SHARP R-770B microwave oven SERVICE MANUAL

R-770B

SERVICE MANUAL

S3811R770BPHR

DOUBLE GRILL

TURNOVER ADD STAND

COVER STIR DEFROST HELP

KG PCS

%

AUTO COOK

3

4

5

1

2

AUTO COOK

AUTO GRILL

PIZZA

CRISPY SNACK

Grilled Chicken

Grilled Lobster

Grilled Fish

Steak

Fish Cake

Potato Skin

Garlic Bread

Chicken

Wings

Salty Peanuts

Convenient Food

RICE COOK

REHEAT

STEAM MENU

HELP

1

6

SLOW COOK

POWER LEVEL

EASY DEFROST

GRILL

GRILL MIX

2

7

3

8

4

9

5

O

STOP/CLEAR

INSTANT COOK/START

MODEL

DOUBLE GRILL

MICROWAVE OVEN

R-770B

In interests of user-safety the oven should be restored to its original condition and only parts identical to those specified should be used.

TABLE OF CONTENTS

Page

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

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

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

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

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

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

FUNCTION OF IMPORTANT COMPONENTS ....................................................................................... 7

SERVICING .............................................................................................................................................. 8

TROUBLESHOOTING GUIDE ................................................................................................................. 9

TEST PROCEDURE .............................................................................................................................. 10

TOUCH CONTROL PANEL ASSEMBLY .............................................................................................. 16

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

MICROWAVE MEASUREMENT ........................................................................................................... 26

WIRING DIAGRAM ................................................................................................................................ 27

PICTORIAL DIAGRAM .......................................................................................................................... 30

POWER UNIT CIRCUIT ......................................................................................................................... 31

CONTROL PANEL CIRCUIT .................................................................................................................. 32

PRINTED WIRING BOARD .................................................................................................................... 33

PARTS LIST .......................................................................................................................................... 34

SHARP CORPORATION

R-770B

SERVICE MANUAL

MICROWAVE OVEN WITH TOP

AND BOTTOM HEATER

R-770B

GENERAL IMPORTANT INFORMATION

This Manual has been prepared to provide Sharp Corp. Service engineers with Operation and Service Information.

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

CAUTION

MICROWAVE RADIATION

Service engineers should not be exposed to the microwave energy which may radiate from the magnetron or other 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.

(C) The door packing is not damaged.

(D) The door is not deformed or warped.

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

Servicing and repair work must be carried out only by trained service engineers.

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

250V.

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

All the parts marked "

∆

" on parts list may cause undue microwave exposure, by themselves, or when they are damaged, loosened or removed.

Never operate the Top and/ or Bottom heater with the oven

outer cabinet removed. (Because air flow is eliminated, and the excess heat generated on adjacent components). It can cause permanent damage or a fire.

SHARP CORPORATION

OSAKA, JAPAN

1

R-770B

PRODUCT SPECIFICATIONS

GENERAL INFORMATION

APPEARANCE VIEW

OPERATING SEQUENCE

FUNCTION OF IMPORTANT

COMPONENTS

SERVICING AND

TROUBLESHOOTING GUIDE

TEST PROCEDURE

TOUCH CONTROL PANEL

COMPONENT REPLACEMENT

AND ADJUSTMENT PROCEDURE

MICROWAVE MEASUREMENT

WIRING DIAGRAM

PARTS LIST

R-770B

PRODUCT DESCRIPTION

SPECIFICATION

ITEM DESCRIPTION

Power Requirements

Power Consumption

Power Output

Grill cooking

Top Heater mode

Bottom heater mode

Top and Bottom heater mode

1.3 kW

0.9 kW

2.1 kW

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

Operating frequency 2450 MHz

Grill heater Power Output (Top heater) 1200 W (600 W x 2)

Bottom heater Power Output 800 W

Case Dimensions

Cooking Cavity Dimensions

220 Volts

50 Hertz

Single phase, 3 wire earthed

Microwave cooking 1.6 kW

Width 520 mm

Height 309 mm including foot

Depth 467 mm

Width 352 mm

Height 207 mm

Depth 368 mm

Turntable diameter

Control Complement

325 mm

Touch Control System

Clock (1:00 - 12:59) / Timer (0 - 90 minutes)

Microwave Power for Variable Cooking

Repetition Rate;

100% ................................................... Full power throughout the cooking time

70% ..................................................................... approx. 70% of FULL Power




Mix cooking

Grill Mix High with Top Heater ............ Top heater with 50% microwave power

Grill Mix Low with Top Heater ............. Top heater with 10% microwave power

Grill Mix High with Bottom Heater ....... Bottom heater with 50% microwave power

Grill Mix Low with Bottom Heater ........ Bottom heater with 10% microwave power

Set Weight

AUTO COOK pad, AUTO GRILL pad, PIZZA pad

CRISPY SNACK pad, RICE COOK pad, REHEAT pad

STEAM MENU pad, LESS ( " )/MORE ( ' ) pads

HELP pad, SLOW COOK pad, POWER LEVEL pad

EASY DEFROST pad, GRILL pad, GRILL MIX pad

Number pads, STOP/CLEAR pad, CLOCK pad

INSTANT COOK/START pad

Approx. 19 kg

GENERAL INFORMATION

WARNING

THIS APPLIANCE MUST BE EARTHED

IMPORTANT

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

GREEN-AND-YELLOW

BLUE

BROWN

: EARTH

: NEUTRAL

: LIVE

2

R-770B

APPEARANCE VIEW

OVEN

1. Oven lamp

2. Top heaters (Grill heaters)

3. See through door

4. Door hinges

5. Door safety latches

6. Door seals and sealing surfaces

7. Bottom heater

8. Oven cavity

9. Turntable motor shaft

10.Ventilation openings

11.Waveguide cover

12.Door opening button

13.Control panel

14.Digital display

15.Power supply cord

16.Outer cabinet

Turntable support

Bottom heater

5

3

4

6

High rack

Turntable

Turntable motor shaft

1 2

8 9 q

0 7 w r e t

0

0 y

0

Low rack

NOTE:

1. Ensure that the bottom heater is in the lowest position as shown the figure, as it is possible to move it up and down to help with cleaning.

2. Place the turntable support over the turntable motor shaft on the floor of the cavity.

3. Then place the turntable on to the turntable support.

TOUCH CONTROL PANEL

1. TOP HEATER SYMBOL

The symbol will light when the top heater is in use.

2. BOTTOM HEATER SYMBOL

The symbol will light when the bottom heater is in use.

3. MICROWAVE SYMBOL

The symbol will light during microwave cooking.

A. AUTO COOK PAD

Press to select 4 popular menus.

B. AUTO GRILL PAD

Press to select 5 popular grill menus.

C. PIZZA PAD

Press to select 3 pizza menus.

D. CRISPY SNACK PAD

Press to select 5 popular snack menus.

E. RICE COOK PAD

Press to cook rice, congee or porridge.

F. REHEAT PAD

Press to reheat dish, soup, beverage or bread.

G. STEAM MENU PAD

Press to steam fish, meat or dumpling.

H. LESS ( " )/MORE ( ' ) pads

Press to adjust the doneness of food in one minute increments during cooking or to increase/ decrease the time whilst programming the automatic operations.

I. HELP PAD

Press to select auto start, child lock, language or demonstration modes. Press to get cooking information.

J. SLOW COOK PAD

Press to cook slowly and longer time.

K. POWER LEVEL PAD

Press to select microwave power setting. If not pressed, HIGH power is automatically selected.

L. EASY DEFROST PAD

Press to defrost meat by entering weight.

M. GRILL pad

Press to select GRILL mode.

N. GRILL MIX PAD

Press to select grill and microwave mix cooking mode.

O. NUMBER PADS

Press to enter cooking times, clock time, weight or quantity of food.

1

2

3

A

B

E

H

J

K

M

O

P

3

4

1

2

5

TURNOVER ADD STAND COVER STIR DEFROST HELP

AUTO COOK

AUTO GRILL

PIZZA

CRISPY SNACK

Grilled Chicken

Grilled Lobster

Grilled Fish

Steak

Fish Cake

Potato Skin

Garlic Bread

Salty Peanuts

Convenient Food

RICE COOK

HELP

SLOW COOK

GRILL

POWER LEVEL EASY DEFROST

GRILL MIX

1 2 3 4 5

6 7 8 9 O

STOP/CLEAR

KG PCS

%

AUTO

REHEAT

COOK

STEAM MENU

INSTANT COOK/START

Indicator

I

C

D

F

G

L

N

Q

R

P. STOP/CLEAR PAD

Press to clear during programming. Press once to stop operation of oven during cooking;

Press twice to cancel cooking programme.

Q. CLOCK PAD

Press to set clock time.

R. INSTANT COOK/START PAD

Press once to cook for 1 minute at 100%

(HIGH power) or increase by 1 minute multiples each time this pad is pressed during cooking. Press to start oven after setting programs.

3

R-770B

OPERATION SEQUENCE

OFF CONDITION

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

interlock relay control switch.

IMPORTANT:

When the oven door is closed, the contacts COM-NC of the monitor switch must be open. When the microwave oven is plugged in a wall outlet (220V 50Hz), the line voltage is supplied to the noise filter and the control unit.

Figure O-1 on page 27

1. The oven display will show " SHARP MICRO- WAVE

OVEN " .

2. Press the STOP/CLEAR pad. The oven display will show " : ".

3. Set the clock as follows.

3-1. Press the CLOCK pad once.

3-2. Enter the time of day by perssing the number pads.

3-3. Start the clock by pressing the CLOCK pad.

NOTE:

1. If you do not set the clock, " : " will appear on the display. When the operation of the oven is finished, " :

" will appear on the display instead of the time of day.

2. The oven can be also used when the clock is not set.

3. When the oven door is opened, the oven lamp comes on at this time.

MICROWAVE COOKING CONDITION

100% (HIGH) COOKING

Enter a desired cooking time by pressing the number pads and start the oven by pressing START pad.

Function sequence Figure O-2 on page 27

CONNECTED COMPONENTS

High voltage transformer

Grill heater (Top)

Bottom heater

Fan motor,

Oven lamp, Turntable motor

RELAY

RY2

RY3

RY4

RY5

RY6

1. The line voltage is supplied to the primary winding of the high voltage 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 magnetron filament and the high voltage (2000 volts) 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 energy is channelled through the waveguide (transport channel) into the oven cavity, where the food is placed to be cooked.

4. When the cooking time is up, a signal tone is heard and the relays RY2 + RY5 + RY6 go back to their home position. The circuits to the oven lamp, high voltage transformer, fan motor and turntable motor are cut off.

5. When the oven door is opened during a cooking cycle, the switches come to the following condition.

Switch

1st. latch switch

2nd. interlock relay control switch

Monitor Switch

Contact Condition

During Oven Door

Cooking Open(No cooking)

COM-NO Closed Opened

COM-NO Closed Opened

COM-NC Opened Closed

The circuit to the high voltage transformer, fan motor and turntable motor are cut off when the 1st. latch switch, 2nd.

interlock relay control switch are made open. The oven lamp remains on even if the oven door is opened after the cooking cycle has been interrupted, because the relay

RY6 stay closed. Shown in the display is remaining time.

6. MONITOR SWITCH CIRCUIT

The monitor switch is mechanically controlled by the oven door, and monitors the operation of the 1st. latch switch and the nd. interlock relay RY2.

6-1. When the oven door is opened during or after the cycle of a cooking program, the 1st. latch switch and

2nd. interlock relay control switch must open their contacts first. After that the contacts (COM-NC) of the monitor switch can be closed.

