LG RFS12SW2B Built in Microwave Oven Owner’s Manual

: July 10, 2024
: LG

Table of Contents

RFS12SW2B Built in Microwave Oven
Product Specifications
Product Usage Instructions
Safety Precautions
Installation
- Frequently Asked Questions (FAQ)
Q: Can this microwave oven be used for residential
Q: What should I do before servicing the unit?
- EV
- EV#
- EV#
- EV
- EV#
- EV#
- EV#
- References
- Read User Manual Online (PDF format)
- Download This Manual (PDF format)

RFS12SW2B Built in Microwave Oven

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Product Specifications

ITEM	MODEL
Power Requirement	120 V~ 60 Hz
Power Output	2000 watt (18 A)
Microwave Frequency	2450 MHz
Magnetron	2M246
Timer	0 ~ 60 min.
Outside Dimensions	21 3/4 (W) x 14 1/4 (H) x 17 7/8 (D)
Cavity Dimensions	14 1/4 (W) x 8 7/8 (H) x 16 3/8 (D)
Net Weight	64 lbs (approx.)
Shipping Weight	71 lbs (approx.)
Control Complement	Touch Control System, Clock: 00 ~ 60, Microwave Power for

Variable Cooking Power level HIGH, 70% (Med.-High), 50% (Med.-Low),
20% (Low)

Product Usage Instructions

Safety Precautions

Before servicing the unit, read the safety precautions in the
manual. This device should only be serviced by qualified personnel.
Follow proper service procedures to ensure safe operation and avoid
exposure to excessive microwave energy.

Installation

Empty the microwave oven and clean it with a soft, damp
cloth.
Check for any damage such as misaligned door, damage around the
door, or dents inside or outside the cavity.
Place the oven on a strong counter, table, or shelf. Handle
with care, as the control panel side is heavier.

Frequently Asked Questions (FAQ)

Q: Can this microwave oven be used for residential

purposes?

A: No, this microwave oven is designed for commercial use only
and not recommended for built-in installation in residential
settings.

Q: What should I do before servicing the unit?

A: Read the safety precautions in the manual carefully and
ensure that only qualified service personnel handle the servicing
of the microwave oven.

“`

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Microwave Oven Service Manual
RFS12MPSB RFS12SW2B

CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

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
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; (1) interlock operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and latches, (5) evidence of dropping or abuse. C) Before turning on microwave power for any service test or inspection within the microwave generating compartments, check the magnetron, wave guide or transmission line, and cavity for proper 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 adjusted by procedures described in this manual before the oven is released to the owner. E) A microwave leakage check to verify compliance with the Federal Performance Standard should be performed on each oven prior to release to the owner.

LGE Internal Use Only

CONTENTS
(Page)
SAFETY PRECAUTIONS – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Inside front cover SPECIFICATIONS – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 1-1 CAUTIONS – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 2-1 INSTALLATIONS – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 3-1 OPERATING INSTRUCTIONS – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 4-1
FEATURES- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 4-1 CONTROL PANEL – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 4-1 COOKING DISPLAYS – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 4-3 OPERATION – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 4-4 PROGRAMMING – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 4-5 SCHEMATIC DIAGRAM – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 4-7 CIRCUIT DESCRIPTION – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 4-8 SERVICE INFORMATION – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5-1 TOOLS AND MEASURING INSTRUMENTS – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5-1 MICROWAVE LEAKAGE TEST – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5-1 MEASUREMENT OF MICROWAVE POWER OUTPUT – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5-3 DISASSEMBLY AND ADJUSTMENT – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5-3 INTERLOCK CONTINUITY TEST- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5-7 COMPONENT TEST PROCEDURE – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5-8 TROUBLE SHOOTING – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5-11 EXPLODED VIEW – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 6-1 Replacement Parts list – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 7-1

LGE Internal Use Only

SPECIFICATIONS

ITEM
MODEL Power Requiremen
Power Output Microwave Frequency Magnetron Timer Outside Dimensions Cavity Dimensions Net Weight Shipping weight Control Complement
Rating Label Location

DESCRIPTION
RFS12MPSB / RFS12SW2B 120 V~ 60 Hz 2000 watt (18 A) Single phase, 3 wire grounded
1200 watt full microwave power (IEC60705) 2450 MHz 2M246 0 ~ 60 min. 213/4″ (W) x 141/4″ (H) x 177/8″ (D) 141/4″ (W) x 87/8″ (H) x 163/8″ (D) 64 lbs (approx.) 71 lbs (approx.)
Touch Control System Clock : 00 ~ 60 Microwave Power for Variable Cooking Power level HIGH …………………………. Full power throughout the cooking time 70% (Med.-High) …………. approx. 70% of Full power 50% (Med.-Low) ………….. approx. 50% of Full power 20% (Low) ………………….. approx. 20% of Full power

Accessories

Time chart

This microwave oven is designed for commercial use only. It is not recommended for buelt-in Installation.

1-1

Only for training and service purposes

LGE Internal Use Only

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.
· DO NOT operate on a 2-wire extension cord during repair and use.
· NEVER TOUCH any oven components or wiring during operation.
· BEFORE TOUCHING any parts of the oven, always remove the power plug from the outlet.
· For about 30 seconds after the oven stops, an electric charge remains in the high voltage capacitor. When replacing or checking, you must discharge the high voltage capacitor by shorting across the two terminals with an insulated screwdriver.

