Lg Lmh1017cvw, Lmh1017cvst Service Manual

Website: http://us.lgservice.com

MICROWAVE OVEN

SERVICE MANUAL

MODEL: LMH1017CVW

CAUTION

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

P/NO : 3828W5S6006

LMH1017CVST

May, 2004

Printed in Korea

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.

CAUTION

MICROWAVE RADIATION

DO NOT BECOME EXPOSED TO RADIATION FROM THE MICROWAVE GENERATOR OR OTHER PARTS CONDUCTING MICROWAVE ENERGY.

CONTENTS

(Page)

SAFETY PRECAUTIONS

SPECIFICATIONS

CAUTIONS

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INSTALLATION

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OPERATING INSTRUCTIONS

FEATURES

CONTROL PANEL

OPERATING SEQUENCE

SCHEMATIC DIAGRAM (I)

SCHEMATIC DIAGRAM (II)

CIRCUIT DESCRIPTION

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SERVICE INFORMATION

TOOLS AND MEASURING INSTRUMENTS

MICROWAVE LEAKAGE TEST

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Inside front cover

1-1

2-1

3-1

4-1

4-2

4-4

4-5

4-6

5-1

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5-1

MEASUREMENT OF MICROWAVE POWER OUTPUT

DISASSEMBLY AND ADJUSTMENT

INTERLOCK CONTINUITY TEST

COMPONENT TEST PROCEDURE

TROUBLE SHOOTING

EXPLODED VIEW

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REPLACEMENT PARTS LIST

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5-3

5-8

5-9

5-13

6-1

7-1

SPECIFICATIONS

ITEM

MODEL

Power Requiremen

Power Output

Microwave Frequency

Magnetron

Timer

Outside Dimensions

Cavity Dimensions

Net Weight

Shipping weight

Control Complement

DESCRIPTION

LMH1017CVW / LMH1017CVST

120 V AC, 60 Hz Single phase, 3 wire grounded Microwave 1,400W Convection 1,350W Combination 1,500W

1,000 Watts full microwave power (IEC60705)

2,450 MHz

2M246-050GF

0 ~ 99 min. 99 sec.

201/

8”(W) x 12

14”(W) x 8

4”(H) x 19

2”(H) x 13

42 lbs (approx.)

46 lbs (approx.)

Touch Control System

Clock : 1:00 - 12:59

16”(D)

Microwave Power for Variable Cooking

Power level

HIGH .................................... Full power throughout the cooking time

9 (Saute)

7 (Med.-High)

5 (Med.-Low)

3 (Low)

1 (Warm)

...............................

.......................

........................

.................................

..............................

approx. 90% of Full power, 8 (Reheat)

approx. 70%, 6 (Medium)

approx. 50%, 4 (Defrost)

approx. 30%, 2 (Simmer)

approx. 10%

• Convection - 100°F and 225°F to 450°F

• Combination

Accessories

Owner's manual

Glass Tray

Rotating Ring

Metal Rack

Metal Tray

This microwave oven is designed for household use only.

It is not recommended for commercial purposes.

..........

approx. 80%

.........

approx. 60%

..........

approx. 40%

.........

approx. 20%

1-1

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 connected. All input and output microwave connections, waveguide, flange, and gasket must be secured 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.

• 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.

ANTENNA

GASKET

COOLING FIN

FILAMENT TERMINALS

MAGNETRON CHASSIS GROUND

MAGNETRON

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

2-1

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, dents inside the cavity, or on the exterior.

2. Put the oven on a counter, table, or shelf at least 100cm (39.4 inches) from floor 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 on a sturdy and flat surface at least 5 cm(2 inches) from the wall.

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

ENSURE PROPER GROUND

EXISTS BEFORE USE

7. Place the microwave oven as far away as possible from TV, RADIO, COMPUTER, etc., to prevent interference.

5cm

Counter,

100cm

table, shelf

3-1

FEATURES

Oven Front Plate

Window Door Screen

Door Seal

Safety Interlock System

Control Panel

Display Window

Metal Tray

Glass Turntable

Rotating Ring

Metal Rack

CONTROL PANEL

OPERATING INSTRUCTIONS

1. DISPLAY. The display includes a clock and indicators that tell you

time of day, cooking time settings, and cooking functions selected.

2. CONVECTION. Touch this button to cook foods on convection

mode.

3. MICROWAVE. Touch this button to cook foods on microwave

mode, and to set cooking time and power level.

