Sharp Microwave Oven MMD24B User Manual

MMD24S

MMD24B

SERVICE MANUAL

S38M289MMD24S

MICROWAVE DRAWER

MODELS

MMD24S

MMD24B

In the interest of user-safety the unit should be restored to its original condition and only parts identical to those speciﬁed should

be used.

WARNING TO SERVICE PERSONNEL:

This service manual is intended for use by persons having electrical and mechanical training and a level of

knowledge of these subjects generally considered acceptable in the appliance repair trade. Sharp Electronics

Corporation cannot be responsible, nor assume any liability, for injury or damage of any kind arising from the

use of this manual.

Microwave ovens contain circuitry capable of producing very high voltage and current. Contact with the

following parts may result in a severe, possibly fatal, electrical shock. (High Voltage Capacitor, High Voltage

Power Transformer, High Voltage Rectiﬁer and Heat sink etc., and Magnetron, High Voltage Harness etc..)

TABLE OF CONTENTS

Page

PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO

AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY..................... INSIDE FRONT COVER

BEFORE SERVICING....................................................................................................... INSIDE FRONT COVER

WARNING TO SERVICE PERSONNEL.................................................................................................................3

MICROWAVE MEASUREMENT PROCEDURE.....................................................................................................4

FOREWORD AND WARNING ...............................................................................................................................5

PRODUCT SPECIFICATIONS ...............................................................................................................................6

SCHEMATICS ......................................................................................................................................................ꢀ0

TEST PROCEDURES..........................................................................................................................................ꢀꢀ

TOUCH CONTROL PANEL ASSEMBLY..............................................................................................................ꢀ9

MICROWAVE DRAWER DISASSEMBLY.............................................................................................................27

WIRING DIAGRAMS............................................................................................................................................33

PRINTED WIRING BOARDS ...............................................................................................................................34

PARTS LIST .........................................................................................................................................................38

PACKING AND ACCESSORIES ..........................................................................................................................43

This document has been published to be used for after sales

service only. The contents are subject to change without

notice.

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MMD24S

MMD24B

WARNING TO SERVICE PERSONNEL

Microwave Oven units contain circuitry capable of producing very high voltage and current,

contact with following parts may result in a severe, possibly fatal, electrical shock.

(Example)

High Voltage Capacitor, High Voltage Power Transformer, Magnetron, High Voltage Rectiﬁer

Assembly, High Voltage Harness, Heating Elements, etc..

Read the Service Manual carefully and follow all instructions.

Before Servicing

When the testing is completed,

ꢀ. Disconnect the power supply cord, and then remove

covers.

2. Open the drawer and keep it open.

3. Discharge high voltage capacitor.

4. Reconnect the leads to the primary of the power

transformer.

ꢀ. Disconnect the power supply cord

remove cabinet.

2. Open the drawer and keep it open.

3. Discharge high voltage capacitor.

, and then

WARNING: RISK OF ELECTRIC SHOCK.

DISCHARGE THE HIGH-VOLTAGE

CAPACITOR BEFORE SERVICING.

5. Reinstall the covers.

6. Reconnect the power supply cord.

7. Run the unit and check all functions.

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 the connecting lead of the

high-voltage rectiﬁer) against the chassis with the use of

an insulated screwdriver.

After repairing

ꢀ. Reconnect all leads removed from components during

testing.

2. Reinstall the covers.

3. Reconnect the power supply cord.

4. Run the oven and check all functions.

Whenever troubleshooting is performed the power supply

must be disconnected. It may, in some cases, be necessary

to connect the power supply after the outer case has been

removed, in this event:

ꢀ. Disconnect the power supply cord, and then remove

neccessary covers.

Microwave ovens should not be operated empty.To test for

the presence of microwave energy within a cavity, place a

cup of cold water on the oven tray, close the drawer and set

the power to HIGH and set the microwave timer for two (2)

minutes.When the two minutes has elapsed (timer at zero)

carefullycheckthatthewaterisnowhot.Ifthewaterremains

cold carry out Before Servicing procedure and re-examine

the connections to the component being tested.

2. Open the drawer and keep it open.

3. Discharge high voltage capacitor.

4. Disconnect the leads to the primary of the power

transformer.

5. Ensure that the leads remain isolated from other

components and oven chassis by using insulation tape.

6. After that procedure, reconnect the power supply cord.

When all service work is completed and the oven is fully

assembled, themicrowavepoweroutputshouldbechecked

and a microwave leakage test should be carried out.

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MMD24S

MMD24B

MICROWAVE MEASUREMENT PROCEDURE

A. Requirements:

ꢀ) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave

oven should not exceed ꢀmW/cm²at any point 5cm or more from the external surface of the oven, measured prior to

acquisition by a purchaser, and thereafter (through the useful life of the oven), 5 mW/cm²at any point 5cm or more

from the external surface of the oven.

2) Safety interlock switches:

Primary interlock relay switch shall prevent microwave radiation emission in excess of the requirement as above

mentioned. Secondary interlock relay and door sensing switch shall prevent microwave radiation emission in excess

of 5 mW/cm2 at any point 5cm or more from the external surface of the oven.

B. Preparation for testing:

Before beginning the actual measurement of leakage, proceed as follows:

ꢀ) Make sure that the actual instrument is operating normally as speciﬁed in its instruction booklet.

Important:

Survey instruments that comply with the requirement for instrumentation as prescribed by the performance standard

for microwave ovens, 2ꢀ CFR ꢀ030.ꢀ0(c)(3)(i), must be used for testing.

Survey instruments that comply with the requirement for instrumentation as prescribed by CSA and NHW performance

standard for microwave ovens must be used for testing recommended instruments are , NARDA 8ꢀ00 and NARDA

8200.

2) Place the load of 275±ꢀ5 ml (9.8 oz) of tap water initially at 20±5^OC (68^OF) in the center of the oven cavity.

The water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm (3-ꢀ/2

in.) 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.

3) Set the cooking control on Full Power Cooking Mode.

4) Close the drawer and select a cook cycle of several minutes.If the water begins to boil before the survey is completed,

replace it with 275 ml of cool water.

C. Leakage test:

Closed-drawer leakage test (microwave measurement):

ꢀ) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the drawer and the body of

the oven.

2) Move the probe slowly, not faster than ꢀ in./sec. (2.5 cm/sec.) along the gap, watching for the maximum indication

on the meter.

3) Check for leakage at the drawer screen, sheet metal seams and other accessible positions where the continuity of

the metal has been breached (eg., around the switches, indicator, and vents).

While testing for leakage around the drawer, pull the drawer away from the front of the oven as far as is permitted

by the closed latch assembly.

4) Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than

4mW/cm², and that the primary interlock switch/secondary interlock relay does turn the oven OFF before any door

movement.

NOTE: After servicing, record data on service invoice and microwave leakage report.

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MMD24S

MMD24B

SERVICE MANUAL

PRODUCT DESCRIPTION

SCHEMATICS

MICROWAVE DRAWER

MMD24S / MMD24B

FOREWORD

This Manual has been prepared to provide Dacor Service Personnel

with Operation and Service Information for the DACOR MICROWAVE

DRAWER.

TEST PROCEDURE

It is recommended that service personnel carefully study the entire

text of this manual so that they will be qualiﬁed to render satisfactory

customer service.

TOUCH CONTROL PANEL

Check the interlock switches and the door seal carefully. Special

attention should be given to avoid electrical shock and microwave

radiation hazard.

MICROWAVE DRAWER

DISSASSEMBLY AND

ADJUSTMENT PROCEDURE

WARNING

Never operate the oven until the following points are ensured.

(A) The door is tightly closed.

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

(D) The door is not deformed or warped.

(E) There is no other visible damage with the oven.

WIRING DIAGRAM

PARTS LIST

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

personnel.

DANGER

Certaininitialpartsareintentionallynotgroundedandpresent

a risk of electrical shock only during servicing. Service

personnel - Do not contact the following parts while the ap-

pliance is energized;

Inverter unit that includes High Voltage Capacitor, High Volt-

agePowerTransformer,HighVoltageRectiﬁer,Heatsink,etc.,

and Magnetron, High Voltage Harness etc.;

If provided, Vent Hood, Fan assembly, Cooling Fan Motor.

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

than 250V.

Removal of the outer wrapper gives access to voltage above

250V.

All the parts marked“∆”on parts list may cause undue microwave

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

or removed.

1440 Bridge Gate Dr.

Diamond Bar, CA 91765

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MMD24S

MMD24B

MICROWAVE DRAWER SPECIFICATION

ITEM

Power Requirements

DESCRIPTION

Canada - ꢀꢀ7 Volts / ꢀ3.0 Amperes / ꢀ500 Kw / 60 Hz (CUL)

U.S.A. - ꢀ20 Volts / ꢀ3.6 Amperes / ꢀ500 Kw / 60 Hz (UL)

Single phase, 3 wire grounded

Power Output

950 watts (IEC TEST PROCEDURE)

Operating frequency of 2450MHz

Cooking Cavity Dimensions

Width ꢀ7-ꢀꢀ/32

Height 5-7/8"

Depth ꢀ7-ꢀ/8"

ꢀ.0 Cubic Feet

Outside Dimensions

Width 23-ꢀ3/ꢀ6"

Height ꢀ5-5/8"

Depth 26-3/8"

(Including drawer handle)

Control Complement

Touch Control System

Clock ( ꢀ:00 - ꢀ2:59 )

Timer (0 - 99 min. 99 seconds)

Microwave Power for Variable Cooking

Repetition Rate;

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

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

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

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

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

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

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

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

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

P-ꢀ0..................................................................... approx. ꢀ0% of Full Power

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

START/EASY MINUTE pad, Defrost pad, Number selection pad, Micro-warm

pad, Power Level pad, Timer/Clock pad, Stop/Clear pad, Sensor Reheat,

Sensor Popcorn, Sensor Cook, Open pad, Close pad, Setup/Help, Control Lock

On/Off, Reheat.

