LG MS-3446VR User Manual

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MICROWAVE OVEN

SERVICE MANUAL

MODEL: MS-3446VR

CAUTION

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

Website http://biz.lgservice.com

P/NO : MFL31039001

May, 2006

Printed in Korea

삼 흥

정 판

Questions and Answers:

M
Mia MillerJul 31, 2025
Why is my LG MS-3446VR Microwave Oven running but not heating?
- K
  Karen DiazJul 31, 2025
  If your LG Microwave Oven seems to be operating but isn't producing much heat, it could be due to several reasons. One possible cause is that the power source voltage is lower than 90%. In this case, it's suggested you contact your local electric power utility company or a qualified electrician. Another cause can be a defective PCB assembly, which would need replacement. Finally, a defective magnetron could also be the reason; this part would also need to be replaced.
R
Ryan BrownAug 6, 2025
Why won't my LG MS-3446VR heat, even though the light and fan are on?
- F
  farmertinaAug 6, 2025
  If your LG Microwave Oven lamp and fan motor run, but there's no microwave oscillation and the display operates properly, it could be due to a defective PCB assembly, high voltage capacitor, high voltage diode, or magnetron. Each of these components would need to be replaced.
L
Louis Fisher MDAug 12, 2025
Why are there sparks in my LG Microwave Oven?
- S
  smithmichaelAug 12, 2025
  Sparks inside your LG Microwave Oven can occur if you're using metallic ware or allowing it to touch the oven wall. Avoid using metallic ware for cooking unless specifically noted in the cooking guide. Also, do not use ceramic ware trimmed with gold or silver powder, as this can also cause sparks.
J
Jenna CastroAug 18, 2025
Why is the output power so low on my LG Microwave Oven?
- T
  Tina WoodsAug 18, 2025
  If your LG Microwave Oven isn't heating food adequately, it might not be a defect. It's possible that the food needs to be cooked for a longer time. Also, ensure that you are using the microwave oven at adequate line voltage, as low AC input voltage can cause low output power.

LG MS-3446VR Specifications

General

Brand	LG
Model	MS-3446VR
Category	Microwave Oven
Language	English

Summary

SAFETY PRECAUTIONS

MICROWAVE ENERGY EXPOSURE

Precautions to avoid exposure to microwave energy during service.

RADIATION CAUTION

Warning regarding microwave radiation from the generator.

CAUTIONS

HIGH-VOLTAGE HAZARDS

Warnings and precautions related to high voltage components.

MAGNETRON HANDLING

Specific handling instructions for the magnetron.

INSTALLATION

INSTALLING PROCEDURES

Steps for correctly installing the microwave oven.

EARTHING REQUIREMENTS

Instructions for proper electrical earthing of the appliance.

OPERATING INSTRUCTIONS

FEATURES OVERVIEW

Description of the microwave oven's features and functions.

CONTROL PANEL LAYOUT

Identification and function of control panel buttons.

OPERATING SEQUENCE

BASIC & TIME-BASED OPERATIONS

Instructions for Auto Touch, Time Cooking, and More/Less operations.

SPECIAL COOKING MODES

Instructions for Multi-Stage, Auto Defrost, Q-Defrost, Auto Cook, Auto Reheat.

SAFETY & LOCK FEATURES

Information on Child Lock and other safety features.

SCHEMATIC DIAGRAM

CIRCUIT DESCRIPTION

GENERAL CIRCUIT DETAILS

Overview of the microwave's electrical system and components.

OPERATIONAL CIRCUITRY

Description of circuits during operation, start, and door opening.

SERVICE INFORMATION

TOOLS AND MEASURING INSTRUMENTS

Lists necessary tools and instruments for servicing.

MICROWAVE LEAKAGE TESTING

Procedures and precautions for testing microwave leakage.

MICROWAVE POWER OUTPUT MEASUREMENT

DISASSEMBLY AND ADJUSTMENT

EXTERNAL COMPONENT REMOVAL

Instructions for removing outer case, power cord, control panel.

INTERNAL COMPONENT REMOVAL

Instructions for removing PCB, door, air duct, magnetron, motor.

HIGH VOLTAGE & INTERLOCK SYSTEMS

Procedures for removing HV transformer, capacitor, diode, and interlock system.

INTERLOCK CONTINUITY TEST

PRIMARY INTERLOCK SWITCH TEST

Procedure to test the primary interlock switch continuity.

SECONDARY & MONITOR SWITCH TESTS

Procedures to test secondary and monitor switch continuity.

COMPONENT TEST PROCEDURE

HIGH VOLTAGE TRANSFORMER & MAGNETRON TESTS

Resistance tests for the high voltage transformer and magnetron.

HV CAPACITOR, DIODE, & MOTOR TESTS

Tests for HV capacitor, diode, relay, fan motor, and turntable motor.

TROUBLE SHOOTING

CONTROL CIRCUIT ISSUES

Troubleshooting display and input problems.

POWER SUPPLY & FUSE PROBLEMS

Troubleshooting power, fuse, and thermostat issues.

COOKING & HEATING PROBLEMS

Troubleshooting cooking start, low heat, and fan/lamp issues.

OSCILLATION & POWER LEVEL PROBLEMS

Troubleshooting no microwave oscillation or incorrect power output.

EXPLODED VIEW

EXTERNAL ASSEMBLY VIEWS

Exploded views of Door, Control Panel, and Oven Cavity assemblies.

LATCH BOARD ASSEMBLY VIEW

Exploded view of the latch board components.

INTERIOR ASSEMBLY VIEW

Exploded view of interior components.

BASE PLATE ASSEMBLY VIEW

Exploded view of base plate components.

REPLACEMENT PARTS LIST

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