Kenmore 721.69252 Service Manual

DIVISION 20

BASIC FIELD MANUAL

FOR

MICROWAVE OVEN

MODEL 721.69252990

721.69259990

June, 1999

MODEL 721.69252990

721.69259990

-1-

CAUTION

WARNING TO SERVICE TECHNICIANS

PRECAUTIONS TO BE OBSERVED

BEFORE AND DURING SERVICING TO

AVOID POSSIBLE EXPOSURE TO

EXCESSIVE MICROWAVE ENERGY

a. Do not operate or allow the oven to be operated with the door open. b. Make the following safety checks on all ovens to be serviced before activating the magnetron or

other microwave source, and make repairs as necessary; (1) Interlock operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and latches, (5) evidence of dropping or abuse.

c. Before turning on microwave for any service test or inspection within the microwave generating

compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity, and connections.

d. Any defective or misadjusted components in the interlock, monitor, door seal, and microwave

generation and transmission systems shall be repaired adjusted by procedures described in this manual before the oven is released to the owner.

e. A Microwave leakage check to verify compliance with the Federal performance standard should be

performed on each oven prior to release to the owner.

• Proper operation of the microwave ovens requires that the magnetron be assembled to the wave guide and

cavity. Never operate the magnetron unless it is properly installed.

• Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the

magnetron.

• Routine service safety procedures should be exercised at all times.

• Untrained personnel should not attempt service without a thorough review of the test procedures and safety

information contained in this manual.

MODEL 721.69252990

721.69259990

-2-

MODEL 721.69252990

721.69259990

FOREWORD

Read this Manual carefully. Failure to adhere to or observe the information in this Manual may result in exposing yourself to the Microwave Energy normally contained within the oven cavity.

MODEL 721.69252990

721.69259990

MECHANICAL SERVICE INFORMATION

TABLE OF CONTENTS

1. Adjustment Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. Precautions on Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3. General Precautions in Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4. Trial Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6. Overall Circuit Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8

7. Operating Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-11

8. Procedure for Measuring Microwave Energy Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-13

9. Disassembly Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-18

10. Interlock Continuity Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

11. Test and Checkout Procedures, and Troubleshooting

A. Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22

B. Checkout Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-25

C. Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26-30

1. ADJUSTMENT PROCEDURES

To avoid possible exposure to microwave energy

leakage, adjust the door latches and interlock switches, using the following procedure.

ONLY AUTHORIZED SERVICE PERSONNEL SHOULD MAKE THIS ADJUSTMENT.

The Interlock Monitor and Primary Interlock Switch acts as the final safety switch protecting the user from microwave energy. The terminals between “COM” and “NC” of the Interlock Monitor must close when the door is opened. After adjusting the Interlock Monitor Switch, make sure that it is correctly connected. See Figures 1-a and 1-b throughout this procedure.

CHECK THE DOOR LATCH AND SWITCH CLOSINGS.

NOTE: The outer cover of the microwave oven is

removed.

(1) Set the microwave oven on its side so that you can

see the latch board and the switches, as shown in Figure 1-a.

(2) Close the door tightly and check gaps A and B to be

sure they are no more than 1/64” (0.5 mm). See Figure 1-b for close-up view of gaps A and B (door

latches). If all gaps are less than 1/64” (0.5 mm), adjustment of the latch board may not be necessary. Go to Steps 5 and 6 to check the sequence of the switches.

NOTE: To correct sequence of the Primary Interlock

Switch, Secondary Interlock Switch and the Interlock Monitor Switch is very important.

If any gap is larger than 1/64” (0.5 mm), you will need to adjust the latch board-U, L. Go to step 3 and follow all steps in order.

ADJUST THE LATCH AND SWITCH CLOSINGS

(3) Loosen the two screws holding the plastic latch board

as shown.

(4) With the oven door closed tightly, move the latch

board upward toward the top of the oven and/or away from the door latch until the gaps are less than 1/64” (0.5 mm).

Hold the latch board tightly in this position until you check the sequence of the switches in steps 5 and 6.