Oven Cavity Light

Safety Standard

Yes

Canadian Standards Association

Health Canada, Industry Canada

UL Listed

FCC Authorized

DHHS Rules, CFR, Title 2ꢀ, Chapter ꢀ, Subchapter J

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MMD24S

MMD24B

GENERAL INFORMATION

GROUNDING INSTRUCTIONS

This oven is equipped with a three prong grounding plug. It must be plugged into a wall receptacle that is properly installed

and grounded in accordance with the National Electrical Code and local codes and ordinances.

In the event of an electrical short circuit, grounding reduces the risk of electric shock by providing an escape wire for the

electric current.

WARNING:

Improper use of the grounding plug can result in a risk of electric shock.

Electrical Requirements

The electrical requirements are a ꢀ20 volt 60 Hz (U.S.A.), ꢀꢀ7 volt 60 Hz (Canadian) AC only, ꢀ5 or 20 amp. fused electrical

supply. It is recommended that a separate circuit serving only this appliance be provided. When installing this appliance,

observe all applicable codes and ordinances.

Where a two-pronged wall-receptacle is encountered, it is the personal responsibility and obligation of the customer to con-

tact a qualiﬁed electrician and have it replaced with a properly grounded three-pronged wall receptacle or have a grounding

adapter properly grounded and polarized. If an extension cord must be used, it should be a 3-wire, ꢀ5 amp. or higher rated

cord. Do not drape over a counter top or table where it can be pulled on by children or tripped over accidentally.

CAUTION: DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE ROUND GROUNDING PRONG FROM

THIS PLUG.

Grounded

Receptacle Box

3-Pronged

Plug

Grounding Pin

3-Pronged Receptacle

NOTE:

The directed features are disabled after one minute when the oven is not in use.These features are automatically enabled

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

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MMD24S

MMD24B

OPERATION

DESCRIPTION OF OPERATING SEQUENCE

The following is a description of component functions dur-

ing oven operation.

the secondary interlock switch and secondary interlock

relay and is mechanically associated with the drawer so

that it will function in the following sequence.

8. When the drawer opens from the closed position, the

primary interlock relay (RY2) and secondary interlock

switch open their contacts. And contacts of the relay

(RYꢀ) remains closed.Then the monitor switch contacts

close.

9. When the drawer is closed from the open position, the

monitor switch contacts open ﬁrst.Then the contacts of

the secondary interlock switch and door sensing switch

close. And contacts of the relay (RYꢀ) open.

If the secondary interlock switch and primary interlock

relay (RY2) fail with the contacts closed when the drawer

is opened, the closing of the monitor switch contacts will

form a short circuit through the fuse, secondary interlock

switch, relay (RYꢀ) and secondary interlock relay (RY2),

causing the fuse to blow.

OFF CONDITION

Closing the drawer activates the door sensing switch and

secondary interlock switch. (In this condition, the monitor

switch contacts are opened.)

When oven is plugged in, ꢀ20 volts A.C. is supplied to the

control unit. (Page ꢀ0).

ꢀ. Thedisplaywillshowﬂashing"EnjoyYourDrawerTouch

Clear and Touch Clock".

To set any program or set the clock, you must ﬁrst touch

the STOP/CLEAR pad.The display will clear, and " : "

will appear.

COOKING CONDITION

Program desired cooking time by touching the NUMBER

pads. Program the power level by touching the POWER

LEVEL pad and then a Number pad.

When the START pad is touched, the following operations

occur:

POWER LEVEL P-0 TO P-90 COOKING

When Variable Cooking Power is programmed, the ꢀ20

volts A.C.is supplied to the power transformer intermittently

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

the control unit within a 32 second time base. Microwave

power operation is as follows:

ꢀ. The contacts of relays are closed and components

connected to the relays are turned on as follows.

(For details, refer to Page ꢀ0)

VARI-MODE

ON TIME

32 sec.

OFF TIME

0 sec.

RELAY

RY-ꢀ

CONNECTED COMPONENTS

oven lamp/stir fan motor/fan motor

power transformer

Power ꢀ0(P-HI)

(ꢀ00% power)

Power 9(P-90)

(approx. 90% power)

Power 8(P-80)

(approx. 80% power)

Power 7(P-70)

(approx. 70% power)

Power 6(P-60)

(approx. 60% power)

Power 5(P-50)

(approx. 50% power)

Power 4(P-40)

(approx. 40% power)

Power 3(P-30)

(approx. 30% power)

RY-2

30 sec.

26 sec.

24 sec.

22 sec.

ꢀ8 sec.

ꢀ6 sec.

ꢀ2 sec.

8 sec.

2 sec.

6 sec.

2. ꢀ20 volts A.C. is supplied to the primary winding of the

power transformer and is converted to about 3.3 volts

A.C. output on the ﬁlament winding, and approximately

2370 volts A.C. on the high voltage winding.

3. The ﬁlament winding voltage heats the magnetron

ﬁlament and the H.V.winding voltage is sent to a voltage

doubler circuit.

4. The microwave energy produced by the magnetron is

channelled through the waveguide into the cavity feed-

box, and then into the cavity where the food is placed

to be cooked.

5. Upon completion of the cooking time, the power

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

generation of microwave energy is stopped. The oven

will revert to the OFF condition.

6. When the drawer is opened during a cook cycle, the

monitorswitch,doorsensingswitch,secondaryinterlock

switch, relay (RYꢀ) and primary interlock relay are

activated with the following results.The circuits to the stir

fan motor, the cooling fan motor, and the high voltage

componentsarede-energized,theovenlampremainson,

and the digital read-out displays the time still remaining

in the cook cycle when the door was opened.

8 sec.

ꢀ0 sec.

ꢀ4 sec.

ꢀ6 sec.

20 sec.

24 sec.

26 sec.

32 sec.

Power 2(P-20)

(approx. 20% power)

Power ꢀ(P-ꢀ0)

(approx. ꢀ0% power)

Power 0(P-0)

(0% power)

6 sec.

0 sec.

Note: TheON/OFFtimeratiodoesnotcorrespondwiththe

percentage of microwave power, because approx.2

seconds are needed for heating of the magnetron

ﬁlament.

7. The monitor switch electrically monitors the operation of

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MMD24S

MMD24B

SENSOR COOKING CONDITION

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

power transformer is not turned on.

Using the SENSOR function, food is cooked without ﬁgur-

ing time, power level or quantity. When the oven senses

enough steam from the food, it relays the information to its

microprocessor which will calculate the remaining cooking

time and power level needed for best results. When the food

is cooked, water vapor is developed. the sensor "senses"

the vapor and its resistance increase gradually. When the

resistance reaches the value set according to the menu,

supplementary cooking is started.

3. After about ꢀ6 seconds, the cook relay (RY-2) is

energized. The power transformer is turned on,

microwaveenergyisproducedandﬁrststageisstarted.

The ꢀ6 seconds is the cooling time required to remove

any vapor from the oven cavity and sensor.

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

touch STOP/CLEAR pad.

4. When the sensor detects the vapor emitted from the

food,thedisplayswitchesovertotheremainingcooking

time and the timer counts down to zero.

Thetimeofsupplementarycookingisdeterminedbyexperi-

ment with each food category and inputted into the LSI. An

example of how sensor works: (Potatoes)

At this time, the drawer may be opened to stir, turn or

season food.

5. Whenthetimerreacheszero, anaudiblesignalsounds.

The shut-off relay and cook relay are de-energized and

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

6. Opening the drawer or touching the STOP/CLEAR

pad, the time of the day will reappear on the display

and the oven will revert to an OFF condition.When the

timer reaches zero, an audible signal sounds.

ꢀ. Potatoes at room temperature. Vapor is emitted very

slowly.

MICR

OWAVE

2.Heat Potatoes. Moisture and humidity is emitted very

rapidly. You can smell the aroma as it cooks.

MICROWAVE

AH SENSOR

3.Sensor detects moisture and humidity and calculates

cooking time and variable power.

Cooking Sequence.

ꢀ. Touch one of the SENSOR pads.

NOTE: The oven should not be operated on sensor

immediately after plugging in the unit. Wait two

minutes before cooking on SENSOR.

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MMD24S

MMD24B

SCHEMATIC (OFF CONDITION)

MAGNETRON

H.V. RECTIFIER

CAPACITOR

xxx µF

AC 2300V

POWER TRANSFORMER

WHT

N.C.

COM

N.O.

RED or BLK

BRN

MONITOR SWITCH

BLU

GRN

GRY

RED or BLK

GRN

WHT

PRIMARY INTERLOCK RELAY

RY2

GRY

GRN

STIRRER MOTOR

BLK

ORG

BLU

YLW

FAN MOTOR

RY3

RY4

BLU

GRY

RED *2

BLK *2

ORG

OVEN LAMP

RED

WHT

GRY

RED *2

WHT

BLK *2

RY1

RY5

HUMDITY

SENSOR

RED

GRN

GRY

BLK

WHT

GRY

"TO LOAD"

0.0033 µF 250V

LINE BYPASS CAPACITOR

0.0033 µF 250V

LINE BYPASS CAPACITOR

NOISE SUPRESSION COIL

LINE CROSS CAPACITOR 1.0 µF 275V

RESISTOR 470 k Ω

1/2W

FUSE

20A

"TO SOURCE"

WHT

BLK

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MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

TOUCH CONTROL PANEL ASSEMBLY TEST

The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,

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

and ohmmeter.

