Kenmore 721.66292, 721.66293 Service Manual

MODEL 721.66292 721.66299 721.66293

DIVISION 20

BASIC FIELD MANUAL

FOR

TOASTER AND MICROWAVE OVEN

MODEL 721.66292500 721.66299500 721.66293500

July, 2005

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.

-1-

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 721.66292 721.66299 721.66293

		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.	Features and Specifications ..............................................................................................................................		6-7
6.	Overall Circuit Diagram .....................................................................................................................................		8-9
7.	Operating Procedures .......................................................................................................................................		10-11
8.	Procedure for Measuring Microwave Energy Leakage .....................................................................................		12-13
9.	Disassembly Instructions ..................................................................................................................................		14-17
10.		Interlock Continuity Test .................................................................................................................................	18
11.		Test and Checkout Procedures, and Troubleshooting
		A. Test Procedures .........................................................................................................................................	19-22
		B. Checkout Procedures .................................................................................................................................	23-25
		C. Troubleshooting ..........................................................................................................................................	26-31
12.		Exploded View ................................................................................................................................................	32-38
13.		Part Reference list ..........................................................................................................................................	39-44

-2-

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 CLOSING.

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 CLOSING

(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/cm2.sq.

-3-

Latch Board

Secondary

Interlock Switch

A

Interlock

Monitor Switch

Primary

Interlock Switch

LATCH

0-1/64"

LATCH BOARD

0-1/64"

-4-

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 34 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. And do not place on or near a hot gas or electric burner or in a heated oven.

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

Microwave Oven

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.

Toaster

A.Never operate the toaster when it is empty. Operating the toaster with no load may overheat this appliance.

B.Oversized food, metal foil packages or utensils must not be inserted in this toaster, as they may create a fire or electrical hazards.

4. TRIAL OPERATION

After installation, the following sequences and results should be checked carefully.

Microwave Oven

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. Four 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.

Toaster

A.Make sure the crumb tray is pushed all the way in place plugging in.

B.Remove all protective wrappings from food before placing into toasting slots. Then place bread into slots and close the door.

C.Select one mode(Toast/Bagel).

D.Press the Darkness Control to the desired setting.

E.Press the Start button. Make sure indicator light comes on. The unit will begin cooking and the display will show the browning level you selected.

F.After 1 minute, make sure the toaster door switch and indicator light operate properly by opening and closing the door several times (In normal state, indicator light blinks when door is opened).

G.Continue operating the unit by pressing the Start button. Beep sound signal is heard when the time is up. The unit will shut off automatically and fan will blow for 1 minute to cool this toaster.

H.Confirm the bread is cooked.

NOTE : If you operate this toaster for the first time, you will notice an odor, that is a characteristic of burning off residues on the new heating elements. This is normal.

-5-

5. FEATURES AND SPECIFICATIONS

Microwave Oven

A.The safety systems incorporated in this oven are:

(1)Primary interlock switch

(2)Secondary interlock switch

(3)Interlock monitor switch

(4)Choke system

(5)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 900W can be selected by the touch control and electronic computer system.

C.Cooking time can be displayed on the digital readout. And MWO mode and Toaster mode can be displayed to avoid confusion.

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.

Toaster

A.The safety systems incorporated in this toaster are:

(1)Toaster door switch

(2)Toaster thermostat

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

B.Cooking mode (Toast/Bagel) and browning level can be displayed on the digital readout.

C.Thermister controls the toasting time by detecting the internal temperature. This makes it possible to cook bread evenly.

-6-

	SPECIFICATIONS
Rated Power Consumption ...................................	1650W
Output
Microwave oven .................................................	1200W (*IEC60705 Rating standard)
	Adjustable 100W through 1200W, 10 steps
Toaster ...............................................................	800W
Frequency .............................................................	2450 MHz ± 50 MHz
Power Supply.........................................................	120V ± 12V AC, 60Hz
Rated Current .......................................................	13.8 Amp.
Magnetron & Heater Cooling ................................	Forced Air Cooling
Microwave Stirring ................................................	Turntable
Rectification ...........................................................	Rectification Voltage Doubler Half-Wave
Door Sealing .........................................................	Choke System
Safety Devices
Microwave oven .................................................	Thermostat : Open at 90°C ± 5°C, Close at 75°C ± 5°C
	Fuse (20A)
	Primary Interlock Switch
	Secondary Interlock Switch
	Interlock Monitor
Toaster ...............................................................	Toaster Door Switch
	Thermostat: Open at 145°C ± 5°C, Close at 60°C ± 5°C
Magnetron .............................................................	2M246
High Voltage Capacitor .........................................	Capacitor: 1.05 µF, 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
Thermistor, NTC ...................................................	150°C ± 3%
Crumb Tray ...........................................................	Crumbs of bread lay on it
Overall Dimensions ...............................................	23”(W) x 121/2”(H) x 171/8”(D)
Oven Cavity Size ..................................................	1411/16”(W) x 95/8”(H) x 155/8”(D)
Effective Capacity of Oven Cavity .........................	1.2 Cu.ft.
Accessories ..........................................................	Use and Care Manual, Glass Turntable,
	Turntable Rotating Ring