TEST THE LATCH AND SWITCH SEQUENCE

(5) Open the oven door slowly. Watch the door latch, the

Primary Switch. Release Rod and Lever on the switches to make sure they are zero to the body of the switches in the following sequence:

- Primary Interlock Switch

- Secondary Interlock Switch

- Interlock Monitor Switch

Adjust the latch board until the switches operate in this sequence. See Steps 3 and 4.

(6) Close the oven door slowly and be sure it is tightly

closed. Watch the three switches to make sure they are zero to the body of the switches in the following sequence:

- Interlock Monitor Switch

- Primary Interlock Switch

- Secondary Interlock Switch

NOTE: The Interlock Monitor Switch is an added safety

check on the Primary and Secondary Interlock Switches. If the Primary and Secondary Interlock Switches allow the oven to operate with the door open, the Monitor Switch will blow the fuse.

(7) When you achieve the proper sequence of switches

in Steps 5 and 6, tighten the latch board screws at that point.

TEST THE MICROWAVE ENERGY LEAKAGE

(8) Using a survey meter, make sure the microwave

energy is below 5 mW/cm.sq.

-3-

MODEL 721.69252990

721.69259990

LATCH BOARD

INTERLOCK MONITOR SWITCH

PRIMARY INTERLOCK SWITCH

SECONDARY INTERLOCK SWITCH

SCREW

LATCH

LATCH BOARD

0-1/64"

DOOR LATCH

RELEASE LEVER

Figure 1-a

Figure 1-b

-4-

MODEL 721.69252990

721.69259990

2. PRECAUTIONS ON INSTALLATION

(Figure 2)

A. Plug the power supply cord into a 120 V AC,

60 Hz, single-phase power source with a capacity of

at least 20 amperes.

B. Since the unit weights about 38 lbs, be sure to place

it on a sturdy and flat surface.

C. Avoid placing the unit in a location where there is

direct heat or splashing water.

D. Place the unit as far away as possible from TV, radio,

etc. to prevent interference.

CAUTION

3. GENERAL PRECAUTIONS IN USE

A. Never operate the unit when it is empty. Operating

the oven with no load may shorten the life of the

magnetron. Whenever cooking dry foods (dried fish,

bread, etc.) or a small amount of food, be sure

to put a glass of water into the cooking

compartment. The turntable tray may become hot

after operating, be careful when touching it.

B. Aluminum foil should be avoided because it will

disrupt cooking and may cause arcing. However,

small pieces may be used to cover some parts of

food to slow the cooking. Any aluminum foil used

should never be closer than 2.5 cm to any side wall of

the oven.

4. TRIAL OPERATION

After installation, the following sequences and results should be checked carefully. A. Put a container filled with water (about 1 liter) into the

oven, and close the door tightly.

B. Touch the STOP/CLEAR and the COOK TIME keys. C. Set cooking time for 10 minutes by touching “1”

and then “0” three times. “1000” appears in the display window.

D. Touch the START key.

Make sure the cavity light comes on. The unit will begin cooking and the display window will show the time counting down by seconds.

E. After about 5 minutes, make sure the primary

interlock switch, the secondary interlock switch and the interlock monitor and oven lamp switch operate properly by opening and closing the door several times. Touch the START key each time the door is closed.

F. Continue operating the unit. Two short and a long

beep sound signal is heard when the time is up.

The unit will shut off automatically. G. Confirm the water is hot. H. Finally, measure the output power according to

“POWER OUTPUT MEASUREMENT” on page 13.

5. FEATURES AND SPECIFICATIONS

A. The safety systems incorporated in this model are:

(1) Primary interlock switch

(2) Secondary interlock switch

(3) Interlock monitor switch

(4) Choke system

(5) Magnetron thermostat

(6) Oven cavity thermostat

(Note: This thermostat located on the oven cavity will open and stop the unit from operation only if a high temperature is reached, such as, a fire created by overcooking food.)