In this service manual, the touch control panel assembly is divided into three units, Control Unit,

Keyboard Unit and Power Unit, and troubleshooting by unit replacement is described according to the

symptoms indicated.

Before testing,

ꢀ) Disconnect the power supply cord, and then disassemble as per "MICROWAVE DRAWER

DISASSEMBLY" page 27.

2) Open the drawer and block it open.

3) Discharge high voltage capacitor.

4) Disconnect the leads to the primary of the power transformer.

5) Ensure that these leads remain isolated from other components and oven chassis by using

insulation tape.

ꢀ. Keyboard Unit.

NOTE ;

ꢀ) Check Keyboard unit connection before replacement.

2) Reconnect all leads removed from components during testing.

3) Re-install the covers.

4) Reconnect the power supply cord after the covers are installed.

5) Run the oven and check all functions.

The following symptoms indicate a defective keyboard 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.

If the Keyboard unit is defective.

ꢀ) Disconnect the power supply cord, and then remove covers.

2) Open the drawer and block it open.

3) Discharge high voltage capacitor.

4) Replace the Keyboard unit.

5) Reconnect all leads removed from components during testing.

6) Re-install the covers.

7) Reconnect the power supply cord after the covers are installed.

8) Run the oven and check all functions.

2. Control Unit

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

the Keyboard unit test (Procedure B) to determine if control unit is faulty.

2-ꢀ In connection with indicators

a) At a certain digit, all or some segments do not light up.

b) At a certain digit, brightness is low.

c) Only one indicator does not light.

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

e) Wrong ﬁgure appears.

f) A certain group of indicators do not light up.

g) The ﬁgure of all digits ﬂicker.

2-2 Other possible problems 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.

3. Power Unit or Touch Control Transformer

a) Fan motor, stirrer motor, oven lamp or electrical parts do not turn on or do not turn off.

b) Digital display on the control unit does not show anything.

When testing is completed,

ꢀ) Disconnect the power supply cord, and then disassemble as per "MICROWAVE DRAWER

DISASSEMBLY" page 27.

2) Open the drawer and block it open.

3) Discharge high voltage capacitor.

ꢀꢀ

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MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

4) Reconnect all leads removed from components during testing.

5) Re-install the covers.

6) Reconnect the power supply cord after the covers are installed.

7) Run the oven and check all functions.

KEY UNIT TEST

ꢀ. Disconnect the power supply cord, and then remove outer case.

2. Open the drawer and block it open.

3. Discharge high voltage capacitor.

4. If the display fails to clear when the STOP/CLEAR pad is depressed,

ﬁrst verify the ﬂat ribbon cable is making good contact, verify that

the door sensing switch (stop switch) operates properly; that is the

contacts are closed when the drawer is closed and open when the

drawer is open. If the door sensing switch (stop switch) is good,

disconnect the ﬂat ribbon cable that connects the key unit to the

control unit and make sure the drawer sensing switch is closed

(either close the drawer 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 making 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 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.

TIMER

CLOCK

POWER

LEVEL

SENSOR

COOK

OPEN

SET UP/

HELP

SENSOR

REHEAT

SENSOR

POPCORN

CONTROL

LOCK

ON/OFF

MICRO

WARM

REHEAT

DEFROST

START/

EASY

MINUTE

STOP/

CLEAR

5. Reconnect all leads removed from components during testing.

6. Re-install the outer case (cabinet).

7. Reconnect the power supply cord after the outer case is installed.

8. Run the oven and check all functions.

RELAY TEST

ꢀ. Disconnect the power supply cord, and then remove outer case.

2. Open the door and block it open.

3. Discharge high voltage capacitor.

4. Disconnect the leads to the primary of the power transformer.

5. Ensure that these leads remain isolated from other components and oven chassis by using insulation

tape.

6. After that procedure, re-connect the power supply cord.

7. Remove the outer case and check voltage between Pin Nos. 5 and 7 of the 4 pin connector (CN-A)

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

The meter should indicate ꢀ20 volts, if not check oven circuit.

RYꢀ, RY2, RY3 and RY4 Relay Test

These relays are operated by D.C. voltage

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

DC. voltage indicated

Defective relay.

DC. voltage not indicated

Check diode which is connected to the relay coil.If diode is good,

control unit is defective.

RELAY SYMBOL

OPERATIONAL VOLTAGE

Approx. 26V D.C.

CONNECTED COMPONENTS

RYꢀ

RY2

RY3

RY4

RY5

Oven lamp / Common

Power transformer

Stirrer motor

Approx. 25V D.C.

Approx. 26V D.C.

Fan motor

Switching regurator for drawer motor

8.Disconnect the power supply cord, and then remove outer case.

9.Open the door and block it open.

ꢀ0.Discharge high voltage capacitor.

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MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

ꢀ2.Re-install the outer case (cabinet).

ꢀ3.Reconnect the power supply cord after the outer case is installed.

ꢀ4.Run the oven and check all function.

DEFROST TEST

WARNING : The oven should be fully assembled before following procedure.

(ꢀ) Place one cup of water in the center of the tray in the oven cavity.

(2) Close the drawer, touch the Defrost pad. Then select Steaks/Chops by touching the number pad

2. And touch the number pad 5. (Now, weight 0.5lb is set.) And then touch the start pad.

(3) The oven is in Defrost cooking condition.

(4) The oven will operate as follows

WEIGHT

ꢀST STAGE

LEVEL TIME

60% 20sec.

2ND STAGE

LEVEL TIME LEVEL TIME

40% 20sec. 30% 45sec.

3RD. STAGE

0.5lb

(5) If improper operation is indicated, the control unit is probably defective and should be checked.

PROCEDURES TO BE TAKEN WHEN THE FUSE ON THE PRINTED WIRING BOARD (PWB) IS OPEN.

To protect the electronic circuits, this model is provided with a fuse added to the primary on the

PWB.

ꢀ. Fuse check and repairs.

ꢀ) Disconnect the power supply cord.

2) Remove the outer case cabinet.

3) Open the door and block it open.

4) Discharge high voltage capacitor.

5) If the Fuse is blown, replace power unit.

6) Make a visual inspection of the varistor. Check for burned damage. If the varistor has been

burned, replace the power unit.

7) Examine the touch control transformer with a tester for the presence of layer short-circuit (check

the primary coil resistance which is approximately ꢀ5ꢀ.6Ω ± ꢀ0%). If any abnormal condition is

detected, replace the touch control transformer.

8) Reconnect all leads removed from components during testing.

9) Re-install the outer case (cabinet).

ꢀ0) Reconnect the power supply cord after the outer case is installed.

ꢀꢀ) Run the oven and check all functions.

2. Follow the troubleshooting guide given below, if indicator does not light up after above check and

repairs are ﬁnished.

ꢀ) Disconnect the power supply cord.

2) Remove the outer case cabinet.

3) Open the door and block it open.

4) Discharge high voltage capacitor.

5) Disconnect the leads to the primary of the power transformer.

6) Ensure that these leads remain isolated from other components and oven chassis by using

insulation tape.

7) After that procedure, re-connect the power supply cord.

8) Follow the troubleshooting guide given below for repair.

STEPS

OCCURRENCE

CAUSE OR CORRECTION

ꢀ

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

Pin Nos. 5 and 7 of the 4-pin connecter (CN-A).

The rated AC voltage is present at primary

side of touch control transformer.

Touch control transformer or secondary circuit defective.

Check and replace touch control transformer or power unit

ꢀ3

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MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

ꢀꢀ) Discharge high voltage capacitor.

ꢀ2) Reconnect all leads removed from components during testing.

ꢀ3) Re-install the outer case (cabinet).

ꢀ4) Reconnect the power supply cord after the outer case is installed.

ꢀ5) Run the oven and check all functions.

AH SENSOR TEST

Checking the initial sensor cooking condition

WARNING : The oven should be fully assembled before following procedure.

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

(2) Room temperature should not exceed 95^οF (35^οC).

(3) The unit should not be installed in any area where heat and steam are generated.The unit should not be

installed, for example, next to a conventional surface unit.Refer to the“INSTALLATION INSTRUCTIONS”

of the operation manual.

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

adequate ventilation, be sure to install so as not to block these vents. There should be some space for

air circulation.

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

with a dry cloth or paper towel.

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

refrigerator temperature and canned soup at room temperature.

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

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

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

Water load cooking test

WARNING : The oven should be fully assembled before following procedure.

Make sure the oven has been plugged in at least two minutes before checking sensor cook operation. The

cabinet should be installed and screws tightened.

(ꢀ) Fill approximately 200 milliliters (7.2 oz) of tap water in a ꢀ000 milliliter measuring cup.

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

(3) Close the drawer.

(4) Touch the TIMER/CLOCK pad once, the POWER LEVEL pad twice and the START pad once. And touch

the number pads ꢀ once and the number pad 4 once. Now, the oven is in the sensor cooking condition,

and "AH20" and "ON" will appear in the display.

(5) The oven will operate for the ﬁrst ꢀ6 seconds, without generating microwave energy.

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

cooking.

(6) After approximately ꢀ6 seconds, microwave energy is produced.

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

explanation below. If the oven stops after 5 minutes and no ERROR code is displayed, then the AH sensor

is normal. Check other parts except the AH sensor.

TESTING METHOD FOR AH SENSOR AND/OR CONTROL UNIT

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

sensor.

(ꢀ) Disconnect the power supply cord, and then disassemble as per "MICROWAVE DRAWER

DISASSEMBLY" page 27.

(2) Open the drawer and block it open.

(3) Discharge high voltage capacitor.

(4) Remove the AH sensor.

(5) Install the new AH sensor.

