Kenmore 721.66339 Microwave Oven Owner’s Manual

Kenmore 721.66339 Microwave Oven

Product Information

Specifications

• Model: Kenmore 721.66339
• Division: 20
• Type: Microwave Oven
• Model Number: 721.66339800

Product Usage Instructions

Adjustment Procedures

To avoid possible exposure to microwave energy leakage, adjust the door latches and interlock switches following these steps:

1. Check the Door Latch and Switch Closing
   • Set the microwave oven on its side to access the latch board and switches.
   • Close the door tightly and check gaps A and B to ensure they are less than 1/64 (0.5 mm).
2. Adjust the Latch and Switch Closing
   • Loosen the screws holding the plastic latch board.
   • Move the latch board upward or away from the door latch until the gaps are less than 1/64 (0.5 mm).
3. Test the Latch and Switch Sequence
   • Open and close the oven door slowly to ensure the switches operate in the correct sequence: Primary Interlock Switch, Secondary Interlock Switch, Interlock Monitor Switch.

FAQ

Frequently Asked Questions

Q: What should I do if my microwave oven is not heating properly?

A: If your microwave oven is not heating properly, make sure the door is closing tightly and follow the adjustment procedures outlined in the manual to check the door latches and interlock switches.

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OVERALL CIRCUIT

OVERALL CIRCUIT DIAGRAM A. SCHEMATIC DIAGRAM

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.

MATRIX CIRCUIT FOR TOUCH KEY BOARD Figure 4 -8

OPERATING INSTRUCTIONS

OPERATING PROCEDURES

A. OVEN CONTROL PANEL

1. DISPLAY. The display includes a clock and indicators that tell you time of day, cooking time settings, and cooking functions selected.
2. QUICK TOUCH SENSOR. This pad allows you to cook most of your favorite foods without having to select cooking times and power levels.
3. MORE / LESS. All of the one touch cook and Timed Cook can be adjusted to cook food for a longer or shorter time. MORE Press MORE will add 10 seconds to the cooking time. LESS Press LESS will subtract 10 seconds to the cooking time.
4. AUTO DEFROST. This pad is an accurate defrosting method for frozen meat, poultry and fish up to 6.0 lbs.
5. TrueCookPlus®. Touch this pad to cook food according to TrueCookPlus® code.
6. NUMBER PADS. Touch Number Pads to enter cooking time, power level, quantities, or food categories.
7. COOK TIME. Touch this pad to set a cooking time.
8. STOP/CLEAR. Touch this pad to stop the oven or clear entries.
9. EXPRESS DEFROST. This pad provides you with the quick defrosting method for 1.0 pound frozen foods.
10. MELT. Touch this pad to melt chocolate, cheese, butter, or marshmallows.
11. SOFTEN. Touch this pad to soften ice cream, cream cheese, butter, or frozen juice.
12. AUTO COOK. Touch this pad to select programming food items.
13. KITCHEN TIMER. Touch this pad to use your microwave oven as a kitchen timer.
14. CLOCK. Touch this pad to enter the time of day.
15. OPTION. Touch this pad to change the oven’s default settings for sound, clock, scroll speed and weight.
16. POWER. Touch this pad to set a cooking power.
17. ADD MINUTE. Touch this pad to cook at 100% cook power for 1 minute to 99 minutes and 59 seconds.
18. START. Touch this pad to start all entries (except the Quick Touch Sensor, Express Defrost, Auto Cook and Add Minute function which start automatically) and to turn Child Lock on or off.

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

B. EASY USE TABLE
(1) KITCHEN TIMER 1. Touch STOP/CLEAR. 2. Touch KITCHEN TIMER. 3. Touch correct number for time. 4. Touch START.
(2) CHILD LOCK To set: 1. Touch STOP/CLEAR. 2. Touch “START” more than 4 seconds. To cancel: 1. Touch STOP/CLEAR. 2. Touch “START” more than 4 seconds.
(3) SENSOR COOK 1. Touch STOP/CLEAR. 2. Touch SENSOR COOK Category.
(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. 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.