B. Any one of 10 power output levels ranging 100W to

1000W can be selected by the touch control and

electronic computer system. C. Cooking time can be displayed on the digital readout. D. Three different cooking stages can be set. The oven

remembers three cooking stages and changes from

one cooking stage to another. This is made possible

with the memory function of the microprocessor.

This unit is equipped with a 3-prong plug for your safety. If the wall outlet is a grounded 3-hole type, the unit will be grounded automatically.

Three-Pronged(Grounding) Plug

Figure 2

-5-

Properly Polarized and Grounded Outlet

MODEL 721.69252990

721.69259990

SPECIFICATIONS

Rated Power Consumption 1530W maximum Output

1100W maximum (*IEC 705 Rating standard)

Adjustable 100W through 1100W, 11 steps Frequency 2,450 MHz 50 MHz Power Supply 120V 12V AC, 60Hz Rated Current 13.3 Amp. Magnetron Cooling Forced Air Cooling Microwave Stirring Turntable Rectification Rectification Voltage Doubler Half-Wave Door Sealing Choke System Safety Devices Thermostat:

Open at 90˚C 5˚C

Open at 75˚C 5˚C Fuse(20A) Primary Interlock Switch Secondary Interlock Switch Interlock Monitor

Magnetron 2M246 High Voltage Capacitor Capacitor: 1.00 F, 2.1KV Ac High Voltage Diode 350mA, 9.0KV Cavity Lamp 125V, 20W Timer Digital, up to 99 mm. 99 sec. (in each cooking stage) Tray Tempered Safety Glass Overall Dimensions 20

/8”(W) x 123/8”(H) x 151/2”(D)

Oven Cavity Size 13

/4”(W) x 93/8”(H) x 143/8”(D)

Effective Capacity of Oven Cavity 1.1 Cu.ft. Accessories Use and Care Manual ,Turntable,

Rotating Ring Assembly.

SWITCH CHART

NOTE: Use the above switch chart with circuit diagram on page 7.

PRIMARY SECONDARY INTERLOCK INTERLOCK INTERLOCK MONITOR SWITCH SWITCH SWITCH

COM COM COM

NO NO NC

-6-

SWITCH MODE

CONDITIONS

DOOR OPEN

DOOR CLOSED

MODEL 721.69252990

721.69259990

6. OVERALL CIRCUIT DIAGRAM A. SCHEMATIC DIAGRAM

-7-

IMPORTANT SAFETY NOTE: THE SHADED AREAS ON THIS SCHEMATIC DIAGRAM INCORPORATE SPECIAL FEATURES

IMPORTANT FOR PROTECTION FROM MICROWAVE RADIATION, FIRE, ELECTRICAL SHOCK, AND

HAZARDS. WHEN SERVICING IT IS ESSENTIAL THAT ONLY MANUFACTURER’S SPECIFIED PARTS

BE USED FOR THE CRITICAL COMPONENTS IN THE SHADED AREAS OF THE SCHEMATIC DIAGRAM.

NOTICE: SINCE THIS IS BASIC SCHEMATIC DIAGRAM, THE VALUES OF COMPONENTS AND

SOME PARTIAL CONNECTIONS ARE SUBJECT TO CHANGE FOR IMPROVEMENT.

1 2 3 4 5 6 7 8

TTM

12345678

SYMBOL

NOTE:

1. DOOR IS OPEN.

2.RS: SENSING ELEMENT RC: COMPENSATING ELEMENT

3. WIRE COLOR.

COLOR WHITE BLACK

YELLOW PINK

BLUE

GREEN BROWN

YL PK

RED

GN BN

CONTROL MODULE

(8 PIN)

CONNECTOR

H.V.DIODE

H.V. CAPACITOR

BL WH GN

RDWH

BN(NC)(C)

CN4

TURNTABLE

MOTOR

SECONDARY

INTERLOCK

SWITCH

WH RD

RC RS

HUMIDITY

SENSOR

RELAY 1

RELAY 2

L.V. TRANSFORMER

(CN1)

FUSE

20A

PRIMARY INTERLOCK SWITCH (NO)