(6) Reconnect all leads removed from components during testing.

(7) Re-install the covers.

(8) Reconnect the power supply cord after the covers are installed.

(9) Reconnect the oven to the power supply and check the sensor cook operation as follows:

9-ꢀ. Fill approximately 200 milliliters (7.2 oz) of tap water in a ꢀ000 milliliter measuring cup.

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MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

LETTER

COMPONENT TEST

9-2. Place the container on the center of tray in the oven cavity.

9-3. Close the drawer.

9-4. Touch the TIMER/CLOCK pad once, the POWER LEVEL pad twice and the START pad once. And

touch the number pads ꢀ once and the number pad 4 once.

9-5. The control panel is in automatic Sensor operation.

9-6. The oven turns off automatically, and the time for detecting moisture will be displayed.

If new sensor does not operate properly, the problem is with the control unit, and refer to explanation be-

low.

CHECKING CONTROL UNIT

(ꢀ) Disconnect the power supply cord, and then disassemble as per "MICROWAVE DRAWER

DISASSEMBLY" page 27.

(2) Open the drawer and block it open.

(3) Discharge high voltage capacitor.

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

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

(6) Disconnect the leads to the primary of the power transformer.

(7) Ensure that these leads remain isolated from other components and oven chassis by using insulation

tape.

(8) After that procedure, re-connect the power supply cord.

(9) Check the sensor cook operation proceed as follows:

9-ꢀ. Close the door.Touch the TIMER/CLOCK pad once, the POWER LEVEL pad twice and the START

pad once. And touch the number pads ꢀ once and the number pad 4 once.

9-2. The control panel is in the sensor cooking operation.

9-3. Afterapproximately25seconds,pushplungerofselectswitchformorethan3seconds.Thiscondition

is same as judgement by AH sensor.

9-4. After approximately 3 seconds, the display shows “ X X . X X “ which is the time for detecting

moisture.

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

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

(ꢀ0) Disconnect the power supply cord, and then remove covers.

(ꢀꢀ) Open the drawer and block it open.

(ꢀ2) Discharge high voltage capacitor.

(ꢀ3) Disconnect the dummy resistor circuit from the sensor connector of control panel.

(ꢀ4) Carry out necessary repair.

(ꢀ5) Reconnect all leads removed from components during testing and repairing.

(ꢀ6) Re-install the covers.

(ꢀ7) Reconnect the power supply cord after the outer case is installed. Run the oven and check all

functions.

(ꢀ8) Carry out "Water load cooking test" again and ensure that the oven works properly.

R1, R2 : 22Ω ± 1% 1/2W

R3 : 4.3kΩ ± 5% 1/4W

R4 : 1MΩ ± 5% 1/4W

Plunger

To connector (F)

on Control Unit.

COM

F-1

F-2

COM

F-3

CONNECTOR

ꢀ5

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MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

COMPONENT TEST

LETTER

Refer to the disassembly instructions found on Page 27.

MAGNETRON ASSEMBLY TEST

ꢀ.

Disconnect the power supply cord.

2. Open the drawer and keep it open.

3. To discharge high voltage capacitor, wait for 60 seconds.

4. To test for an open ﬁlament, isolate the magnetron from the high voltage circuit. A continuity check across

the magnetron ﬁlament leads should indicate less than ꢀ ohm.

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

and chassis ground. This test should indicate an inﬁnite resistance. If there is little or no resistance the

magnetron is grounded and must be replaced.

6. Reconnect all leads removed from components during testing.

7. Reassemble the unit.

8. Reconnect the power supply cord.

9. Run the oven and check all functions.

MICROWAVE OUTPUT POWER

The following test procedure should be carried out with the microwave oven in a fully assembled condition.

HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE, SO EXTREME CAUTION SHOULD BE

OBSERVED.

Power output of the magnetron can be measured by performing a water temperature rise test. This test

should only be used if above tests do not indicate a faulty magnetron and there is no defect in the following

components or wiring: This test will require a ꢀ6 ounce (453cc) measuring cup and an accurate mercury

thermometer or thermocouple type temperature tester. For accurate results, the following procedure must

be followed carefully:

ꢀ. Fill the measuring cup with ꢀ6 oz. (453cc) of tap water and measure the temperature of the water with

a thermometer or thermocouple temperature tester. Stir the thermometer or thermocouple through the

water until the temperature stabilizes. Record the temperature of the water.

2. Place the cup of water in the oven. Operate oven at POWER ꢀ0(HIGH) selecting more than 60 seconds

cook time. Allow the water to heat for 60 seconds, measuring with a stop watch, second hand of a watch

or the digital read-out countdown.

3. Remove the cup from the oven and again measure the temperature, making sure to stir the thermometer

or thermocouple through the water until the maximum temperature is recorded.

4. Subtract the cold water temperature from the hot water temperature. The normal result should be 28^οto

54^οF (ꢀ6^οto 30^οC) rise in temperature. If the water temperatures are accurately measured and tested

for the required time period the test results will indicate if the magnetron tube has low power output (low

rise in water temperature) which would extend cooking time or high power output (high rise in water

temperature) which would reduce cooking time. Because cooking time can be adjusted to compensate

for power output, the magnetron tube assembly should be replaced only if the water temperature rise

test indicates a power output well beyond the normal limits.The test is only accurate if the power supply

line voltage is ꢀ20 volts and the oven cavity is clean.

THERMAL CUT-OUT TEST

ꢀ.

Disconnect the power supply cord.

2. Open the drawer and keep it open.

3. To discharge high voltage capacitor, wait for 60 seconds.

4. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the

temperature of the thermal cut-out reaches approximately 293^οF(ꢀ45^οC).

An open thermal cut-out indicates overheating of the oven, exchange the oven thermal cut-out and

check inside of oven cavity and for improper setting of cooking time or operation of control unit.

Check for restricted air ﬂow through the vent holes of the oven cavity, especially the cooling fan and

air guide.

5. Reconnect all leads removed from components during testing.

6. Reassemble the unit.

7. Reconnect the power supply cord.

8. Run the unit and check all functions.

CAUTION: IFTHETHERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOMTEMPERATURE,

REPLACE THERMAL CUT-OUT.

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MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

COMPONENT TEST

SECONDARY INTERLOCK SWITCH TEST

LETTER

ꢀ. Disconnect the power supply cord.

2. Open the drawer and keep it open.

3. To discharge high voltage capacitor, wait for 60 seconds.

4. Isolate the switch and connect the ohmmeter to the common (COM.) and normally

open (NO) terminal of the switch. The meter should indicate an open circuit with

the drawer open and a closed circuit with the drawer closed.If improper operation

is indicated, replace the secondary interlock switch.

5. Reconnect all leads removed from components during testing.

6. Reassemble the unit.

7. Reconnect the power supply cord.

8. Run the oven and check all functions.

STOP SWITCH TEST

STOP SWITCH

ꢀ. Disconnect the power supply cord.

2. Open the drawer and keep it open.

3. To discharge high voltage capacitor, wait for 60 seconds.

4. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO)

terminal of the switch.The meter should indicate an open circuit with the drawer open and a closed

circuit with the drawer closed. If improper operation is indicated, replace the stop switch.

5. Reconnect all leads removed from components during testing.

6. Reassemble the unit.

7. Reconnect the power supply cord.

8. Run the oven and check all functions.

NOTE: If the stop switch contacts fail in the open position and the door is closed, the cooling fan motor,

stirrer motor and oven light will be activated by RYꢀ.

MONITOR SWITCH TEST

ꢀ. Disconnect the power supply cord.

2. Open the drawer and keep it open.

3. To discharge high voltage capacitor, wait for 60 seconds.

4. Before performing this test, make sure that the secondary interlock switch, according to the above

Switch Test Procedure. Disconnect the wire lead from the monitor switch (COM) terminal. Check

the monitor switch operation by using the ohmmeter as follows.When the drawer is open, the meter

should indicate a closed circuit.When the monitor switch actuator is pushed by a screw driver through

the lower latch hole on the front plate of the oven cavity with the drawer opened (in this condition the

plunger of the monitor switch is pushed in), the meter should indicate an open circuit. If improper

operation is indicated, the switch may be defective and both the monitor switch, plus fuse will need

to be replaced. After testing the monitor switch, reconnect the wire lead to the monitor switch (COM)

terminal and check the continuity of the monitor circuit.

5. Reconnect all leads removed from components during testing.

6. Reassemble the unit.

7. Reconnect the power supply cord.

8. Run the oven and check all functions.

MONITOR

SWITCH

(BLK)

Screw Driver

(RED)

Ohmmeter

(BRN,GRY)

(BRN,BLK)

SECONDARY

INTERLOCK

SWITCH

ꢀ7

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MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

COMPONENT TEST

LETTER

BLOWN MONITOR FUSE TEST

ꢀ. Disconnect the power supply cord.

2. Open the drawer and block it open.

3. To discharge high voltage capacitor, wait for 60 seconds.

4. If the monitor fuse is blown when the drawer is opened, check the primary interlock switch, secondary

interlock switch and monitor switch according to the "TEST PROCEDURE" for those switches before

replacing the blown monitor fuse.

CAUTION: BEFOREREPLACINGABLOWNMONITORFUSE,TESTTHESECONDARYINTERLOCK

SWITCH, STOP SWITCH AND MONITOR SWITCH FOR PROPER OPERATION.

If the monitor fuse is blown by improper switch operation, the monitor fuse and monitor switch must

be replaced with "monitor fuse and monitor switch assembly" part number FFS-BA0ꢀ8/KIT, even if

the monitor switch operates normally. The monitor fuse and monitor switch assembly is comprised

of a 20 ampere fuse and switch.

