This document provides a service manual for the LG Microwave Oven models MB-4352T and MH-6352T, offering comprehensive information for qualified service personnel. It covers safety precautions, specifications, installation guidelines, operating instructions, service procedures, troubleshooting, exploded views, and parts lists.
Function Description
The LG Microwave Oven is a household appliance designed for cooking, grilling, and defrosting food using microwave energy. It features various power levels and cooking modes to accommodate different food types and preparation needs. The oven incorporates a control panel for setting cooking time, clock, power level, and selecting specific cooking functions like Grill, Auto Cook, and Auto Defrost.
Important Technical Specifications
- Model: MB-4352T / MH-6352T
- Power Requirement: 230 Volts AC 50 Hz, Single phase, 3 wire grounded
- Microwave Power: 1,200W
- Grill Power: 1,100W
- Combination Power: 2,250W
- Power Output: 800 Watts full microwave power (IEC 60705)
- Microwave Frequency: 2,450 MHz
- Magnetron: 2M214-39F
- Timer: 90 min.
- Outside Dimensions: 485 (W) x 280 (H) x 406 (D) mm
- Cavity Dimensions: 332 (W) x 200 (H) x 331 (D) mm
- Net Weight: 13.5 kg (approx.)
- Shipping Weight: 15.0 kg (approx.)
- Control Complement (Microwave Power for Variable Cooking):
- MAX: Full power throughout the cooking time
- MED.-HIGH: approx. 80% of Full power
- MEDIUM: approx. 60% of Full power
- DEFROST: approx. 40% of Full power
- LOW/WARM: approx. 20% of Full power
- Grill, COMBI
- Accessories: Owner's manual, Glass tray, Rotating ring, Grill rack.
This microwave oven is designed for household use only and is not recommended for commercial purposes.
Usage Features
The microwave oven offers a user-friendly control panel with several key functions:
- COOK TIME: Allows users to set a desired cooking duration.
- CLOCK: Used to set the current time of day.
- POWER: Enables selection of various power levels for cooking, ranging from MAX to LOW/WARM, and specific settings for Grill and Combination cooking.
- Grill: Activates the grill function for browning and crisping.
- AUTO COOK: Provides one-touch cooking for a list of pre-programmed food items.
- AUTO DEFROST: Facilitates automatic defrosting based on the weight of the food.
- STOP/CLEAR: Stops current operations and clears all entries, except for the time of day.
- START: Initiates the cooking process with a single tap.
- CHILD LOCK: A safety feature that locks the control panel to prevent accidental operation. It can be activated and deactivated by specific button presses.
- Quick Start: Allows for immediate cooking at a high power level for a set duration.
- Multi-Stage Microwave Cooking: Supports programming multiple cooking stages with different power levels and times.
The oven is designed for easy installation, requiring placement on a sturdy, flat surface at least 10 cm (4 inches) from the wall, away from heat and steam sources, and other electronic devices to prevent interference. Proper earthing is crucial for safe operation.
Maintenance Features
The service manual emphasizes safety precautions for servicing, particularly concerning exposure to excessive microwave energy and high voltage components. Only properly qualified service personnel should perform maintenance.
Key Safety and Maintenance Procedures:
- Pre-Service Checks: Before activating the magnetron or other microwave sources, checks must be performed on interlock operation, door closing, seal and sealing surfaces, hinges, latches, and any evidence of dropping or abuse.
- Microwave Leakage Test: A microwave leakage check is mandatory before releasing the oven to the owner and after any servicing. The leakage should not exceed 4 mW/cm². Special care is required when measuring around the magnetron and waveguide.
- High Voltage Capacitor Discharge: Before touching any parts of the oven, the power plug must be removed, and the high voltage capacitor discharged by shorting its terminals with an insulated screwdriver.
- Component Testing: Detailed procedures are provided for testing various components, including:
- Interlock Continuity Test: Checks the primary, secondary, and monitor switches to ensure proper door lock mechanism operation.
- High Voltage Transformer: Measures resistance of primary, secondary, and filament windings.
- Magnetron: Measures resistance of filament terminal and filament to chassis.
- High Voltage Capacitor: Measures resistance terminal to terminal and terminal to case.
- High Voltage Diode: Measures continuity in forward and reverse directions.
- Fuse: Checks for continuity.
- Heater Element: Measures resistance.
- Grill Thermostat / Oven Thermostat / Magnetron Thermostat: Checks continuity at different temperature ranges.
- Relays (RELAY 2, RELAY 3): Checks continuity for fan motor, turntable motor, oven lamp, microwave, and grill functions.
- Fan Motor / Turntable Motor: Measures resistance.
- Disassembly and Adjustment: Instructions are provided for removing the outer case, power supply cord, control panel assembly, door gross assembly, high voltage transformer, fan motor assembly, high voltage capacitor and diode, magnetron, turntable motor, PCB assembly, and adjusting the interlock system.
- Troubleshooting: A comprehensive troubleshooting guide helps diagnose common issues based on symptoms like the oven not working, low output power, sparks, uneven cooking, display problems, and heater malfunctions. It outlines checks, expected results, probable causes, and remedies.
- Parts Replacement: Exploded views and replacement parts lists are included for various sections of the oven, such as door parts, control panel parts, oven cavity parts, latch board parts, interior parts, and base plate parts, to facilitate accurate part identification and replacement.
The manual stresses the importance of using identical replacement parts for continued protection against excessive radiation emission. It also advises against operating the oven with no load and to avoid damaging the door seal or oven cavity.
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