MONITOR SWITCH

H.V.TRANSFORMER

FAN

MOTOR

OVEN LAMP

MGT/OVEN

THERMOSTAT

AC 120V/60Hz SINGLE PHASE ONLY

MAGNETRON

321

MODEL 721.69252990

721.69259990

CLOCK

LESS

B. MATRIX CIRCUIT FOR TOUCH KEY BOARD

-8-

N.C

QUICK

COOK

TIME

KITCHEN

TIMER

USER

CHOICE

N.C

AUTO

DEFROST

QUICK

TOUCH

COOK

START

SENSOR

COOK

SENSOR

REHEAT

STOP/

CLEAR

SENSOR

POPCORN

N.C

POWER

3 4 5 6 7

Figure 4

MODEL 721.69252990

721.69259990

7. OPERATING PROCEDURES A. OVEN CONTROL PANEL

-9-

Display Window- Shows: * Time of day. * Cooking time. * Cooking power level. It also function as a countdown timer when cooking.

Quick Touch

Pre-set timing used for certain food items.

Used in setting Time of Day.

Used in setting Auto Defrost.

Used to set cooking time quickly and directly.

NOTE: A "beep" sounds when you touch a "key" on the control panel, to indicate that you have entered a setting.

Clock

Auto Defrost

Kitchen Timer-

You can use your microwave oven as a timer.

Numbers-

Used to enter the: * Time of day. * Cooking time. * Cooking power. * Food weight for defrost.

Used to set cooking time.

Starts the oven.

Cook Time

Stop/Clear-

Stops the oven and clears all entries except CLOCK. Once cooking has begun, however, CLEAR will function only after STOP has been touched.

Start

Quick On

Power-

Used select cooking power level.

Figure 5

MODEL 721.69252990

721.69259990

B. PANEL INSTRUCTIONS

The entire operation is done by simple touch control pads.

(1) DISPLAY WINDOW

The display includes a clock and indicators to tell you time of day, cooking time setting and cooking functions selected.

(2) COOK TIME Key

The TIME key is used to set the cooking time. Touch the TIME key and then the number keys that correspond to the desired cooking time. The remaining time is continuously displayed during cooking.

(3) CLOCK Key

Used in setting CLOCK.

(4) AUTO DEFROST key (DEFROST MEAT, POULTRY

& FISH) Used in setting AUTO DEFROST.

(5) POWER Key

Used to select cooking power level.

(6) STOP/CLEAR Key

Used to stop the oven or clear all entries except CLOCK.

(7) START Key

Touch the START key after setting the desired cooking times etc. Also touch the START key to resume cooking after the cooking is temporarily stopped by opening the door. The key will not function unless the door is closed.

(8) QUICK ON Key

Used in setting cooking time quickly and directly.

(9) QUICK TOUCH COOKING key

Pre-set timing used for certain food item.

-10-

MODEL 721.69252990

721.69259990

C. EASY USE CHART

(1) CLOCK

1. Touch STOP/CLEAR.

2. Touch CLOCK.

3. Touch numbers for correct time of day.

4. Touch START.

(2) “HI-POWER” COOKING

1. Touch STOP/CLEAR.

2. Touch COOK TIME.

3. Touch numbers for desired cooking time.

4. Touch START.

(3) “MULTI-STAGE” COOKING

1. Touch STOP/CLEAR.

2. Touch COOK TIME.

3. Touch numbers for cooking time.

4. Touch POWER.

5. Touch number for cooking power level.

6. Repeat steps 2-5 to set 2nd cooking stage.

7. Touch START.

(4) CHILD LOCK

To set:

