Related Manuals for LG MC-784DC
Summary of Contents for LG MC-784DC
- Page 1 MICROWAVE/GRILL/ CONVECTION OVEN SERVICE MANUAL MODEL : MC-784DC/MC-785DC/MC-785BC CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
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Page 2: Safety Precautions
SAFETY PRECAUTIONS This device is to be serviced only by properly qualified service personnel. Consult the Service Manual for proper service procedures to assure continued safety operation and for precautions to be taken to avoid possible exposure to excessive microwave energy. PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO... -
Page 3: Table Of Contents
TABLE OF CONTENTS (Page) SAFETY PRECAUTIONS ....................Inside front cover SPECIFICATIONS ............................4 CAUTIONS ..............................5 INSTALLATIONS ............................6 OPERATING INSTRUCTIONS ........................7 FEATURES .............................. 7 CONTROL PANEL ........................... 7 OPERATING SEQUENCE ........................8 SCHEMATIC DIAGRAM ..........................9 CIRCUIT DESCRIPTION ........................10 SERVICE INFORMATION .......................... -
Page 4: Specifications
SPECIFICATIONS ITEM DESCRIPTION MODEL MC-785DC / MC-784DC MC-785BC Power Requirement 230V AC50Hz Single phase, 3 wire grounded Microwave 1350W Grill 1250W Convection 1350W (MAX. 2550W) Combination 2650W Power Output 850W full microwave power(IEC705) Microwave Frequency 2,450MHz Magnetron 2M214 - 39F, 2M254J, 2M218J Timer 99min. -
Page 5: Cautions
CAUTIONS Unlike other appliances, the microwave oven is MICROWAVE RADIATION high-voltage and high-current appliance. Personnel should not be exposed to the microwave Though it is free from danger in ordinary use, energy which may radiate from the magnetron or extreme care should be taken during repair. other microwave generating device if it is improperly used or connected. -
Page 6: Installations
INSTALLATIONS BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY. Installing microwave oven Earthing Instructions 1. Empty the microwave oven and clean inside it with a This microwave oven is designed to be used in a fully soft, damp cloth. Check for damage such as earthed condition. -
Page 7: Operating Instructions
OPERATING INSTRUCTIONS Features Oven front face Window door screen Door seal FOR MC-785BC ONLY Control panel ROTI-BAR Latch Shaft Metal tray Glass turntable Rotating ring ROTI-HANDLE Grill rack Convection rack Control Panel 1. DISPLAY WINDOW 7. CLOCK Used to show : To set the time of day. -
Page 8: Operating Sequence
Operating Sequence 6. Combination Cooking The following is a description of component functions during oven operation. DESIRED 1. Setting the clock CONVECTION TEMP COMBINATION (150°C~250°C) PLUG THE POWER SET THE CORD INTO AN CORRECT CLOCK ELECTRIC OUTLET HOUR GRILL SET THE CORRECT CLOCK DESIRED POWER... -
Page 9: Schematic Diagram
SCHEMATIC DIAGRAM DIAGRAM SCHEMATIC MICROWAVE GRILL/CONV. OVEN MODEL:MC-785DC MC-784DC PRIMARY MONITOR SWITCH SWITCH TRANSFORMER 0.8A FUSE 230VAC G - Y CAPACITOR 24VAC T.T.M INPUT POWER COM. H.V DIODE SOLENOID NOISE FILTER MAGNETRON OVEN MAGNETRON THERMOSTAT THERMOSTAT SECONDARY SWITCH 7 6 5 4 3 2 1... -
Page 10: Circuit Description
Circuit Description As the door is opened, if the contact of primary switch As the door is closed, the contact of MONITOR fail to open, the 10A fuse opens due to the large SWITCH opens. This switch creates the short circuit to current surge caused by the monitor switch activation blow 10 A fuse during operation under abnormal which in turn stops magnetron, oscillation. - Page 11 EXPLODED VIEW INTRODUCTION OVEN CAVITY PARTS INTERIOR PARTS DOOR PARTS BASE PARTS LATCH BOARD PARTS CONTROL PANEL PARTS...
- Page 12 DOOR PARTS 13581A 13552A 13213A 13720D 14026A 14890A 14970A 54974A 13806F...
- Page 13 CONTROL PANEL PARTS 24781S 268712 268711 23572A 250201 23806C 24351A 250202 250203 249401 250204...
- Page 14 OVEN CAVITY PARTS WTT021 WTT021 33112U 54974A For MC-785BC ONLY 34810R WTT011 348102 WTP013 35300A 34370Z 36549R WMT002 33550H WSZ002 348101 35301A 34774U 33052M WTT010 35026C 34371T 35026G WTT011 33390M 34930R 33390G 34960A 35889A 34036W 36549S 34271A WTP013 (Only MC-785BC)
- Page 15 LATCH BOARD PARTS 43501A 43500A 466001 466003 WSZ085 466002...
- Page 16 INTERIOR PARTS 53551S 56322V WTT028 368771 WTT028 WSZ062 WTT028 56411A 56208A 53504A 54975G 35300S 36549C WNH002 54350A 56930V 55900N WWP008 WWS005 WSZ002 50FZZA 55900C WNH003 WMT002 56201A WTT037 WTT028 54974S 56549F 56930M 55900A WSZ002 56324A 50CZZH 56021A 54370D 54810C 568771 56912B WTT028 54810U...
- Page 17 BASE PLATE PARTS 63303A 63302A 56170D 34774L 948504 WSZ085 948501 WSZ062 WSZ002 647781 WTT030...
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Page 18: Service Information
SERVICE INFORMATION Tools and Measuring Instruments NECESSARY TOOLS NECESSARY MEASURING INSTRUMENTS Tools normally used for TV servicing are sufficient. Standard tools are listed below. TESTER (VOLTS-DC, AC, Multmeter) Diagonal pliers Microwave survey meter Long nose pliers —Holaday H1-1500, Hi-1501 —Narda 8100, 8200 Cross head screwdriver Inch scale Wrench (size 5 mm) - Page 19 MEASUREMENT WITH THE OUTER NOTES WHEN MEASURING CASE REMOVED Do not exceed meter full scale deflection. The test probe must be removed no faster than, When you replace the magnetron, measure microwave 1 inch/sec (2.5 cm/sec) along the shaded area, energy leakage before the out case is installed and otherwise a false reading may result.
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Page 20: Measurement Of Microwave Power Output
Measurement of Microwave Power Output Microwave power output measurement is made with The microwave power output P in watts is calculated the microwave oven supplied at its rated voltage and from the following formula: operated at its maximum microwave power setting with 4187 (∆T) a load of (1000 ±... - Page 21 D. REMOVING CONTROL PANEL PCB ASSEMBLY ASSEMBLY AND PCB ASSEMBLY 1) Disconnect the leadwire from the PCB SUB ASM. 2) Remove the screws for the earth and securing the control panel. 3) Lift control panel assembly from the oven by the tab unhooked.
- Page 22 F. NOISE FILTER ASS'Y HIGH VOLTAGE H.V. Transformer DIODE, HIGH VOLTAGE CAPACITOR, AND COOLING FAN MOTOR REMOVAL 1 ) Disconnect lead wires from the noise filter ass'y and remove screw securing the noise filter earth wire to the back plate. 2) Push two hook of the guide suction and lift up the rear of noise filter ass'y.
- Page 23 J. TURNTABLE MOTOR REMOVAL K. INTERLOCK SYSTEM 1) Remove the turntable. 1) INTERLOCK MECHANISM The door lock mechanism is a device which has been 2) Remove the turntable shaft VERY CAREFULLY with specially designed to completely eliminate microwave a slotted screw driver. activity when the door is opened during cooking and 3) Lay the set down on its back.
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Page 24: Interlock Continuity Test
Interlock continuity Test WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMISSION,REPLACE ONLY WITH IDENTICAL REPLACEMENT RARTS. TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR PRIMARY / SECONDARY SWITCH TYPE NO. SZM-V 16-FA-61 OR VP-531A-OF FOR MONITOR SWITCH A. PRIMARY INTERLOCK SWITCH TEST B. -
Page 25: Component Test Procedure
Component Test Procedure CAUTIONS 1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUT 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. - Page 26 COMPONENTS TEST PROCEDURE RESULTS Antenna Gasket Chassis Filament Terminals 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. HIGH VOLTAGE Normal : Momentary indicates (Multi-meter scale : Rx1000) CAPACITOR...
- Page 27 COMPONENTS TEST PROCEDURE RESULTS Normal Abnormal FUSE, H.V. FUSE Check for continuity of the switch with a (Wire leads removed.) Multi-meter. 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.
- Page 28 COMPONENTS TEST PROCEDURE RESULTS Normal : COM-230V : Approx. 150 Ω CIRCULATION Measure the resistance. COM-24V : Approx. 20 Ω (Wire leads removed) (Multi-meter scale : Rx1) Abnormal : Infinite or several ohm. (BN) 230V(BL) (YL) NOTE: ) = WIRE COLOR Normal : Approx.
- Page 29 COMPONENTS TEST PROCEDURE RESULTS Cooking Start RELAY 3,4, OF P.C.B (Disconnect the 7 pin connector from P.C.B) See Schematic Dagram on page 9) Relay 3 Relay 4 Cooking Start RELAY 1,2,3 OF P.C.B (Wire leads removed.) RY1 : Microwave RY2 : Convection RY3 : Turn Table, Fan Motor, Roti-Motor...
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Page 30: Trouble Shooting Guide
Trouble Shooting Guide CAUTIONS 1. Check grounding before checking for other trouble. 2. Be careful of the high voltage circuit. 3. When checking the continuity of the switches or transformer, disconnect one lead wire from these parts and then check continuity without turning the power source on. 4. - Page 31 (TROUBLE 2) Oven does not at all even thought MOTOR and P.C.B program. TEST PROCEDURE OR CONDITION CAUSE CORRECTION No input can be Defective tact switch key of Test procedure tact switch programmed. P.C.B. key of P.C.B. Some inputs can not be Loose connection.
- Page 32 (TROUBLE 3) Oven does not operating microwave cooking TEST PROCEDURE OR CONDITION CAUSE CORRECTION Oven does not go into a Primary and secondary Test procedure primary and cook cycle when START key interlock switches defective secondary switches. is touched. or out of adjustment. Test procedure relay 1 of Defective relay 1 of P.C.B.
- Page 33 (TROUBLE 3) Oven does not operating microwave cooking TEST PROCEDURE OR CONDITION CAUSE CORRECTION Test procedure relay 1 of No microwave oscillation. Defective relay 1 of P.C.B. P.C.B. Defective high voltage Test procedure high voltage transformer. transformer. Defective high voltage Test procedure high voltage capacitor.
- Page 34 (TROUBLE 4) Oven does not operate convection cooking TEST PROCEDURE OR CONDITION CAUSE CORRECTION Defective circulation motor Check and repair C-Motor wire Convection indicator lights wire ass'y. ass'y. (COM:YL, 24V:BN, 230V:BL) but oven does not go into cook cycle when START key is touched.
- Page 35 (TROUBLE 5) Oven does not operating Grill cooking TEST PROCEDURE OR CONDITION CAUSE CORRECTION Test procedure relay 5 of Grill indicator lights Defective relay 5 of P.C.B. P.C.B. but oven does not go into cook cycle when START key is touched. Open or loose wire Check and repair wiring.