6-2. When the oven door is closed, the contacts (COM-

NC) of the monitor switch must be opened. After that the contacts of the 1st. latch switch and the 2nd.

interlock relay control switch are closed.

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

1st. latch switch and 2nd. interlock relay remain closed, the fuse M10A will blow, because the monitor switch is closed and a short circuit is caused.

70% (MEDIUM HIGH), 50% (MEDIUM), 30% (ME-

DIUM LOW), 10% (LOW COOKING)

When the microwave oven is preset for variable cooking power, the line voltage is supplied to the high voltage transformer intermittently within a 32-second time base through the relay contact which is coupled with the current-limiting relay RY2. The following levels of microwave power are given.

32 sec. ON

SETTING

100% Approx. 100%

24 sec. ON 8 sec. OFF

70% Approx. 70%


50% Approx. 50%


30% Approx. 30%


10% Approx. 10%

Note: The On/Off time ratio does not exactly correspond to the percentage of microwave power, because approx. 2 seconds are needed for heating up the magnetron filament.

GRILL COOKING CONDITIONS

The oven has three grill cooking condition. They are the

TOPHEATER mode, BOTTOM HEATER mode and TOP

AND BOTTOM HEATER mode.

4

R-770B

TOP

HEATER

MODE

In this mode, the food is cooked by the top heaters. Press the GRILL pad once and then enter the cooking time by pressing the number pads. When the START pad is pressed, the following operations occur:

Figure O-3(a) on page 27

1. The relay RY3 + RY5 + RY6 are energized.

2. The numbers of the digital read-out start the count down to zero.

3. Then the top heaters, turntable motor, oven lamp and fan motor are energized.

4. Now, the food is grilled by the top heaters.

5. Upon completion of the selected cooking time, audible signal sounds and the contacts of relays RY3 + RY6 are opened, then the top heaters, turntable motor and oven lamp are de-energized. But the relay RY5 stays closed and the fan motor operates for 5 minutes. But if the cooking time is less than 2 minutes the relay RY5 will not stay close.

BOTTOM

HEATER

MODE

In this mode, the food is cooked by the bottom heater.

Press the GRILL pad twice and then enter the cooking time by pressing the number pads. When the START pad is pressed, the following operations occur:

Figure O-3(b) on page 28

1. The relay RY4 + RY5 + RY6 are energized.


3. Then the bottom heater, turntable motor, oven lamp and fan motor are energized.

4. Now, the food is grilled by the bottom heater.

5. Upon completion of the selected cooking time, audible signal sounds and the contacts of relays RY4 + RY6 are opened, then the bottom heating elements, turntable motor and oven lamp are de-energized. But the relay RY5 stays closed and the fan motor operates for

5 minutes. But if the cooking time is less than 2 minutes the relay RY5 will not stay close.

TOP AND BOTTOM HEATER MODE

In this mode, the food is cooked by both the top heaters and bottom heater. Press the GRILL pad three times and then enter the cooking time by pressing the number pads.

When the START pad is pressed, the following operations occur:

Figure O-3(c) on page 28

1. The relay RY3 + RY4 + RY5 + RY6 are energized.


3. Then the top heaters, bottom heater, turntable motor, oven lamp and fan motor are energized.

4. Now, the food is grilled by the top heaters and the bottom heater.

5. Upon completion of the selected cooking time, audible signal sounds and the contacts of relays RY3 + RY4 +

RY6 are opened, then the top heating elements, bottom heating element, turntable motor and oven lamp are de-energized. But the relay RY5 stays closed and the fan motor operates for 5 minutes. But if the cooking time is less than 2 minutes the relay RY5 will not stay closed.

GRILL

MIX COOKING CONDITION

The oven will cook food by supplying grill heaters (top heaters or Bottom heater) and microwave energy alternately within a 48 seconds time base. And the oven has four programmed cooking mode.

GRILL MIX HIGH WITH TOP HEATER MODE AND

GRILL MIX LOW WITH TOP HEATER MODE

In these modes, the food is cooked by the top heaters and the microwave energy. Press the GRILL MIX pad once for

GRILL MIX HIGH with TOP HEATER mode. Press the

GRILL MIX pad twice for GRILL MIX LOW with TOP

HEATER mode. And then enter the cooking time by pressing the number pads. When the START pad is pressed, the following operations occur:

Figure O-4(a) on page 29

1. The relay RY5 + RY6 are energized.


3. The turntable motor, oven lamp and fan motor are energized.

4. The relay RY2 + RY3 are energized alternately within a 48 seconds time base by the control unit.

5. The top heaters operate through the relay RY3 is energized. And the high voltage transformer operates through the relay RY2 is energized.

6. The relationship between the top heating elements and magnetron operations are as follows.

26 SEC.

22 SEC.

ON

(MICRO.)

OFF

MICROWAVE POWER

= APPROX. 50%

ON

TOP

HEATERS OFF

GRILL MIX HIGH with TOP HEATER mode

5

8 SEC.

ON

40 SEC.

(MICRO.)

OFF

MICROWAVE POWER

= APPROX. 10%

ON

TOP

HEATERS

OFF

GRILL MIX LOW with TOP HEATER mode



RY6 are opened, then the top heaters, high voltage transformer, turntable motor and oven lamp are deenergized. But the relay RY5 stays closed and the fan motor operates for 5 minutes. But if the cooking time is less than 2 minutes the relay RY5 will not stay close.

GRILL MIX HIGH WITH BOTTOM HEATER MODE AND

GRILL MIX LOW WITH BOTTOM HEATER MODE

IIn these modes, the food is cooked by the bottom heater and the microwave energy. Press the GRILL MIX pad three (3) times for GRILL MIX HIGH with BOTTOM

HEATER mode. Press the GRILL MIX pad four (4) times for GRILL MIXLOW with BOTTOM HEATER mode. And then enter the cooking time by pressing the number pads.

R-770B

When the START pad is pressed, the following operations occur:

Figure O-4(b) on page 29

1. The relay RY5 + RY6 are energized.


3. The turntable motor, oven lamp and fan motor are energized.

4. The relay RY2 + RY4 are energized alternately within a 48 seconds time base by the control unit.

5. The bottom heater operate through the relay RY4 is energized. And the high voltage transformer operates through the relay RY2 is energized.

6. The relationship between the top heating elements and magnetron operations are as follows.

ON

26 SEC.

22 SEC.

(MICRO.)

OFF

MICROWAVE POWER

= APPROX. 50%

ON

BOTTOM

HEATER OFF

GRILL MIX HIGH with BOTTOM HEATER mode

8 SEC.

ON

40 SEC.

(MICRO.)

OFF

MICROWAVE POWER

= APPROX. 10%

ON

BOTTOM

HEATER

OFF

GRILL MIX LOW with BOTTOM HEATER mode



RY6 are opened, then the bottom heater, high voltage transformer, turntable motor and oven lamp are deenergized. But the relay RY5 stays closed and the fan motor operates for 5 minutes. But if the cooking time is less than 2 minutes the relay RY5 will not stay close.

AUTOMATIC OPERATIONS

This oven has the following automatic operations;

PIZZA

CRISPY SNACK

AUTO COOK

AUTO GRILL

REHEAT

STEAM MENU

RICE COOK

EASY DEFROST

Thease will automatically compute the cooking mode and the cooking time. And the oven will cook or defrost the food according to the special cooking sequence.

LIMITATIONS OF POWER OUTPUT IN MANUAL

OPERATION

After the same cooking mode is carried out for more than the specified cooking time, the power output is automatically reduced by turning the control relays on and off intermittently, as shown in the table below. This is to

6 protect the oven door against temperature rising.

Specified cooking Limited power Time base

Cooking mode time (minutes) output (%) (seconds)

Microwave

100% Power

Top heaters

Bottom heater

Top browner and

Bottom browner or Oven cooking

20

30

15

10 (Top)

10 (Bottom)

70

50

50

50

50

32

48

48

48

48

NOTE:

1. In case of Automatic operations, the limitations of power output are not carried out.

2. In case that the STOP/CLEAR pad is pressed or the oven door is opened during cooking, the limitations of power output are carried out after the total cooking time beyond the specified cooking time.

3. In case of the two or more same cooking modes are carried out, the limitations of power output are carried out after the total cooking time beyond the specified cooking time.

4. In case of the two or more different cooking modes are carried out, the specified cooking time is started to count from the point when the cooking mode is changed.

5. If the cooking mode has the power level display, the power level is also displayed when the limitations of power output are carried out.

R-770B

DOOR OPEN MECHANISM

The door can be opened by pushing the open button on the control panel. When the open button is pushed, the switch lever is moved upward, operating the latch head. The latch head is moved upward and released from the latch hook.

Now, the door can be opened.

Latch Heads

Latch Hook

Door

Monitor Switch

1st. Latch Switch

Switch Lever

Figure D-1. Door Open Mechanism

1ST. LATCH SWITCH AND 2ND. INTERLOCK

RELAY CONTROL SWITCH

1. When the oven door is closed, the contacts (COM-NO) of each switch must be closed.

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

NO) of each switch must be opened.

MONITOR SWITCH

1. When the door is closed, the contacts (COM-NC) must be opened.

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

3. If the oven door is opened and he contacts (COM-NO) of the 1st. latch switch and 2nd. interlock relay RY2 fail to open, the fuse M10A blows immediately after closing the contacts (COM-NC) of the monitor switch.

CAUTION: BEFORE REPLACING A BLOWN FUSE

M10A TEST THE 1ST. LATCH SWITCH, 2ND.

INTERLOCK RELAY RY2, MONITOR

SWITCH AND MONITOR RESISTOR FOR

PROPER OPERATION. (REFER TO CHAP-

TER “TEST PROCEDURE”).

FUSE M10A 250V

1. If the wire harness or electrical components are shortcircuited, this fuse blows to prevent an electric shock or fire hazard.

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

interlock relay RY2 remain closed with the oven door open and when the contacts (COM-NC) of monitor switch closes.

FUSE 15A

If the wire harness or electrical components are shortcircuited, this fuse blows to prevent an electric shock or fire hazard.

FUNCTION OF IMPORTANT COMPONENTS

2nd. Interlock

Relay Control

Switch

HIGH VOLTAGE FUSE 0.75A

The high voltage fuse blows when the high voltage rectifier or the magnetron is shorted.

THERMAL CUT-OUT 125˚C (MG)

This thermal cut-out protects the magnetron against overheating. If the temperature goes up higher than 125˚C because the fan motor is interrupted or the ventilation openings are blocked, the thermal cut-out will open and line voltages to the high voltage transformer will be cut off and the operation of the magnetron will be stopped. The thermal cut-out will cut back in at 95˚C.

THERMAL CUT-OUT170˚C (OVEN)

The thermal cut-out located on the top of the oven cavity is designed to prevent damage to the oven if the foods in the oven catch fire due to over heating produced by improper setting of the cooking time or failure of control unit. Under the normal operation, the oven thermal cut-out remains closed. However, when abnormally high temperature are reached within the oven cavity, oven thermal cut-out will open at 170˚C causing the oven to shut down.

The thermal cut-out will cut back in at 155˚C.

TURNTABLE MOTOR

The turntable motor drives the turntable roller assembly to rotate the turntable.

FAN MOTOR

The fan motor drives a blade which draws external cool air.

This cool air is directed through the air vanes surrounding the magnetron and cools the magnetron. This air is channelled through the oven cavity to remove steam and vapours given off from heating food. It is then exhausted through the exhausting air vents of the oven cavity.