SWITCH TABLE

		PRIMARY	SECONDARY	INTERLOCK	TOASTER
	SWITCH MODE	INTERLOCK	INTERLOCK	MONITOR	DOOR
		SWITCH	SWITCH	SWITCH	SWITCH
	CONDITIONS	COM	COM	COM	COM
		NO	NO	NC	NO
	DOOR OPEN			0
	DOOR CLOSED	0	0		0

NOTE: Use the above switch table with circuit diagram on page 8.

-7-

6. OVERALL CIRCUIT DIAGRAM

A. SCHEMATIC DIAGRAM

-8-

B. MATRIX CIRCUIT FOR TOUCH KEY BOARD

-9-

7.OPERATING PROCEDURES A. OVEN CONTROL PANEL

MICROWAVE CONTROL AREA

1.DISPLAY. The Display includes a clock and indicators that tell you time of day, cooking time settings, and cooking functions selected.

2.STOP/CLEAR. Touch this pad to stop the oven or clear entries.

3.START. Touch this pad to start all entries (except the Auto Cook and Add Minute function which start automatically)and to turn Child Lock on or off.

4.AUTO COOK. Touch this pad to select programming food items.

5.ADD MINUTE. Touch this pad to cook at 100% cook power for 1 minute to 99 minutes 59 seconds.

6.AUTO DEFROST. This pad is an accurate defrosting method for frozen meat, poultry and fish up to 6.0 lbs.

7.EXPRESS DEFROST. This pad provides you with the quick defrosting method for 1.0 pound frozen foods.

8.OPTION. Touch this pad to change the oven's default settings for sound, clock, scroll speed and Lbs/Kg.

9.KITCHEN TIMER. Touch this pad to use your microwave oven as a kitchen timer.

10.COOK TIME. Touch this pad to set a cooking time.

11.POWER. Touch this pad to set a cooking power.

12.NUMBER PADS. Touch Number Pads to enter cooking time, power level, quantities, or weights.

13.QUICK TOUCH SENSOR. This pad allows you to cook most of your favorite foods without having to select cooking times and power levels.

TOASTER CONTROL AREA

1.Toast. Toast bread

2.Bagel. Toasts Bagels

3.Off/Clear. Touch this pad to stop the toaster or clear entries.

4.On. Touch this pad to start the toasting process.

5.Darkness Control. Adjust darkness control to desired setting before cooking foods. (Default : 5, "1" is the lightest and "9" is the darkest)

6.Indicator Light. When operating toaster with door closed, this will be illuminated. If you open the door during toasting, this will blink.

-10-

B. EASY USE TABLE
MICROWAVE OVEN		TOASTER
(1) KITCHEN TIMER		(1) TOAST
1. Touch STOP/CLEAR.			1. Touch STOP/CLEAR.
2. Touch KITCHEN TIMER.			2. Touch TOAST.
3.	Touch correct number for time.		3. Touch Darkness Control (1~9 step)
4.	Touch START.		4. Touch START.
(2) CHILD LOCK		(2) BAGEL
To set:			1. Touch STOP/CLEAR.
1. Touch STOP/CLEAR.			2. Touch BAGEL.
2.	Touch “START” more than 4 seconds.		3. Touch Darkness Control (1~9 step)
To cancel:			4. Touch START.
1. Touch STOP/CLEAR.		(3) DARKNESS SETTINGS
2.	Touch “START” more than 4 seconds.
(3) AUTO COOK
			Degree of darkness	Select darkness level
1. Touch STOP/CLEAR.
2.	Touch AUTO COOK Category.		Light	1~3
3. Touch START.			Medium	4~6
	(Although you don’t touch start, it will start after
			Dark	7~9
	4 seconds automatically)
(4) ADD MINUTE
1. Touch STOP/CLEAR.
2. Touch ADD MINUTE.
(5) AUTO DEFROST
1. Touch STOP/CLEAR.
2. Touch AUTO DEFROST.
	Three different defrosting levels are provided.
	(Touch 1 : Meat
	Touch 2 : Poultry
	Touch 3 : 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.
(6) TIMED COOKING
1. Touch STOP/CLEAR.
2. Touch COOK TIME.
3.	Touch number for cooking time.
4. Touch POWER.
5.	Touch number for cooking power level.
6.	Touch START.
(7) MULTI-STAGE COOKING
1. Touch STOP/CLEAR.
2. Touch COOK TIME.
3.	Touch number 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.

-11-