-10-

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 100°C

B. MEASURING MICROWAVE ENERGY LEAKAGE (1) Pour 275±15cc of 20±5°C 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.

Figure 6 -11-

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 is moved horizontally along the oven surface.
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.

9. DISASSEMBLY INSTRUCTIONS IMPORTANT NOTES: UNIT MUST BE DISCONNECTED FROM ELECTRICAL OUTLET WHEN MAKING REPAIRS, RE-PLACEMENTS, ADJUSTMENTS AND CONTINUITY 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 10KOHM RESISTOR IN SERIES TO GROUND. WHEN RECONNECTING THE WIRE LEADS TO ANY PART, MAKE SURE THE WIRING CONNECTIONS AND LEAD COLORS ARE CORRECTLY MATCHED ACCORDING TO THE OVERALL CIRCUIT DIAGRAM. (ESPECIALLY SWITCHES AND HIGH VOLTAGE CIRCUIT.)
A. REMOVING OUTSIDE 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.

(6) Pull down and remove the circuit board from the control panel.
(7) Remove the F.P.C connector from the terminal socket.

B. REMOVING POWER AND CONTROL CIRCUIT BOARD(Figure 9)
(1) Open the door. (2) Remove two screws, securing the circuit 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.

F.P.C.Connector Control Panel

-13-

Circuit Board
Figures 9

C. DOOR ASSEMBLY / REMOVAL (1) Open the door. (2) Remove the choke cover very carefully with a flat-blade
screwdriver. CAUTION : Be careful not to damage door seal plate by
screwdriver. (3) Lift up and push the door.
NOTE: 1. After replacing the door, be sure to check that the primary
switch, monitor switch, and secondary switch operate normally. 2. After replacing the door, check for microwave energy leakage with a survey meter. Microwave energy must be below the limit of 5 mW/cm.sq. (with a 275 ml water load) 3. When mounting the door assembly to the oven assembly, be sure to adjust the door assembly parallel to the chassis. Also adjust so the door has no play between the inner door surface and oven frame assembly. If the door assembly is not mounted properly, microwaves may leak from the clearance between the door and the oven.

Remove choke cover Remove Door

Figure 10 -14-

D. MAGNETRON REMOVAL (1) Disconnect the wire lead from the magnetron. (2) Carefully remove the mounting screws holding the
magnetron and the waveguide. (3) Remove the magnetron assembly until the tube is clear
from the waveguide.
NOTE: 1. When removing the magnetron, make sure its dome
does not hit any adjacent parts, or it may be damaged. 2. When replacing the magnetron, be sure to install the
magnetron gasket in the correct position and be sure that the gasket is in good condition. 3. After replacing the magnetron, check for microwave leakage with a survey meter around the magnetron. Microwave energy must be below the limit of 5 mW/cm2 . (With a 275 ml. water load). Make sure that gasket is rigidly attached to the magnetron. To prevent microwave leakage, tighten the mounting screws properly, making sure there is no gap between the waveguide and the magnetron.

E. REMOVING THE TURNTABLE MOTOR 1) Remove the turntable and rotating ring. 2) Lay the unit down on its back. 3) Remove the turntable motor cover.
The turntable base cover is easily removed by pinching the eight parts with a wire cutting. 4) Disconnect the leadwire from the turntable motor terminals. 5) Remove the screw securing the turntable motor to the oven cavity ASSEMBLY. 6) After repairing the motor, rotate the removed turntable motor cover. 7) Fit the turntable motor cover’s projecting part to the base plate slit.
8) The taptite screw shall be used when a turntable motor cover is secured with a screw.
NOTE: 1. Remove the wire lead from the turntable motor VERY
CAREFULLY. 2. Be sure to grasp the connector, not the wires, when
removing.

Air duct
Magnetron Waveguide Dome Waveguide Bracket Magnetron Gasket Magnetron
Figures 11
-15-

Taptite Screw Wire Leads
Turntable Motor Figures 12

F. HIGH VOLTAGE TRANSFORMER REMOVAL

1. Discharge the high voltage capacitor. 2) Disconnect the leadwire from magnetron, high voltage
   transformer, and capacitor. 3) Remove the screw holding the high voltage transformer to
   the baseplate.