NOISE FILTER

The noise filter assembly prevents radio frequency interference that might flow back in the power circuit.

TOP HEATERS

The top heaters are located on the top of the oven cavity assembly. The top heaters send out heat to grill foods.

BOTTOM HEATER

The bottom heater is located on the floor of the oven cavity assembly. The bottom heater sends out heat to grill foods.

7

R-770B

SERVICING

WARNING TO SERVICE PERSONNEL

Microwave ovens contain circuitry capable of producing very high voltage and current. Contact with following parts will result in electrocution.

High voltage capacitor, High voltage transformer, Magnetron, High voltage rectifier assembly, High voltage harness.

REMEMBER TO CHECK 3D

1) Disconnect the supply.

2) Door opened, and wedged open.

3) Discharge high voltage capacitor.

WARNING: AGAINST THE CHARGE OF THE

HIGH-VOLTAGE CAPACITOR.

The high-voltage capacitor remains charged about

60 seconds after the oven has been switched off.

Wait for 60 seconds and then short-circuit the connection of the high-voltage capacitor (that is, of the connecting lead of the high-voltage rectifier) against the chassis with the use of an insulated screwdriver.

Sharp recommend that wherever possible fault-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 high voltage transformer. Ensure that these leads remain isolated from other components and the oven chassis. (Use insulation tape if necessary.) When the testing is completed carry out 3D checks and reconnect the leads to the primary of the high voltage transformer.

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 power level to HIGH (100%) and set the microwave timer for two (2) minutes. And push the start key. When the two minutes has elapsed (timer at zero) carefully check that the water is now hot. If the water remains cold carry out 3D checks and re-examine the connections to the component being tested.

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.

TROUBLESHOOTING GUIDE

When troubleshooting the microwave oven, it is helpful 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 because of a blown fuse M10A in the 1st. latch switch - 2nd. interlock relay(RY2)- monitor switch - monitor resistor circuit, check the

1st. latch switch, 2nd. interlock relay(RY2), monitor switch and monitor resistor before replacing the fuse M10A.

8

TEST PROCEDURE A B C D E E E F F G H I J J K K L

R-770B

M N O O O O O P

CONDITION PROBLEM

Fuse 15A blows when power cord is plugged into wall outlet.

OFF

CONDITION

COOKING

CONDITION

(COMMON MODE)

MICROWAVE

COOKING

CONDITION

GRILL

COOKING

CONDITION

GRILL MIX

COOKING

CONDITION

Fuse M10A blows when the door is opened.

Oven lamp does not light when door is opened. (Display operates.)

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

"SHARP MICRO- OVEN PRESS

STOP" does not appear in display when power cord is plugged into wall outlet.

Display does not operate properly when STOP/CLEAR pad is pressed.

Oven does not start when the IN-

STANT COOK/ START pad is pressed. (Display operates.)

Oven lamp does not light. (Turntable motor operates.)

Fan motor does not operate. (Oven lamp lights.)

Turntable motor does not operate.

(Oven lamp lights.)

Oven or electrical parts does not stop when cooking time is 0 or STOP/

CLEAR pad is pressed.

Oven goes into cook cycle but shuts down before end of cooking cycle.

Oven seems to be operating but little or no heat is produced in oven load.

Oven does not operating properly during variable cooking condition except 100% cooking condition.

Top heaters do not operate.

Bottom heater does not operate.

Oven seems to be operating but little or no heat is produced in oven load. (Microwave power does not seem to be generated properly.)

Top heaters do not operate.

Bottom heater does not operate.

9

R-770B

TEST PROCEDURES

PROCEDURE

LETTER

A MAGNETRON TEST

COMPONENT TEST

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

WHILE THE OVEN IS IN OPERATION.

CARRY OUT 3D CHECKS.

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

To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron filament terminals, the meter should show a reading of less than 1 ohm.

To test for short filament to anode condition, connect ohmmeter between one of the filament terminals and the case of the magnetron (ground). This test should be indicated an infinite resistance. If a low or zero resistance reading is obtained then the magnetron should be replaced.

MICROWAVE OUTPUT POWER (1 litre load)

The following test procedure should be carried out with the microwave oven in a fully assembled condition (outer case fitted). Microwave output power from the magnetron can be measured by way of IEC 705, i.e. it is measured by how much power the water load can absorb. To measure the microwave output power in the microwave oven, the relation of calorie and watt is used. When P(W) heating works for t(second), approximately P x t/4.187 calorie is generated. On the other hand, if the temperature of the water with V(ml) rises

∆

T (

°

C) during this microwave heating period, the calorie of the water is V x

∆

T.

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

Water load.................................. 1000 g

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

Initial temperature .............................. 10

±

2

°

C

Heating time .............................. 47 sec.

P = 90 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 5K.

5. Select stirring devices and measuring instruments in order to minimize addition or removal of heat.

6. The graduation of the thermometer must be scaled by 0.1

°

C at minimum and be an accurate thermometer.

7. The water load must be (1000

±

5) g.

8. “t” is measured while the microwave generator is operating at full power. Magnetron filament heatup time is not included.

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

Measuring method:

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

(Example: The initial temperature T1 = 11

°

C)

2. Add the 1 litre water to the vessel.

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

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

∆

T of

(10

±

2) K.

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

6. Measure the final water temperature. (Example: The final temperature T2 = 21

°

C)

7. Calculate the microwave power output P in watts from above formula.

10

R-770B

TEST PROCEDURES

PROCEDURE

LETTER COMPONENT TEST

Initial temperature .................................................................................................. T1 = 11

°

C

Temperature after (47 + 2) = 49 sec ...................................................................... T2 = 21

°

C

Temperature difference Cold-Warm .......................................................................

∆

T1 = 10C

Measured output power

The equation is “P = 90 x

∆

T” ...................................................... P = 90 x 10

°

C = 900 Watts

JUDGMENT: The measured output power should be at least

±

15 % of the rated output power.

CAUTION: 1

°

C CORRESPONDS TO 90 WATTS. REPEAT MEASUREMENT IF THE POWER IS

INSUFFICIENT.

1000g

1000g

1000g

B

C

D

T1˚C

T2˚C

Heat up for 49 sec

HIGH VOLTAGE TRANSFORMER TEST

WARNING: High voltage and large currents are present at the secondary winding and filament winding of the high voltage 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.


Disconnect the leads to the primary winding of the high voltage transformer. Disconnect the filament and secondary winding connections from the rest of the HV circuitry. Using an ohmmeter, set on a low range, it is possible to check the continuity of all three windings. The following readings should be obtained:a. Primary winding ................................ approximately 1.5

Ω b. Secondary winding .......................... approximately 117

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

Ω

If the readings obtained are not stated as above, then the high voltage transformer is probably faulty and should be replaced.

CARRY OUT 4R CHECKS.

HIGH VOLTAGE RECTIFIER ASSEMBLY TEST

B C

HIGH VOLTAGE RECTIFIER TEST


HIGH VOLTAGE RECTIFIER

Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal B+C of the high voltage rectifier and note the reading obtained. Reverse the meter leads and note this second reading.

The normal resistance is infinite in one direction and more than 100 k

Ω

in the other direction.


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

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

OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.

HIGH VOLTAGE CAPACITOR TEST


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 10M

Ω

after it has been charged.

11

R-770B

TEST PROCEDURES

PROCEDURE


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

E. An open capacitor constantly shows a resistance about 10 M

Ω

because of its internal 10M

Ω resistance.

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

G. The resistance across all the terminals and the chassis must be infinite when the capacitor is normal.

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


E SWITCH TEST


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

Table: Terminal Connection of Switch

Plunger Operation COM to NO COM to NC

Released

Depressed

Open circuit

Short circuit

Short circuit

Open circuit

COM; Common terminal,

NO; Normally open terminal

NC; Normally close terminal

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


F

G

H

THERMAL CUT-OUT TEST


Disconnect the leads from the terminals of the thermal cut-out. Then using an ohmmeter, make a continuity test across the two terminals as described in the below.

Parts Name

Table: Thermal Cut-out Test

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

condition (closed circuit).

condition (open circuit).

(When room temperature

(˚C) (˚C) is approx. 20˚C.)

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

Above 125˚C

Thermal cut-out 170˚C Cuts back in at 155˚C.

Above 170˚C

Closed circuit

Closed circuit

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

An open circuit thermal cut-out (MG) indicates that the magnetron has overheated, this may be due to resistricted ventilation, cooling fan failure or a fault condition within the magnetron or HV. circuit.

An open circuit thermal cut-out (OVEN) indicates that the food in the oven cavity may catch fire, this may be due to over heating produced by improper setting of the cooking timer or failure of the control panel.


BLOWN FUSE M10A


If the fuse M10A is blown when the door is opened, check the 1st. latch switch, 2nd. interlock relay, monitor switch and monitor resistor.

If the fuse M10A is blown, there could be a short or ground in electrical parts or wire harness. Check them and replace the defective parts or repair the wire harness.


CAUTION: Only replace fuse M10A with the correct value replacement.

BLOWN FUSE 15A


If the fuse 15A is blown, there could be a short or ground in electrical parts or wire harness. Check them and replace the defective parts or repair the wire harness.

12

R-770B

TEST PROCEDURES

PROCEDURE



CAUTION: Only replace fuse 15A with the correct value replacement.

I

J

K

L

NOISE FILTER TEST


N WHT

Disconnect the leads from the terminals of noise filter.

Using an ohmmeter, check between the terminals as described in the following table.

L

MEASURING POINTS

Between N and L

Between terminal N and WHITE

Between terminal L and RED

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


F8A

INDICATION OF OHMMETER

Approx. 680 k

Ω

Short circuit

Short circuit

RED

MOTOR WINDING TEST


Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two terminals as described in the table below.

Table: Resistance of Motor

Motors

Fan motor

Turntable motor

Resistance

Approximately 290

Ω

Approximately 14 k

Ω

If incorrect readings are obtained, replace the motor.


TOP HEATERS AND BOTTOM HEATER TEST


Before carrying out the following tests make sure the heater is cool completely.

1. Resistance of heater.

Disconnect the wire leads to the heater to be tested. Using ohmmeter with low resistance range.

Check the resistance across the terminals of the heater as described in the following table.

Table: Resistance of heater

Top heaters

Parts name

Bottom heater

Resistance

Approximately 24

Ω

x 2 = 48

Ω

Approximately 72

Ω

2. Insulation resistance.

Disconnect the wire leads to the heater to be tested. Check the insulation resistance between the heater terminal and cavity using a 500V - 100M

Ω

insulation tester. The insulation resistance should be more than 10 M

Ω

in the cold start.

If the results of above test 1 and/or 2 are out of above specifications, the heater is probably faulty and should be replaced.


HIGH VOLTAGE FUSE TST


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

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


CAUTION: Only replace high voltage fuse with the correct value replacement.

13

R-770B

TEST PROCEDURES

PROCEDURE

LETTER

M CONTROL PANEL ASSEMBLY TEST

COMPONENT TEST

The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper maintenance can not 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 also the Control unit is divided into two units, CPU unit and Power unit, and troubleshooting by replacement is described according to the symptoms indicated.

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

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

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

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

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

2. Control Panel

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

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

2-1 In connection with pads a) When touching the pads, a certain group of pads do not produce a signal.

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

2-2 In connection with indicators a) At a certain digit, all or some segments do not light up.

b) At a certain digit, brightness is low.

c) Only one indicator does not light up.

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

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.

