Kenmore 721.69259990 Service Manual

MODEL 721.69252990 721.69259990

DIVISION 20

BASIC FIELD MANUAL

FOR

MICROWAVE OVEN

MODEL 721.69252990 721.69259990

June, 1999

MODEL 721.69252990 721.69259990

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.

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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

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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.

MODEL 721.69252990 721.69259990

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.

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SCREW

DOOR LATCH

A

B

RELEASE

LEVER

C

SCREW

0-1/64"

LATCH BOARD

MODEL 721.69252990 721.69259990

LATCH BOARD

SECONDARY

INTERLOCK

SWITCH

INTERLOCK

MONITOR

SWITCH

PRIMARY

INTERLOCK

SWITCH

Figure 1-a

LATCH

0-1/64"

Figure 1-b

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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

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.

Properly Polarized and

Grounded

Outlet

Three-Pronged(Grounding)

Plug

Figure 2

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.

MODEL 721.69252990 721.69259990

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.

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					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	207/8”(W) x 123/8”(H) x 151/2”(D)
Oven Cavity Size	133/4”(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
	PRIMARY		SECONDARY		INTERLOCK
SWITCH MODE	INTERLOCK		INTERLOCK		MONITOR
	SWITCH		SWITCH		SWITCH
CONDITIONS	COM		COM		COM
	NO		NO		NC
DOOR OPEN					0
DOOR CLOSED	0		0

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

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MODEL 721.69252990 721.69259990

6. OVERALL CIRCUIT DIAGRAM A. SCHEMATIC DIAGRAM

MGT/OVEN	N	L AC 120V/60Hz
THERMOSTAT		SINGLE PHASE ONLY

WH

BK

L.V. TRANSFORMER

1		BK
2		WH	OL
	BL
3			OVEN	RD
4			LAMP
			WH

RELAY 1	5
			FM
	6
			GN
		GN	FAN
	7
			MOTOR
			WH

	(CN1)	8	PK
			SECONDARY		BK
RELAY 2			INTERLOCK
			SWITCH
				TTM
				TURNTABLE
3	2 1			MOTOR
		CN4
WH	RD	BK	YL	MONITOR SWITCH
			(C)	(NC)		BN
	RC	RS		H.V.TRANSFORMER
		WH						RD
HUMIDITY						MAGNETRON
	SENSOR
			H.V. CAPACITOR
NOTE:
1. DOOR IS OPEN.
2.RS: SENSING			H.V.DIODE
	ELEMENT
	RC: COMPENSATING
	ELEMENT
3. WIRE COLOR.
	SYMBOL COLOR			CONTROL MODULE
	WH	WHITE		BK	BL	WH	GN	PK
	BK	BLACK		1	2 3	4 5	6 7	8
	BL	BLUE
	YL	YELLOW				(8 PIN)
	PK	PINK
					CONNECTOR
	RD	RED
	GN	GREEN
	BN	BROWN

FUSE 20A

BK

PRIMARY INTERLOCK SWITCH (NO)

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.
IMPORTANT

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MODEL 721.69252990 721.69259990

B. MATRIX CIRCUIT FOR TOUCH KEY BOARD

					1					2				3				4				5			6			7
				SENSOR				N.C			SENSOR						AUTO			USER			KITCHEN			CLOCK
				POPCORN								COOK				DEFROST			CHOICE				TIMER
	8
				N.C			QUICK				SENSOR					QUICK								MORE			LESS
																TOUCH				N.C
								ON			REHEAT
																COOK
	9
				POWER			COOK					STOP/				START			8				9			0
								TIME			CLEAR
	10
				1			2				3					4			5				6			7
	11

Figure 4

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7. OPERATING PROCEDURES A. OVEN CONTROL PANEL

Quick Touch

Pre-set timing used for certain food items.

Clock

Used in setting

Time of Day.

Cook Time

Used to set cooking 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.

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

Figure 5

MODEL 721.69252990 721.69259990

Display Window- Shows:

*Time of day.

*Cooking time.

*Cooking power level. It also function as a countdown timer when cooking.

Auto Defrost

Used in setting

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.

Power-

Used select cooking power level.

Quick On

Used to set cooking time quickly and directly.

Start

Starts the oven.

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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.

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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.

MODEL 721.69252990 721.69259990

(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.

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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

Figure 6

B. MEASURING MICROWAVE ENERGY LEAKAGE

(1)Pour 27515cc of 2050C 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)

Move probe along shaded area.

Probe scanning speed less than 2.5 cm/sec.

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.

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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.

MODEL 721.69252990 721.69259990

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.

SPECIAL TIP

• This oven used the button head screws.

Button Head (Torx style 2)

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

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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)

Figure 8

(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.

MODEL 721.69252990 721.69259990

(6)Pull down and remove the circuit board from the control panel.

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

Remove screw

securing screw

ground screw

Lift up and pull out control panel

F.P.C.Connector

Circuit Board

Control Panel

Figures 9

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