I. REMOVING SENSOR

1. Disconnect the leadwire from PCB Assembly. 2) Remove a screw securing the sensor duct.

G. FAN MOTOR ASSEMBLY / REMOVAL

1. Discharge the high voltage capacitor. 2) Disconnect the leadwire from fan motor and high voltage capacitor. 3) Remove the two screws holding the the suction guide ASSEMBLY to the oven cavity. 4) Remove the two screws holding the fan motor ASSEMBLY to the suction guide ASSEMBLY.

H. HIGH VOLTAGE CAPACITOR AND DIODE REMOVAL

1. Discharge the high voltage capacitor. 2) Disconnect the leadwire from fan motor and high voltage capacitor. 3) Remove the screw holding the suction guide ASSEMBLY to the oven cavity. 4) Remove the screw holding the high voltage capacitor bracket and remove the high voltage diode earth screw.

Figures 14

INTERLOCK SYSTEM

1. INTERLOCK MECHANISM
   The door lock mechanism is a device which has been specially designed to eliminate microwave activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage.
2. MOUNTING OF THE PRIMARY/MONITOR/ SECONDARY SWITCHES TO THE LATCH BOARD
3. INSTALLATION AND ADJUSTMENT OF THE LATCH BOARD TO THE OVEN ASSEMBLY
   · Mount the latch board to the oven assembly. · Adjust the latch board in the arrow direction so that oven door will not have any play in it when the door is closed. · Tighten the mounting screw. · Check for play in the door by pushing the door
   release button. Door movement should be less than 0.5 mm. (1/64 inch) Don’t push the door release button while making this adjustment. Make sure that the latch moves smoothly after adjustment is completed and that the screws are tight. Make sure the primary, monitor, and secondary switches operate properly by following the continuity test procedure.

INTERLOCK CONTINUITY TEST

WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.
TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF OR V-5230Q FOR PRIMARY SWITCH TYPE NO. SZM-V 16-FA-62, VP-532A-OF OR V-5220Q FOR MONITOR SWITCH TYPE NO. SZM-V 15-FA-63, VP-533A-OFF OR SECONDARY SWITCH

A. PRIMARY INTERLOCK SWITCH TEST When the door release button is depressed slowly with the door closed, an audible click should be heard at the same time or successively at intervals. When the button is released slowly, the latches should activate the switches with an audible click. If the latches do not activate the switches when the door is closed, the switches should be a adjusted in accordance with the adjustment procedure. Disconnect the wire lead from the primary switch. Connect the ohmmeter leads to the common (COM) and normally open (NO) terminal of the switch. The meter should indicate an open circuit in the door open condition. When the door is closed, the meter should indicate a closed circuit. When the primary switch operation is abnormal, make the necessary adjustment or replace the switch only with the same type of switch.

B. SECONDARY INTERLOCK SWITCH TEST Disconnect the wire lead from the secondary switch. Connect the ohmmeter leads to the common (COM) and normally open (NO) terminals of the switch. The meter should indicate a open circuit in the door open condition. When the door is closed, meter should indicate an closed circuit. When the secondary switch operation is abnormal, make the necessary adjustment or replace the switch only with the same type of switch.
C. MONITOR SWITCH TEST Disconnect the wire lead from the monitor switch. Connect the ohmmeter leads to the common (COM) and normally closed (NC) terminals of the switch. The meter should indicate closed circuit in the door open condition. When the door is closed, meter should indicate an open circuit. When the monitor switch operation is abnormal, replace with the same type of switch. NOTE: After repairing the door or the interlock system, it is necessary to do this continuity test before operating the oven.

COMPONENTS SWITCHES (Wire leads removed)

TEST PROCEDURE Check for continuity of the switch with an Ohm-meter

Primary Switch

NO COM

RESULTS Door open

Door closed

Monitor Switch

NC COM

Secondary Switch

NO COM

NOTE : After checking for the continuity of switches, make sure that they are connected correctly.

-18-

11. TEST AND CHECKOUT PROCEDURES, AND TROUBLESHOOTING
CAUTIONS 1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUTER CASE
FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER. 2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF WATER IN CONTAINER) IN THE OVEN.

A. TEST PROCEDURES
COMPONENTS HIGH VOLTAGE TRANSFORMER (Wire leads removed)

TEST PROCEDURE
FILAMENT WINDING

RESULTS

MAGNETRON (Wire leads removed)

PRIMARY TERMINAL
1. Measure the resistance. (Ohm-meter scale: Rx1 and Rx100) · Primary winding · Secondary winding · Filament winding
2. Measure the resistance. (Ohm-meter scale: Rx1000) · Primary winding to ground · Filament winding to ground
1. Measure the resistance. (Ohm-meter scale: Rx1) · Filament terminal
2. Measure the resistance. (Ohm-meter scale: Rx1000) · Filament to chassis

Approx.: 0.2 ~ 0.4 ohm Approx.: 70 ~ 100 ohm Less than: 1 ohm
Normal: Infinite Normal: Infinite
Normal: Less than 1 ohm
Normal: Infinite

-19-

COMPONENTS
HIGH VOLTAGE CAPACITOR

TEST PROCEDURE
Antenna Gasket Chassis

RESULTS

Filament

NOTE: When testing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition.

Measure the resistance. (Ohm-meter scale: Rx1000) · Terminal to terminal.

Normal: Momentarily indicates several ohms, and then gradually returns to infinite.

Measure the resistance. (Ohm-meter scale: Rx1000) · Terminal to case.

Normal: Infinite.

HIGH VOLTAGE DIODE

Measure the continuity (Forward). (Ohm-meter scale: Rx10000)

Normal: Continuity. Abnormal: Infinite.

NOTE : Some inexpensive meters may indicate infinite resistance in both direction.

Measure the continuity (Reverse). (Ohm-meter scale: Rx10000)

Normal: Infinite. Abnormal: Continuity.

Normal: A: Approx. 85 ~ 100 ohm. B: Approx. 10 ~ 25 ohm.

Abnormal: Infinite or several ohm.

Measure the resistance. (Ohm-meter scale: R x 1)

Normal: Approx.100~150 ohm Abnormal: Infinite or several
ohm.

SENSOR

1. Disconnect sensor connector from micom computer board.
2. Measure resistance terminal to terminal (ohm meter scale: R X 1000)

1

BK

2

RD

3

WH

NOTE : · A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON.
· MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION. · WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE
TO GRASP THE CONNECTOR, NOT THE WIRES.

Normal: Approximately BK – RD: 5.2 Kohm RD – WH: 2.1 Kohm BK – WH: 2.1 Kohm
Abnormal: Infinite or several.

• Sensor cooking condition 1. Oven should be plugged in at least
  5 minutes before sensor cooking. 2. Room temperature should not
  exceed 95°F . 3. Be sure the exterior of the cooking container and the interior of the oven are dry. Wipe each off with paper towel. 4. The oven will not generate microwave energy for the first 28 seconds of the sensor cooking cycle.

CHECKOUT PROCEDURES (1) CHECKOUT PROCEDURES FOR FUSE BLOWING
CAUTION: REPLACE BLOWN FUSE WITH 20 AMPERE FUSE.

PROBLEMS Fuse blows immediately after the door is closed.
Fuse blows immediately after the door is opened.
Fuse blows when the door is closed and START key is touched.

CAUSES
Improper operation of the primary interlock, secondary interlock switches and/or the interlock monitor switch.
Malfunction of the high voltage transformer; the high voltage capacitor including the diode, the magnetron, the blower motor or the circuit board.

NOTES: – If the fuse is blown by an improper switch operation, replace the defective switches and the fuse at the same time.
After replacing the defective switches with new ones, make sure that they are correctly connected. – Check for microwave energy leakage according to “1. ADJUSTMENT PROCEDURES” on page 3, when the
primary interlock, secondary interlock switches and/or the interlock monitor switches are adjusted or replaced.

(2) CHECKOUT PROCEDURES FOR RELAY

– PROBLEM (A) FAN motor and oven lamp turn on without touching START key when the door is closed.

NO

YES

GOOD

Remove the mate connector of I/O CON from the circuit board does the unit still operate?
NO
Replace the circuit board

– PROBLEM (B) FAN motor and oven lamp turn on When the door is closed and START key is touched.

YES

NO

GOOD

Replace the micro switches.

Defective RELAY or poor connection of relay

Replace RELAY or correct the connection.

(3) CHECKOUT PROCEDURES FOR CIRCUIT BOARD The following symptoms indicate a defective circuit board. (1) The start function fails to operate but the high voltage Systems, the interlock switches, the door sensing and the relay check good. (2) The unit with a normal relay continuously operates. (3) The buzzer does not sound or continues to sound. (4) Some segments of one or more digits do not light up, or they continue to light up, or segments light when they should not. (6) Wrong figures appear. (7) The figures of all digits flicker. (8) Some of the indicators do no light up. (9) The clock does not keep time properly.

NOTE: A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON.

TROUBLE SHOOTING

WHEN YOU GET A COMPLAINT FROM YOUR CUSTOMER, EVALUATE THE COMPLAINT CAREFULLY. IF THE FOLLOWING SYMPTOMS APPLY, PLEASE INSTRUCT THE CUSTOMER IN THE PROPER USE OF THE MICROWAVE OVEN. THIS CAN ELIMINATE AN UNNECESSARY SERVICE CALL.
CAUTIONS 1. Check grounding before checking for trouble. 2. Be careful of the high voltage circuit. 3. Discharge the high voltage capacitor. 4. When checking the continuity of the switches or of the high voltage transformer, disconnect one lead wire from these
parts and then check continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter. 5. Do not touch any part of the circuit on the PCB since static electric discharge may damage this control panel. Always touch yourself to ground while working on this panel to discharge any static charge built up in your body. (Micom model only)

CONDITION Microwave oven does not work.
Output power is too low.
Sparks occur.
Uneven cooking.

CAUSE
Inserting many plugs into one outlet and using them at the same time. (blown fuse or breaker)
Microwave oven plug is not inserted tightly.
Low AC input voltage.
Food temperature is too low.
Using metallic ware and allowing it to touch the oven wall.
Ceramic ware trimmed in gold or silver powder is used.
Inconsistent intensity of microwave by their characteristics.

REMEDY
Avoid using other electrical appliances when you use the microwave oven.
Insert microwave oven plug securely.
Use the microwave oven at adequate line voltage.
This may not be a defect. It is possible that the food should be cooked for a longer time period.
Do not use metallic ware for cooking except where noted in the cooking guide.
Do not use any type of cookware with metallic trimming.
1. Use plastic wrap or lid. 2. Stir once or twice while
cooking soup, cocoa or milk, etc.

-25-

(TROUBLE 1) The following visual conditions indicate a probable defective control circuit.
1. Incomplete segments. · Segment missing. · Partial segment missing. · Digit flickering (NOTE: Slight flickering is normal.)
2. Colon does not turn on or blink. 3. A distinct change in the brightness of one or more numbers in display. 4. One or more digits in the display are not lighting. 5. Display indicates a number different from one touched, for example, key in 5 and 3 appears in the display. 6. Specific numbers (for example 7 or 9) will not display when key pad is touched. 7. Display does not count down with time blinking or up with clock operation. 8. Display obviously jumps in time while counting down. 9. Display counts down too fast while cooking. 10. Each indicator light does not turn on after setting cooking cycle. 11. Display time of day does not reappear when cooking is finished.

CONDITION
1. No input can be programmed.
2. Some inputs cannot be programmed.
3. Display shows a number or figure different from one touched.
4. Random programming when touching other pads.
5. Display is fixed at some figure and can not accept any input.