N KEY UNIT TEST

If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable is marking good contact, verify that the door sensing switch (stop switch) operates properly; that is the contacts are closed when the door is closed and open when the door is open. If the door sensing switch

(stop switch) is good, disconnecct the flat ribbon cable that connects the key unit to the control unit and make sure the door sensing switch is closed (either close the door or short the door sensing switch connecter). Use the Key unit matrix indicated on the control panel schematic and place a jumper wire between the pins that correspond to the STOP/CLEAR pad marking momentary contact. If the control unit responds by clearing with a beep the key unit is faulty and must be replaced. If the control unit does not respond, it is a 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.

G 8

5

G 7

4

0 9

INSTANT

COOK/

START

GRILL

MIX

G 6

3

8

EASY

DEFROST

G 5

2

7

G 4

1

6

G 3

CRISPY

SNACK

G 2

AUTO

COOK

AUTO

GRILL

G 1

PIZZA

RICE

COOK

STOP/

CLEAR

POWER

LEVEL

STEAM

MENU

HELP

REHEAT GRILL

SLOW

COOK


14

R-770B

PROCEDURE

LETTER

O RELAY TEST

TEST PROCEDURES (CONT'D)

COMPONENT TEST


Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 4 pin connector (E) on the control unit with an A.C. voltmeter.

The meter should indicate 220 volts, if not check oven circuit.

Relay Test

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

RY2

RY3

RY4

RY5

RY6

OPERATIONAL VOLTAGE

Approx. 24.0V D.C.

Approx. 24.0V D.C.

Approx. 24.0V D.C.

Approx. 24.0V D.C.

Approx. 24.0V D.C.

CONNECTED COMPONENTS

High voltage transformer

Grill heaters (Top)

Bottom heater

Fan motor

Oven lamp / Turntable motor


P 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 input circuit on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide given below for repair.

Problem: POWER ON, indicator does not light up.


STEPS

1

2

OCCURANCE

The rated AC voltage is not present at

Power terminal of CPU connector (CN-A).

The rated AC voltage is present at primary side of low voltage transformer.

3 Only pattern at "a" is broken.

4 Pattern at "a" and "b" are broken.

CAUSE OR CORRECTION

Check supply voltage and oven power cord.

Low voltage transformer or secondary circuit defective.

Check and repair.

*Insert jumper wire J1 and solder.

(CARRY OUT 3D CHECKS BEFORE REPAIR)

*Insert the coil RCILF2003YAZZ between "c" and "d".

(CARRY OUT 3D CHECKS BEFORE REPAIR)

NOTE: *At the time of these repairs, make a visual inspection of the varistor for burning damage and examine the transformer with tester for the presence of layer short circuit (check primary coil resistance).

If any abnormal condition is detected, replace the defective parts.

VRS1

FAN


b c a d

AC

1

CN - A

15

R-770B

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 Control unit consists of Power unit and CPU unit.)

The principal functions of these units and signals communicated among them are explained below.

Key Unit

The key unit is composed of a matrix, signals generated in the LSI are sent to the key unit from P40, P41, P72, P73

P74, P75, P76 and P77.

When a key pad is touched, a signal is completed through the key unit and passed back to the LSI through P44 - P47 to perform the function that was requested.

Control Unit

Control unit consists of LSI, power source circuit, synchronizing signal circuit, ACL circuit, buzzer circuit, relay circuit, indicator circuit and back light circuit.

1) LSI

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

2) Power Source Circuit

This circuit generates voltage necessary in the control unit.

Symbol

VC

Voltage Application

-5.2V

LSI(IC1)

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

A circuit to generate a signals which resets the LSI to the initial state when power is supplied.

5) Buzzer Circuit

The buzzer is responsive to signals from the LSI to emit audible sounds (key touch sound and completion sound).

6) Door Sensing Switch (Stop Switch)

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

7) Relay Circuit

To drive the magnetron, grill heaters, bottom heater, fan motor, turntable motor and light the oven lamp.

8) Back Light Circuit

A circuit to drive the back light (Light emitting diodes

LD1 - LD10).

9) Indicator Circuit

This circuit consists of 7-digits, 39-segments and 3common electrodes using a Liquid Crystal Display.

16

R-770B

DESCRIPTION OF LSI

LSI(IZA859DR)

The I/O signal of the LSI(IZA859DR) are detailed in the following table.

Pin No.

Signal I/O Description

1

2

3-5

6-7

8

9-10

11

12

C1

VL1

AN7-AN5

AN4-AN3

AN2

AN1-AN0

P57

P56

IN

IN

IN

IN

IN

IN

IN

OUT

Terminal not used.

Power source voltage input terminal.

Standard voltage for LCD.

Heating constant compensation terminal.

Terminal not used.

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

Door closed; "H" level signal.

Door opened; "L" level signal.

Terminal not used.

Terminal not used.

Signal to sound buzzer.

A: key touch sound.

B: Completion sound.

A

0.12 sec

2.4 sec

B

13-18

19

20

21

22

23

24

P55-P50 IN/OUT Terminal not used.

P47

P46

IN

IN

Signal coming from touch key.

When any one of G12 line keys on key matrix is touched, a corresponding signal from P40, P41, P72, P73, P74, P75, P76 and P77 will be input into P47. When no key is touched, the signal is held at "L" level.

Signal similar to P47.

When any one of G11 line keys on key matrix is touched, a corresponding signal will be input into P46.

P45 IN

P44 IN





INT1

INT0

IN

IN

Terminal not used.

Signal to synchronized LSI with commercial power source frequency(50Hz).

This is basic timing for time processing of LSI.

H : GND

L (-5V)

20 msec

25

26

27

28

29

30

P41

P40

P77

P76

P75

P74

OUT

OUT

OUT

OUT

OUT

OUT

Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal while one of G8 line key on matrix is touched.











17

R-770B

Pin No.

31

32

33

34

35

36

Signal

P73

P72

P71

P70

RESET

P81

I/O

OUT

OUT

OUT

IN

IN

OUT

Description





Oven lamp and turntable motor driving signal(Square Waveform : 50Hz).

20 msec To turn on and off shut-off relay (RY6). The square waveform voltage is delivered to the relay (RY6) driving circuit and relays

(RY2,RY3,RY4,RY5) control circuit.

During cooking

H

L

Connected to VC.

Auto clear terminal.

Signal is input to reset the LSI to the initial state when power is applied. Temporarily set to "L" level the moment power is applied, at this time the LSI is reset. Thereafter set at "H" level.

Magnetron high-voltage circuit driving signal.

To turn on and off the cook relay (RY2). In 100% POWER operation, the signals hold "L" level during microwave cooking and "H" level while not cooking. In other cooking modes (70%, 50%, 30%, 10%) the signal turns to "H" level and

"L" level in repetition according to the power level.

ON/OFF time ratio in Micro cooking

(a. 32second time base)

MICRO ON

COOK

100% 32sec.

70%

50%

OFF

0sec.

24sec.

8sec.

18sec.

14sec.

30%

10%

12sec.

20sec.

6sec.

26sec.

ON/OFF time ratio in Micro cooking

(a. 48second time base)

MICRO ON

COOK

100% 48sec.

70%

50%

OFF

0sec.

36sec.

12sec.

26sec.

22sec.

30%

10%

16sec.

32sec.

8sec.

40sec.

39

40

41

37

38

42

43

44

45-48

49-50

P80

XIN

XOUT

VSS

P27

P26

P25

P24

P23-P20

P17-P16

OUT

IN

OUT

Grill heaters (TOP HEATER) driving signal.

To turn on and off the grill heaters relay

(RY3). "L" level during grill (TOP GRILL,

TOP AND BOTTOM) cooking, or Grill Mix

(MICRO+TOP) cooking, "H" level otherwise.

ON

During cooking

(Grill or Grill Mix)

OFF

H.

GND

L

Internal clock oscillation frequency input setting.

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

Internal clock oscillation frequency control output.

Output to control oscillation input of XOUT.

IN

OUT

Power source voltage: -5V.

VC voltage of power source circuit input.

Bottom heater driving signal.

To turn on and off the bottom relay (RY4).

"L" level during grill (BOTTOM HEATER,

TOP AND BOTTOM) cooking, or Grill

Mix(MICRO+BOTTOM) cooking. "H" level otherwise.

IN/OUT Terminal not used.

OUT Fan motor driving signal.

To turn on and off the fan motor relay

RY5. "L" level during cooking, or for 5 minutes after grill cooking or Grill Mix cooking. "H" level otherwise.

ON

ON

During cooking

(Grill or Grill Mix)

OFF

H.

GND

L

OFF

H.

GND

L

During cooking, or for 5 minutes after grill cooking or grill mix cooking

OUT

OUT

OUT

Terminal not used.

Segment data signal.

Connected to LCD. No connection in LCD.



18

R-770B

Pin No.

Signal I/O

51-80

SEG39-SEG10

OUT

81

82-90 SEG8-SEG0 OUT

91

92

93

94

95

96

97

98-99

100

SEG9

VCC

VREF

AVSS

COM3

COM2

COM1

COM0

VL3-VL2

C2

OUT

OUT

OUT

IN

IN

IN

IN

IN

OUT

OUT

Description


Connected to LCD.

The relation between signals are as follows:

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

SEG 0 (90) ............... SEG39 (51) SEG20 (70) ............ SEG20 (20)

SEG 1 (89) ............... SEG38 (50)

SEG 2 (88) ............... SEG37 (49)

SEG 3 (87) ............... SEG36 (48)

SEG 4 (86) ............... SEG35 (47)

SEG 5 (85) ............... SEG34 (46)

SEG 6 (84) ............... SEG33 (45)

SEG 7 (83) ............... SEG32 (44)

SEG 8 (82) ............... SEG31 (43)

SEG 9 (81) ...................... NC (31)

SEG10 (80) .............. SEG30 (30)

SEG11 (79) .............. SEG29 (29)

SEG12 (78) .............. SEG28 (28)

SEG13 (77) .............. SEG27 (27)

SEG14 (76) .............. SEG26 (26)

SEG15 (75) .............. SEG25 (25)

SEG16 (74) .............. SEG24 (24)

SEG17 (73) .............. SEG23 (23)

SEG18 (72) .............. SEG22 (22)

SEG19 (71) .............. SEG21 (21)

SEG21 (69) ............ SEG19 (19)

SEG22 (68) ............ SEG18 (18)

SEG23 (67) ............ SEG17 (17)

SEG24 (66) ............ SEG16 (16)

SEG25 (65) ............ SEG15 (15)

SEG26 (64) ............ SEG14 (14)

SEG27 (63) ............ SEG13 (13)

SEG28 (62) ............ SEG12 (12)

SEG29 (61) ............ SEG11 (11)

SEG30 (60) ............ SEG10 (10)

SEG31 (59) .............. SEG 9 ( 9)

SEG32 (58) .............. SEG 8 ( 8)

SEG33 (57) .............. SEG 7 ( 7)

SEG34 (56) .............. SEG 6 ( 6)

SEG35 (55) .............. SEG 5 ( 5)

SEG36 (54) .............. SEG 4 ( 4)

SEG37 (53) .............. SEG 3 ( 3)

SEG38 (52) .............. SEG 2 ( 2)

SEG39 (51) .............. SEG 1 ( 1)




Connected to LCD. Signal is similar to SEG39.

Connected to GND.

Connected to GND.

Connected to VC.

Common data signal.

Connected to LCD (Pin No. 36). No connection in LCD.

Common data signal: COM3.

Connected to LCD (Pin No. 35).





Power source voltage input terminal.

Standard voltage for LCD.

Terminal not used.