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 connection. All input and output microwave connections, waveguide, flange, and gasket must be secure never operate the device without a microwave energy absorbing load attached. Never look into an open waveguide or antenna while the device is energized.
· Proper operation of the microwave oven requires that the magnetron be assembled to the waveguide and cavity. Never operate the magnetron unless it is properly installed.
· Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the magnetron.

ANTENNA

Gasket

· Remove your watches whenever working close to or replacing the Magnetron.
· DO NOT touch any parts of the control panel circuit. A resulting static electric discharge may damage this P.C.B.
· NEVER operate the oven with no load. · NEVER injure the door seal and front plate of the oven
cavity. · NEVER put iron tools on the magnetron. · NEVER put anything into the latch hole and the
interlock switches area.

MAGNETRON CHASSIS GROUND
MAGNETRON

COOLING FIN
FILAMENT TERMINALS

THE OVEN IS TO BE SERVICED ONLY BY PROPERLY QUALIFIED SERVICE PERSONNEL.

LGE Internal Use Only

2-1

Only for training and service purposes

INSTALLATION

BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY.

INSTALLING
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 or dents inside the cavity or on the exterior.
2. Put the oven on a counter, table, or shelf that is strong enough to hold the oven and the food and utensils you put in it. (The control panel side of the oven is the heavy side. Use care when handling.)
3. Do not block the vent and the air intake openings. Blocking vent or air intake openings can cause damage to the oven and poor cooking results. Make sure the microwave oven legs are in place to ensure proper air flow.
4. The oven should not be installed in any area where heat and steam are generated, because they may damage the electronic or mechanical parts of the unit. Do not install the oven next to a conventional surface unit or above a conventional wall oven.
5. Use microwave oven in an ambient temperature less than 104°F(40°C).
6. Place the microwave oven as far away as possible from TV, RADIO, COMPUTER, etc., to prevent interference.
7. Place the microwave oven on a stardy and flat surface.

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 electrical shock. The plug must be plugged into an outlet that is properly installed and grounded.
WARNING
Improper use of the grounding plug can result in a risk of electric shock. Do not, under any circumstances, cut or remove the third ground prong from the power cord plug.
PREFERRED METHOD

A A
A B

ENSURE PROPER GROUND EXISTS BEFORE USE

A – Allow at least 11/2 inches (3.81 centimeters) of clearance around top and sides of equipment. Proper air flow around equipment cools electrical components. With restricted air flow, oven may not operate properly and life of electrical parts is reduced.
B – Allow at least 3 inches from door front to edge of countertop to avoid accidental tipping of oven.

3-1

Only for training and service purposes

LGE Internal Use Only

OPERATING INSTRUCTIONS
FEATURES
Window Door Screen

Electronic Control

CONTROL PANEL

Safety Door Lock System
Display
Some items in display can be seen but will not glow.

RFS12MPSB
LGE Internal Use Only

Pads

TIME ENTRY

Use to enter heating time without changing preprogrammed number pads.

Pads 1-0

Use to begin heating with preprogrammed times and power levels or to enter times for “Manual Time Entry” cooking.

HOLD 0%,

Use to select power level. Oven can heat at

DEFROST 20%, full or reduced power. If oven power level is

MEDUIM 50%, set to 0% oven does not heat for

MED-HI 70% programmed time. If no power level is

selected, oven operates at 100% power.

STOP/RESET Use to exit programming mode and stop cooking during cooking cycle.

START

Use to start “Manual Time Entry” program or restart interrupted cooking cycle. Use to advance to next user option. Use to save times and power levels when programming pads.

QTY2x

Use to automatically increase the programmed time for double quantities.

4-1

Only for training and service purposes

OPERATING INSTRUCTIONS
FEATURES
Window Door Screen

Electronic Control

CONTROL PANEL

Safety Door Lock System
Display
Some items in display can be seen but will not glow.

RFS12SW2B
Copyright © 2009 LG Electronics. Inc. All right reserved. Only for training and service purposes

Pads

TIME ENTRY
Pads 1-0
HOLD 0%, DEFROST 20% MEDUIM 50%, MED-HI 70%
STOP/RESET
START

Use to enter heating time without changing preprogrammed number pads.
Use to begin heating with preprogrammed times and power levels or to enter times for “Manual Time Entry” cooking.
Use to select power level. Oven can heat at full or reduced power. If oven power level is set to 0% oven does not heat for programmed time. If no power level is selected, oven operates at 100% power.
Use to exit programming mode and stop cooking during cooking cycle.
Use to start “Manual Time Entry” program or restart interrupted cooking cycle. Use to advance to next user option. Use to save times and power levels when programming pads.

4-2

LGE Internal Use Only

Cooking Cooking Displays Programming Displays

Shows when power is connected to oven. Open and close door to clear.
READY shows when oven control will accept entries. Appears after oven door is opened and closed.
33:33 shows heating time. When more than 1 heating stage is programmed, total time for all stages displays. COOK shows when oven is operating. 20 indicates the microwave power level used. If power level does not show, oven is heating at 100% power.
Indicates programming mode. See “Programming” section of manual for programming procedure.
Indicates programming user options mode. See “User Options” section of manual for programming procedure.