5. Reconnect all leads removed from components during testing.

6. Reassemble the unit.

7. Reconnect the power supply cord.

8. Run the oven and check all functions.

POWER TRANSFORMER TEST

ꢀ. Disconnect the power supply cord.

2. Open the drawer and block it open.

3. Discharge high voltage capacitor.

4. Disconnect the primary input terminals and measure the resistance of the transformer with an

ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x ꢀ scale, the resistance

of the primary coil should be less than ꢀ ohm and the resistance of the high voltage coil should be

approximately 90 ohms; the resistance of the ﬁlament coil should be less than ꢀ ohm.

5. Reconnect all leads removed from components during testing.

6. Reassemble the unit.

7. Reconnect the power supply cord.

8. Run the oven and check all functions.

(HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO

MEASURE THE FILAMENT AND HIGH VOLTAGE.)

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MMD24S

MMD24B

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following units.

6) Power Source Circuit

This circuit generates voltages necessary in the control

unit from the AC line voltage.

Inaddition, thesynchronizingsignalisavailableinorder

to compose a basic standard time in the clock circuit.

(ꢀ) Key unit

(2) Control Unit

(3) Power unit

Symbol

Voltage

+5V

Application

LSI(ICꢀ)

The principal functions of these units and the signals com-

municated among them are explained below.

7) Relay Circuit

Key unit

A circuit to drive the magnetron, fan motor, stirrer motor

and light the oven lamp.

The key unit is composed of a matrix, signals generated in

the LSI are sent to the key unit from Pꢀ0 - Pꢀ7.

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

the key unit and passed back to the LSI through P20 - P23

to perform the function that was requested.

8) Buzzer Circuit

The buzzer is responsive to signals from the LSI to

emit audible sounds (key touch sound and completion

sound).

Control Unit and Power Unit

9) Synchronizing Signal Circuit

ControlunitconsistsofLSI, IC, resetcircuit, indicatorcircuit,

power source circuit, relay circuit, buzzer circuit, synchro-

nizing signal circuit, keyboard unit circuit, humidity sensor

circuit and back light 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.

1) IC1 (LSI)

This is a microcomputer, responsible for controlling the

entire control unit.

10) Door Sensing Switch (Microwave drawer)

A switch to “tell” the LSI if the drawer is open or

closed.

2) IC2

This is the IC to drive the Liquid Crystal Display.

11) Door Position Switch Front / Rear

The switch to “tell”the position of the Microwave drawer

door.

3) IC5

This is the IC to amplify the signal from the humidity

sensor.

12) Back Light Circuit

4) Reset Circuit

A circuit to drive the back light (Light emitting diodes

LDꢀ- LD3).

This circuit generates a signal which resets the LSI (ICꢀ)

to the initial state when power is supplied.

13) Humidity Sensor Circuit

5) Indicator Circuit

This circuit detects moisture of the cooking food to allow

its automatic cooking.

A circuit to drive the Liquid Crystal Displays (LCDꢀ).

14) Microwave drawer door open-close Circuit

A circuit to drive the microwave drawer door open-close

motor.

ꢀ9

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MMD24S

MMD24B

DESCRIPTION OF LSI (IC-1)

The I/O signal of the LSIis detailed in the following table.

Pin No.

Signal

I/O

Description

ꢀ - 3

AN5- AN3

Terminal to change cooking input according to the Model.

By using A/D converter contained in the LSI, DC voltage in accordance with the Model

in operation is applied to set up its cooking constant.

AN2

Input signal which inform the drawer door is in the middle position between the opened

position and the closed position, to LSI from the door position switch rear.

ANꢀ

AN0

Terminal not used.

CNVSS

Power source voltage: 0V (GND).

VC voltage of power source circuit input. Connected GND.

RESET

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.

P62

P6ꢀ

VSS

OUT Terminal not used.

IN/OUT Terminal not used.

ꢀ0

ꢀꢀ

Power source voltage: 0V (GND).

VS voltage of power source circuit input. Connected GND.

ꢀ2

XIN

Internal clock oscillation frequency setting input.

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

respect to Xout terminal.

ꢀ3

ꢀ4

ꢀ5

ꢀ6

XOUT

VCC

P60

OUT Internal clock oscillation frequency control output.

Output to control oscillation input of Xin.

Power source voltage: +5V.

VC voltage of power source circuit input.

Plus signal coming from the Microwave drawer door open-close motor is input into P60

as revolution number.

P37

Input signal which communicates the drawer door open information to LSI from

the door position switch front.

Door opened; “L” level signal(0V).

Door closed; “H” level signal(+5V).

ꢀ7

ꢀ8

P36

OUT Signal to change the rotational direction is output to the Microwave drawer door

open-close motor.

TXOUT

OUT Signal to change the rotational speed is output to the Microwave drawer door open-close

motor.

ꢀ9

P34

OUT Power source to drive the Microwave drawer door open-close motor is output.

RXD2

Input terminal to check the data of display.

Data signal from IC-2 is input to RXD2 to check the ﬂow of the data.

2ꢀ

TXD2

SCLK2

P30

Output terminal to send IC-2 the data.

The data of display is output to IC-2.

OUT Clock timing signaI output terminal.

Clock timing signal is sent to IC-2.

OUT Signal to reset LSI.

Signal is output to reset IC-2.

24 - 25 COM3 - COM2 OUT Terminal not used.

COMꢀ

OUT Common data signal.

Connected to LCD signal C5.

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MMD24S

MMD24B

Pin No.

Signal

I/O

Description

COM0

OUT Common data signal.

Connected to LCD signal C4.

VL3

Connected VC (+5V).

29 - 3ꢀ P27- P25 OUT Terminal not used.

SEG20

OUT Segment data signal.

Connected to LCD segment S24.

Signal coming from touch key.

P23

WhenanyoneofJ-4linekeysonkeymatrixistouched, acorrespondingsignalfromPꢀ0-

Pꢀ7 will be input into P23. When no key is touched, the signal is held at "L" level.

4ꢀ

P22

P2ꢀ

P20

Pꢀ7

Pꢀ6

Pꢀ5

Pꢀ4

Pꢀ3

Pꢀ2

Pꢀꢀ

Pꢀ0

P07

Signal similar to P23.

When any one of J-3 line keys on key matrix is touched, a corresponding signal will be

input into P22.

Signal similar to P23.

When any one of J-2 line keys on key matrix is touched, a corresponding signal will be

input into P2ꢀ.

Signal similar to P23.

When any one of J-ꢀ line keys on key matrix is touched, a corresponding signal will be

input into P20.

OUT Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P20 - P23 terminal while

one of J-ꢀ2 line key on matrix is touched.

OUT Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P20 - P23 terminal while

one of J-ꢀꢀ line key on matrix is touched.

OUT Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P20 - P23 terminal while

one of J-ꢀ0 line key on matrix is touched.

OUT Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P20 - P23 terminal while

one of J-9 line key on matrix is touched.

OUT Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P20 - P23 terminal while

one of J-8 line key on matrix is touched.

OUT Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P20 - P23 terminal while

one of J-7 line key on matrix is touched.

OUT Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P20 - P23 terminal while

one of J-6 line key on matrix is touched.

OUT Key strobe signal.

Signal applied to touch-key section. A pulse signal is input to P20 - P23 terminal while

one of J-5 line key on matrix is touched.

OUT Fan motor (Drawer) driving signal.

H: +5V

To turn on and off relay(RY4).

“H” level: During fan motor ON.

“L” level: During fan motor OFF.

L: GND

OFF

P06

OUT Stirrer motor driving signal.

To turn on and off relay(RY3).

“H” level: During fan motor ON.

H: +5V

“L” level: During fan motor OFF.

L: GND

OFF

2ꢀ

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MMD24S

MMD24B

Pin No.

Signal

I/O

Description

P05

OUT Magnetron high-voltage circuit driving signal.

Microwave cooking mode

Other cooking mode

VARI MODE

ꢀ00% power

90% power

80% power

70% power

60% power

50% power

40% power

30% power

20% power

ꢀ0% power

0% power0 sec.

ON TIME OFF TIME ON TIME OFF TIME

To turn on and off the cook relay(RY2). In ꢀ00%

poweroperation, thesignalsholds“H”levelduring

microwavecookingand“L”levelwhilenotcooking.

In other cooking modes (90%, 80%, 70%, 60%,

50%, 40%, 30%, 20%, ꢀ0%, 0%) the signal turns

to “H” level and “L” level in repetition according to

the power level.

32 sec.

30 sec.

26 sec.

24 sec.

22 sec.

ꢀ8 sec.

ꢀ6 sec.

ꢀ2 sec.

8 sec.

0 sec.

2 sec.

60sec.

54sec.

48sec.

42sec.

36sec.

30sec.

24sec.

ꢀ8sec.

ꢀ2sec.

4sec.

0ec.

6sec.

6 sec.

ꢀ2sec.

ꢀ8sec.

24sec.

30sec.

36sec.

42sec.

48sec.

56sec.

8 sec.

ꢀ0 sec.

ꢀ4 sec.

ꢀ6 sec.

20 sec.

24 sec.

26 sec.

0sec.

6 sec.

32 sec.

60sec.

48-52

P04-P00

P57

OUT Used for initial balancing of the bridge circuit (absolute humidity sensor).

OUT Common relay driving signal. (Square Waveform : 60Hz)

ꢀ6.7 msec.

To turn on and off the shut-off relays (RYꢀ). The

H: +5V

square waveform voltage is delivered to the relay

L: GND

During cooking

(RYꢀ) driving circuit.

P56

TXDꢀ

RXDꢀ

P53

Terminal not used.

0.ꢀ sec

P52

OUT Signal to sound buzzer.

