Subscribe to Our Youtube Channel
Related Manuals for Sears 721.88512900
Summary of Contents for Sears 721.88512900
- Page 1 MODEL 721.88512 721.88513 721.88519 DIVISION 22 BASIC FIELD MANUAL MICROWAVE HOOD COMBINATION MODEL 721.88512900 721.88513900 721.88519900 January, 2009...
-
Page 2: Warning To Service Technicians
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;... -
Page 3: Table Of Contents
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 721.88512 721.88513 721.88519 TABLE OF CONTENTS (Page) SAFETY PRECAUTIONS ........................Inside front page SPECIFICATIONS .............................. -
Page 4: Specifications
SPECIFICATIONS Rated Power Consumption ........Microwave 1600W Convection 1700W Microwave Output ..........Microwave 950W (IEC60705) Adjustable 95W through 950W, 10 steps Convection 1500W Frequency ............2450 MHz ±50 MHz Power Supply .............120 VAC, 60 Hz Rated Current ............Microwave 13.5A Convection 14.0A Magnetron Cooling ..........Forced Air Cooling Rectification ............Rectification Voltage Double Half-Wave Door Sealing ............Choke System Safety Devices ...........Magnetron Thermostat: Open at 150 °C ±... -
Page 5: Cautions
CAUTIONS Unlike other appliances, the microwave oven is MICROWAVE RADIATION high-voltage and high-current equipment. Personnel should not be exposed to the Though it is free from danger in ordinary use, microwave energy which may radiate from the extreme care should be taken during repair. magnetron or other microwave generating device if it is improperly used or connection. -
Page 6: Installations
INSTALLATIONS BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY. PRECAUTIONS ON INSTALLATION A. Plug the power supply cord into a 120V AC, 60Hz, single-phase power source with a capacity of at least 20 amperes. B. Avoid placing the unit in a location where there is direct heat or splashing water. -
Page 7: Operating Instructions
OPERATING INSTRUCTIONS CONTROL PANEL... -
Page 8: Control Panel Instructions
CONTROL PANEL INSTRUCTIONS 1. DISPLAY. The Display includes a clock and 15. NUMBER. Touch number pads to enter indicators to tell you time of day, cooking time cooking time, power level, quantities, weights, settings and cooking functions selected. or cooking temperature. 2. -
Page 9: Overall Circuit Diagram
OVERALL CIRCUIT DIAGRAM SCHEMATIC DIAGRAM... -
Page 10: Matrix Circuit For Touch Key Board
MATRIX CIRCUIT FOR TOUCH KEY BOARD KEY MATRIX... -
Page 11: General Information For Service
GENERAL INFORMATION FOR SERVICE GENERAL PRECAUTIONS IN USE FEATURES AND SPECIFICATIONS FEATURES A. Never operate the unit when it is empty. A. The safety systems incorporated in this model are: Operating the oven with no load may shorten the (1) Primary interlock switch life of the magnetron. -
Page 12: Service Information
SERVICE INFORMATION PRECAUTIONS AND REPAIR SERVICE TIPS PRELIMINARY (3) Do not operate the unit until it is completely repaired, if any of the following conditions exist. The unit must not be operated. A. SINCE NEARLY 4000 VOLTS EXISTS IN SOME (a) The door does not close firmly. -
Page 13: Microwave Leakage Test
MICROWAVE LEAKAGE TEST CAUTIONS EQUIPMENT- • Be sure to check microwave leakage prior to • TESTER ((VOLTS-DC, AC, Ohmmeter) servicing the oven if the oven is operative prior to • Microwave survey meter servicing. - Holaday HI-1500 • The service personnel should inform the HI-1501 manufacture importer, or assembler of any certified - Narda... -
Page 14: Power Output Measurement
MEASUREMENT WITH THE OUTER CASE RECORD KEEPING AND NOTIFICATION REMOVED AFTER MEASUREMENT (1) When you replace the magnetron, measure for (1) After adjustment and repair of any microwave microwave energy leakage before the outer case energy interruption or microwave energy blocking is installed and after all necessary components device, record the measured values for future are replaced or adjusted. -
Page 15: Disassembly Instructions
DISASSEMBLY INSTRUCTIONS IMPORTANT NOTES: (4) Remove 3 screws securing the circuit board. UNIT MUST BE DISCONNECTED FROM ELEC- TRICAL OUTLET WHEN MAKING REPAIRS, RE- PLACEMENTS, ADJUSTMENTS AND CONTIN- UITY CHECKS. WAIT AT LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE CAPACITOR IN THE Circuit Board HIGH VOLTAGE POWER SUPPLY HAS FULLY DISCHARGED. - Page 16 HOW TO REMOVE THE F.P.C. CONNECTOR HOW TO INSERT THE F.P.C. CONNECTOR Follow the steps below as illustrated in Figures 4 Follow the steps below as illustrated in Figures 6 and 5 to remove the F.P.C. connector. and 7 to insert the F.P.C. connector. (1) Insert the F.P.C.
- Page 17 B. REMOVING THE OUT CASE(Figure 8) (1) Remove the vent grille by removing two screws securing it to the out case. (2) Remove two screws securing it to the air duct. (3) Remove the mounting plate by turning the screws (1 or 2 screws)securing it to the out case.
- Page 18 C. REMOVING THE DOOR INTERLOCK SWITCHES (Figures 9, 10) (1) Disconnect the wire leads from the interlock switches. (2) Remove two screws securing the Latch Board. (3) Make necessary replacements and check microwave energy leakage according to “ADJUSTMENT PROCEDURES” on page 7-12. Latch Board Primary Latch Board...
- Page 19 D. REMOVING MAGNETRON NOTES: • When removing the magnetron, make sure that its (Figures 11 Through 13b) dome does not hit any adjacent parts, or it may be (1) Remove the vent grille by loosening two screws. damaged. (Figure 11) (2) Remove the outcase.
- Page 20 E. REMOVING STIRRER FAN F. REMOVING DOOR (Figure 16) (Figures 14 and 15) (1) Remove the vent grille by two screws securing it to (1) Remove two screws securing it to the oven the outcase loosening. upper plate by using drive screw. (2) Lift up and draw the door.
- Page 21 H. ASSEMBLING DOOR J. REPLACING THE HUMIDITY SENSOR (1) When mounting the door assembly to the oven (For sensor model only) assembly, be sure to adjust the door assembly (1) Remove the sensor by removing two screws parallel to the chassis. Also adjust so the door has no securing it to the air duct.
- Page 22 K. REMOVING THE TURNTABLE MOTOR L. REMOVING CONVECTION HEATER (1) Remove the turntable. AND THERMISTOR (Figure 23) (2) Remove the turntable shaft VERY CAREFULLY (1) Remove the out case. with a slotted screwdriver. (Figure 21) (2) Remove the air duct by removing six screws (3) Remove the base plate by removing 7 screws securing it to the oven front plate, guide air and securing it to the oven cavity.
-
Page 23: Interlock System
INTERLOCK SYSTEM INTERLOCK MECHANISM The door lock mechanism is a device which has been specially designed to eliminate completely microwave activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage. ADJUSTMENT PROCEDURES CHECK THE DOOR LATCH AND SWITCH To avoid possible exposure to microwave energy CLOSING. - Page 24 TEST THE LATCH AND SWITCH SEQUENCE (7) When you achieve the proper sequence of switches in Steps 5 and 6, tighten the latch board screws at that point. (5) Open the oven door slowly. Watch the door latch, the Secondary Switch. Release Rod and Lever TEST THE MICROWAVE ENERGY LEAKAGE on the switches to make sure they are zero to the body of the switches in the following sequence:...
-
Page 25: Interlock Continuity Test
INTERLOCK CONTINUITY TEST A. PRIMARY INTERLOCK SWITCH TEST B. SECONDARY INTERLOCK SWITCH TEST When the door is opened slowly, an audible click Disconnect the wire lead from the secondary should be heard at the same time or successively switch. at intervals and the latches should activate the Connect the ohmmeter leads to the common switches with an audible click (COM)and normally open (NO)terminals of the... -
Page 26: Test And Checkout Procedures And Troubleshooting
TEST AND CHECKOUT PRECEDURES 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 LEAD WIRES FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER. 2. - Page 27 COMPONENTS TEST RESULTS H.V.CAPACITOR 1. Check DC 9V battery before performing tests. 2. Select the DCV scale on the meter. 3. Using the meter, battery,and jump wire, connect the items as illustrated in figures. • Terminal to terminal Normal: Approximately 9V •...
- Page 28 COMPONENTS TEST RESULTS STEP 1. Test the diode to see if it is shorted. H.V.DIODE (RECTIFIER) Procedure: 1. Select the ohm scale on the meter. 2. Place the meter leads across the diode as pictured in Figure 1. The reading should be “40M Ω,” “OL,” or a reading of infinity.
- Page 29 COMPONENTS TEST RESULTS 1. Measure continuity. Power RELAY 8 Closed Open Level (ohm meter scale:Rx1) 2. Remove the lead wires and operate 4 Sec 18 Sec oven at power level 1 through power 6 Sec 16 Sec level 10. 14 Sec 8 Sec 12 Sec 10 Sec...
- Page 30 COMPONENTS TEST RESULTS TOUCH KEY BOARD Measure the resistance between terminal When When not pins of connector KEY CONNECTOR. touched touched NOTE: Resistance When reconnecting the FPC connector, value More than Less than make sure that the holes on the FPC 1 mega ohm 400 ohms connector are properly engaged with hooks...
-
Page 31: Checkout Procedures
B. CHECKOUT PROCEDURES (1) CHECKOUT PROCEDURES FOR FUSE BLOWING CAUTION: REPLACE BLOWN FUSE WITH 20 AMPERE FUSE. PROBLEMS CAUSES Fuse blows immediately after the door is closed. Improper operation of the primary interlock, secondary Fuse blows immediately after interlock switches and/or the interlock monitor switch. the door is opened. - Page 32 (2)CHECKOUT PROCEDURES FOR RELAY. -PROBLEM (A)- -PROBLEM (A)-- FAN motor turns on without touching START key Oven lamp turns on without touching START key when the door is closed. when the door is closed. Remove the wiring harness from Remove the mate connector of I/O GOOD GOOD the circuit board.
- Page 33 (3) CHECKOUT PROCEDURES FOR CIRCUIT BOARD The following symptoms indicate a defective circuit 6) Wrong figures appear. board. 7) The figures of all digits. 1) The start function fails to operate but the high 8) Some of the indicators do no flicker light up. voltage Systems, the interlock switches, the door 9) The clock does not keep time properly.
-
Page 34: Troubleshooting
C. 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. - Page 35 (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.
- Page 36 (TROUBLE 2) Microwave oven does not operate at all, Display window does not display any figures, and no input is accepted. POSSIBLE SYMPTOM CHECK CAUSE REMEDY CAUSE Malfunction of the Check continuity 1. Fuse blows. Continuity. Replace fuse, monitor switch. of monitor primary, monitor switch (with...
- Page 37 (TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired program times are set and START pad is touched. POSSIBLE SYMPTOM CHECK CAUSE REMEDY CAUSE Defective Replace Check continuity 1.Setting time No continuity. secondary switch. secondary switch.
- Page 38 (TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run (Display operates properly) POSSIBLE SYMPTOM CHECK CAUSE REMEDY CAUSE No microwave Disconnect the Defective P.C.B Replace P.C.B No continuity. oscillation. wire leads from assembly assembly relay 8 and check continuity Continuity.
- Page 39 (TROUBLE 6) Convection oven does not operate at all or convection cook is bad. POSSIBLE SYMPTOM CHECK CAUSE REMEDY CAUSE Defective Relay Replace Relay Convection indicator Check the Relay Abnormal. light but oven does 10 of P.C.B. not go into cook assembly.
-
Page 40: Exploded View
#EV# EXPLODED VIEW DOOR PARTS (I) 1005 1004 1000 1008 1382 W171 1007 1011 1006 W109 W244 W127 1009 -8-1-... - Page 41 #EV# CONTROLLER PARTS (I) 2004 2006 W144 2381 2022 2008 2002 2000 W136 2009 2007 MBM2...
-
Page 42: Oven Cavity Parts
#EV# OVEN CAVITY PARTS W108 3010 W108 3031 3024 W108 3001 3103 3221 3029 W105 3009 6001 W202 5382 W178 6000 3005 3037 3032 9000 W121 3011 3025 3026... -
Page 43: Latch Board Parts
#EV# LATCH BOARD PARTS 4001 4000 4002 W102 4003 4002 4004... - Page 44 #EV# INTERIOR PARTS (I) W109 W110 W101 5052 3048 W109 5003 5012 3044 5007 5002 5000 3002 3012 5018 W101 5023 3006 5009 W109 3008 5024 5049 5035 5008 W109 5062 5029 3206 W119 W121 W125 W141 W105 W124 3207 5403 W121 5021...
- Page 45 #EV# INTERIOR PARTS (II) W172 W178 5045 5385 W136 5800 3005 5011 W202 3021 W109 5382 3051 W109 W109 5006 5412 W140 W109 5016 W136 W109 5037 5010 3027 5001 5041 5410 5014 W140 -8-8-...
- Page 46 #EV# INSTALLATION PARTS 6008 6011 6010 6009 VINYL COOKING MFL1 MFL3 MEZ1 UPPER MBM4 WALL MBM5 INSTALLATION & GUIDE TEMPLATE TEMPLATE MANUAL CARE LABEL -8-9-...
- Page 47 P/NO : MFL57016002 Printed in Korea...
Need help?
Do you have a question about the 721.88512900 and is the answer not in the manual?
Questions and answers