1. Touch STOP/CLEAR.

2. Touch “START” more than 2 seconds. To cancel:

1. Touch STOP/CLEAR.

2. Touch “START” more than 2 seconds.

(5) KITCHEN TIMER

1. Touch STOP/CLEAR.

2. Touch KITCHEN TIMER.

3. Touch correct numbers for time.

4. Touch START.

(6) QUICK ON COOKING

1. Touch STOP/CLEAR.

2. Touch QUICK ON.

3. Touch number for desired minutes.

(7) AUTO DEFROST

1. Touch STOP/CLEAR.

2. Touch AUTO DEFROST. Three different defrosting levels are provided. (MEAT, POULTRY, FISH)

3. Enter the weight of your food in decimal increments from 0.1 to 6.0 pounds.

4. Touch START

5. At beeping, turn food over by following the instructions in the manual.

6. After turning food over, touch START to resume defrosting.

(8) QUICK TOUCH COOKING

1. Touch STOP/CLEAR.

2. Select one of categories, and then touch the number.

-11-

MODEL 721.69252990

721.69259990

8. PROCEDURE FOR MEASURING MICROWAVE ENERGY LEAKAGE

A. CAUTIONS

(1) Be sure to check a microwave emission prior to

servicing the oven if the oven is operative prior to servicing.

(2) The service personnel should inform the

manufacturer, importer, or assembler of any certified oven unit found to have a microwave emission level in excess of 5mW/cm.sq. and should repair any unit found to have excessive emission levels at no cost to the owner and should ascertain the cause of the excessive leakage. The service personnel should instruct the owner not to use the unit until the oven has been brought into compliance.

(3) If the oven operates with the door open, the service

personnel should;

- Tell the user not to operate the oven

- Contact the manufacturer and CDRH (Center for Devices and Radiological Health) immediately. NOTE: Address on CDRH Office of Compliance (HFZ-312) Center for Devices and Radiological Health 1390 Piccard Drive Rockville, Maryland 20850

(4) The service personnel should check all surface and

vent openings for microwave emission testing.

(5) Check for microwave energy leakage after every

servicing. The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 1mW/cm.sq. And always start measuring of an unknown field to assure safety for operating personnel from radiation leakage. NOTE: The standard is 5mW/cm.sq. while in the customer’s home. 1mW/cm.sq. stated here is manufacturer’s own voluntary standard for units in customer’s home.

EQUIPMENT

Electromagnetic energy leakage monitor (NARDA 8100B, HOLADAY HI 1501) 600cc glass beaker

Glass thermometer 1000C

B. MEASURING MICROWAVE ENERGY LEAKAGE

(1) Pour 275 15cc of 20 50C water in a beaker which is

graduated to 600 cc, and place the beaker in the center of the oven.

(2) Set the energy leakage monitor to 2,450 MHz and use

it following the manufacturer’s recommended test procedure to assure correct result.

(3) When measuring the leakage, always use the 2 inch

(5cm) spacer supplied with the probe. (4) Operate the oven at its maximum output. (5) Measure the microwave radiation using and

electromagnetic radiation monitor by holding the

probe perpendicular to the surface being

measured. (See Figure 7)

C. MEASUREMENT WITH THE OUTER CASE

REMOVED

(1) When you replace the magnetron, measure for

microwave energy leakage before the outer case is

installed and after all necessary components are

replaced or adjusted. Special

care should be taken in measuring the following parts.

- Around the magnetron

- The waveguide

WARNING: AVOID CONTACTING ANY HIGH

VOLTAGE PARTS.

-12-

Move probe along shaded area.

Probe scanning speed less than 2.5 cm/sec.

Figure 7

Figure 6

MODEL 721.69252990

721.69259990

D. MEASUREMENT WITH A FULLY ASSEMBLED

OVEN

(1) After all components, including the outer panels, are

fully assembled, measure for microwave energy leakage around the door viewing window, the exhaust opening and air inlet openings.

(2) Microwave energy leakage must not exceed the

values prescribed below.

NOTES:

Leakage with the outer panels removed - less than 5mW/cm.sq. Leakage for a fully assembled oven (Before the latch switch (primary) is interrupted) with the door in a slightly opened position - less than 1 mW/cm .sq.

E. NOTE WHEN MEASURING

(1) Do not exceed meter full scale deflection. (2) The test probe must be removed no faster than 1

inch/sec (2.5cm/sec) along the shaded area, otherwise a false reading may result.

(3) The test probe must be held with the grip portion of

the handle. A false reading may result if the operator’s hand is between the handle and the probe.