A: Key touch sound.

B: Completion sound.

2.0 sec

C: When the oven stops so that the food can be

checked in Automatic cooking mode.

ꢀ.0 sec

H: +5V

L: GND

P5ꢀ

Input signal which communicates the drawer door close information to LSI.

Door opened; “H” level signal(+5V).

Door closed; “L” level signal(0V).

INT0

Signal to synchronize LSI with commercial power source frequency.

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

H : +5V

L : GND

ꢀ6.7 msec.

6ꢀ

AVSS

VREF

AN7

A/D converter power source voltage.

The power source voltage to drive the A/D converter in the LSI.

Reference voltage input terminal.

A reference voltage applied to the A/D converter in the LSI. Connected to +5V.

AH sensor input.

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

A/D converter built into the LSI.

AN6

Used for initial balancing of the bridge circuit (absolute humidity sensor). This input is

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

built into the LSI.

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MMD24S

MMD24B

HUMIDITY SENSOR CIRCUIT

(1) Structure of Humidity Sensor

the resistance values results in that there is the same

potential at both F-3 terminal of the absolute humidity

sensor and AN6 terminal of the LSI.The voltage of AN7

terminalwillindicateabout+2.5V.Thisinitialbalancingis

setupaboutꢀ6secondsaftertheunitisputintheSensor

Cookingmode. Asthesensorcookingproceeds,thefood

is heated to generate moisture by which the resistance

balance of the bridge circuit is deviated to increase the

voltage available at AN6 terminal of the LSI.

The humidity sensor includes two thermistors as shown

in the illustration.One thermistor is housed in the closed

vessel ﬁlled with dry air while another in the open vessel.

Eachsensorisprovidedwiththeprotectivecovermadeof

metal mesh to be protected from the external airﬂow.

ventilation opening for sensing

Then the LSI observes that voltage at AN7 terminal and

comparesitwithitsinitialvalue,andwhenthecomparison

rate reaches the preset value (ﬁxed for each menu to

be cooked), the LSI causes the unit to stop sensor

cooking; thereafter, the unit goes in the next operation

automatically.

Thermistors

Sensing part

(Closed vessel)

(Open vessel)

When the LSI starts to detect the initial voltage at AN7

terminal ꢀ6 seconds after the unit has been put in the

Sensor Cooking mode, if it is not possible to balance

the bridge circuit due to disconnection of the absolute

humidity sensor, ERROR will appear on the display and

the cooking is stopped.

(2) Operational Principle of Humidity Sensor

The ﬁgure below shows the basic structure of an

absolute humidity sensor. A bridge circuit is formed by

two thermistors and two resistors (Rꢀ and R2).

The output of the bridge circuit is to be ampliﬁed by the

operational ampliﬁer.

VA : +15V

VC : +5V

D40

D41

C. Thermistor in

closed vessel

Eachthermistorissuppliedwithacurrenttokeepitheated

at about ꢀ50^οC (302^οF), the resultant heat is dissipated

in the air and if the two thermistors are placed in different

humidity conditions they show different degrees of heat

conductivity leading to a potential difference between

themcausinganoutputvoltagefromthebridgecircuit,the

intensity of which is increased as the absolute humidity

of the air increases. Since the output is varied every

minute, it is ampliﬁed by the operational ampliﬁer.

S. Thermistor in

open vessel

3 . 3

R 4

IC5

AN7

3.5

R50 10K

R52 47K

LSI

(IC1)

R43 1.8K

R44 360K

R51 47K

AN6

P00

R45 620K

SW1

SW2

SW3

SW4

SW5

R46 300K

P01

R47 150K

R48 75K

P02

P03

Absolute humidity vs,

output voltage characteristic

Operational

R49 37.4K

Rꢀ

amplifier

P04

Output

voltage

S : Thermistor

open vessel

C : Thermistor

closed vessel

Absolute humidity (g/m²)

(3) Detector Circuit of Humidity Sensor Circuit

This detector circuit is used to detect the output voltage

of the absolute humidity circuit to allow the LSI to

control sensor cooking of the unit. When the unit is set

in the sensor cooking mode, ꢀ6 seconds clearing cycle

occurs than the detector circuit starts to function and

the LSI observes the initial voltage available at its AN6

terminal.

With this voltage given, the switches SWꢀ to SW5 in

the LSI are turned on in such a way as to change the

resistance values in parallel with R45 ~ R49. Changing

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MMD24S

MMD24B

TOUCH CONTROL PANEL SERVICING

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

touch control panel and the oven itself is so short that

thetwocan’tbeseparated.Forthosemodels, checkand

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 long enough

that they may be separated from each other. For those

models, 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

panelwithajumper,whichactivatesanoperationalstate

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 dummy resistor(s) with

resistance equal to that of the controls are used.

(2) Servicingthetouchcontrolpanelwithpowersupply

from an external power source:

1. Precautions for Handling Electronic Components

ThisunitusesCMOSLSIintheintegralpartofthecircuits.

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.

ꢀ) When storing and transporting, thoroughly wrap them

in aluminium foil. Also wrap all 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. ꢀM ohm

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

activates 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).

2. Servicing of Touch Control Panel

We describe the procedures to permit servicing of the

touch control panel of the microwave oven and the

precautionsyoumusttakewhendoingso.Toperformthe

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:

3. Servicing Tools

THE HIGH VOLTAGE TRANSFORMER OF THE

MICROWAVE OVEN IS STILL LIVE DURING

SERVICING AND PRESENTS A HAZARD.

Therefore, beforecheckingtheperformanceofthetouch

control panel,

ꢀ) Disconnect the power supply cord, and then remove

outer case.

2) Open the door and block it open.

3) Discharge high voltage capacitor.

4) Disconnect the leads to the primary of the power

transformer.

5) Ensure that these leads remain isolated from other

components and oven chassis by using insulation

tape.

6) After that procedure, re-connect the power supply

cord.

Tools required to service the touch control panel

assembly.

ꢀ) Soldering iron: 30W

(It is recommended to use a soldering iron with a

grounding terminal.)

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

ꢀ0MHz type or more advanced model.

3) Others: Hand tools

4. Other Precautions

ꢀ) Before turning on the power source of the control

unit, remove the aluminium foil applied for preventing

static electricity.

2) Connect the connectors 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.

After checking the performance of the touch control

panel,

ꢀ) Disconnect the power supply cord.

2) Open the door and block it open.

3) Re-connect the leads to the primary of the power

transformer.

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.

4) Re-install the outer case (cabinet).

5) Re-connect the power supply cord after the outer

case is installed.

6) Run the oven and check all functions.

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MMD24S

MMD24B

PRECAUTIONS FOR USING LEAD-FREE SOLDER

1. Employing lead-free solder

The "Main PWB" of this model employs lead-free solder.This is indicated by the "LF" symbol printed on the PWB and

in the service manual. The sufﬁx letter indicates the alloy type of the solder.

Example:

Indicates lead-free solder of tin, silver and copper.

2. Using lead-free wire solder

When repairing a PWB with the "LF" symbol, only lead-free solder should be used. (Using normal tin/lead alloy solder

may result in cold soldered joints and damage to printed patterns.)

As the melting point of lead-free solder is approximately 40^oC higher than tin/lead alloy solder, it is recommend that

a dedicated bit is used, and that the iron temperature is adjusted accordingly.

3. Soldering

As the melting point of lead-free solder (Sn-Ag-Cu) is higher and has poorer wettability, (ﬂow), to prevent damage

to the land of the PWB, extreme care should be taken not to leave the bit in contact with the PWB for an extended

period of time. Remove the bit as soon as a good ﬂow is achieved.The high content of tin in lead free solder will cause

premature corrosion of the bit. To reduce wear on the bit, reduce the temperature or turn off the iron when it is not

required.

Leaving different types of solder on the bit will cause contamination of the different alloys, which will alter their

characteristics, making good soldering more difﬁcult. It will be necessary to clean and replace bits more often when

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MMD24S

MMD24B

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE

WARNING AGAINST HIGH VOLTAGE:

Microwave ovens contain circuitry capable of producing very high voltage and current. Contact with the following parts

may result in severe, possibly fatal, electric shock.

(Example)

High Voltage Capacitor, Power Transformer, Magnetron, High Voltage Rectiﬁer Assembly, High Voltage Harness

etc..

WARNING: To Avoid possible exposure to microwave energy, please follow the instructions below

before operating the oven.

ꢀ. Disconnect the power supply cord.

ꢀ. Drawer does not close ﬁrmly.

2. Make sure that a deﬁnite” click” can be heard when

the microwave oven drawer is unlatched. (Hold the

drawer in a closed position with one hand, then pull

the drawer open, this causes the latch leads to rise, it

is then possible to hear a “click’as the drawer switches

operate.)

2. Drawer latch hook is damaged.

3. The drawer gasket or seal is damaged.

4. The drawer is bent or warped.

5. There are defective parts in the drawer interlock

system.

6. There are defective parts in the microwave generating

and transmission assembly.

7. There is visible damage to the oven.

3. Visually check the drawer and cavity face plate for

damage (dents, cracks, signs of arcing etc.).

Carry out any remedial work that is necessary before

Do not operate the oven:

operating the oven.

Do not operate the oven if any of the following conditions

exist:

ꢀ. Without the RF gasket (Magnetron).

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

3. If the drawer is not closed.

WARNING FOR WIRING

To prevent an electric shock, take the following pre-

cautions:

ꢀ. Before wiring:

ꢀ) Disconnect the power supply cord.

2) Open the drawer.

3) Wait 60 seconds, then discharge the high voltage

capacitor.