LGE Internal Use Only

4-3

Only for training and service purposes

Operation
CAUTION
To avoid fire, do not dry newspapers or clothes in microwave oven.
Interrupting Operation
· Open oven door to interrupt operation. Oven fan continues to operate. Close door and press START pad to resume oven operation.
· Press STOP/RESET pad to interrupt operation. Display continues to show countdown time. Press START pad to resume oven operation and countdown timing.
Canceling Mistakes
· If oven is operating,press STOP/RESET pad once to stop oven, then again to clear display.
· If oven door is open and time shows in display, close oven door and press STOP/RESET pad to clear display.
Operating Preprogrammed Pads
Oven has 10 ~20 preprogrammed number pads. Instructions are written for factory programmed ovens. Ovens that are reprogrammed can respond differently than described below. 1. Open oven door , place food in oven, and close
oven door · If pad is not pressed in 30 seconds, open and
close oven door again. 2. Press desired number pad.
· Oven operates and time counts down. 3. Oven stops heating and oven signal sounds when
heating timing elapses.

Operating QTY 2X Pads

1. Press

Pad.

2. Press desired number pad

· Example : press

= 18 sec.

Preprogrammed Times and Cook Level All preprogrammed pads arrive set at full power.

Option: Single Digit

Option: Double Digit

Pads Heating Pads Heating Pads Heating

Times

1 10 sec.

1 10 sec. 11 20 sec.

2 20 sec.

2 20 sec. 12 40 sec.

3 30 sec.

3 30 sec. 13 1 min.

4 45 sec.

4 45 sec. 14 1:30 min.

5 1 min.

5 1 min. 15 2 min.

6 1:30 min. 6 1:30 min. 16 3 min.

7 2 min.

7 2 min. 17 4 min.

8 3 min.

8 3 min. 18 6 min.

9 4 min.

9 4 min. 19 8 min.

0 5 min.

10 5 min. 20 10 min.

Manual Time Entry
Manual Time Entry feature allows the operator to enter time and power levels, and heat without changing the preprogrammed pads. 1. Open oven door, place food in oven, and close
door. · Display shows “READY”. · If pad is not pressed in 30 seconds, open and
close oven door again. 2. Press TIME ENTRY pad.
· Display shows “00:00”. 3. Press number pads to nter desired cooking time.
· For example, to heat for 2 minutes 30 seconds, press 2, 3, and 0 pads.
4. Press desired power level pad to change power level. · If a power level pad is not pressed, oven defaults to 100% power. · For xample, pressing MEDIUM 50% pad sets oven to 50% power. · Display shows current power level if other than 100 percent power.
5. Press START pad. · Oven operates and time counts down.
6. Oven stops heating and oven signal sounds when heating timing elapses.

4-4

Only for training and service purposes

LGE Internal Use Only

PROGRAMMING
Preprogrammed Number Pads
Oven has 10 preprogrammed number pads. Follow instructions below to program heating times and power levels for customized cooking.
1. Open oven door. · If door is closed or STOP/RESET pad is pressed before finishing programming sequence, oven exits programming mode.
2. Press and hold pad 1 for approximately 5 seconds. · After 5 seconds, signal sounds. Display shows “PROGRAM” indicating program mode.
3. Press desired number pad. · Display shows heating time, “COOK LEVEL” and power level if other than 100 percent power.
4. Press number pads to enter desired cooking time. · For example, to heat for 2 minutes 30 seconds, press 2, 3, and 0 pads.
5. Press desired power level pad to change power level. · If a power level pad is not pressed, oven defaults to 100% power. · For example, pressing MEDIUM 50% pad sets oven to 50% power. · Display shows current power level if other than 100% power.
6. Press START pad to save new heating time and power level in oven memory. · Repeat step 3-6 to program additional pads.
7. Press STOP/RESET pad or close oven door to exit programming mode.

Multiple Heating Stages
Follow instructions below to program oven to perform 3 consecutive heating cycles without interruption.
1. Open oven door. · If door is closed or STOP/RESET pad is pressed before finishing programming sequence, oven exits programming mode.
2. Press pad 1 for approximately 5 seconds. · After 5 seconds, signal sounds.
3. Press desired number pad. · Display shows heating time and preprogrammed number.
4. Press number pads to enter desired cooking time. · For example, to heat for 2 minutes 30 seconds,
5. Press desired power level pad to change power level. · If a power level pad is not pressed, oven defaults to 100% power. · For example, pressing MEDIUM 50% pad sets oven to 50% power. · Display shows current power level if other than 100 percent power.
6. Press TIME ENTRY pad · Display briefly shows “STAGE 2”. Then cook time and power level for stage show in display. · Repeat steps 5-6 to create additional stages.
7. Press START pad to save new heating time and power level in oven memory.
8. Press STOP/RESET pad or close oven door to exit programming mode.