19

R-770B

SERVICING

1. Precautions for Handling Electronic Components

This unit uses CMOS LSI in the integral part of the circuits. When handling these parts, the following precautions should be strictly followed. CMOS LSI have extremely high impedance at its input and output terminals. For this reason, it is easily influenced by the surrounding high voltage power source, static electricity charge in clothes, etc., and sometimes it is not fully protected by the built-in protection circuit.

In order to protect CMOS LSI.

1) When storing and transporting, thoroughly wrap them in aluminium foil. Also wrap PW boards containing them in aluminium foil.

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

approx. 1M ohm

2. Shapes of Electronic Components separated from each other. For those models, therefore, it is possible 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 switch

(on PWB) of the touch control panel with a jumper, which brings about an operational state that is equivalent to the oven door being closed.

As for the sensor-related controls of the touch control panel, checking them is possible if the dummy resistor(s) with resistance equal to that of the controls are used.

(2) Servicing the touch control panel with power supply from an external power source:

Disconnect 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 an operational state that is equivalent to the oven door being closed. Connect an external power source to the power input terminal of the touch control panel, then it is possible to check and repair the controls of the touch control panel; it is also possible to check the sensor-related controls of the touch control panel by using the dummy resistor(s).

E

C

B

Transistor

2SB1238

E

C B Transistor

KRC243M

3. Servicing of Touch Control Panel

We describe the procedures to permit servicing of the touch control panel of the microwave oven and the precautions you must take when doing so.

To perform the servicing, power to the touch control panel is available either from the power line of the oven itself or from an external power source.

(1) Servicing the touch control panel with power supply of the oven :

CAUTION:

THE HIGH VOLTAGE TRANSFORMER OF THE

MICROWAVE OVEN IS STILL LIVE DURING

SERVICING AND PRESENTS A HAZARD .

Therefore, when checking the performance of the touch control panel, put the outer cabinet on the oven to avoid touching the high voltage transformer, or unplug the primary terminal (connector) of the high voltage transformer to turn it off; the end of such connector must be insulated with an insulating tape. After servicing, be sure to replace the leads to their original locations.

A. On some models, the power supply cord between the touch control panel and the oven itself is so short that the two can't be separated.

For those models, check and repair all the controls (sensor-related ones included) of the touch control panel while keeping it connected to the oven.

B. On some models, the power supply cord between the touch control panel and the oven proper is so long enough that they may be

4. Servicing Tools

Tools required to service the touch control panel assembly.

1) Soldering iron: 30W

(It is recommended to use a soldering iron with a grounding terminal.)

2) Oscilloscope: Single beam, frequency range: DC -

10MHz type or more advanced model.

3) Others: Hand tools

5. Other Precautions

1) Before turning on the power source of the control unit, remove the aluminium foil applied for preventing static electricity.

2) Connect the connector of the key unit to the control unit being sure that the lead wires are not twisted.

3) After aluminium foil is removed, be careful that abnormal voltage due to static electricity etc. is not applied to the input or output terminals.

4) Attach connectors, electrolytic capacitors, etc. to

PWB, making sure that all connections are tight.

5) Be sure to use specified components where high precision is required.

20

R-770B

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE

WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below before operating the oven.

1. Disconnect the oven from power supply.

2. Make sure that a definite” click” can be heard when the microwave oven door is unlatched. (Hold the door in a closed position with one hand, then push the door open button with the other, this causes the latch leads to rise, it is then possible to hear a “click’ as the door switches operate.)

3. Visually check the door and cavity face plate for damage (dents, cracks, signs of arcing etc.).

Carry out any remedial work that is necessary before operating the oven.

Do not operate the oven if any of the following conditions exist;

1. Door does not close firmly.

2. Door hinge, support or latch hook is damaged.

3. The door gasket or seal or damaged.

4. The door is bent or warped.

5. There are defective parts in the door interlock system.

6. There are defective parts in the microwave generating and transmission assembly.

7. There is visible damage to the oven.

Do not operate the oven:

1. Without the RF gasket (Magnetron).

2. If the wave guide or oven cavity are not intact.

3. If the door is not closed.

4. If the outer case (cabinet) is not fitted.

Please refer to ‘OVEN PARTS, CABINET PARTS, CONTROL PANEL PARTS, DOOR PARTS’, when carrying out any of the following removal procedures:

WARNING FOR WIRING

To prevent an electric shock, take the following manners.

1. Before wiring,

1) Disconnect the power supply.

2) Open the door and wedge the door open.

3) Discharge the high voltage capacitor and wait for

60 seconds.

2. Don't let the wire leads touch to the following parts;

1) High voltage parts:

Magnetron, High voltage transformer, High voltage capacitor and High voltage rectifier assembly.

2) Hot parts:

Oven lamp, Magnetron, Grill heaters, Bottom heater, High voltage transformer and Oven cavity.

3) Sharp edge:

Bottom plate, Oven cavity, Waveguide flange,

Chassis support and other metallic plate.

4) Movable parts (to prevent a fault)

Fan blade, Fan motor, Switch, Switch lever,

Open button.

3. Do not catch the wire leads in the outer case cabinet.

4. Insert the positive lock connector certainly until its pin is locked. And make sure that the wire leads should not come off even if the wire leads is pulled.

5. To prevent an error function, connect the wire leads correctly, referring to the Pictorial Diagram.

OUTER CASE REMOVAL

To remove the outer case proceed as follows.

1. Disconnect oven from power supply.

2. Open the oven door and wedge it open.

3. Remove the two (2) screws (LHSTIX screws) holding the back plate to the oven cavity rear plate, by using

LHSTIX screw driver (LHSTIX "LR-4").

4. Remove the back plate.

5. Remove the five (5) screws from rear and along the side edge of case.

6. Slide the entire case back about 3cm to free it from retaining clips on the cavity face plate.

7. Lift the entire case from the oven.

8. Discharge the H.V. capacitor before carrying out any further work.

9. Do not operate the oven with the outer case removed.

N.B.; Step 1, 2 and 8 form the basis of the 3D checks.

Ouer Case Cabinet

LHSTIX Screw

Back Plate

LHSTIX Screw Driver(Size LR-4)

CAUTION: DISCHARGE HIGH VOLTAGE CAPACITOR

BEFORE TOUCHING ANY OVEN

COMPONENT OR WIRING.

21

R-770B

HIGH VOLTAGE COMPONENTS REMOVAL

(HIGH VOLTAGE CAPACITOR, HIGH VOLTAGE RECTIFIER ASSEMBLY AND HIGH VOLTAGE FUSE)

To remove the components, proceed as follows.

1. CARRY OUT 3D CHECKS.

2. Disconnect all the leads and terminals of high voltage rectifier assembly from the high voltage capacitor.

3. Disconnect the high voltage fuse from the high voltage transformer.

4. Now, the high voltage fuse is free.

5. Remove one (1) screw holding earth side terminal of the high voltage rectifier assembly.

6. Remove one (1) screw holding capacitor holder to the oven cavity rear plate.

7. Release the capacitor holder from the fan duct.

8. Remove the capacitor from the capacitor holder.

9. Now, the high voltage rectifier assembly and the capacitor should be free.

CAUTION: WHEN REPLACING HIGH VOLTAGE REC-

TIFIER ASSEMBLY, ENSURE THAT THE

CATHODE (EARTH) CONNECTION IS

SECURELY FIXED TO THE CAPACITOR

HOLDER AND BASE PLATE WITH AN

EARTHING SCREW.

HIGH VOLTAGE TRANSFORMER REMOVAL


2. Disconnect the filament leads of high voltage transformer from high voltage capacitor and the magnetron.

3. Disconnect the high voltage fuse from the high voltage transformer.

4. Disconnect the main wire harness from the high voltage transformer.

5. Remove the four (4) screws holding the transformer to base plate.

6. Remove the transformer.

7. Now the high voltage transformer is free.

MAGNETRON REMOVAL


2. Release the tabs of air intake duct from the chassis support and the oven cavity.

3. Disconnect the high voltage wire of the high voltage rectifier assembly and filament lead of the transformer from the magnetron.

4. Remove the one (1) screw holding the chassis support to the magnetron.

5. Move the air intake duct to left.

6. Carefully remove four (4) screws holding magnetron to waveguide, when removing the screws hold the magnetron to prevent it from falling.

7. Remove the magnetron from the waveguide with care so the magnetron antenna is not hit by any metal object around the antenna.

CAUTION: WHEN REPLACING THE MAGNETRON,

BE SURE THE R.F. GASKET IS IN PLACE

AND THE MAGNETRON MOUNTING

SCREWS ARE TIGHTENED SECURELY.

POSITIVE LOCK

®

CONNECTOR (NO-CASE TYPE) REMOVAL

Terminal


2. Push the lever of positive lock ® connector.

3. Pull down on the positive lock ® connector.

CAUTION: WHEN CONNECTING THE POSITIVE LOCK ®

CONNECTORS TO THE TERMINALS, IN-

STALL THE POSITIVE LOCK ® SO THAT THE

LEVER FACES YOU

Positive lock® connector

Lever

4

Push

5

Pull down

Figure C-1 Positive lock ® connector

CONTROL PANEL ASSEMBLY REMOVAL

CONTROL PANEL ASSEMBLY


2. Disconnect the main wire harness and the switch harness from the power unit.

3. Straighten the tab of the oven cavity front flange holding the tab of the control panel frame.

4. Lift up the control panel assembly.

5. Now, the control panel assembly is free.

CONTROL UNIT

6. Disconnect the flat ribbon cable from the connector CN-G.

7. Remove the two (2) screws holding the CPU unit to the control panel frame.

8. Release the four (4) tabs of the control panel frame holding the CPU unit to the control panel frame.

9. Release the liquid crystal display (LCD) from the LCD holder.

10.Now, the LCD sheet is free.

11.Release the two (2) tabs of the LCD holder holding the

CPU unit to the LCD holder.

12.Remove the LCD holder from the CPU unit.

13.Remove the two (2) screws holding the power unit to the control panel frame.

14.Release the four (4) tabs of the control panel frame holding the power unit to the control panel frame.

1 5.

Now, the control unit (CPU unit + Power unit) is free.

NOTE: 1. Before attaching a new key unit, wipe off remaining adhesive on the control panel frame

22

R-770B surfaces completely with a soft cloth soaked in alcohol.

2. When attaching the key unit to the control panel frame, adjust the upper edge and right edge of the key unit to the correct position of control panel frame.

3. Stick the key unit firmly to the control panel frame by rubbing with soft cloth not to scratch.

REMOVAL

Coil

FAN MOTOR REPLACEMENT


2. Remove the one (1) screw holding the noise filter to the chassis support.

3. Release the noise filter from the tab on the fan duct.

4. Disconnect the wire leads from the fan motor.

5. Remove the one (1) screw holding the capacitor holder to the oven cavity rear plate.

6. Remove the one (1) screw holding the fan duct to the oven cavity rear plate.

7. Release the tabs of the capacitor holder from fan duct.

8. Remove the fan duct from the oven.

9. Remove the fan blade from the fan motor shaft according to the following procedure.

1) Hold the edge of the rotor of the fan motor by using a pair of groove joint pliers.

CAUTION:

• Make sure that any pieces do not enter the gap between the rotor and the stator of the fan motor. Because the rotor is easy to be shaven by pliers and metal pieces may be produced.

• Do not let the pliers touch the coil of the fan motor because the coil may be cut or damaged.

• Do not distort the bracket by touching with the pliers.

2) Remove the fan blade from the shaft of the fan motor by pulling and rotating the fan blade with your hand.

3) Now, the fan blade will be free.

CAUTION:

• Once the fan blade has been removed, it must be replaced with new one.