2. Don’t let the wire leads touch to the following parts:

ꢀ) High voltage parts:

Magnetron, High voltage transformer, High voltage

capacitor and High voltage rectiﬁer assembly.

2) Hot parts:

Ovenlamp,Magnetron,Highvoltagetransformerand

Oven cavity.

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MMD24S

MMD24B

MICROWAVE DRAWER DISASSEMBLY

WARNING: Follow all safety precautions as stated at the beginning of this Service

Manual before proceeding!

ꢀ. Before removing Microwave Drawer, take measures to protect

the Drawer louver by either removing the louver or by letting

the louver over hang off ﬂat protected surface (Fig 1).

Fig. 1

Louver

2. Open the Drawer to access the 4 mounting screws holding the

unit on to the wall or cabinet opening. (Fig 1).

3. Close Drawer and carefully pull the unit out from opening and

unplug the power supply cord.

4. Remove top cover. (Fig 2).

5. Remove air cover from back of unit, then both side panels. (Fig 2).

screws

Top plate

6. Remove exhaust duct and back cover. (Fig 2).

Exhaust duct

Right side panel

Air cover

Back cover

Fig. 2

Cavity

Left side panel

NOTE: You now have access to various components for the Drawer.

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MMD24S

MMD24B

7. To remove the Control Panel Frame Assembly,

remove the 9 screws holding the C/P frame to the cavity. (Fig 3).

With the C/P frame assembly now loose, you can unplug all wires.

Fig. 3

At this point, you will have access to all parts of the Microwave Drawer.

POWER CORD REPLACEMENT

ꢀ. Un-hook the black and white AC terminals from the Noise Filter PWB and green ground wire from the back plate.

(Fig 4).

2. Attach the black and white AC terminals from the new Power Cord to the Noise Filter as shown in ﬁgure 4.

Note: The green ground wire terminal can be attached when reassembling the back plate to the drawer cavity.

Fig. 4

Un-hook/Attach Ground to metal Tab on Back Plate.

Un-hook/Attach Black AC Wire to Top Terminal

Noise

Filter

Unit

Base plate

Un-hook/Attach White AC Wire to Bottom Terminal

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MMD24S

MMD24B

STOP SWITCH, SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH REMOVAL

ꢀ. Follow the Microwave Drawer disassembly as previously stated

2. Open the drawer and keep it open.

3. To discharge the high voltage capacitor, wait for 60

seconds.

in the top position, located on the left side of the unit.

The door sensing switch by itself on the right side of the

unit.

4. Remove the screw holding the latch hook to the oven

ﬂange.

2. Re-connect wire leads to each switch. Refer to pictorial

diagram.

5. Remove the latch hook from the oven ﬂange.

6. Disconnect the wire leads of each switch.

7. Remove each switch from the latch hook by pushing the

one (ꢀ) stopper tab holding each switch.

8. Now, each switch is free.

3. Secure the latch hooks with mounting screws to oven

ﬂange.

4. Make sure that the monitor switch is operating properly

and check continuity of the monitor circuit. Refer to

chapter "Test Procedure" and "Adjustment procedure".

Re-install

ꢀ. Re-installeachswitchinitsplace.Thesecondaryinterlock

switch is in the lower position and the monitor switch is

Latch Hook Left

Latch Hook Right

STOP SWITCH, SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH ADJUSTMENT

ꢀ. FollowtheMicrowaveDrawerdisassemblyaspreviously

stated

2. Open the drawer and keep it open.

3. To discharge the high voltage capacitor, wait for 60

seconds.

4. If the door sensing switch, secondary interlock switch

and monitor switch do not operate properly due to a

misadjustment, the following adjustment should be

made.

screws (Fig. S-1).

ꢀꢀ.Check and assure that the cap nuts on the Drawer

Support Angles are centered when passing through the

cavity face plate.

After adjustment, check the following.

ꢀ. In and out play of door remains less than 0.5mm when

in the latched position.First check upper position of latch

hook,pushingandpullingupperportionofdrawertoward

theovenface.Thenchecklowerportionofthelatchhook,

pushing and pulling lower portion of the door toward the

oven face. Both results (play in the door) should be less

than 0.5mm.

2. The secondary interlock switch interrupts the circuit

before the door can be opened.

3. Monitor switch contacts close when door is opened.

4. Door sensing switch contacts open when door is

opened.

6. Loosen the screw holding latch hook to the oven cavity

ﬂange.

7. With drawer closed, adjust latch hook by moving it back

and forth, and up and down. In and out play of the door

allowed by the upper and lower position of the latch hook

should be less than 0.5mm. The vertical position of the

latch hook should be adjusted so that the secondary

interlock switch is activated with the drawer closed.The

horizontal position of the latch hook should be adjusted

so that the monitor switch and drawer sensing switch

are activated with the drawer closed.

5. Reassemble the unit and check for microwave leakage

around door with an approved microwave survey meter.

(Refer to Microwave Measurement Procedure.

8. Secure the screws with washers ﬁrmly.

9. Check all of the switches operation. If any switch has

not activated fully, you will need to adjust the slide rail

attached to the Microwave cavity.

ꢀ0.This is done by following the steps to remove the

"DRAWER/SLIDE RAIL REMOVAL" on page 30. After

you have removed the slide rails, loosen the "2" screws

holding the slide rail to the Microwave cavity and tilt the

front end up and the rear end down, then tighten the

Fig. S-1

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MMD24S

MMD24B

DRAWER/SLIDE RAIL REMOVAL

DRAWER ASSEMBLY AND CHOKE REMOVAL

ꢀ. Follow the Microwave Drawer disassembly as previously

NOTE:

Fig. D-1

stated

To remove only the

Microwave Drawer, follow steps

ꢀ, 2, 5, 8, 9 & ꢀ0

as instructed under

"DRAWER ASSEMBLY AND

CHOKE REMOVAL".

2. Open the drawer and keep it open.

3. To discharge the high voltage capacitor, wait for 60

seconds.

4. Remove the both right and left side panels.

5. Remove (2) Drawer Support Covers from Choke Cover as

shown in (Fig. D-1).

6. Insert a putty knife (thickness of about 0.5mm) into the gap

between the choke cover and the door frame.

7. Carefully slide choke cover away from drawer as far as

possible.

8. Remove (6) screws from all (3) drawer Support Angles as

shown in (Fig. D-2).

9. Unhook Drawer Support Angles from drawer, then

remove.

ꢀ0.Now, the door assembly is free and the Choke Cover can

now be removed.

Fig. D-2

DRAWER SUPPORT ANGLE REMOVAL

ꢀ. Remove Drawer Assembly and Choke Cover as stated in

"DRAWER ASSEMBLY AND CHOKE REMOVAL".

2. Remove (2) screws from right or left Latch Angle Assembly,

then remove Angle assembly (Fig. D-4).

3. Separate Slide Rails by moving inside lever of Slide Rails.

The Slide Rail will now separate by pulling straight forward

and out (Fig. D-3).

4. At this point, you can replace either Latch Angle Assy or

Latch Angles.

To reassemble, just reverse the above order.

Fig. D-3

After reassembly, do the following.

(A) Make sure that drawer sensing switch, secondary

interlock switch and monitor switch are operating

properly. (Refer to chapter "Test Procedures".)

(B) An approved microwave survey meter should be used

toassurecompliancewithpropermicrowaveradiation

emission limitation standards.

After any servicing, make sure of the following :

ꢀ. Drawer latch heads smoothly catch latch hook through

latch holes and that latch head goes through center of latch

hole.

2. Deviation of door alignment from horizontal line of cavity

face plate is to be less than ꢀ.0mm.

3. Drawer is positioned with its face pressed toward cavity face

plate.

4. Reassembletheunitandcheckformicrowaveleakagearound

drawer with an approved microwave survey meter. (Refer

to Microwave Measurement Procedure.)

Fig. D-4

Note: The drawer 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)-tightorlight-tight.

Therefore,occasionalappearanceofmoisture,light

orsensingofgentlewarmairmovementaroundoven

drawer is not abnormal and do not of themselves

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MMD24S

MMD24B

SWITCH ANGLE REMOVAL/ADJUSTMENT

SWITCH ANGLE REMOVAL

Fig. S-1

(Locate either the right or left switch angle)

ꢀ. Follow the Microwave Drawer disassembly as previously stated

2. Open the drawer and keep it open.

3. To discharge the high voltage capacitor, wait for 60 seconds.

4. To remove switch, remove screw (ꢀ) holding switch to switch angle

(Fig. S-1).

5. To replace switch angle, remove bottom cover and remove the 2 screws

holding the switch lever (Fig. S-2).

6. Proceed in reverse to reinstall.

7. Adjust switch.

Fig. S-2

ACTUATOR REMOVAL/ADJUSTMENT

ꢀ. Follow the Microwave Drawer disassembly as previously stated

2. Open the drawer and keep it open.

3. To discharge the high voltage capacitor, wait for 60 seconds.

4. Locate either the right or left actuator and remove the 2 screws holding the actuator to the door support

angles.

5. Relpace with the new actuator (Fig. A-3).

Actuator adjustment

6. It is very critical that proper adjustment is made to actuator.

7. Adjust each actuator to fully depress ("0" gap) switch lever switches on left and right side (Fig. A-4).

NOTE: If this adjustment is not adjusted correctly, it will effect the performance of the Auto Drawer.

Fig. A-3

Fig. A-4

3ꢀ

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MMD24S

MMD24B

AUTO DRAWER GEAR REMOVAL/INSTALLATION

(This procedure requires a ꢀ4" or greater phillips screwdriver)

ꢀ. Disengage any power going to the unit.