LGE Internal Use Only

4-5

Only for training and service purposes

User Options
Follow the instructions below to customized the microwave oven’s operation. End-of-cycle signal, maximum heating time and other options can be changed to meeting your cooking needs.
1. Open oven door. · If door is closed or STOP/RESET pad is pressed before finishing programming sequence, oven exits programming mode.
2. Press and hold pad 2 for approximately 5 seconds. · After 5 seconds, signal sounds. Display shows “OPTION”.
3. Press number pad that matches desired option. · “OP” represents optional program mode, first number represents option number and second number represents functions currently selected for option.

4. Press START pad to advance to next option. See table for options.
5. Press number pad (0,1-3) to change option. 6. Press START pad to save changes.
· Repeat steps 4-6 to change additional options. 7. Press STOP/RESET pad or close oven door to exit
programming mode.

Optional Program Pad Option

Indicator

Number Selected

4-6

Only for training and service purposes

LGE Internal Use Only

SCHEMATIC DIAGRAM

LGE Internal Use Only

4-7

Only for training and service purposes

CIRCUIT DESCRIPTION
GENERAL DETAILS
· 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).
WHEN SELECTING COOKING POWER LEVEL AND TIME
· The micom controller memorizes the function you set. · The time you set appears in the display window. · Each indicator light turns on to indicate that the stage
has been set.
WHEN TOUCHING THE START PAD
· The coil of the relay is energized by the micom controller.
· Power input is supplied to the high voltage transformer through the fuse to top primary switch and relay 3 (208V : relay 4) and the btm primary switch and realy 5 (208V : relay 6).
· Stirrer fan rotates.

· A high voltage of approximately 2100 volts AC is generated in the secondary of the high voltage transformer which is increased by the action of the high voltage diode and charging of the high voltage capacitor.
· The negative 4,000 Volts DC is applied to the filament of the magnetron.
WHEN THE OVEN IS SET AT ANY LEVEL EXCEPT MAXIMUM.
· The micom controller controls the ON-OFF time of relay 3 and relay 5 (208V : relay 4 & relay 6) by the applied signal to vary the average output power of microwave oven as POWER LEVEL. (refer to page 1-1)
· One complete cycle of relay 3 is 12.
WHEN THE DOOR IS OPENED DURING COOKING
· Between the btm primary switch and relay 5 (208V : relay 6) and top primary switch and relay 3 (208V : relay 4) cut off the primary winding voltage of the high voltage transformer.
· ON-OFF of relay 3 relay 5 (208V : relay 4 and relay 5) is coupled electrically with opening and closing of the secondary switch.
· When the door is opened, the secondary switch is opened and when the door is closed, the secondary switch is closed.
· The cooking time stops counting down. · Relay stops functioning. · As the door is opened, if the contact of top primary
switch and relay 3 (208V : relay 4) and the btm primary switch and relay 5 (208V : relay 6) and/or secondary switch fail to open, the fuse opens due to the large current surge caused by the monitor switch activation, which in turn stops magnetron oscillation.

· The fan motor rotates and cools the magnetron by blowing the air (coming from the intake on the baseplate).
· The air is also directed into the oven to exhaust the vapor in the oven through the upper plate.
· Cooking time starts counting down. · 3.3 volts AC is generated from the filament winding of
the high voltage transformer. This 3.3 volts is applied to the magnetron to heat the magnetron filament through two noise-preventing choke coils.

4-8

Only for training and service purposes

LGE Internal Use Only

SERVICE INFORMATION

TOOLS AND MEASURING INSTRUMENTS

NECESSARY TOOLS
Tools normally used for TV servicing are sufficient. Standard tools are listed below.
· Diagonal pliers · Long nose pliers · Phillips screwdriver · Flat blade screwdriver · Wrench (size 5mm) · Nutdriver (size 5mm) · Adjustable wrench · Soldering iron · Solder · Vinyl insulation tape · Polishing cloth
MICROWAVE LEAKAGE TEST

NECESSARY MEASURING INSTRUMENTS
· TESTER (VOLTS-DC, AC, Ohmmeter) · Microwave survey meter
– Holaday HI-1500 HI-1501
– Narda 8100 8200
· Inch scale · 600 cc non conductive material beaker (glass or plastic),
inside diameter: approx. 8.5 cm (31/2 in.)
· Cylindrical and made of borosilicate glass vessel. max. thickness: 3 mm outside diameter: approx. 190mm height: approx. 90mm
· Glass thermometer: 100°C or 212°F (1 deg scale)

CAUTIONS
· Be sure to check microwave leakage prior to servicing the oven if the oven is operative prior to servicing.
· The service personnel should inform the manufacturer, importer, or assembler of any certified oven unit found to have a microwave emission level in excess of 5 mW/cm2 and should repair any unit found to have excessive emission levels at no cost to the owner and should ascertain the cause of the excessive leakage. The service personnel should instruct the owner not to use the unit until the oven has been brought into compliance.
· If the oven operates with the door open, the service personnel should: – Tell the user not to operate the oven. – Contact the manufacturer and CDRH (Center for Devices and Radiological Health) immediately.
NOTE: Address on CDRH Office of Compliance(HFZ-312) Center for Devices and Radiological Healthe 1390, Piccard Drive, Rockville. MD 20850
· The service personnel should check all surface and vent vent openings for microwave leakage.
· Check for microwave leakage after every servicing. The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 4 mW/cm2. Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage.