(4) When testing near a corner of the door, keep the

probe perpendicular to the surface making sure the probe horizontally along the oven surface, this may possibly cause probe damage.

F. RECORD KEEPING AND NOTIFICATION AFTER

MEASUREMENT

(1) After adjustment and repair of any microwave energy

interruption or microwave energy blocking device, record the measured values for future reference. Also enter the information on the service invoice.

(2) Should the microwave energy leakage not be more

than 1mW/cm.sq. after determining that all parts are in good condition, functioning properly and genuine replacement parts which are listed in this manual have been used.

(3) At least once a year, have the electromagnetic

energy leakage monitor checked for calibration by its manufacturer.

G. POWER OUTPUT MEASUREMENT

(1) Fill the test beaker with 59 ˚F(15 ˚C) ~ 75 ˚F(24 ˚C)

1 liter tap water.

(2) Stir the water in the beaker with thermometer

( ˚F or ˚C) and measure temperature as T1. (3) Place the beaker on the center of turntable. (4) Set for one (1) minute and three (3) seconds and operate

the oven at high power.

NOTE: The additional three (3) seconds is to allow the

magnetron to begin generating power.

(5) When the heating is finished, stir the water again with

thermometer and measure the temperature of water as

T2. (6) Subtract T1 from T2, this will give you the temperature

rise. (7) The microwave power output is within specification, if the

temperature rise is as shown below:

Temperature Rise

Line Voltage Degrees ˚F Degrees ˚C

120 V 11.7 ~ 17.1 6.5 ~ 9.5 108 V Min. 10.8 Min 6

(8) Power output will be influenced by line voltage of power

supply. Consequently, correct power output must be

measured within 120V AC 1 Volt while unit is

operating.

-13-

MODEL 721.69252990

721.69259990

SPECIAL TIP

• This oven used the button head screws.

• When you remove the screws, using the tamper-resistant Torx driver have a pin-in-head.

Button Head

(Torx style 2)

9. DISASSEMBLY INSTRUCTIONS

IMPORTANT NOTES:

UNIT MUST BE DISCONNECTED FROM ELECTRICAL OUTLET WHEN MAKING REPAIRS, REPLACEMENTS, ADJUSTMENTS AND CONTIN-UITY CHECKS. WAIT AT LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE CAPACITOR IN THE HIGH VOLTAGE POWER SUPPLY HAS FULLY DISCHARGED. THE CAPACITOR SHOULD BE DISCHARGED BY USING INSULATED WIRE - I.E. TEST PROBE CONNECTED TO 10K-OHM RESISTOR IN SERIES TO GROUND. WHEN RECONNECTING THE WIRE LEADS TO ANY PART, MAKE SURE THE WIRING CONNE-CTIONS AND LEAD COLORS ARE CORRECTLY MATCHED ACCORDING TO THE OVERALL CIR-CUIT DIAGRAM. (ESPECIALLY SWITCHES AND HIGH VOLTAGE CIRCUIT.)

A. REMOVING OUT CASE (Figures 8)

(1) Remove three screws from the rear section. (2) Remove one screw from the side section. (3) Push the outer case back about 1 inch (3cm). (4) Lift the case from the set.

B. REMOVING POWER AND CONTROL CIRCUIT

BOARD(Figure 9)

(1) Open the door. (2) Remove two screws, securing the circuir board. (3) Disconnect the lead wire from RELAY(RY2) on the

circuit board.

(4) Lift up and pull out control panel assembly carefully

from the cavity.

(5) Disconnect the lead wire from connector(CN1) on the

circuit board.

CAUTION: DISCHARGE THE HIGH VOLTAGE

CAPACITOR BEFORE SERVICING.

(6) Pull down and remove the circuit board from the

control panel.

(7) Remove the F.P.C connector from the terminal

socket.

-14-

Lift up and pull out control panel

securing screw

ground screw

Remove screw

Figures 9

Figure 8

F.P.C.Connector

Control Panel

Circuit Board

MODEL 721.69252990

721.69259990

+ 34 hidden pages