10.Remove the two (2) screws holding the fan motor to the fan duct.

11.Now, the fan motor is free.

INSTALLATION

1.

Install the fan motor to the fan duct with the two (2) screws.

2.

Fix the fan blade to the fan motor shaft according to the following procedure.

1) Hold the centre of the bracket which supports the shaft of the fan motor on a flat table.

2) Install the fan blade to the shaft of fan motor by pushing the fan blade with a small, light weight, ball peen hammer or rubber mallet.

CAUTION:

• Do not hit the fan blade when installing it because the bracket may be deformed.

• Make sure that the fan blade rotates smoothly after installation.

• Make sure that the axis of the shaft is not slanted.

3. Install the fan duct to the oven cavity rear plate with the one (1) screw.

4. Insert the tabs of the capacitor holder to the fan duct.

5. Install the capacitor holder to the oven cavity rear plate with the one (1) screw.

6. Install the noise filter to the fan duct and the chassis support with the one (1) screw.

7. Re-connect the wire leads to the fan motor.

Groove joint pliers

Shaft

Stator

Gap

Bracket

Rotor

Rear view

Shaft

Axis

Stator

Side view

Rotor

These are the position where should be pinched with pliers

Table

Center of bracket

TURNTABLE MOTOR REPLACEMENT

1. Disconnect the oven from the power supply.

2. Remove the turntable motor cover by snipping of material in four corners.

3. Where the corners have been snipped off, bend corner areas flat. No sharp edge must be evident after removal of turntable motor cover.

4. Disconnect the wire leads from the turntable motor and remove the two (2) screws holding the turntable motor.

5. Now, the turntable motor is free.

6. After replacement use the one (1) screw provided with the turntable motor assembly to fit turntable motor cover.

NOTE: The one (1) screw to fit the turntable motor cover should be XFPSD40P12K00, XFPSD40P10K00 or XFPSD40P08K000.

OVEN LAMP REMOVAL


2. Remove the two (2) screws holding the air guide to the top of the oven cavity.

3. Straighten the tab holding the lamp cover to the top of the oven cavity.

4. Remove the lamp cover.

5. Disconnect the wire leads from the oven lamp.

6. Straighten the tab holding the oven lamp.

7. Remove the oven lamp from the top of the oven cavity.

23

R-770B

WARNING: Do not touch the oven lamp right after it is turned off or during it is turned on. Because the oven lamp is halogen type and it is very hot then.

POWER SUPPLY CORD REPLACEMENT

Removal


2. Remove the one (1) screw holding the green/yellow wire to the cavity rear plate.

3. Disconnect the leads of the power supply cord from the noise filter, referring to the Figure C-2(a).

4. Release the power supply cord from the oven cavity rear plate.

5. Now, the power supply cord is free.

Oven Cavity

Back Plate

Power Supply Cord

Re-install

1. Insert the moulding cord stopper of power supply cord into the square hole of the oven cavity rear plate, referring to the Figure C-2(b).

2. Install the earth wire lead of power supply cord to the cavity rear plate with one (1) screw and tight the screw.

3. Connect the brown and blue wire leads of power supply cord to the noise filter correctly, referring to the Pictorial

Diagram.

Moulding

Cord Stopper

Screw

Brown Wire

Bule Wire

Power

Supply Cord

Green/Yelow

Wire

L N

T1 T2

WHT

RED

Chassis

Support

Oven Cavity

Rear Plate

Noise Filter Square Hole

Figure C-2 (a) Replacement of Power Supply Cord Figure C-2(b). Power Supply Cord Replacement

GRIL HEATERS (TOP HEATERS) REMOVAL


2. Remove the one (1) screw holding the exhaust duct to the oven cavity.

2. Remove the exhaust duct from the oven cavity.

4. Disconnect the wire leads from the grill heaters.

5. Lay down the two (2) tabs holding the reflector to the oven cavity.

6. Remove the reflector from the oven cavity by sliding it leftward.

7. Remove the grill heaters and the short terminal together from the oven cavity top plate.

8. Remove the two (2) screws holding the short terminal to the grill heaters.

9. Now the individual grill heaters are free.

BOTTOM HEATER REMOVAL

1. CARRY OUT 3D CHECKS

2. Remove the fan duct from the oven cavity, referring to

"FAN MOTOR REPLACEMENT".

3. Disconnect the wire leads from the bottom heater.

4. Remove the two (2) nuts holding the bottom heater with the bottom heater angle and the heat seal spring to the oven cavity right wall.

5. Remove the two (2) nuts holding the bottom heater with the bottom heater angle and the heat seal spring to the oven cavity left wall.

6. Remove the bottom heater from the oven cavity .

1ST. LATCH SWITCH, 2ND. INTERLOCK RELAY CONTROL SWITCH, AND MONITOR SWITCH REMOVAL

Latch Hook


2. Remove the control panel assembly referring to "CON-

TROL PANEL ASSEMBLY REMOVAL".

3. Disconnect the leads from all switches.

4. Remove the two (2) screws holding the latch hook to the oven cavity.

5. Remove the latch hook.

6. Push the retaining tab slightly and remove the switch.

Tab

2nd. Interlock

Relay Control

Switch

Monitor Switch

Tab

1st. Latch Switch

Tab

Figure C-3. Switches

24

R-770B

1ST. LATCH SWITCH, 2ND. INTERLOCK RELAY CONTROL SWITCH, AND MONITOR SWITCH ADJUSTMENT

If the 1st. latch switch, 2nd. interlock relay control switch and monitor switch do not operate properly due to a misadjustment, the following adjustment should be made.


2. Loosen the two (2) screws holding the latch hook to the oven cavity front flange.

3. With the 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 hook should be less than

0.5 mm. The horizontal position of the latch hook should be placed where the monitor switch has activated with the door closed. The vertical position of the latch hook should be placed where the 1st. latch switch and 2nd. interlock relay control switch have activated with the door closed.

4. Secure the screws with washers firmly.

5. Make sure of the 1st. latch switch, 2nd. interlock relay control switch and monitor switch operation. If those switches have not activated with the door closed, two

(2) screw holding latch hook to oven cavity front flange and adjust the latch hook position.

After adjustment, make sure of following:

1. In and out play of door remains less than 0.5 mm when latched position. First check latch hook position, pushing and pulling the door toward the oven face. The results (play of the door) should be less than 0.5mm.

2. The contacts (COM-NO) of the 1st. latch switch and

2nd. interlock relay control switch interrupt the circuit before the door can be opened.

3. The contacts (COM-NC) of the monitor switch 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.)

Latch Heads

Latch Hook

Door

2nd. Interlock

Relay Control

Switch

Monitor Switch

1st. Latch Switch

Switch Lever

Figure C-4 Latch Switches Adjustment

REMOVAL


2. Push the open button and open the door slightly.

3. Insert an putty knife (thickness of about 0.5mm) into the gap between the choke cover and door frame as shown in Figure C-5 to free engaging parts.

4. Try the principles of the lever and lift up the choke cover by inserting a putty knife as shown in Figure C-5.

5. Release choke cover from door panel.

6. Now choke cover is free.

Choke Cover

DOOR REPLACEMENT

Putty Knife

Door Frame

Figure C-5. Door Disassembly

7. Release two (2) pins of door panel from two (2) hole of upper and lower oven hinges by lifting up.

8. Now, door sub assembly is free from oven cavity.

9. Remove the four (4) screws holding the door panel to the door frame.

10.Release door panel froms seven (7) tabs of door frame by sliding door panel downward.

11.Now, door panel is free.

12.Slide latch head upward and remove it from door frame with releasing latch spring from door frame and latch head.

13.Now, latch head and latch spring are free.

14.Remove the two (2) screws holding the glass stopper to the door frame.

15.Remove the glass stopper from the door frame.

16.Slide the front door glass leftwards and then slide upwards to release the tabs holding it.

17.Now, the front door glass is free

RE-INSTALL

1. Re-install the front door glass to the door frame as follows.

1) Insert the lower edge of the front door glass into the six

(6) tabs of the door frame.

2) Slide the front door glass upwards and insert the upper edge of the front door glass into the five (5) tabs of the door frame.

3) Slide the front door glass rightwards and insert the right edge of the front door glass into the two (2) tabs of the door frame.

2. Re-install the glass stopper to the door frame as follows.

1) Re-install the glass stopper to the door frame so that the two (2) holes of the glass stopper meet the two (2) pins of the door frame.

2) Hold the glass stopper to the door frame with the two

(2) screws.

3. Re-install the latch spring to the latch head. Re-install the latch spring to the door frame. Re-install latch head to door frame.

4. Re-install door panel to door frame by fitting seven (7) tabs of door frame to seven (7) holes of door panel.

5. Hold the door panel to the door frame with four (4) screws.

6. Catch two (2) pins of door panel on two (2) hole of upper and lower oven hinges.

7. Re-install choke cover to door panel by pushing.

Note: After any service to the door;

(A) Make sure that door sensing switch and primary latch switch are operating properly. (Refer to chapter "Test Procedures".).

(B) An approved microwave survey meter should be

25

R-770B used to assure compliance with proper microwave radiation emission limitation standards.

(Refer to Microwave Measurement Procedure.)

After any service, make sure of the following :

1. Door latch heads smoothly catch latch hook through latch holes and that latch head goes through centre of latch hole.

2. Deviation of door alignment from horizontal line of cavity face plate is to be less than 1.0mm.

3. Door is positioned with its face pressed toward cavity face plate.

4. Check for microwave leakage around 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 oven cavity during cook cycle. This function does not require that door be air-tight, moisture (condensation)-tight or lighttight. Therefore, occasional appearance of moisture, light or sensing of gentle warm air movement around oven door is not abnormal and do not in themselves indicate a leakage of microwave energy from oven cavity.

Pin

Upper

Oven

Hinge

Upper Oven

Hinge

Door

Panel

Lower

Oven

Hinge

Choke Cover

Pin

Lower

Oven

Hinge

Figure C-6. Door Replacement

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/cm 2 at any point 5cm or more from external surface of the oven.

PREPARATION FOR TESTING:

Before beginning the actual test for leakage, proceed as follows;

1. Make sure that the test instrument is operating normally as specified in its instruction booklet.

Important:

Survey instruments that comply with the requirement for instrumentations as prescribed by the performance standard for microwave ovens must be used for testing.

Recommended instruments are:

NARDA 8100

NARDA 8200

HOLADAY HI 1500

SIMPSON 380M

2. Place the oven tray into the oven cavity.

3. Place the load of 275

±

15ml of water initially at 20

±

5˚C in the centre of the oven tray. The water container should be a low form of 600 ml beaker with inside diameter of approx. 8.5cm and made of an electrically non-conductive material such as glass or plastic.

The placing of this standard load in the oven is important not only to protect the oven, but also to insure that any leakage is measured accurately.

4. Close the door and turn the oven ON with the timer set for several minutes. If the water begins to boil before the survey is completed, replace it with 275ml of cool water.

5. Move the probe slowly (not faster that 2.5cm/sec.) along the gap.

6. The microwave radiation emission should be measured at any point of 5cm or more from the external surface of the oven.

mW cm 2

SHARP mW cm 2

Microwave leakage measurement at 5 cm distance

26

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED.

2. : OR CLOCK APPEAR ON DISPLAY.

NOTE: Indicates components with potential above 250 V.

FUSE

M10A

THERMAL CUT-OUT

(MG.)

CONTROUNIT

RY2: 2ND. INTERLOCK

RELAY

1ST.