MEASURING MICROWAVE ENERGY LEAKAGE
· Pour 275±15cc of 20±5°C(68±9°F) water in a beaker which is graduated to 600 cc, and place the beaker on the center of the turntable.
· Set the energy leakage monitor to 2,450 MHz and use it following the manufacturer’s recommended test procedure to assure correct result.
· When measuring the leakage, always use the 2-inch (5cm) spacer supplied with the probe.
· Operate the oven at its maximum output. · Measure the microwave radiation using and
electromagnetic radiation monitor by holding the probe perpendicular to the surface being measured
Move probe along shaded area
Probe scanning speed Less than 2.5 cm/sec (1 in/sec)

LGE Internal Use Only

5-1

Only for training and service purposes

MEASUREMENT WITH OUTER CASE REMOVED
· When you replace the magnetron, measure for microwave energy leakage before the outer case is installed and after all necessary components are replaced or adjusted. Special care should be taken in measuring the following parts. (Circled area of Fig. below) – Around the magnetron – The waveguide
WARNING : AVOID CONTACTING ANY HIGH VOLTAGE PARTS

NOTES WHEN MEASURING
· Do not exceed meter full scale deflection. · The test probe must be moved no faster than
1 inch/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. · When testing near a corner of the door, keep the probe perpendicular to the surface making sure the probe is moved horizontally along the oven surface.
RECORD KEEPING AND NOTIFICATION AFTER MEASUREMENT
· After adjustment and repair of any microwave energy interruption or microwave energy blocking device, record the measured values for future reference. Also enter the information on the service invoice.
· The microwave energy leakage should not be more than 4 mW/cm.sq. after determining that all parts are in good condition, functioning properly and genuine replacement parts which are listed in this manual have been used.
· At least once a year, have the electromagnetic energy leakage monitor checked for calibration by its manufacturer.

MEASUREMENT WITH A FULLY ASSEMBLED OVEN
· After all components, including the outer case, are fully assembled, measure for microwave energy leakage around the door viewing window, the exhaust opening, and air inlet openings.
· Microwave energy leakage must not exceed the values prescribed below.
NOTE: Leakage with the outer case removed less than 5 mW/cm.sq. Leakage for a fully assembled oven (Before the latch switch (primary) is interrupted) with the door in a slightly opened position-less than 2 mW/cm.sq.

5-2

Only for training and service purposes

LGE Internal Use Only

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 3 mm and an outside diameter of approximately 190 mm.
· The oven and the empty vessel are at ambient temperature prior to the start of the test.
· The initial temperature (T1) of the water is (10±2)°C It is measured immediately before the water is added to the vessel. After addition of the water to the vessel, the load is immediately placed on the center of the ceramic plate which is in the lowest position and the microwave power switched on.
· The time T for the temperature of the water to rise by a value T of (10±2)°K is measured, where T is the time in seconds and T is the temperature rise. The initial and final water temperatures are selected so that the maximum difference between the final water temperature and the ambient temperature is 5°K.

· The microwave power output P in watts is calculated from the following formula :
P = 4187 x (T) + 0.55 X (T2 – T0 ) X M T
· T2: Temperature after heating · T0: Temperature of bowl · M: Weight of bowl
is measured while the microwave generator is operating at full power. Magnetron filament heat-up time is not included. (about 3 sec) · The water is stirred to equalize temperature throughout the vessel, prior to measuring the final water temperature. · Stirring devices and measuring instruments are selected in order to minimize addition or removal of heat.

WATER LOAD

CERAMIC PLATE

DISASSEMBLY AND ADJUSTMENT
A. OUTER CASE REMOVAL

Disconnect the power supply cord from the outlet. 2) Remove the screws from the rear of the case.
The outer case must be moved backward to be lifted off.
B. POWER SUPPLY CORD
Remove the outer case. 2) Disconnect two terminals, and remove one screw of
the ground terminal.
C. CONTROL PANEL ASSEMBLY
Open the door. 2) Remove the screw for securing the control panel. 3) Disconnect the leadwire from RELAY of the PCB SUB
ASS’Y. 4) Disconnect the leadwire from connector (CN1) of the
PCB SUB ASS’Y. 5) Lift up and pull out control panel assembly carefully
from the cavity.
CAUTION: DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE SERVICING (refer to page 2-1)

Remove the screw Lift up and pull out control panel

LGE Internal Use Only

5-3

Only for training and service purposes

D. PCB ASSEMBLY REMOVAL

Remove the control panel assembly from the cavity. (Refer to control panel assembly removal on previous page.)
Remove screws which hold the PCB SUB ASS’Y to the control panel.
Disconnect the flat cable from the PCB SUB ASS’Y and take off the PCB SUB ASS’Y
Control Panel PCB Sub Asm

Remove choke cover

E. DOOR ASSEMBLY / REMOVAL

Open the door. 2) Remove the choke cover cap very carefully with a flat-
blade screwdriver. CAUTION: Be careful not to damage door seal plate
by screwdriver. 3) Lift up and push the door.
NOTE: 1. After replacing the door, be sure to check that the
primary switch, monitor switch, and secondary switch operate normally. 2. After replacing the door, check for microwave energy leakage with a survey meter. Microwave energy must be below the limit of 4 mW/cm2. (with a 275 ml water load) 3. When mounting the door assembly to the oven assembly, be sure to adjust the door assembly parallel to the chassis. Also adjust so the door has no play between the inner door surface and oven frame assembly. If the door assembly is not mounted properly, microwaves may leak from the clearance between the door and the oven.

