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Sears 721.88502800 Manual Download Page 33

7-22

C. TROUBLE SHOOTING

Bef

ore following this troubleshooting read TRIAL OPERATION on page 6- 1.

• DISPLAY Problems, A thru C

• HELP UP Problems, D thru E                        • BUZZER Problems, F

PROBLEM - A: 

“PLEASE SET TIME OF DAY” does not appear in display window when power supply cord is

plugged into wall outlet.

PROBLEM - B: 

Display does not show correct numbers and/ or

correct indications when programmed.

Check: 1. POWER SUPPLY

2. FUSE (See “CHECKOUT PROCEDURES FOR FUSE BLOWING: on page 7- 19)

3. OVEN CAVITY THERMOSTAT

1

1

Summary of Contents for 721.88502800

Page 1: ...DIVISION 22 BASIC FIELD MANUAL FOR MICROWAVE HOOD COMBINATION MODEL 721 88502800 721 88503800 721 88509800 June 2008 MODEL 721 88502 721 88503 721 88509...

Page 2: ...oper 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 replaced or ad...

Page 3: ...S 4 2 OVERALL CIRCUIT DIAGRAM 5 1 SCHEMATIC DIAGRAM 5 1 MATRIX CIRCUIT FOR TOUCH KEY BOARD 5 2 GENERAL INFORMATION FOR SERVICE 6 1 GENERAL PRECAUTIONS IN USE 6 1 TRIAL OPERATION 6 1 FEATURES AND SPECI...

Page 4: ...k Switch Interlock Monitor Switch Magnetron 2M282J Toshiba Cook top Lamp 120 V 20 W Halogen Cavity Lamp 120 V 20 W Halogen Timer Digital up to 99 min in each cooking stage Tray Tempered Safety Glass O...

Page 5: ...OUCH any oven components or wiring during operation BEFORE TOUCHING any parts of the oven always remove the power plug from the outlet Remove your watches whenever working close to or replacing the Ma...

Page 6: ...o etc to prevent interference GROUNDING INSTRUCTIONS For personal safety this appliance must be fully grounded at all times In the event of an electrical short circuit grounding reduces the risk of el...

Page 7: ...4 1 OPERATING INSTRUCTIONS CONTROL PANEL 1 2 6 4 5 9 3 7 8 12 10 11 15 13 17 16 14 20 18 19...

Page 8: ...Use this dial to select oven functions such as quantities of food and cooking times powers 6 BACK Press this pad to step back one or more levels in the program process 7 AUTO DEFROST Touch this pad to...

Page 9: ...5 1 OVERALL CIRCUIT DIAGRAM SCHEMATIC DIAGRAM...

Page 10: ...5 2 MATRIX CIRCUIT FOR TOUCH KEY BOARD...

Page 11: ...he cavity light comes on The unit will begin cooking and the display window will show the time counting down by seconds D After about 5 minutes make sure the primary interlock switch the secondary int...

Page 12: ...the limit of 5 mW cm2 All service adjustments should be made for minimum microwave energy leakage readings 3 Do not operate the unit until it is completely repaired if any of the following conditions...

Page 13: ...ervicing 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 pe...

Page 14: ...this manual have been used 3 At least once a year have the electromagnetic energy leakage monitor checked for calibration by its manufacturer POWER OUTPUT MEASUREMENT 1 Microwave power output measurem...

Page 15: ...CIRCUIT BOARD Figures 1 2 and 3 1 Remove a screw securing the control panel assembly to the oven cavity 2 Remove the control panel with pushing it upward 3 Remove the connectors and sensor wire leads...

Page 16: ...INSERT THE F P C CONNECTOR Follow the steps below as illustrated in Figures 6 and 7 to insert the F P C connector 1 Insert the F P C connector into the terminal socket securely with the fingers 2 Hold...

Page 17: ...ng plate by turning the screws 1 or 2 screws securing it to the out case 4 Remove two screws on the left central edge and two screws on the right central edge of Base plate Remove the Mount All from t...

Page 18: ...e two screws securing the Latch Board 3 Make necessary replacements and check microwave energy leakage according to ADJUSTMENT PROCEDURES on page 7 12 RD RD BK BK RD from turntable Motor MGT Fan Motor...

Page 19: ...the magnetron make sure that its dome does not hit any adjacent parts or it may be damaged When replacing the magnetron be sure to install the magnetron gasket in the correct position and be sure that...

Page 20: ...o check that the primary interlock switch the secondary interlock switch and the interlock monitor switch is in good operating normally After replacing the door check for microwave energy leakage with...

Page 21: ...ounted properly microwaves may leak from the clearance between the door and the oven I REMOVING THE VENTILATION MOTOR 1 Remove the mounting plate by loosening mounting plate screws 1 or 2 screws secur...

Page 22: ...ct the leadwire from the turntable motor terminals 5 Remove the 1 screws securing the turntable motor to the oven cavity ASS Y Figure 21 NOTES Remove the leadwire from the turntable motor VERY CAREFUL...

Page 23: ...microwave oven on its side so that you can see the latch board and the switches as shown in Figure 23 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...

Page 24: ...o 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 P...

Page 25: ...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 sw...

Page 26: ...ads 2 Measure resistance ohm meter scale Rx1 Primary winding High Low Secondary winding Filament winding 3 Measure resistance ohm meter scale Rx1000 Primary winding to ground Filament winding to groun...

Page 27: ...cale Rx1000 CAPACITOR DIODE Some inexpensive ohm meters may indicate infinite resistance in both directions 1 Measure continuity ohm meter scale Rx1 2 Remove the lead wires and operate oven at power l...

Page 28: ...0 ohm 1 Remove lead wires 2 Measure resistance ohm meter scale Rx1 1 Remove wire leads 2 Measure resistance ohm meter scale Rx1000 VENTILATION MOTOR TURNTABLE MOTOR 1 Disconnect sensor connector from...

Page 29: ...lastic fastener MATRIX CIRCUIT FOR TOUCH KEY BOARD CONNECTOR KEY CON TOUCH KEY BOARD Resistance value When touched Less than 400 ohms When not touched More than 1 mega ohm FPC CONNECTOR Top NOTES A MI...

Page 30: ...ADJUSTMENT PROCEDURES on page 7 12 when the primary interlock secondary interlock switches and or the interlock monitor switches are adjusted or replaced Fuse blows immediately after the door is close...

Page 31: ...ithout touching START key when the door is closed GOOD Remove the mate connector of I O CON from the circuit board Does the unit still operate Defective Wire Assembly Replace the circuit board Replace...

Page 32: ...the high voltage Systems the interlock switches the door sensing and the relay check good 3 The unit with a normal relay continuously operates 4 The buzzer does not sound or continues to sound 5 Some...

Page 33: ...ru E BUZZER Problems F PROBLEM A PLEASE SET TIME OF DAY does not appear in display window when power supply cord is plugged into wall outlet PROBLEM B Display does not show correct numbers and or corr...

Page 34: ...M E Display does not start countdown when START key is touched Check 1 TOUCH KEY BOARD START KEY FUNCTION Check 1 AIR VENTS PROBLEM D Unit operation seems to be normal but no heating is produced in ov...

Page 35: ...7 24 PROBLEM E Unit does not heat up even if display counts down when START key is touched for HIGH POWER cooking Check 1 PRIMARY AND SECONDARY INTERLOCK SWITCHES 2 THERMOSTAT 1 2...

Page 36: ...7 25 PROBLEM F No buzzing when touching the key between stages or at end of cooking 1 PROBLEM G Ventilation fan does not operate when VENT ON OFF key is touched 1 Check 1 POWER SUPPLY 2 FUSE...

Page 37: ...8 1 EXPLODED VIEW DOOR PARTS I 1005 1382 1008 1000 1004 1007 1006 1011 W109 W171 1009 EV FOR MODELS...

Page 38: ...8 3 CONTROLLER PARTS I 2030 MBM2 2009 2041 W136 2004 2006 2400 2021 2000 2002 2381 2008 2007 W130 W136 EV FOR MODELS...

Page 39: ...8 5 OVEN CAVITY PARTS 3031 3001 3005 3026 3025 3011 3018 6000 6009 3036 3037 3029 3102 3032 5382 3010 3024 3003 W109 W178 W202 W121 W142 W142 W142 9000 EV...

Page 40: ...8 6 LATCH BOARD PARTS 4000 W102 4001 4002 4003 4002 4004 EV...

Page 41: ...RIOR PARTS I 3002 3381 Back Roller part is Tray Assembly Included 5003 5007 5012 5008 5049 3009 W105 W173 5051 3007 5023 5009 5002 5000 5018 W108 W108 W109 W109 W109 W110 W101 5058 5043 5062 W210 5024...

Page 42: ...8 8 INTERIOR PARTS II W150 W150 5707 3027 5041 5027 5011 5014 5010 5037 5029 5006 5016 W144 W109 5001 5412 W178 5045 5382 5800 W202 3005 EV...

Page 43: ...8 9 INSTALLATION PARTS 6008 6011 6009 6010 MFL1 USE CARE MEZ1 COOKING GUIDE LABEL MBM4 TEMPLATE UPPER MBM5 TEMPLATE WALL MFL3 INSTALLATION MANUAL EV...

Page 44: ...L ABSOLUTE HUMIDITY SENSOR YL BK RD RD RD V1 BK RD RD BK BL BL BK BK BK BN RD BL WH WH WH WH WH YL YL YL BL BK BL WH YL RD PK 1 2 3 1 1 2 2 3 3 5 CN2 CN4 RY10 POWER RELAY 1 2 3 4 5 6 1 2 3 4 5 6 1 2 1...

Page 45: ...tic changing values rapidly in the mV scale Test Results H V Diode RECTIFIER Other component tests Components Test Results Components Test Results 1 Measure continuity ohm meter scale Rx1 2 Remove the...

Page 46: ...er is energized relays will close and complete circuit N L FUSE 20A OVEN TCO WH WH WH BK BK BL BL BK 1 UNIT IS PLUGGED IN CLOCK DISPLAY ON POWER TRANS 3 1 2 MICROWAVE COOKING ON RY1 O L 3 VENTOR MOTOR...

Page 47: ...P NO MFL57016001 Printed in Korea...

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