LATCH SWITCH

Figure O-1 Oven Schematic-OFF Condition

SCHEMATIC


1. DOOR CLOSE.

2. MICROWAVE POWER LEVEL PAD PRESSED ONCE(100%).

3. COOKING TIME PROGRAMMED.

4. STRAT PAD PRESSED.

FUSE

M10A

THERMAL CUT-OUT

(MG.)

CONTROUNIT

RY2: 2ND. INTERLOCK

RELAY

1ST.

LATCH SWITCH

SCHEMATIC


1. DOOR CLOSE.

2. GRILL PAD PRESSED ONCE.



Figure O-2 Oven Schematic-Microwave cooking Condition

FUSE

M10A

THERMAL CUT-OUT

(MG.)

CONTROUNIT

RY2: 2ND. INTERLOCK

RELAY

1ST.

LATCH SWITCH

Figure O-3(a) Oven Schematic-Grill cooking Condition (TOP HEATER mode)

27

R-770B

R-770B

SCHEMATIC


1. DOOR CLOSE.

2. GRILL PAD PRESSED TWICE.




FUSE

M10A

THERMAL CUT-OUT

(MG.)

CONTROUNIT

RY2: 2ND. INTERLOCK

RELAY

1ST.

LATCH SWITCH

Figure O-3(b) Oven Schematic-Grill cooking Condition (BOTTOM HEATER mode)

SCHEMATIC

NOTE: CONDITION OF OVEN FOR GRILL COOKING

1. DOOR CLOSE.

2. GRILL PAD PRESSED TREE TIMES.



FUSE

M10A

THERMAL CUT-OUT

(MG.)

CONTROUNIT

RY2: 2ND. INTERLOCK

RELAY

1ST.

LATCH SWITCH

Figure O-3(c) Oven Schematic-Grill cooking Condition (TOP AND BOTTOM HEATERS mode)

28

SCHEMATIC


1. DOOR CLOSE.

2. GRILL MIX PAD PRESSED ONCE FOR GRILL MIX HIGH WITH TOP HEATER.

GRILL MIX PAD PRESSED TWICE FOR GRILL MIX LOW WITH TOP HEATER.




NOTE: RY2 and RY3 could not turn on simultaneously.

FUSE

M10A

THERMAL CUT-OUT

(MG.)

CONTROUNIT

RY2: 2ND. INTERLOCK

RELAY

R-770B

1ST.

LATCH SWITCH

Figure O-4(a) Oven Schematic-Grill Mix cooking Condition

(Grill Mix High with Top Heater mode and Grill Mix Low with Top Heater mode)

SCHEMATIC


1. DOOR CLOSE.

2. GRILL MIX PAD PRESSED THREE TIMES FOR GRILL MIX HIGH WITH BOTTOM HEATER.

GRILL MIX PAD PRESSED FOUR TIMES FOR GRILL MIX LOW WITH BOTTOM HEATER.



NOTE: RY2 and RY4 could not turn on simultaneously.

FUSE

M10A

THERMAL CUT-OUT

(MG.)

CONTROUNIT

RY2: 2ND. INTERLOCK

RELAY

1ST.

LATCH SWITCH

Figure O-4(b) Oven Schematic-Grill Mix cooking Condition

(Grill Mix High with Bottom Heater mode and Grill Mix Low with Bottom Heater mode)

29

F

G

D

E

R-770B

1

A

2

B

POWER SUPPLY CORD

LIVE

NEUTRAL

EARTH

C

REDWHT

NOISE FILTER

15A

3

4 5 6

A

B

C

D

E

F

G

H

1 2 3

30

4 5 6

H

1 2 3

4 5 6

R-770B

A A

B

C

D

E

F

G

H

1

AC220V

50Hz

FAN MOTOR

A 1 a b d

4

T1

8

D3

D1-4

11ES1

D1

6

1 D4

D2

D5

R4 27

D6

Q2 2SB1238

R5 4.7k

A 3 c

RY5

R2 510 1/2w

C10

C 2

LED

GND

R3 510 1/2w

SP1

C 3

C 1

C 9

C 4

VC

VA

VR

INT

R6 3.3k

C 5 BUZZER

C15

FAN MOTOR

RY6

C16 N.C.

OVEN LAMP

TURNTABLE

MOTOR

N.O.

COM

Q3

KRC243M

RY4

C5

10 µ /35v

C 6 OVEN LAMP

TURNTABLE

MOTOR

C14 BOTTOM

HEATER

BOTTOM

HEATER

TOP

HEATER

MICRO

N.O.

COM

N.O.

COM

N.O.

COM

RY3

RY2

C 8

C11

TOP

HEATER

N.C.

C 7 MICRO

C17 N.C.

C13 N.C.

C12 DOOR

SWITCH

B 2 B 1

DOOR SWITCH

B

C

D

E

F

G

NOTE : IF NOT SPECIFIED, 1/4w

±

5%

: IF NOT SPECIFIED, 1SS270A

H

2

Figure S-2. Power Unit Circuit

3

4

31

5 6

R-770B

1

A

B

C

D

E

F

G

N C

N C

N C

N C

N C

N C

N C

COM3

COM2

COM1

N C

N C

SEG31

SEG30

SEG29

SEG28

SEG27

SEG26

SEG25

SEG24

SEG23

SEG22

SEG21

SEG20

SEG19

SEG32

SEG18

SEG33

SEG17

SEG34

SEG16

SEG35

SEG15

SEG36

SEG14

SEG37

SEG13

SEG38

SEG12

SEG39

SEG11

SEG10

SEG1

SEG2

SEG3

SEG4

SEG6

SEG7

SEG5

SEG8

SEG9

2

/50v 0.1

C13

µ

/50v

µ

/16v

µ

+ –

C10 47

C11 0.1

C14

R15 4.7k

R10 1k

15k

R14

15k

R13

15k

R12

/50v 0.1

C12

µ

R11 4.7k

UDZ4.3B

ZD10

VL2

C 2

VL3

COM0

COM1

COM2

COM3

AVSS

VCC

VREF

SEG0

SEG1

SEG2

SEG3

SEG4

SEG5

SEG6

SEG7

SEG8

SEG9

85

90

95

3

4

RH-IZA859DR

IC-1

35

45

50

P80

P81

XIN

XOUT

P24

P25

P26

P27

P22

P23

VSS

P16

P17

P20

P21

RESET

P71

P72

P73

P70

R55 4.7k

680F

(J1)

R56 1M CF1 4.19 MHz

15p/50v

C81

C82

15p/50v

R70 15k

R71 15k

R69 15k

R68 15k

5 6

A

R65 15k

R64 15k

R63 15k

R62 15k

R61 15k

R60 15k

R67 15k

R66 15k

G 9 G10 G11 G12

B

C

D

E

R31 15k

F

G

H

1 2 3

32

4 5 6

H

A

B

1

D8

2 3

4 5

DIP

3

1

2

R5

SP1

AC RY6

CN - C 18

D6

R4

D5

4

C

6

R-770B

A

B

C

D D

E

F

H

G

1

VRS1

AC

1

FAN

LOT NO.

F

CN - A

6

5

CON

RY1

RY5

2

Figure S-4. Printed Wiring Board

3

4

33

5 6

H

E

F

G

R-770B

∆

∆

R6

RY2

RY3-4

RY5

RY6

SP1

T1

VRS1

3- 2

3- 3

3- 3-1

3- 3-2

3- 3-3

3- 4

3- 5

3- 6

3- 1

3- 1A

3- 1B

3- 1C

C1

C2

C3

C4-5

D1-4

D5-6

D8-12

Q2

Q3

R2-3

R4

R5

∆

*

∆

*

*

*

*

*

*

1- 1

1- 2

1- 3

1- 3

1- 4

1- 5

1- 5

1- 6

1- 7

1- 8

1- 9

1-10

1-11

1-12

1-13

1-14

1-15

1-16

1-17

1-18

1-19

1-19

1-20

PARTS LIST

Note: The parts marked "

∆

" may cause undue microwave exposure.

The parts marked "*" are used in voltage more than 250V.

REF. NO.

2- 1

2- 2

2- 3

2- 4

4- 1

4- 2

4- 3

4- 4

4- 5

4- 6

4- 7

PART NO.

DESCRIPTION

ELECTRIC PARTS

QSW-MA110WRE0 1st. latch switch and 2nd. interlockrelay control switch

QSW-MA111WRE0 Monitor switch

RMOTDA228WRE0 Turntable motor

RMOTDA207WRE0 Turntable motor (Interchangeable)

FH-DZA080WRK0 High voltage rectifier assembly

RC-QZA215WRE0 High voltage capacitor

RC-QZA182WRE0 High voltage capacitor (Interchangeable)

RMOTEA361WRE0 Fan motor

FPWBFA317WRK0 Noise filter

QACC-A067WRE0 Power supply cord

QFS-BA007WRE0 Fuse 15A

QFS-CQ001YBE0 Fuse 10A

QTANNA017WRW0 Short terminal

RHET-A200WRE0 Grill heater (Top heater)

RHET-A201WRE0 Bottom heater

RLMPUA001WRE0 Oven lamp (Halogen lamp)

RR-WZA022WRE0 Monitor resistor 0.8 ohm 20W

RTHM-A048WRE0 Thermal cut out 170˚C OFF / 155˚C ON

RTHM-A078WRE0 Thermal cut-out 125˚C

RTRN-A555WRE0 High voltage transformer

RV-MZA222WRE0 Magnetron

RV-MZA197WRE0 Magnetron (Interchangeable)

QFS-IA002WRE0 High voltage fuse 0.75A

CABINET PARTS

GCABDA092WRW0 Back plate

GCABUA649WRP0 Outer case cabinet

GDAI-A305WRW0 Base plate

GLEGPA074WRE0 Leg

CONTROL PANEL PARTS

CPWBFA780WRK0 Power unit

QCNCMA244DRE0 2-pin connector (CN-A)

QCNCMA275DRE0 2-pin connector (CN-B)

FW-VZA230DRE0 15pin wire harness (WH-1)

RC-KZA087DRE0 Capacitor 0.1 uF 50V

VCEAB31HW477M Capacitor 470 uF 50V

RC-KZA087DRE0 Capacitor 0.1 uF 50V

VCEAB31VW106M Capacitor 10 uF 35V

VHD11ES1///-1 Diode (11ES1)

VHD1SS270A/-1 Diode (1SS270A)

VHD1SS270A/-1 Diode (1SS270A)

VS2SB1238//-3 Transistor (2SB1238)

VSKRC243M//-3 Transistor (KRC243M)

VRD-B12HF511J Resistor 510 ohm 1/2W

VRD-B12EF270J Resistor 27 ohm 1/4W

VRD-B12EF472J Resistor 4.7k ohm 1/4W

VRD-B12EF332J Resistor 3.3k ohm 1/4W

RRLY-A081DRE0 Relay (VRB24)

RRLY-A076DRE0 Relay (OMIF-S-124LM)

RRLY-A080DRE0 Relay (OJ-SH-124LM)

RRLY-A076DRE0 Relay (OMIF-S-124LM)

RALM-A014DRE0 Buzzer (PKM22EPT-THAI)

RTRNPA105DRE0 Transformer

RH-VZA032DRE0 Varistor (10G471K)

CPWBFA787WRK0 CPU unit

DPNLCB491WRK0 Control panel frame with key unit

JBTN-B086WRF0 Open button

MSPRCA050WRE0 Open button spring

FUNTKA861WRE0 Key unit

LHLD-A185WRF0 LCD holder

PSHEPA624WRE0 LED sheet

XEPSD30P08XS0 Screw; 3mm x 8mm

OVEN PARTS

DOVN-A487WRY0 Oven cavity

PHOK-A106WRF0 Latch hook

PDUC-A695WRP0 Air duct

PSKR-A333WRP0 Partition plate

LANGQA478WRP0 Turntable motor angle

MSPRTA186WRE0 Plate spring

NCPL-A051WRE0 Turntable motor shaft

34

1

1

1

1

1

1

1

Q'TY CODE

1

1

1

1

1

1

2

1

2

1

1

1

1

1

1

1

1

1

1

1

1

1

1

AW

AW

AT

AF

AE

AD

AX

BD

AK

AK

AU

AT

AM

AY

AY

BB

AK

AH

AK

BR

BN

BN

AQ

1

1

1

2

AW

AZ

AX

AC

1

1

1

1

1

1

1

4

1

1

1

1

1

1

2

1

1

2

1

1

2

5

1

1

1

1

1

1

1

1

2

4

BU

AL

BB

AY

AP

AE

AN

BC

BE

AF

AB

AW

AL

AE

AA

AA

AL

AK

AG

AK

AG

AS

AE

AA

AA

AA

AB

AB

AB

AA

BF

AB

AB

AF

AB

AE

AB

AB

AB

R-770B

Note: The parts marked "

∆

" may cause undue microwave exposure.