5-4

Only for training and service purposes

Remove door assembly Door seal plate
Spacer
LGE Internal Use Only

F. MAGNETRON REMOVAL

Disconnect the lead wire from the magnetron. 2) Remove the duct ASS’Y. 3) Carefully remove the mounting screws holding the
magnetron and the waveguide. 4) Remove the magnetron ASS’Y until the tube is
clear from the waveguide.
NOTE: 1. When removing the magnetron, make sure its
dome does not hit any adjacent parts, or it may be damaged. 2. When replacing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition. 3. After replacing the magnetron, check for microwave leakage with a survey meter around the magnetron. Microwave energy must be below the limit of 5 mW/cm2. (With a 275 ml. water load). Make sure that gasket is rigidly attached to the magnetron. To prevent microwave leakage, tighten the mounting screws properly, making sure there is no gap between the waveguide and the magnetron.

G. REMOVING THE BOTTOM STIRRER FAN MOTOR

Lay the unit down on its back. 2) Remove the screw securing the base cover.
Disconnect the leadwire from the stirrer fan motor
terminals. 4) Remove the screw securing the stirrer fan motor to
the oven cavity ASS’Y 5) After repairing the motor, replace the removed
base cover. 6) The taptite screw shall be used when a turntable
motor cover is secured with a screw.
NOTE: 1. Remove the wire lead from the stirrer fan motor
VERY CAREFULLY. 2. Be sure to grasp the connector, not the wires, when
removing.

LGE Internal Use Only

Magnetron

Taptite Screw

Base cover

Wire Leads Stirrer Fan Motor

5-5

Only for training and service purposes

H. HIGH VOLTAGE TRANSFORMER REMOVAL

Discharge the high voltage capacitor. 2) Disconnect the lead wire from magnetron, high voltage
transformer, and capacitor. 3) Remove the screw holding the high voltage
transformer to the baseplate.
I. BLOWER MOTOR ASSEMBLY REMOVAL
Discharge the leadwire from blower 2) Remove the two screws holding the blower motor
bracket to the upper plate. 3) Remove the screw holding the blower motor bracket
to the back cover. 4) Romove the screw holding the high voltage capacitor
bracket. 5) Remove the screw holding the duct Ass’y.
J. HIGH VOLTAGE CAPACITOR AND DIODE REMOVAL
Discharge the high voltage capacitor. 2) Disconnect the leadwire from high voltage capacitor. 3) Remove the screw holding the high voltage diode
earth screw. 4) Remove the screw holding the high voltage capacitor
bracket.
Blower Motor ASS’Y

K. 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.
MOUNTING OF THE PRIMARY/MONITOR/ SECONDARY SWITCHES TO THE LATCH BOARD
INSTALLATION AND ADJUSTMENT OF THE LATCH BOARD TO THE OVEN ASSEMBLY
· Mount the latch b oard to the oven assembly. · Adjust the latch board in the arrow direction so that
oven door will not have any play in it when the door is closed. · Tighten the mounting screw. · Check for play in the door by pushing the door release button. Door movement should be less than 0.5 mm. (1/64 inch) Don’t push the door release button while making this adjustment. Make sure that the latch moves smoothly after adjustment is completed and that the screws are tight. Make sure the primary, monitor, and secondary switches operate properly by following the continuity test procedure.following the continuity test procedure.
ADJUSTMENT DIRECTION

H.V capacitor bracket
H.V Transformer

Suction Guide
H.V Transformer

MONITOR SWITCH
PRIMARY SWITCH
SECONDARY SWITCH

5-6

Only for training and service purposes

LGE Internal Use Only

INTERLOCK CONTINUITY TEST

WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.
TYPE NO. SZM-V 16-FD-63 OR V-16-3C 25 FOR PRIMARY SWITCH TYPE NO. SZM-V 16-FD-62 OR V-16-2C 25 FOR MONITOR SWITCH TYPE NO. SZM-V 16-FD-63 OR V-16-3C 25 FOR SECONDARY SWITCH

A. PRIMARY INTERLOCK SWITCH TEST
When the door release button is depressed slowly with the door closed, an audible click should be heard at the same time or successively at intervals. When the button is released slowly, the latches should activate the switches with an audible click. If the latches do not activate the switches when the door is closed, the switches should be a adjusted in accordance with the adjustment procedure. Disconnect the wire lead from the primary switch. Connect the ohmmeter leads to the common (COM) and normally open (NO) terminal of the switch. The meter should indicate an open circuit in the door open condition. When the door is closed, the meter should indicate a closed circuit. When the primary switch operation is abnormal, make the necessary adjustment or replace the switch only with the same type of switch.

B. SECONDARY INTERLOCK SWITCH TEST
Disconnect the wire lead from the secondary switch. Connect the ohmmeter leads to the common (COM) and normally open (NO) terminals of the switch. The meter should indicate a open circuit in the door open condition. When the door is closed, meter should indicate an closed circuit. 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 switch. Connect the ohmmeter leads to the common (COM) and normally closed (NC) terminals of the switch. The meter should indicate closed circuit in the door open condition. When the door is closed, meter should indicate an open circuit. When the monitor switch operation is abnormal, replace with the same type of switch. NOTE: After repairing the door or the interlock system, it is necessary to do this continuity test before operating the oven.

COMPONENTS
SWITCHES (Wire leads removed)

TEST PROCEDURE
Check for continuity of the switch with an Ohm-meter

RESULTS

Door open

Door closed

Primary Switch

NO COM

Monitor Switch

NC COM

LGE Internal Use Only

Secondary Switch

NO COM

NOTE : After checking for the continuity of switches, make sure that they are connected correctly.

5-7

Only for training and service purposes

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
HIGH VOLTAGE TRANSFORMER (Wire leads removed)

TEST PROCEDURE

FILAMENT WINDING

SECONDARY TERMINAL
PRIMARY TERMINAL

RESULTS

MAGNETRON (Wire leads removed)

1. Measure the resistance. (Ohm-meter scale: Rx1 and Rx100) · Primary winding · Secondary winding · Filament winding

208V Approx.: 0.8 ~ 1.0 ohm Approx.: 70 ~ 80ohm Less than: 1 ohm

220-240 V 0.9 ~ 1.1 ohm 70 ~ 80 ohm

2. Measure the resistance. (Ohm-meter scale: Rx1000) · Primary winding to ground · Filament winding to ground

Normal: Infinite Normal: Infinite

1. Measure the resistance. (Ohm-meter scale: Rx1) · Filament terminal
2. Measure the resistance. (Ohm-meter scale: Rx1000) · Filament to chassis

Normal: Less than 1 ohm Normal: Infinite

5-8

Only for training and service purposes

LGE Internal Use Only

COMPONENTS

TEST PROCEDURE
Antenna Gasket Chassis

RESULTS

HIGH VOLTAGE CAPACITOR

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.

Measure the resistance. (Ohm-meter scale: Rx1000) · Terminal to terminal.

Normal: Momentarily indicates several ohms, and then gradually returns to infinite.

Measure the resistance. (Ohm-meter scale: Rx1000) · Terminal to case.

Normal: Infinite.

HIGH VOLTAGE DIODE

Measure the continuity (Forward). (Ohm-meter scale: Rx10000)

Normal: Continuity. Abnormal: Infinite.

NOTE : Some inexpensive meters may indicate infinite resistance in both direction.

Measure the continuity (Reverse). (Ohm-meter scale: Rx10000)

Normal: Infinite. Abnormal: Continuity.

LGE Internal Use Only

5-9

Only for training and service purposes

COMPONENTS

TEST PROCEDURE

208V: RELAY 4 / RELAY 6 220-240V: RELAY 3 / RELAY 5

Check for continuity of relay 3 an ohm-meter. (Remove wire leads from relay 2 and operate the unit.)

Relay 3

RESULTS

POWER LEVEL

1

3 sec

9 sec

2

4 sec

8 sec

3

5 sec

7 sec

4

6 sec

5

7 sec

6

8 sec

4 sec

7

9 sec

3 sec

8

10 sec

2 sec

9

11 sec

1 sec

10

12 sec

0 sec

BLOWER MOTOR (Wire leads removed)
STIRRER MOTOR (Wire leads removed)

Measure the resistance. (Ohm-meter scale: R x 100)
208V 220-240V 0V
Measure the resistance. (Ohm-meter scale: R x 1)

Normal: Approx. 208V: 28~31 ohm 220-240V: 31~35 ohm
Abnormal: Infinite or several K-ohm.
Normal: Approx. 12~14 kohm Abnormal: Infinite or several ohm.

NOTE : · A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON.
· MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION. · WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE TO GRASP THE
CONNECTOR, NOT THE WIRES.

5-10

LGE Internal Use Only

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. When checking the continuity of the switches or of the high voltage transformer, disconnect one lead wire
from these parts and then check continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter. 5. Do not touch any part of the circuit on the PCB since static electric discharge may damage this control panel. Always touch yourself to ground while working on this panel to discharge any static charge built up in your body. (Micom model only)

CONDITION
Microwave oven does not work.
Output power is too low.
Sparks occur.
Uneven cooking.
LGE Internal Use Only

CAUSE

REMEDY

Inserting many plugs into one outlet and using them at the same time (blown fuse or breaker)
Microwave oven plug is not inserted tightly.

Avoid using other electrical appliances when you use the microwave oven.
Insert microwave oven plug securely.

Low AC input voltage. Food temperature is too low.

Use the microwave oven at adequate line voltage.
This may not be a defect. It is possible that the food should be cooked for a longer time period.

Using metallic ware and allowing it to touch the oven wall.
Ceramic ware trimmed in gold or silver powder is used.

Do not use metallic ware for cooking except that noted in the cooking guide.
Do not use any type of cookware with metallic trimming.

Inconsistent intensity of microwave by their characteristics.
Display “CALL SERVICE”
5-11

1. Use plastic wrap or lid. 2. Stir once or twice while
cooking soup, cocoa or milk, etc.
This may be cause incomplete connect to H.V. transformer.
Copyright © 2009 LG Electronics. Inc. All right reserved. Only for training and service purposes

(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. Specific numbers (for example 7 or 9) will not display when key pad is touched. 7. Display does not count down with time blinking or up with clock operation. 8. Display obviously jumps in time while counting down. 9. Display counts down too fast while cooking. 10. Each indicator light does not turn on after setting cooking cycle. 11. Display time of day does not reappear when cooking is finished.

CONDITION

CHECK

1. No input can be programmed.

Check the connection between membrane key assembly and PCB assembly.

2. Some inputs cannot be programmed.
3. Display shows a number or figure different from one touched.

Replace key membrane assembly and check operation.

4. Random programming when touching other pads.
5. Display is fixed at some figure and can not accept any input.

RESULT
Continuity. No continuity. Everything works as specified.
Still have trouble.

CAUSE
Defective PCB assembly.
Loose connection.
Defective key membrane assembly.
Defective PCB assembly.

REMEDY
Replace PCB assembly.
Connect them tightly.
Replace key membrane assembly.
Replace PCB assembly.

5-12

LGE Internal Use Only

(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).
Replace fuse
Check continuity of primary switch (with door opened).

RESULT
Continuity. No continuity.
Continuity. No continuity.

Check continuity of secondary switch (with door opened).

Continuity. No continuity.

Disconnect one side of the wire lead connected from transformer to the high voltage capacitor and operate the unit.

Fuse blows again Normal.

CAUSE
Malfunction of the monitor switch.
Shorted contact at the primary switch.
Malfunction of secondary switch.
Defective high voltage transformer.

REMEDY
Replace fuse, primary, monitor, secondary switches, and RELAY(RY3, 5 or RY4, 6 ) of P.C.B Assembly.
Replace fuse, primary, monitor, secondary switches, and RELAY(RY3,5 or RY4,6 ) of P.C.B Assembly.
Replace fuse, primary, monitor, secondary switches, and RELAY(RY3,5 or RY4,6 ) of P.C.B Assembly.
Replace high voltage transformer.

Measure to resistance high voltage capacitor (refer to page 5-9)

Normal. Abnormal.

Defective high voltage capacitor.

Set is good condition (defective fuse only)
Replace high voltage capacitor.

NOTE : All these switches must be replaced at the same time. Refer to page 5-7, 5-8

2. Fuse does not blow.

Check continuity of thermostat.

No continuity.

Defective thermostat.

Replace thermostat.

Continuity.

LGE Internal Use Only

Check continuity of power supply cord.

No continuity. 5-13

Defective power supply cord.

Replace power supply cord.

(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
1.Setting time does not count down when touching START pad.

CHECK
Check continuity of secondary switch (with door closed).

2. Blower motor or oven lamp do not turn on.

Check the connection between CN1 connector and PCB assembly.
Check blower motor.
Check oven lamp.

RESULT
No continuity. Continuity.
Continuity No continuity
Abnormal. Abnormal. Normal.

CAUSE
Defective secondary switch.

REMEDY
Replace secondary switch.

Defective PCB assembly.
Loose connection.
Defective blower motor.
Defective oven lamp.

Replace PCB assembly.
Connect them tightly.
Replace blower motor.
Replace oven lamp.

(TROUBLE 4) Oven seems to be operating but little heat is produced in oven load.

CONDITION

CHECK

RESULT

CAUSE

REMEDY

Output is low.

Check the power source voltage.
Disconnect the wire leads from relay 3, 5 or relay 4, 6 and check on and off time with multitester.

Lower than 90% of rating voltage. Normal.
Abnormal. Normal.

Decrease in power source voltage with load.
Defective PCB assembly.

Suggest customer contact local electric power utility co. or qualified electrician.
Replace PCB assembly.

Measure the output power.

Abnormal.

Defective magnetron.

Replace magnetron.

NOTE: Simple test of power output-conducted by heating one liter water for one min. if available. Minimum 8.5°C temperature rise is normal condition.

5-14

LGE Internal Use Only

(TROUBLE 5) No microwave oscillation even though oven lamp and blower motor run. (Display operates properly)

CONDITION
No microwave oscillation.

CHECK
Disconnect the wire leads from relay 3,5 or relay 4,6 and check continuity of relay 3,5 or relay 4,6 (Operate the unit)
Check high voltage transformer

RESULT
No continuity. Continuity.
Abnormal Normal

CAUSE
Defective PCB assembly
Defective high voltage transformer.

REMEDY
Replace PCB assembly
Replace high voltage transformer.

Check high voltage capacitor

Abnormal Normal

Defective high voltage capacitor.

Replace high voltage capacitor.

Check high voltage diode
Check magnetron.

Abnormal Normal Abnormal

Defective high voltage diode.

Replace high voltage diode.

Defective magnetron.

Replace magnetron.

NOTE : · Make sure the wire leads are in the correct position. · When Removing the wire leads from the parts, be sure to grasp the connector, not the wires. · When removing the magnetron, be sure to install the magnetron gasket in the correct position and in good condition.

Output is full power when you set lower power level.
LGE Internal Use Only

Disconnect the wire leads from relay 3,5 or relay 4,6 and check continuity of relay 3,5 or relay 4,6 (Operate the unit)

Abnormal. 5-15

Defective PCB assembly.

Replace PCB assembly.