CHECK
Check the connection between membrane key assembly and PCB assembly.
Replace key membrane assembly and check operation.

RESULT Continuity No continuity Everything works as specified.
Still have trouble.

CAUSE
Defective PCB assembly.
Loose connection.
Defective key membrane assembly.
Defective PCB assembly.

REMEDY
Replace PCB assembly.
Connect them tightly.
Replace key membrane assembly.
Replace PCB assembly.

(TROUBLE 2) Oven does not operate at all, Display window does not display any figures, and no input is accepted.

CONDITION 1. Fuse blows.

CHECK
Check continuity of monitor switch (with door closed).
Replace fuse
Check continuity of primary switch (with door opened).

RESULT Continuity. No continuity.
Continuity. No continuity.

CAUSE
Malfunction of the monitor switch.

REMEDY
Replace fuse, primary, monitor switches, and RELAY(RY2) of P.C.B Assembly.

Shorted contact at the primary switch.

Replace fuse, primary, monitor switches, and RELAY(RY2) of P.C.B Assembly.

Disconnect one side of the wire lead connected from transformer to the high voltage capacitor and operate the unit.

Normal. Fuse blows again

Defective high voltage capacitor.
Defective high voltage transformer.

Replace high voltage capacitor.
Replace high voltage transformer.

2. Fuse does not blow.

Check continuity of thermostat.

No continuity. Continuity.

Check continuity of power supply cord.

No continuity.

Defective thermostat.

Replace thermostat.

Defective power supply cord.

Replace power supply cord.

(TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired program times are set and START pad is touched.

CONDITION
1. Setting time does not count down when touching START pad.

CHECK
Check continuity of secondary switch (with door closed).

2. Fan motor or oven lamp do not turn on.

Check the connection between CN1 connector and PCB assembly.
Check fan motor.
Check oven lamp.

RESULT No continuity. Continuity.
Continuity No continuity Abnormal Abnormal Normal

CAUSE
Defective secondary switch.

REMEDY
Replace secondary switch.

Defective PCB assembly.
Loose connection.
Defective fan motor. Defective oven lamp.

Replace PCB assembly.
Connect them tightly.
Replace fan motor.
Replace oven lamp.

(TROUBLE 4) Oven seems to be operating but little heat is produced in oven load.

CONDITION Output is low

CHECK
Check the power source voltage.

RESULT
Lower than 90% of rating voltage.
Normal

CAUSE
Decrease in power source voltage with load.

Disconnect the wire leads from relay 2 and check on and off time with multitester.

Abnormal Normal

Defective PCB assembly.

Measure the output power.

Abnormal

Defective magnetron.

NOTE : Simple test of power output-conducted by heating one liter water for one min. if available. Minimum 8.5°C temperature rise is normal condition.

REMEDY
Suggest customer contact local electric power utility co. or qualified electrician. Replace PCB assembly.
Replace magnetron.

(TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run. (Display operates properly)

CONDITION
No microwave oscillation.

CHECK
Disconnect the wire leads from relay 2 and check continuity of relay 2. (Operate the unit)

RESULT No continuity. Continuity.

CAUSE
Defective PCB assembly.

Check high voltage transformer

Abnormal Normal

Defective high voltage transformer.

REMEDY Replace PCB assembly.
Replace high voltage transformer.

Check high voltage capacitor.

Abnormal Normal

Defective high voltage capacitor.

Replace high voltage capacitor.

Check high voltage diode.

Abnormal Normal

Defective high voltage diode.

Replace high voltage diode.

Check magnetron.

NOTE: Make sure the wire leads are in the correct position. · When Removing the wire leads from the parts, be sure to grasp the connector, not the wires. · When removing the magnetron, be sure to install the magnetron gasket in the correct position and in good condition.

Output is full power when you set lower power level.

Printed in Korea

References

• assembly.no in parked
• Repair Your Grill: Shop Replacement Parts for 24,880 Models
• Kenmore Microwave Parts - Select From 532 Models

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