2. Open the drawer and keep it open.

3. Remove the top cover and right side cabinet.

4. Unhook wiring to Auto Drawer Gear.

5. Remove bottom screw below Auto Drawer Gear (Fig. G-1).

6. Remove the (4) screws holding the auto drawer gear to the bottom cavity angle (Fig. G-2).

7. Disengage (pull) Auto Drawer Gear from rack gear and slide to the right (toward the rear), then turn motor 90⁰and slip

out along rear of drawer (Fig. G-3).

8. Then tilt Auto Gear Motor 20^oto extract the assembly out. The Auto Drawer Gear is now free.

Installation:

ꢀ. Proceed in reverse to reinstall the Auto Drawer Gear taking care that the gear teeth are set into the cavity angle correctly

Base plate

Bottom cover

Fig. G-1

Fig. G-3

Fig. G-2

RACK GEAR REMOVAL

ꢀ. Follow the Microwave Drawer disassembly as previously stated

2. Open the drawer and keep it open.

3. To discharge the high voltage capacitor, wait for 60 seconds.

4. Remove the Microwave Drawer by following steps ꢀ, 2, 5, 8, 9 & ꢀ0 as

instructed under "DRAWER ASSEMBLY AND CHOKE REMOVAL".

5. Remove the (3) screws holding the Rack Gear to the bottom slide rail

(Fig. G-5).

Tilt 20^o

7. Proceed in reverse to reinstall the new Rack Gear.

Fig. G-4

Fig. G-5

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MMD24S

MMD24B

RED

BLK

WHT

GRN

WHT

Power Supply

cord 120V 60Hz

WHT

GRY

NOISE FILTER

BOARD

to Back Plate

RED

GRN

BLK

CN502

CN501

CNA

ORG

RED

(SWITCHING POWER SUPPLY)

CN502

BLK or

RED

ORG

BLK

GRN

MAGNETRON

THERMAL

CUT-OUT

OVEN

THERMAL

CUT-OUT

GRY

WHT

GRY

BLU

RED

N.O.

YLW or

ORG

WHT

RED or

BLK

YLW or

BLK

N.C.

THIRD

DOOR

SWITCH

BRN

MONITOR

SWITCH

COOLING

FAN

MOTOR

CNB

COM.

RED

GRY

WHT

GRY

RED or

BLK

RY1

N.O.

BLK

or YLW

CN501

RED or

BLK

WHT

RY1

COM.

N.O.

BRN

(POWER SUPPLY)

CN-H

ORG

or YLW

COM.

STIRRER

MOTOR

BLK

RY2

N.O.

GRY

RED

SECONDARY

INTERLOCK

SWITCH

N.O.

ORG

COM.

N.O.

RY2

COM.

WHT

BLU

CN-B

RED or

BLK

RED or

BLK

OVEN LAMP

BLU

RED

GRY

YLW

ORG

BLK

CN-A

DC MOTOR

TO DC

MOTOR

CNH

RED

(CONTROL UNIT)

REAR

ACTUATOR

SWITCH

HIGH VOLTAGE COMPONENTS

MAGNETRON

WHT

N.O.

GRN

BLU

HIGH VOLTAGE

CAPACITOR

GRY

GRN

COM.

CNE

CNN

BLU

CNM

HIGH VOLTAGE

WIRE A

WHT

BLK

FRONT

ACTUATOR

SWITCH

YLW

BLU

ORG

RED

CNN

CNE

GRN

N.O.

HIGH

POWER

VOLTAGE

RECTIFIER

COM.

TRANSFORMER

GRY

RED

BLK

CNM

CNK

GRY

STOP SWITCH

COM.

GRN

N.O.

GRY

WHT

CNK

GRN

WHT

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MMD24S

MMD24B

PA154DR

CN-A

D1 -- D4

1N4002L x4

2.5A

A-7

A-5

CN-H

FUSE

AC 120V

60Hz

H-1

K-1

VRS1

10G471K

GND

H-3

H-2

K-3

INT

K-2

RY5

SW Reg.

PWR

H-8

K-8

502-3

SW Reg. OUT

+24V

H- 9

H-11

E-3

RY2

N.O.

MICRO

H-4

K-4

COM

RY1

N.O.

H-6

K-6

COM

(O.L)

COM

J11

<NOTE>

: IF NOT SPECIFIED, 1SS270A

(

) : NOT INSERT PARTS

: CHECK POINTS

B-1

B-3

RY3

RY4

H-5

H-7

A-1

A-3

K-5

K-7

Figure S-2. Power Unit Circuit

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MMD24S

MMD24B

M O C

0 C

1 C

2 C

3 C

C O M

3 2 G E S

2 2 G E S

S 0

S 1

S 2

S 3

S 4

S 5

S 6

S 7

S 8

1 2 G E S

0 2 G E S

9 1 G E S

8 1 G E S

7 1 G E S

6 1 G E S

5 1 G E S

4 1 G E S

3 1 G E S

2 1 G E S

1 1 G E S

0 1 G E S

9 1 G E S

8 1 G E S

7 1 G E S

6 1 G E S

5 1 G E S

4 1 G E S

3 1 G E S

2 1 G E S

1 1 G E S

0 1 G E S

7 3 P

0 6 P

M 1

5 1

C C V

5 3

0 4

5 4

1 2 1 R

T U O X

N I

S 9

S S V

1 6 P

0 1 S

1 1 S

2 1 S

3 1 S

4 1 S

5 1 S

6 1 S

7 1 S

8 1 S

9 1 S

0 2 S

1 2 S

2 2 S

3 2 S

K 7 . 4

3 3 R

2 6 P

T E S E R

S S V N C

0 N A

G E S

1 N A

2 N A

3 N A

4 N A

5 N A

K 7 . 4

6 2 R

4 2 S

4 C

5 C

C O M

3 0 1 C

2 0 1 C

1 0 1 C

0 0 1 C

p 0 3 3 V 0 5

5 1 1 R

4 1 1 R

3 1 1 R

K 0 7 2

2 1 1 R

0 3

6 1 R

2 2 D

1 2 D

u 1 0 .

V 0 5

K 7 . 4

4 1 R

2 1 C

K 7 .

3 2 P

2 2 P

1 2 P

0 2 P

7 1 P

6 1 P

5 1 P

4 1 P

3 1 P

2 1 P

1 1 P

0 1 P

7 0 P

6 0 P

5 0 P

4 0 P

7 3 P

0 6 P

5 1

C C V

5 3

3 1 R

T U O X

N I

S S V

1 6 P

1 1 C

0 1

0 : k s a M

K 0 1 : h s a l

2 6 P

0 4

T E S E R

S S V N C

0 N A

8 1 R

2 B 6 . 3 U Z H

1 N A

2 N A

5 4

3 N A

4 D Z

K 7 . 4

4 N A

5 N A

1 1 R

K 7 .

0 1 C

7 1 R

V 5 3 / F u 0 1

V 0 5 / u 1 0 . 0

4 4 C

8 C

9 C

V 0 5 / u 1 0 .

1 4 D

S P

5 4 C

K 3 .

9 4 R

8 4 R

7 4 R

6 4 R

5 4 R

P 0

0 4 D

F K 4 . 7 3

F K 5 7

F K 0 5 1

K 0 0 3

7 C

8 6 R

W 2 0 9 3

8 R

V 5 3 / F u 0 1

6 C

K 7 . 4

8 9 R

3 4 C

0 0 P

K 0 2 6

2 5 C

1 5 C

3 2 C

K 7 .

K 7 . 4

9 9 R

K 7 . 4

5 5 R

K 7 . 4

7 5 R

3 2 R

D K 7 5 . 3

2 4 R

V 5 3 / F u 0 1

3 C

2 4 C

W 1

) 2 2 C (

2 B 6 1 U Z H

0 3 4

0 4 R

Z D 2

K 7 . 4

0 2 R

9 1 D

7 9 D

5 9 D

6 9 D

V 5 3

1 4 C

F u 0 1

0 9 C

0 4 C

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MMD24S

MMD24B

J11

N.O.

COM.

N.O.

COM.

RY3

RY4

R11

C11

FUSE

2.5A

Figure S-4. Printed Wiring Board of Power Unit

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MMD24S

MMD24B

C F 2

R 2 6

R 2 7

R 2 8

R 2 9

C 5

C 4

C 5

C 4

S 2 4

R 1 6

D 2 2

D 2 1

R 1 5

R 9 7

Q 9 7

D 9 7

D 9 5

D 9 6

S 0

S P

R 6 9

R 6 8

S 0

C 0

S 0

C 3

S P

R 9 5 R 9 9

R 9 6 R 9 8

C 9 0

C 0

C 9 0

R 4 1

C 3 0

C 4 1

C 1 0 1 C 1 0 0

R 1 1 3 R 1 1 2

C 1 0 2

R 1 1 4

C 1 0 3

J 6

J 4

J 3

J 1

R 1 1 5

J 2

R 4 2

D 4 0

C 5 4

D 4 1

C 4 4

C 1 3

R 1 0 4

R 1 0 5

R 1 0 6

R 2 1

R 1 8

R 1 0 0

R 1 4

R 4 6

R 1 0 1

R 1 0 2

R 1 0 3

R 1 0 7

R 3 4

C 1 0

R 1 1

C 8

Z D 4

C 9

R 1 7

C 1 2

R 1 3

C 1 1

C 7

D 2 0

D 1 9

C 6

C 5

C 2

C 5

C 2 1

C 2 0

R 2 2

C 2 + 1

C 4

C 3

R 7

Z D 2

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MMD24S

MMD24B

Nopartofthispublicationmaybereproduced,

stored in retrieval systems, or transmitted

in any form or by any means, electronic,

mechanical, photocopying, recording, or

otherwise, without prior written permission

of the publisher.

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