The parts marked "*" are used in voltage more than 250V.

∆

∆

∆

5- 1

5- 2

5- 3

5- 4

5- 5

5- 6

5- 7

5- 8

5- 9

6- 1

6- 2

6- 3

6- 4

6- 5

6- 6

6- 7

6- 8

6- 9

6-10

6-11

6-15

6-16

7- 1

7- 2

7- 3

7- 4

7- 5

7- 6

7- 7

7- 8

7- 9

7-10

7-11

7-12

REF. NO.

4-19

4-20

4-21

4-22

4-23

4-24

4-25

4-26

4-27

4-28

4-29

4-30

4-31

4-32

4-33

4- 8

4- 9

4-10

4-11

4-12

4-13

4-14

4-15

4-16

4-17

4-18

PART NO.

PSPA-A109WRE0 Spacer

LBNDKA136WRP0 HV capacitor holder

NFANJA041WRE0 Fan blade

PDUC-A697WRF0 Fan duct

GCOVHA388WRW0 Bottom heater cover

GLEGPA071WRF0 Leg

LANGFA185WRP0 Chassis support

LANGQA480WRP0 Lamp cover

LFLG-A025WRE0 Bearing

MLEVPA226WRF0 Switch lever

MSPR-A004WRE0 Heat seal spring

PCOV-A011WRP0 Bottom heater angle

PCOVPA339WRE0 Waveguide cover

PCUSGA385WRP0 Cushion

PCUSUA190WRP0 Cushion

PCUSUA191WRP0 Cushion

PDUC-A691WRF0 Air intake duct

PDUC-A692WRP0 Exhaust

PDUC-A696WRP0 Air guide

PGLSPA506WRE0 Light glass

PCUSGA399WRE0 Cushion

PREFHA061WRW0 Reflector

PSHEPA487WRE0 Heater film

PSKR-A331WRP0 Air separate angle

MSPRCA113WRE0 H-spring

PCUSGA420WRP0 Cushion

DESCRIPTION

DOOR PARTS

DDORFA857WRK0 Door panel assembly

GWAKPA544WRR0 Door frame

LSTPPA176WRF0 Latch head

LSTPPA177WRF0 Glass stopper

MSPRTA187WRE0 Latch spring

PGLSPA508WRE0 Front door glass

XCPSD40P06000 Screw : 4mm x 6mm

XCPSD40P08000 Screw : 4mm x 8mm

GCOVHA387WRF0 Choke cover

MISCELLANEOUS

FAMI-A099WRM0 High rack

FAMI-A100WRM0 Low rack

FSRAHA062WRY0 Turntable support

NTNT-A092WRH0 Turntable

TCADCA640WRR0 Cook book for microwave

TINSEA749WRR0 Instruction book

FW-VZB045WRE0 Switch harness

FW-VZB651WRE0 Main wire harness

TCADCA641WRR0 Cookbook in russian

LHLDWA011WRE0 Purse lock M

TCAUHA214WRR0 K caution label

TSPCNC572WRR0 Rating label

TCAUHA240WRR0 Lamp caution

SCREWS,NUTS AND WASHERS

XFPSD40P08K00 Screw : 4mm x 8mm

XEPSD40P25000 Screw : 4mm x 25mm

LX-EZA042WRE0 Special screw

LX-NZ0061WRE0 Flange nut

XBPWW30P05K00 Screw : 3mm x 5mm

XCTWW40P08000 Screw : 4mm x 8mm

XHPSD30P06000 Screw : 3mm x 6mm

XHTSD40P08RV0 Screw : 4mm x 8mm

XOTSD40P12RV0 Screw : 4mm x 12mm

XOTSD40P12000 Screw : 4mm x 12mm

XOTSD40R12RV0 Line head screw : 4mm x 12mm

XOTSE40P08000 Screw : 4mm x 8mm

HOW TO ORDER REPLACEMENT PARTS

To have your order filled prompty and correctly, please furnish the following information.

1. MODEL NUMBER 2. REF. NO.

3. PART NO.

4. DESCRIPTION

1

1

1

1

1

1

2

4

1

Q'TY CODE

1

1

1

1

1

1

1

2

1

2

1

1

1

1

1

1

1

1

1

1

1

2

1

1

1

1

AN

AF

BE

AA

AY

AC

AE

AM

AF

AH

AC

AC

AG

AS

AT

AF

AG

AM

AX

AM

AF

AF

AB

AQ

AF

AM

BB

AX

AN

AF

AC

AV

AA

AA

AS

14

2

2

4

2

1

1

3

13

7

2

1

1

1

1

1

1

1

1

1

1

1

1

1

1

AB

AA

AA

AA

AA

AA

AA

AA

AA

AB

AA

AA

AN

AB

AC

AC

AC

AS

AS

BC

AZ

AX

AL

AG

BA

35

R-770B

A

1 2

OVEN AND CABINET PARTS

2-2

3

4 5 6

A

7-9

4-25 4-33

7-10

7-11

2-1

6-11

B

C

D

E

F

G

1-13

4-23

4-26

7-4

4-15

4-19

1-14

4-27

4-20

6-4

6-3

7-10

7-11

B

4-29

4-4

7-10 7-5

7-12

1-11

4-30

1-12

1-16

7-1

1-8

4-31

7-10 4-3

C

4-32

4-18

4-1

7-6

4-22

4-6

7-1

4-16

6-7

7-1

7-1

4-7

4-8

4-5

1-3

7-1

4-12

7-1

1-18

4-24

7-8

1-15

7-7

7-10

4-18

4-32

4-19

7-4

7-9

4-2

1-1

1-5

4-21

1-20

1-17 7-8

1-9

7-1

1-10

4-14

4-11

1-7

1-6 7-2

D

E

1-2

4-10

7-3

1-1

4-9

1-4

7-1

1-19

F

4-17

7-1

4-28

G

2-3

7-9

2-4

4-13

H 2-4

7-9

H

1 2 3

4 5

7-9

6

36

A

1 2

CONTROL PANEL PARTS

3-3

3-2

3

3-5

3-4

4

B

3-3-3

6-12

C

3-1

5

3-6

3-6

DOOR PARTS

3-3-1

D

3-3-2 5-8

5-9

5-1

E

5-6

5-2

F

G

H

6-2

1

6-1

2

6

R-770B

A

B

C

D

E

5-4

5-7

F

5-3

5-5

MISCELLANEOUS

6-8

G

6-7

3

6-10 Actual wire harness may be different than illustration.

H

5 6

37

4

R-770B

PACKING AND ACCESSORIES

TRAY HOLDER

(SPADFA424WRE0)

TURNTABLE TRAY

HIGH RACK

LOW RACK

LAMP CAUTION

COOK BOOK &

INSTRUCTION BOOK

TURNTABLE SUPPORT

TRAY PAD

(SPADPA577WRE0)

Not Replaceable Items.

TOP PAD ASSEMBLY

(FPADBA373WRK0)

WRAP COVER

(SSAKHA034WRE0)

DOOR PROTECTION SHEET

(SPADPA204WRE0)

BOTTOM PAD ASSEMBLY

(FPADBA374WRK0)

PACKING CASE

(SPAKCD046WRE0)

38

'98SHARP CORP. (03K0.120E) Printed in Japan

SHARP R-770B microwave oven SERVICE MANUAL

Assistant Bot

SERVICE MANUAL

MODEL

DOUBLE GRILL

MICROWAVE OVEN

R-770B

TABLE OF CONTENTS

SHARP CORPORATION

SERVICE MANUAL

SHARP CORPORATION

OSAKA, JAPAN

PRODUCT DESCRIPTION

SPECIFICATION

ITEM DESCRIPTION

WARNING

THIS APPLIANCE MUST BE EARTHED

APPEARANCE VIEW

OPERATION SEQUENCE

OFF CONDITION

MICROWAVE COOKING CONDITION

70% (MEDIUM HIGH), 50% (MEDIUM), 30% (ME-

DIUM LOW), 10% (LOW COOKING)

GRILL COOKING CONDITIONS

HEATER

HEATER

MIX COOKING CONDITION

AUTOMATIC OPERATIONS

LIMITATIONS OF POWER OUTPUT IN MANUAL

OPERATION

DOOR OPEN MECHANISM

1ST. LATCH SWITCH AND 2ND. INTERLOCK

RELAY CONTROL SWITCH

MONITOR SWITCH

FUSE M10A 250V

FUSE 15A

FUNCTION OF IMPORTANT COMPONENTS

HIGH VOLTAGE FUSE 0.75A

THERMAL CUT-OUT 125˚C (MG)

THERMAL CUT-OUT170˚C (OVEN)

TURNTABLE MOTOR

FAN MOTOR

NOISE FILTER

TOP HEATERS

BOTTOM HEATER

SERVICING

WARNING TO SERVICE PERSONNEL

REMEMBER TO CHECK 3D

REMEMBER TO CHECK 4R

TROUBLESHOOTING GUIDE

N WHT

L

RED

b c a d

TOUCH CONTROL PANEL ASSEMBLY

DESCRIPTION OF LSI

SERVICING

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE

WARNING FOR WIRING

OUTER CASE REMOVAL

HIGH VOLTAGE COMPONENTS REMOVAL

(HIGH VOLTAGE CAPACITOR, HIGH VOLTAGE RECTIFIER ASSEMBLY AND HIGH VOLTAGE FUSE)

HIGH VOLTAGE TRANSFORMER REMOVAL

MAGNETRON REMOVAL

POSITIVE LOCK

CONNECTOR (NO-CASE TYPE) REMOVAL

CONTROL PANEL ASSEMBLY REMOVAL

REMOVAL

FAN MOTOR REPLACEMENT

INSTALLATION

TURNTABLE MOTOR REPLACEMENT

OVEN LAMP REMOVAL

POWER SUPPLY CORD REPLACEMENT

Removal

Re-install

GRIL HEATERS (TOP HEATERS) REMOVAL

BOTTOM HEATER REMOVAL

1ST. LATCH SWITCH, 2ND. INTERLOCK RELAY CONTROL SWITCH, AND MONITOR SWITCH REMOVAL

1ST. LATCH SWITCH, 2ND. INTERLOCK RELAY CONTROL SWITCH, AND MONITOR SWITCH ADJUSTMENT

After adjustment, make sure of following: