V, VF2: -26V, VA: -15V and Vp: -3IV] necessary in the control unit.

3) 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.

4) ACL Circuit A circuit to generate signals resetting the LSI to the initial state when power is supplied.

5) Buzzer Circuit The buzzer is responsive to signals from the LSI to emit noticing sounds (key touch sound and completion sound).

6) Temperature Measurement Circuit [I] : Oven The temperature in the oven cavity is sensed by the thermistor. The variation of resisance according to sensed temperature is detected by the temperature measurement circuit and

the result applied to LSI.

The result of detecting is given to LSI controlling the relay and display.

7) Door Switch (Stop switch) A switch to “tell” the LSI if the door is open or closed.

8) Relay Circuit

To drive the megnetron, heating element, grill heating element, fan motor, convection motor, damper motor

and light the oven lamp.

9) Indicator Circuit Indicator element is a Fluorescent Display. Basically, a Fluorescent Display is triode having a cathode,

a grid and an anode. Usually, the cathode of a Fluorescent

Didplay is directly heated and the filament serves as

cathode. The Fluorescent Display (i-digits, 15.segments

10) Absolute Humidity Sensor Circuit

The circuit detects absolute humidity of a food which is tinder cooking, to allow its automatic cooking.

,-8380

DESCRIPTION OF LSI

LSI WA1 21 DR)

The I/O signal of the LSI (IZA121 DR) is detailed in the following table.

/ I

-r I /

Pin. No.

Description

VREF

Reference voltage input terminal.

A reference voltage applied to the A/D converter in the LSI.

Connected to GND. (OV)

Terminal to change functions according to the model. Signal in accordance with the model in operation is applied to set up its function.

---I-

IN7

Terminal for manufacture test. Connected to VC (-5V).

Heating constant compensation terminal.

Input signal which communicates the damper open/close information to LSI. Damper opened (Damper switch ON); “H”level signal (OV: GND)

Damper closed (Damper switch OFF); “L”level signal (-5V: VC)

Terminal not used. Connected to GND. IN3

IN2 1 IN

Temperature measurement input: OVEN THERMISTOR.

By inputting DC voltage corresponding to the temperature detected by the thermistor, this input is converted into temperature by the A/D converter built into the LSI.

-I-

IN1

) IN

AH sensor input

This input is an analog input terminal from the AH sensor circuit, and connected to the A/D converter built into the LSI.

IN0 ! IN

/ I

I !

I I

Used for initial balancing of the bridge circuit (absolute humidity sensor). This input is an analog input terminal from the AH sensor circuit, and connected to the A/D converter built into the LSI.

&ed for initial balancing of the bridge circuit(absolute humidity sensor).

P47

OUT

P46 / OUT

P45

’ OUT

P44 / OUT

---I---

P43

j OUT

P42

OUT

Timing signal output terminal for temperature measurement (OVEN).

“H” level (GND) : Temperature measuring timing. (convection and grillcooking). “L” level (-5V) : Thermistor OPEN timing.

R-8380

Pin No.

Signal

I/O

Description

P41 OUT

Terminal not used.

P40

OUT Cooling fan motor driving signal.

To turn on and off shut-off relay (RY2). “L” level during both microwave and convection cooking; “H” level otherwise.

18 P37 OUT CONVECTION MOTOR driving signal.

To turn on and off shut-off relay (RY3). “L” levei during CONVECTION; “H” level otherwise.

P36

OUT

20 P35 OUT

Terminal nat used

Heating element driving signal.

To turn on and off the heater relay . “L” level during convection cooking; “H” level otherwise. During convection cooking, the signal becomes

“H” level when the temperature of the

oven cavity exceeds the predetermined temperature.

_’

21 P34

OUT

Oven lamp driving signal (Square waveform: 50Hz).

To turn on and off shut-off relay (RY4). The Square waveform voltage is delivered to the RY4 driving circuit and relays (RY3, COOK RELAY and HEATER RELAY) control circuit.

R-8380

Pin No.

Signal

P33

P32

P31

P30

CNVSS

RESET

I/O

OUT

Description

Magnetron high-voltage circuit driving signal.

To turn on and off the cook relay

in High operation, the signals holds “L” level during microwave cooking and “H” level

while not cooking. In other cooking modes (MED HIGH, MED, MED LOW, LOW) the

signal turns to “H” level and “L” level in repetition according to the power level.

HIGH

MED MED Lo~~l~~~;~~

Low p~~,GND

Signal to sound buzzer.

A : Key touch sound.

8 : Completion sound.

C : When the temperature of the oven cavity reaches the preset temperature in the pre-

heating mode, or when the preheating hold time (15 minutes) is elapsed.

0.12 WC

d=-----

2.4rec

1.2

Signal synchronized with commercial power source frequency.

This is the basic timing for all time processing of LSI.

A----LJND

I- 20msec J---- ii-5vi

Damper motor relay driving signal.

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

Connected to VC.

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.

R-8380

I Pin No.

j Signal

I/O

Description

28 i

XIN I IN

internal clock oscillation frequency setting input.

The internal clock frequency is set by inserting the ceramic filter oscillatron circuit with respect to XOUT terminal.

29 XOUT

OUT

Internal clock oscillation frequency control output.

Output to control osillatlon input of XIN.

30 XCIN IN

Terminal not used.

A-

31 XCOUT

OUT

32 VSS

Power source voltage: -5V.

VC voltage of power source CirCUlt Input.

9 ~

OUT

Termrnal not used.

Signal coming from touch-key.

When either one of G-l line keys on key matrix is touched, a correspondrng slgnal out of PO1 - P03, PO5, PO6 and PlO will be Input into R3. When no key IS touched, the signal IS held at “L” level.

Signal similar to R3.

When either one of G-2 me keys on key matrix IS touched, a corresponding signal will

be input into R2.

Signal similar to R3.

When either one of G-3 line keys on key matrix is touched, a corresponding signal WI/

be input into Rl.

36 Rl

IN Signal similar to R3.

When either one of G-4 line keys on key matrix is touched, a corresponding signal will

be input into RO.

38 VP IN ~ Anode (segment) of Fluorescent Display light-up voltage: -3lV.

~ VP voltage of power source circuit input.

OUT ,

Segment data signals.

I The relation between signals and indicators are as follows:

PI7

Signal

PI7 . . PI5 . . PI4 . . PI2

Pll . . . .

PI0 PO6

PO5

Segment .LB2 .UB2 .LBl .UBl

Signal PO3 PO2

PO1 P27 . P26 P24 P23

Segment

. 9

. f . e

d c b a

. . .

. .

. . .

8380

Pin No.

P14

PI2

PI 1

PI0

Signal

P16

PI5

P13

OUT

~ I

, I

47 I

PO7

PO6

PO5

I/O

OUT

1) Segment data signal.

Signal similar to Pl7.

2) Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to RO -R3 terminal while one of G-6 line keys on key matrix

is touched.

1) Segment data signal.

-~ -~~ ..-_

Signal similar to P17.

2) Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to RO-R3 terminal while one of G- 7 line keys on key matrix

Description

Digit selection signal.

The relation between digit signal and digit are as follows:

Digit signal

digit

Digit signal

digit

PI6 . . .lst

PO4 . . . .4th

P13 . . . . . . .2nd

PO0 . . . . . . .5th

PO7 . . . . .3rd

P25 . . . . . . . . . . . . . . .6th

Normally, one pulse is output in every fL period, and input to the grid of the Fluorescent Display.

” 150HZl

1 r--K;-;

-_------- ------- GNcl

Segment data signal.

Signal similar to P17.

Digit selection signal.

Signal similar to P16.

Segment data signal.

Signal similar to PI 7.

1) Segment data signal.

,+ Signal similar to P17.

2) Key strobe signal.

Signal applied to touch-key section. Apulse signal is input to R6 - R3 terminal while one of G-5 line keys on key matrix

is touched.

Digit selection signal.

Signal similar to P16.

IS touched.

R-8380

Pin No.

Signal

I/O

Description

Digit selection signal.

Signal similar to PI 6.

1) Segment data signal.

Signal similar to P17.

2) Key strobe signal.

Signal applied to touch-key section.

A pulse signal is input to RO - R3 terminal while one of G-8 line keys on key matrix is touched.

I !

50 PO4

OUT

PO3

PO2 1) Segment data signal.

Signal similar to P17.

2) Key strobe signal.

Signal applied to touch-key section.

A pulse signal is input to RO - R3 terminal while one of G-9 line keys on key matrix is touched.

1) Segment data signal. Signal similar to PI 7.

2) Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to RO - R3 terminal while one of G-10 line keys on key matrix is topched.

Digit selection signal.

Signal similar to P16.

OUT

53 PO1

/ I

54 PO0 OUT

55 I

P27

OUT

I) Segment data singal.

Signal similar to P17.

2) Key strobe signal. Signal applied to touch-key section.

A pulse singal is input to RO - R3 terminal while one of G-l 1 lilne keys on key matrix is touched.

56 1

P26

OUT 1) Segment data signal.

Signal similar to p17.

2) Key strobe signal.

Signal applied to touch-key section.

A pulse signal is input to RO - R3 terminal while one of G-12 line keys on key

matrix is touched.

f i

P25

OUT

Digit selection signal.

Signal similar to P16.

OUT Segment data signal.

Signal similar to P17.

OUT Terminal not used.

OUT

, Terminal not used.

P21

62 / P20

IN 1

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

Door closed;

“H” level signal (OV)

Door opened; “L” level signal (-5V)

63 /

AVCC

Connected to G N D

Connected to GND.

R-8380

ABSOLUTE HUMIDITY SENSOR CIRCUIT

(1) Structure of Absolute Humidity Sensor

The absolute humrdrty sensor rncludes two thermrstors as shown In the rllustratton. One thermrstor IS housed tn the

closed vessel frlled wrth dry arr whrle another rn the open

vessel

Each sensor IS provided wrth the protectrve cover made

of metal mesh to be orotected from the external airflow

Sensmg part

(Open vessel)

(Closed vessel )

Figure T-l.

(2) Operational Principle of Absolute Humidity Sensor

The ftgure below shows the basrc structure of an absolute humrdrty sensor

A bridge crrcurt IS formed by two ther-

mrstors and two resrstors (Rl and R21. The output of the brrdge crrcurt IS to be amplrfred by the

operatronal amplifier.

Each thermrstor IS supplred wrth a current to keep Itself heated at about 150°C (302°F) and the resultant heat IS drssrpated In the arr and If the two thermrstors are placed in dlfferent humrdrty condrtrons they show different degrees of heat conductrvity leading to potential difference between

them causing an output voltage from the bridge circuit, tne

intensity of which IS increased as the absolute humldlty of the

arr increases

Since the output IS very minute. It ~111 be

amplrfred by the operanonal amplifier

C Therm,rtor sr

cioxed verre

Figure T-2.

Absolute humdrty ,g,m

(3) Detector Circuit of Absolute Humidity Sensor

This detector crrcuit IS used to detect the output voltage of

the absolute humidity circuit to allow the LSI to control the sensor cooking of the unit. When the unit is set in the Sensor Cooking mode, 16 seconds later the detector circuit starts to function and the LSI observes the initial voltage available at its IN1 terminal. With

this voltage given, the switches SW1 to SW5 in the LSI are turned on in such a way as to change the resistance values in parallel with R50-1. Changing the resistance values results in

that there is the same potential at both F-3 terminal of the absolute humidity sensor and IN0 terminal of the LSI. The

voltage of IN1 terminal will be indicate about -2.5V. This initial balancing is set up about 16 seconds after the unit is put in the Sensor Cooking mode.

As the sensor cooking proceeds, the food is heated to generate moisture by which the resistance balance of the bridge circuit

is deviated to increase the voltage available at IN1 terminal of the LSI. Then the LSI observes that voltage at IN1 terminal

and compares it with its initial value, and when the com-

parison rate reaches the preset value (fixed for each menu to

be cooked), the LSI causes the unit to stop the sensor cooking; thereafter, the unit gets in the next necessary operation automatically. When the LSI starts to detect the initial voltage at IN1 terminal 16 seconds after the unit has been put in the Sensor Cooking mode, if it is impossible to take a balance of the

bridge circuit due to disconnection of the absolute humidity sensor, ERROR will reappear on the display and the cooking is stopped.

1) Absolute humidity sensor circuit

t T~rlnllto, 8”

Cl0.d “....I

s TNmlk.lO, 8”

op” “..“I

RSO onw”- *I....

-. fll

.-. --_

!i-fg-y-j ;;;-sz

-4,

SW3 1

P45/-

VA ‘--15V

Figure T-3.

2) Internal equivalent circuit of I2

;* i

:“i

r----------l

r----

1 I 1 II ‘/

._.

i; /

1’ /

I :

1 :... I

\I\ -~I 1

&---.-;

.I, * ‘,

~~~~~~ ! --:

/ “ill,

“,,I’, :

IifI i

I ’

i :

/ :

/ ~ I

I kb

I _ /...

L ---.___ -----A L---i

Top View

Figure T-4.

1. Precautions for Handling Electronic Components

This unrt uses PMOS LSI In the Integral part of the crrcurts.

When handlrng these parts, the following precautions should

be strrctly followed.

PMOS LSI have extremely high Impedance at Its Input and output termrnals. For this reason, it IS easily influenced by the surrounding hrgh voltage power source, statrc electncrty charged In clothes, etc, and sometrmes it IS not fully protected by the burlt-rn protection ctrcuit.

1) When stonng and transportrng, thoroughly wrap them In alumrnum forl. Also wrap PW boards contatnrng them in aluminum foil.

2) When solderrng, ground the technician as shown in the figure and use grounded soldenng iron and work table.

approx 1 MR

2. Shapes of Electronic Components

Transistor Transistor

R-8380

SERVICING

DTD143EA

Transistor

DTAI 43ES DTAI 14VS DTCI 14Ei DTB143ES

3. Servicing of Touch Control Panel

We descrrbe the procedures to permrt servrcrng the touch control panel of the mrcrowave_oven and the cautrons you must consider when doing so. To carry the servrcrng, power supply to the touch control panel is avarlable either from the power line of the oven proper Itself of from an external power source.

(1) Servicing the touch control panel with power supply

from the oven proper: CAUTION: THE HIGH VOLTAGE TRANSFORMER OF THE MICROWAVE OVEN IS STILL ALIVE TO GIVE YOU DANGER DURING SERVICING.

[Therefore. when checking the performance of the touch control Panel, put the outer cabinet on the oven proper to keep YOU from touching the hrgh tension transformer, or unplug the primary terminal (connector) of the hrgh power transformer to turn It off; and the end of such connector shall be Insulated with an Insulating tape. After servicing, be sure to replace the leads to their orrgrnal locations.

A. On some models, the power supply cord between the

touch control panel and the oven proper is so short that they can’t be separated from each other. For those models, therefore, check and repair all the con trols (with the sensor-related ones included) of the touch control panel while keeping it in contact with the oven proper.

5. On some models, on the other hand, the power supply cord between the touch control panel and the oven proper IS so long that they may be separated from each other. For those models, therefore, It IS allowed to check and repair the controls of the touch control panel while keeping it apart from the oven proper; in this case you must short both ends of the door sensing (on PWB) of the touch control panel wrth a lumper, whrch brings about an operational state that IS equrvalent to that wrth the oven door being closed. As to the sensor-related controls of the touch control panel, their checkrng IS allowed If the dumrny resrstorisl whose resistance IS equal to that of those controls IS used.

(2) Servicing the touch control panel with power supply

from an external power source:

Drsconnect the touch control panel completely from the

,oven proper, and short both ends of the door sensing

switch (on PWB) of the touch control panel, which brings

about such an operational state that is equivalent to that with the oven door being closed. And connect an external power source to the power input terminal of the touch control panel, and then it is allowed to check and repair the controls of the

touch control panel; as in the case of (1)-B above, it

is here also possible to check the sensor-related

controls of the touch control panel by using the dummy resistor(s).

4. Sevicing Tools

Tools requrred when servrctng the touch control panel assembly.

1) Soldering: 30W (To prevent leaking current, It IS recommended to use a soldering Iron wrth grounding terminal.)

2) Oscilloscope: Srn.gle beam, frequency range: DC 10MHz type or more advanced model

3) Others:

Hand tools

5. Other Precautions

When turning on the power source of the control unrt,

remove the alumrnum forI applred for preventrng statrc electncity. Connect the connectors of the Indicator and key unrts to the control unrt takrng care that the lead wares are not twisted. After alu,mrnum foil IS removed, take extra care that abnormal voltage due to statrc electrrcrty etc. IS not applied to the Input or output terminals. Attach connectors, electrolytrc capacrtors, etc to PW board, takrng care that all connectrons are tight. Be sure to use specrfred components where nigh orecr~ sron IS required.

-8380

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE

WARNING: To avoid oossible exposure to microwave

4. There is any defective parts in the interlock,

energy; ’

Before operating the oven

1. Make sure that unlatching the door slowly is accompanied by a click indicating actuation of the monitor switch and latch switches.

2. Check visually the door seal for arcing and damage.

Do not operate the oven until after repair if any of

the following conditions exist;

1. Door does not close firmly against the front of appliance.

2. There is a broken door hinge or support.

3. The door is bent or warped.

oven door or microwave generating and transmission assembly.

5. There is any other visible damage to the oven.

C. Do not operate the oven

1. Without the RF gasket.

2. If the door is not closed.

CAUTION: DISCONNECT OVEN FROM POWER

SUPPLY

BEFORE REMOVING

OUTER CASE. DISCHARGE HIGH

VOLTAGE

CAPACITOR

BEFORE

TOUCHING ANY OVEN COMPO-

NENTS OR WIRING.

(RDA1203U)

POWER TRANSFORMER REMOVAL

Disconnect oven from power supply and remove

outer case.

Discharge high voltage capacitor. Disconnect filament leads of the transformer from

the magnetron and capacitor.

Disconnect high voltage lead of capacitor from the

transformer.

Disconnect wire leads from the transformer. Remove two (2) screws and one (1) washer hold-

ing the transformer to the cabinet base.

Remove the transformer.

Re-install

32:

Rest the transformer on the base cabinet with its

primary terminals toward the front.

Insert the two edges of the transformer into two metal tabs of the base cabinet. Make sure the transformer is mounted correctly to the corners underneath those tabs. After re-installing the transformer, secure the transformer with two (2) screws to the cabinet base, one is with outer-tooth -washer and the other is without outer-tooth washer. Re-connect the wire leads (primary and high voltage) and high voltage lead to the transformer and filament leads of transformer to the magnetron and capacitor, referring to the “Pictorial Diagram”.

Re-install the outer case and check that the oven

is operating properly.

HIGH VOLTAGE RECTIFIER ASSEMBLY REMOVAL

Disconnect oven from power suppply and remove outer case. Discharge the high voltage capacitor. Remove one (1) screw holdingthe high voltage rectifier assembly to the capacitor holder. Disconnect the high voltage rectifier assembly from

the capacitor.

CAUTION: WHEN REPLACING THE HIGH VOLT-

AGE RECTIFIER ASSEMBLY, THE

GROUND SIDE TERMINAL MUST BE

SECURED FIRMLY WITH A GROUND-

ING SCREW.

COOLING FAN MOTOR REMOVAL

Disconnect oven from power supply and remove outer case. Discharge the high voltage capacitor. Remonve seven (7) screws holding the rear cabinet to heater duct and base cabinet, unit angle and chassis support.

6. Disconnect wire leads from the fan thermal cut-out.

7. Remove one (1) screw holding the cooling fan duct to the waveguide.

8. Now, cooling fan duct assembly is free.

9. Remove fan blace from fan motor shaft by pulling fan retainer clip.

Release tabs of cooling duct assembly holding to

lO.Remove two (2) screws and nuts holding the

rear cabinet. And remove rear cabinet.

cooling fan motor to the cooling fan duct.

Disconnect wire leads from the cooling fan motor.

11 .Now, cooling fan motor is free.

R-8380

MAGNETRON REMOVAL

Disconnect oven from power supply and remove

outer case.

Discharge the high voltage capacitor.

Disconnect filament lead of the transformer from the magnetron. Disconnect high voltage wire lead from the magnetron.

Disconnect wire leads from the magnetron. Take off three (3) screws secured the chassis support to oven cavity and waveguide.

Disconnect wire leads from the magnetron temp.

6. Release tab on magnetron duct holding thermal protection plate(right) and remove magnetron duct.

7. Carefully remove four (4) mounting screws holding the magnetron to waveguide, when remkoving the screws holding the magnetron to prevent it from falling.

8. Take off the magnetron from the unit with care so the magnetron tube should not hit by any metal object around the tube.

CAUTION: WHEN REPLACING THE MAGNETRON,

BE SURE THE R.F. GASKET IS IN

fuse.

PLACE

AND

THE MAGNETRON

Remove one (1) screw holding the magnetron duct

MOUNTING SCREWS ARE TIGHTENED

to the magnetron.

SECURELY.

HIGH VOLTAGE CAPACITOR REMOVAL

9. Disconnect high voltage wire lead and high voltage rectifier assembly from the capacitor.

12.Remove one (1) screw holding the capacitor holder

1 O.Disconnect filament lead of tramsformer from

to the unit angle.,.

capacitor.

13.Remove the capacitor from the holder.

11 .Remove one (1) screw holding the high voltage

14.Now high voltage capacitor is free.

rectifier from the capacitor holder.

DA;MER ASSEMBLY REMOVAL

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

2. Discharge the high voltage capacitor.

3. Disconnect wire leads from damper motor and damper switch.

4. Remove three (3) screws holding the chassis suport from rear cabinet, control mounting back plate and wave guide flange..

5. Disconnect the sensor harness from control panel.

6. Remove one (1) screw holding the magnetron duct and wire holder to the magnetron and remove magnetron duct.

7. Remove three (3) ovenside screws holding damper motor angle to oven cavity.

8. Damper ass’y is free.

9. Remove two (2) screw holding the damper motor to damper motor angle and one (1) screw holding damper switch to damper motor angle.

1 O.Damper motor and switch are free.

TURNTABLE MOTOR AND/OR COUPLING REMOVAL

I. Disconnect the oven from power supply.

2. Remove single (1) screw holding the turntable

TURN TABLE

motor cover to the base cabinet and take off the

COUPLING

turntable motor cover.

3. Disconnect wire lead from the turntable motor.

4. Remove the two (2) screws holding the turntable motor to the mounting plate of the oven cavity bottom.

5. The turntable motor is now free.

6. Remove the seal ring (O-ring) from turntable motor.

BOTTOM

OVEN CAVITY

T.T. MOTOR ANGLE

O-RING

7. Pull turntable coupling out the oven cavity,

8. The turntable coupling will be free.

Figure C-l. Turntable Coupling

q-8380

Disconnect oven from power supply and remove the

vection heater

outer case.

(A).

Discharge the high voltage capacrtor.

Remove seven(7) screws holding the rear cabinet to heater duct and base cabinet, unit angle and chassis support.

Release tabs of cooling duct assembly holding to

rear cabinet. And remove rear cabinet.

Disconnect the wire leads from the thermistor, convetion motor, thermal cut-out and convection heater.

Remove the eleven(ll) screws holding the heater duct to the oven cabity and base cabinet. The heater unit is now free.

CONVECTION HAETER AND THERMISTOR

Remove the four(4) screws holding the convection

heater to heater duct and convection heater

insulater( B). Loosen the two(2) screws holding the convection heater insulator (A) to heater duct and take con-

UPPER/LOWER LATCH SWITCHES, STOP SWITCH

AND MONITOR SWITCH REMOVAL

Disconnect oven from power supply and remove

outer case.

Discharge high voltage capacitor. Remove four (4) screws holding the control panel back plate to the oven flange and unit angle and

chassis support.

Remove control panel assembly. Disconnect wire leads from each switch and micro relay.

Remove two (2) screws holding the latch hook to

oven flange.

Remove latch hook assembly from oven flange. Push outward on the two (2) retaining tabs holding upper latch switch, stop switch 2nd monitor switch in place.

Remove two (2) screws and two (2) nuts holding lower latch switch to latch hook.

5. tie-install control panel assemory

HEATER UNIT ASSEMBLY

(HEATING ELEMENT/CONVECTION FAN/CONVECTION

REMOVAL

MOTOR/THERMISTOR)

out of convection heater insulator

1 O.Now, the convection heater is free. 11 .Remove the two (2) screws holding the thermistor

to heater duct.

12.Thermistor is free.

CONVECTION FAN AND MOTOR REMOVAL

13.Remove the one(l) nut holding the convection fan to the convection fan motor shaft, at this time, washers and caller will be free. Don’t loose them.

14Convection fan is free.

15.Remove the two(2) screws holding the convection

motor mounting plate to the heater duct.

1 G.Convection motor mounting plate with convection

mtor is free.

17.Remove the two(2) screws holding the convection motor to the convection motor mounting angle.

17.Convection motor is free.

1 OSwitches are free.

Re-install

1. Re-install upper latch switch, lower latch switch, stop swich and and monitor switch in their places. The upper latch switch is on the top possition of

latch hook. The stop switch is on the second. The monitor switch is on the third. The lower lstch switch is on the bottom.

2. Re-connect wire leads to each switch and micro relay. Refer to chapter “Pictorial Diagram”.

3. Secure the latch hook (with two (2) mounting

screws) to oven flange.

4. Make sure that monitor switch is operating properly. Refer to chapter “Test Procedure”, and Adjustment procedure.

--. . .

I I

R-8380

UPPER/LOWER LATCH SWITCHES, STOP SWITCH

AND MONITOR SWITCH ADJUSTMENT

If the upper latch switch, lower latch switch, stop switch and monitor switch do not operate properly due to a mis-adjustment, the following adjustment should

be made.

1. Loosen the two (2) screw holding the latch hook to the flange the oven front face.

2. With door closed adjust the latch hook by moving it back and forward, or up and down. In and out play of the door allowed by the latch hooks should be less than 0.5 mm.

3. Secure the screws with washers firmly.

After adjustment, make sure of following:

1. The in and out play of door remains less than 0.5 mm when latched position.

2. The stop and lower latch switches interrupts the

circuit before the door can be opened.

3. The monitor switch contacts close when the door is opened.

4. Re-install outer case and check for microwave leakage around the door with an approved microwave survey meter. (Refer to Microwave Measurement Procedure.)

~~~~~~ STOP SWITCH

~. car -MONITOR SWITCH

LOWER LATCH SWITCH

LATCHLEVER

* .:

DOOR OPEN LEVER

LATCH LEVER -<

P,/’ _.

.c’

~I-y-& ‘XL% _j

‘_

, /’

\_ I-2

CPEN BUTTaN

Figure.C-2. Latch Switches

DOOR DISASSEMBLY

Remove door assembly, refer to “Door Replacement”. Replacement of door components are as follows:

1. Place door assembly on a soft cloth with latches facing up.

Note:

As the engaging part of choke cover and door panel are provided at 17 places, do not force any particular.part.

2. Insert an iron plate (thickness of about 0.5mm) to the gap between the choke cover and corner portion

of door panel as shown to free engaging parts.

3. Lift up choke cover.

4. Choke cover is free from door panel.

Figure C-3. Door Disassembly

DOOR REPLACEMENT AND ADJUSTMENT

DOOR REPLACEMENT DOOR ADJUSTMENT

Disconnect oven from power supply and remove the

outer case.

Remove turntable tray and turntable support from

oven cavity.

Discharge high voltage capacitor. Remove three(3) screws holding the lower oven

hinge using a screw-driver.

Remove lower oven hinge from oven cavity bottom

flange.

Remove door assembly from upper oven hinge on

the oven.

Door assembly is now free.

Note: When individual parts are replaced, refer to

“Door Disassembly”. On re-installing new door assembly, insert the upper oven hinge into the door hinge pin. Then while

holding door in place. Make sure the door is parallel with oven face line (left and upper side lines) and the door latch heasd pass through the latch holes correctly. Insert the lower oven hinge to oven cavity bottom

flange and then door hinge pin. Then secure the

lower oven hinge firmly with three (3) mounting

screws.

Note: After any service to the door; (A)

Make dure that the upper latch switch, stop

switch, monitor awitch and lower latch switch

are operating properly. (Refer to chapter “Test

Procedure”)

(B)

An approved microwave survey meter should

be used to assure compliance with proper

microwave

radiation emission

limitation

standars.

The door can be adjusted by keeping the screws of

each hinge loose. The lower oven hinge can be loosened with screw driver.

After adjustment, make sure of the following :

Door latch heads smoothly catch, the latch hooks

through the latch holes, and also the latch head

goes through the center of the latch hole.

Deviation of the door alignment from horizontal line

of cavity face plate is to be less than 1 .Omm.

The door is positioned with its face depressed to-

ward the cavity face plate.

Re-install outer case and check for microwave leakage around the door with an approved microwave survey meter.

(Refer to Microwave Measurement Procedure.)

Note: The door on a microwave oven is designed to

act as an electronic seal preventing the leakage of microwave energy from the oven cavity during the cook cycle. This function does not require that

the door be

air-tight, moisture

(condensation)-tight or light-tight. Therefore, the occasional apperance of moisture, light or the sensing of gentle warm.air movement around the oven door is not abnormal and do not of themselves, indicate a leakage of microwave energy from the oven cavity. If such were the case, your oven could not be equipped with a vent, the very purpose of which is to exhaust the vapor-laden air from the oven cavity.

Figure C-4. Door Replacement and Adjustment

R-8380

MICROWAVE MEASUREMENT

After adjustment of door latch switches, monitor

switch and door are completed individually or collectively, the following leakage test must be performed with a survey instrument and it must be confirmed that the result meets the requirements of the performance standard for microwave oven.

REQUIREMENT

The safety switch must prevent microwave radiation emission in excess of 5mW/cm2 at any point 5cm or

Sharp R-8380 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual