LG MB-314XF Service Manual
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LG MB-314XF Service Manual

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MICROWAVE OVEN
SERVICE MANUAL
MODEL : MB-314XF
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : 3828W5S1803
MB-314XB
Website: http://biz.lgservice.com
Printed in Korea
March, 2001

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  • Page 1 Website: http://biz.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL : MB-314XF MB-314XB CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. March, 2001 P/NO : 3828W5S1803 Printed in Korea...

  • 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 EXCESSIVE MICROWAVE ENERGY...

  • Page 3: Table Of Contents

    CONTENTS (Page) SAFETY PRECAUTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Inside front cover SPECIFICATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-1 CAUTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-1 INSTALLATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-1...

  • Page 4: Specifications

    SPECIFICATIONS DESCRIPTION ITEM MB-314XF/MB-314XB MODEL 120 Volts AC 60 Hz Power Requirement MICROWAVE 1,400 Watts (12.0) GRILL 1,000 Watts Single phase, 3-wire grounded 1,000 Watts full microwave power (IEC60705) Power Output 2,450 MHz Microwave Frequency 2M246 Magnetron 0 ~ 99 min. 99 sec.

  • 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. INSTALLING GROUNDING INSTRUCTIONS 1. Empty the microwave oven and clean inside it with For personal safety, this appliance must be fully a soft, damp cloth. Check for damage such as grounded at all times.

  • Page 7: Operating Instructions

    OPERATING INSTRUCTIONS FEATURES OVEN CAVITY DOOR SEAL DISPLAY WINDOW CONTROL PANEL GLASS TURNTABLE SAFETY INTERLOCK ROTATING RING SYSTEM GRILL RACK CONTROL PANEL 1. INDICATORS. 2. LOCAL MENU: This menu has been preprogrammed to cook food automatically by one touch. 3. AUTO GRILL: This feature provides you with the best grill cooking method by selecting menu.

  • Page 8: Operating Sequence

    OPERATING SEQUENCE 7. AUTO WEIGHT DEFROST COOKING The following is a description of component functions during oven operation. DESCONGELADO NUMBER OF PARAR/BORRAR INICIO AUTO. WEIGHT 1. SETTING THE CLOCK 8. CHILD LOCK PARAR/BORRAR RELOJ NUMBER INICIO This oven has a CHILD LOCK feature TO SET CHILD LOCK ex.) To set 4:30, touch number key [4],[3], and [0].

  • Page 9: Schematic Diagram

    SCHEMATIC DIAGRAM...

  • Page 10: Circuit Description

    CIRCUIT DESCRIPTION • A high voltage of approximately 2100 volts AC is GENERAL DETAILS generated in the secondary of the high voltage transformer which is increased by the action of the high • The low voltage transformer supplies the necessary voltage diode and charging of the high voltage voltage to the micom controller when power cord is capacitor.

  • Page 11: Service Information

    SERVICE INFORMATION TOOLS AND MEASURING INSTRUMENTS NECESSARY TOOLS NECESSARY MEASURING INSTRUMENTS Tools normally used for TV servicing are sufficient. • TESTER (VOLTS-DC, AC, Ohmmeter) Standard tools are listed below. • Microwave survey meter • Diagonal pliers - Holaday HI-1500 • Long nose pliers HI-1501 •...
  • Page 12 MEASUREMENT WITH OUTER CASE NOTES WHEN MEASURING REMOVED • Do not exceed meter full scale deflection. • The test probe must be removed no faster than • When you replace the magnetron, measure for 1 inch/sec (2.5 cm/sec) along the shaded area, microwave energy leakage before the outer case is otherwise a false reading may result.

  • Page 13: 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 x (∆T) a load of (1000±5) g of potable water.
  • Page 14 D. PCB 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 PCB SUB ASSEMBLY to the control panel. 3) Disconnect the flat cable from the PCB SUB ASSEMBLY and take off the PCB SUB ASSEMBLY.
  • Page 15 F. MAGNETRON REMOVAL G. REMOVING THE TURNTABLE MOTOR 1) Remove the turntable and rotating ring. 1) Disconnect the leadwire from the magnetron. 2) Lay the unit down on its back. 2) Carefully remove the mounting screws holding the 3) Remove the turntable motor cover. magnetron and the waveguide.
  • Page 16 H. HIGH VOLTAGE TRANSFORMER K. INTERLOCK SYSTEM REMOVAL 1) INTERLOCK MECHANISM The door lock mechanism is a device which has 1) Discharge the high voltage capacitor. been specially designed to eliminate completely 2) Disconnect the leadwire from magnetron, high voltage microwave activity when the door is opened during transformer, and capacitor.

  • Page 17: Interlock Continuity Test

    INTERLOCK CONTINUITY TEST WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS. ALL THESE SWITCHES MUST BE REPLACED AT THE SAME TIME. 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.

  • Page 18: Component Test Procedure

    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.
  • Page 19 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 Measure the resistance. Normal: Momentarily indicates CAPACITOR (Ohm-meter scale: Rx1000) several ohms, and...
  • Page 20 COMPONENTS TEST PROCEDURE RESULTS HEATER ELEMENT Measure the resistance. Normal: (Wire leads removed.) (Multi-meter scale:RX1) Gill heater Approx.15 ½ (at 20-30ûC) Normal: Measure the resistance with 500V-100M more than 1.0M ½ Ohm insulation resistance meter. NOTE: Make sure heater is fully cooled when tested. 0ûC~Approx 180ûC Approx 180ûC MAGNETRON...
  • Page 21 COMPONENTS TEST PROCEDURE RESULTS Check for continuity of relay 2 with an RELAY 2 POWER ohm-meter. LEVEL (Remove wire leads from relay 2 and operate the unit.) 4 sec 18 sec 6 sec 16 sec 8 sec 14 sec 10 sec 12 sec 12 sec 10 sec...

  • Page 22: Troubleshooting

    TROUBLESHOOTING 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.
  • Page 23 (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 24 (TROUBLE 2) Oven does not operate at all, display window does not display any figures, and no input is accepted. CONDITION CHECK RESULT CAUSE REMEDY Malfunction of the Replace fuse, Check continuity 1. Fuse blows. Continuity. primary, monitor, monitor switch. of monitor secondary switch (with...
  • Page 25 (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 RESULT CAUSE REMEDY Defective Replace Check continuity 1. Setting time No continuity. secondary switch. secondary switch.
  • Page 26 (TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run. (Display operates properly) CONDITION CHECK RESULT CAUSE REMEDY No microwave Defective PCB Replace PCB Disconnect the No continuity. oscillation. assembly. assembly. wire leads from relay 2 and check continuity Continuity.

  • Page 27: Exploded View

    #EV# EXPLODED VIEW INTRODUCTION Model: MB-314XF MB-314XB OVEN CAVITY PARTS INTERIOR PARTS BASE PLATE PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS...
  • Page 28 #EV# DOOR PARTS 13581A 15006A 13552A 13536A 13213A 14890A 13720D 14026A 14970A...
  • Page 29 #EV# CONTROLLER PARTS 23572A 268711 23506A WTT028 24510L 24970A 250201 24781M...
  • Page 30 #EV# OVEN CAVITY PARTS 33112U WTT021 33052M WNZ015 340511 WTT010 35300S 35026G 33390G WSZ184 36549S 35889A WTP013...
  • Page 31 #EV# LATCH BOARD PARTS 43501A WSZ085 466001 43500A 466003 466001...
  • Page 32 #EV# INTERIOR PARTS WSZ062 568771 56411A 56930V 50FZZA 34930W 56930V 55006F WTT028 56549F 54974S WSZ002 WSZ002 55900A WTT037 35012A WSZ002 948501 56324A 50CZZH 56912B WSZ002 WSZ002 56851D WTP002 55262A 54810C 56930G 54810A WTT028...
  • Page 33 #EV# BASE PLATE PARTS 63303L 56170D 63302L 948502 647781 WTT028 63302R WSZ002 63303R...

  • Page 34: Schematic Diagram Of P.c.b

    SCHEMATIC DIAGRAM OF P.C.B.

  • Page 35: Printed Circuit Board

    PRINTED CIRCUIT BOARD...

This manual is also suitable for:

Mb-314xb

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