삼 정 흥 판 MODEL 721.67902 721.67903 721.67909 DIVISION 20 BASIC FIELD MANUAL FOR MICROWAVE OVEN MODEL 721.67902600 721.67903600 721.
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.
CONTENTS MODEL 721.67902 721.67903 721.
SPECIFICATIONS Rated Power Consumption - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1500W Output Microwave - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1000W (*IEC60705 Rating standard) Adjustable 100W through 1000W, 10 steps Convection - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1500W Combination - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
CAUTIONS Unlike other appliances, the microwave oven is high-voltage and high-current equipment. Though it is free from danger in ordinary use, extreme care should be taken during repair. MICROWAVE RADIATION Personnel should not be exposed to the microwave energy which may radiate from the magnetron or other microwave generating device if it is improperly used or connected.
INSTALLATIONS BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY. INSTALLING GROUNDING INSTRUCTIONS 1. Empty the microwave oven and clean inside it with a soft, damp cloth. Check for damage such as misaligned door, damage around the door, dents inside the cavity, or on the exterior. 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 electrical shock.
OPERATING INSTRUCTIONS FEATURES Oven Front Plate Window Door Screen Door Seal Display Window Metal Rack Control Panel Glass Tray Safety Interlock System Rotating Ring CONTROL PANEL 1 2 4 3 5 6 7 9 8 11 10 12 13 14 15 16 17 18 19 20 22 21 1. DISPLAY. The Display includes a clock and indicators to tell you time of day, cooking time settings and cooking functions selected. 2. MICRO. Touch this pad when setting microwave cooking. 3. CONV.
OPERATING SEQUENCE The following is a description of component functions during oven operation. 6. MORE / LESS 1. SETTING THE CLOCK Stop/ Clear Clock Enter time of day • The More and Less functions will adjust the cook time of many oven functions. • More/Less will add/subtract 10 seconds to the cook time each time you press it. NOTE: • For convection cooking, More and Less are used as temperature selection pads. Start/Pause 2.
OPERATING SEQUENCE 11. EXPRESS DEFROST 9. SENSOR TOUCH COOKING • Sensor cook and reheat Stop/ Clear Sensor Cook Stop/ Clear Select Sensor menu Express Defrost Select Food Category Start/Pause Sensor Reheat 12. AUTO BAKE/ROAST • Sensor Popcorn Stop/ Clear Stop/ Clear Popcorn Auto Defrost Enter the Weight Food Category Auto Roast 10. AUTO DEFROST Stop/ Clear Auto Bake Select Food category Enter the Weight Start/Pause Start/Pause 13.
SCHEMATIC DIAGRAM NOTE: 1. DOOR IS OPENED. 2. WIRE COLOR.
CIRCUIT DESCRIPTION GENERAL DETAILS WHEN THE DOOR IS OPENED DURING COOKING • The low voltage transformer supplies the necessary voltage to the micom controller when power cord is plugged in. • When the door is closed, the primary switch is ON, the secondary switch is ON, and the monitor switch opens (contact COM and NO). • Both the primary switch and relay 2 cut off the primary winding voltage of the high voltage transformer.
SERVICE INFORMATION TOOLS AND MEASURING INSTRUMENTS NECESSARY TOOLS NECESSARY MEASURING INSTRUMENTS Tools normally used for TV servicing are sufficient. Tools needed for service are listed below.
MEASUREMENT WITH OUTER CASE REMOVED NOTES WHEN MEASURING • Do not exceed meter full scale deflection. • The test probe must be removed no faster than 1 inches/sec (2.5 cm/sec) along the shaded area, otherwise a false reading may result. • 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.
MEASUREMENT OF MICROWAVE POWER OUTPUT • Microwave power output measurement is made with the microwave oven supplied at its rated voltage and operated at its maximum microwave power setting with a load of (1000 ± 5)g of potable water. • The water is contained in a cylindrical borosilicate glass vessel having a maximum material thickness of 0.12 inches (3mm) and an outside diameter of approximately 7.5 inches (190mm). • The oven and the empty vessel are at ambient temperature prior to the start of the test.
D. P.C.B ASSEMBLY REMOVAL Remove choke cover 1) Remove the control panel assembly from the cavity. (Refer to control panel assembly removal on previous page.) 2) Remove screws which hold the P.C.B. SUB Assembly to the control panel. 3) Pull P.C.B. SUB Assembly carefully from the control panel. Control Panel PCB Sub Asm Key Membrane Remove door Door seal plate E. DOOR ASSEMBLY / REMOVAL 1) Open the door. 2) Remove the choke cover very carefully with a flat-blade screwdriver.
F. AIR DUCT ASSEMBLY / REMOVAL G. MAGNETRON REMOVAL 1) Disconnect the leadwires from the lamp, micro switch, damper motor, and damper switch. 2) Remove the screws holding the oven cavity and latch board, air duct, and air tunnel assembly. 3) Remove the mounting screws holding the magnetron and air duct assembly. 4) Remove air tunnel. 5) Pull latch board assembly and air duct assembly. 1) Remove the mounting screw holding the magnetron and air duct assembly. 2) Disconnect the leadwire from the magnetron.
H. THE TURNTABLE MOTOR REMOVAL I. HIGH VOLTAGE TRANSFORMER REMOVAL 1) Remove the turntable and rotating ring. 2) Lay the unit on its back. 3) Remove the turntable motor cover. The turntable base cover can be easily removed by pinching the six tabs with wire cutters. 4) Disconnect the lead wire from the turntable motor terminals. 5) Remove the screws securing the turntable motor to the oven cavity assembly.
L. INTERLOCK SYSTEM M. C-MOTOR, THERMISTOR AND SHEATH HEATER REMOVAL 1) INTERLOCK MECHANISM The door lock mechanism is a device which has been specially designed to stop microwave activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage. 1) Remove the back cover by removing the four screws securing the cover assembly to the oven cavity. 2) Disconnect the leadwire from the circulation motor and the sheath heater terminal.
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 FOR PRIMARY SWITCH TYPE NO. SZM-V 16-FA-62 OR VP-532A-OF FOR MONITOR SWITCH TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH A. PRIMARY INTERLOCK SWITCH TEST B.
COMPONENT TEST PROCEDURE 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. (SEE PAGE 2-1) 2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF WATER IN CONTAINER) IN THE OVEN.
COMPONENTS TEST PROCEDURE RESULTS Antenna Gasket Chassis 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. HIGH VOLTAGE CAPACITOR Measure the resistance. (Ohm-meter scale: Rx10,000) • Terminal to terminal. Normal: Momentarily indicates several ohms, and then gradually returns to infinite. Measure the resistance. (Ohm-meter scale: Rx10,000) • Terminal to case. Normal: Infinite.
COMPONENTS H.V.Diode (RECTIFIER) TEST PROCEDURE STEP 1. Test the diode to see if it is shorted. 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 “40MΩ,” “OL,” or a reading of infinity. 3. Reverse the meter leads. The reading should again indicate a reading of infinity. If the diode shows “infinity” in BOTH directions, it is NOT shorted. 4. If the diode is not shorted, proceed to step 2. STEP 2.
COMPONENTS FUSE (Wire leads removed.) TEST PROCEDURE Check for continuity of the switch with a Multi-meter. RESULTS Normal Abnormal NOTE: If the fuse is blown, check the primary, the secondary, and the monitor switches, H.V.D. and H.V.C. before replacing the fuse. If the fuse is blown by improper switch operation replace the defective switch and the fuse at the same time. Replace just the fuse if the switches operate normally. CONVECTION HEATER (Wire leads removed) Measure the resistance.
COMPONENTS TEST PROCEDURE RESULTS CIRCULATION MOTOR (Wire leads removed) Measure the resistance. (Multi-meter scale : R x 1) Normal : Approx. 29.5 ohm Abnormal : Infinite or several ohm. TURNTABLE MOTOR (Wire leads removed) Measure the resistance. (Ohm-meter scale : R x 1000) Normal : Approx. 3.48 Kohm Abnormal : Infinite or several ohm. DAMPER MOTOR (Wire leads removed) Measure the resistance. (Ohm-meter scale : R x 1000) Normal : Approx. 2.93 Kohm Abnormal : Infinite or several ohm.
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. (See page 2-1) 4.
(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.
(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). RESULT Continuity. CAUSE REMEDY Malfunction of the monitor switch. Replace fuse, primary, monitor, secondary switches, and RELAY(RY2) of P.C.B Assembly. No continuity. Replace fuse Check continuity of primary switch (with door opened). Continuity.
(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 CHECK 1.Setting time does not count down when touching START pad. Check continuity of secondary switch (with door closed). CAUSE REMEDY Defective secondary switch. Replace secondary switch. Continuity Defective P.C.B assembly. Replace P.C.B assembly. No continuity Loose connection. Connect them tightly. Check fan motor. Abnormal.
(TROUBLE 5) No microwave oven operation 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 relay2. (Operate the unit) Check high voltage transformer RESULT No continuity. CAUSE REMEDY Defective P.C.B assembly Replace P.C.B assembly Defective high voltage transformer. Replace high voltage transformer. Defective high voltage capacitor. Replace high voltage capacitor.
(TROUBLE 6) Convection oven does not operate at all or convection cook is bad. CONDITION CHECK Convection indicator light but oven does not go into cook cycle when START pad is touched. Check the Relay 4 or 6 of P.C.B. assembly . Temperature in the oven cavity is lower or higher than preset. RESULT Abnormal CAUSE REMEDY Defective Relay 4 or 6. Replace Relay 4 or 6. Normal Check the connection between P.C.B. assembly and headwire connector. No continuity. Loose connection. Connect them tightly.
#EV# EXPLODED VIEW INTRODUCTION MODEL 721.67902600 721.67903600 721.
#EV# DOOR PARTS For Model: 721.67902 721.67909 1005 1004 1013 1000 1008 1382 W105 1006 1007 1009 For Model: 721.
#EV# CONTROLLER PARTS For Model: 721.67902 721.67909 2004 2381 2006 2002 2000 W106 For Model: 721.
#EV# OVEN CAVITY PARTS 3001 W108 For Model 721.67903 721.67909 W107 For Model 721.
#EV# LATCH BOARD PARTS 4001 4002 4000 4003 4004 W102 W109 4002 W105 5045 5015 3049 5028 5006 4002 W109 6-5 W117
#EV# INTERIOR PARTS 5019 3013 W108 5010 W121 W101 5401 5413 5021 5402 W121 5403 5405 5407 3207 3006 5404 3206 W177 5408 W121 W141 W123 W125 W108 W182 W124 5001 W132 5406 5041 3036 3208 W146 W102 5003 5012 5007 W101 5000 5014 5009 W101 5002 5018 W101 W109 6-6
#EV# BASE PLATE PARTS 5008 6001 6000 W108 6007 6017 W101 6-7
#EV# SENSOR PARTS W104 5011 W108 5004 5016 6-8
P/NO : MFL06275102