4. ROAST. Touch this button to roast foods on combination mode.

5. BAKE. Touch this button to bake foods on combination mode.

6. AUTO COOK. Touch this pad to cook foods automatically on

combination mode.

7. SENSOR COOK. Touch this button to cook most of your favorite

foods without entering cooking time or power level.

8. SENSOR REHEAT. Touch this button to reheat foods without

entering cooking time and power level.

9. SENSOR POPCORN. Touch this button to cook popcorn

automatically.

10. AUTO DEFROST. Meat, Poultry, Fish, Bread. Touch this pad to

select food type and defrost food by weight.

11. Q DEFROST. This pad provides you with the rapid defrosting

method for 1.0 pounds frozen foods.

12. MORE. Touch this pad to add ten seconds of cooking time each

time you press it.

13. LESS. Touch this pad to subtract ten seconds of cooking time each

time you press it.

14. CUSTOM SET. Touch this button to change the oven's default

settings for sound, clock, scroll speed, and Lbs/kg.

15. NUMBER. Touch number pads to enter cooking time, power level,

quantities, or weights.

16. KITCHEN TIMER. Touch this button to use as a kitchen timer

without operating the oven.

17. POWER. Touch this pad to set a cook power.

18. STOP/CLEAR: Touch this button to stop the oven or to clear

entries and to engage or disengage the child lock. See page 12.

19. Ez-ON: You can extend cooking time in multiples of 30 seconds by

repeatedly touching this pad during cooking.

20. ENTER/START. Touch this button to start entries.

4-1

OPERATING SEQUENCE

The following is a description of component functions during oven operation.

1. SETTING THE CLOCK

Clear

Clock

Desired

clock

Start/Pause

2. CANCEL FUNCTION

1) Touch Start/Pause pad to start oven or pause the oven temporarily during cooking.

2) Touch Clear pad to cancel a program during cooking or Erase during programming.

3. CHILD LOCK

TO SET CHILD LOCK

• Touch the Clear pad

• Touch and hold 0 pad LOCKED appear on

the display.

TO CANCEL CHILD LOCK

• Touch and hold 0 pad LOCKED disappear

in the display.

4. EZ ON

5. MORE / LESS

This pad is to be used as a temperature selection pad in convection mode and cook time adjustment

pad in the microwave mode.

6. CUSTOM SET

You can select Sound Control, Clock On/Off, Scroll, Speed, LBS°F/KG°C, Demo On/Off, and English/Spanish.

• To turn off the clock.

Custom

Set

2 2

7. TIMED COOKING

Cook Time

Power

Level

Number

Start/Pause

Cook

Power

Clear

EZ On

8. MULTI-STAGE COOKING

1ST STAGE

Cook Time

2ND STAGE

Cook Time

Power

Level

Number

Start/Pause

Cook

Power

Level

Cook

Power

4-2

OPERATING SEQUENCE

9. SENSOR TOUCH

Clear

10. DEFROST AUTO/TIME

Clear

11. Q-DEFROST

Sensor Cook/

Reheat

Popcorn

Auto/Time

Defrost

Enter the

Weight

Auto/Time

Defrost

Start/Pause

Select Recipe

Categories

4-3

SCHEMATIC DIAGRAM (I) *Check the Model No.

H.V

FUSE

OVEN

THERMOSTAT

TRANSFORMER

O.L

T.T.M

TURN

AC 120V/60Hz

SINGLE PHASE ONLY

MOTOR

L.V.TRANSFORMER

F.M

OVEN LAMP

FAN MOTOR

TABLE

RELAY

MONITOR

SWITCH

(NC)(C)

CONTROL MODULE

(9 PIN )

CONNECTOR

BK BL BN

CHOKE FILTER(Optional)

CAPACITOR

H.V.DIODE

MAGNETRON

H.V.

FAN

RELAY

MOTOR

HEATER

POWER RELAY

MAIN

THERMISTOR

C.M

PRIMARY SWITCH

MGT

THERMOSTAT

CIRC. MOTOR RELAY

CONVECTION

HEATER

CONVECTION

MOTOR

YLBL

YLWH PK PK

(RY5)

(RY2)

(RY1)

(RY4)

(RY6)

(CN1)

MAIN PCB

(CN2)

(CN4)

BNWHRD

SENSOR

1756

4-4

SCHEMATIC DIAGRAM (II) *Check the Model No. (ADD Noise filter)

H.V

OVEN

THERMOSTAT

TRANSFORMER

O.L

T.T.M

TURN

MOTOR

L.V.TRANSFORMER

F.M

OVEN LAMP

FAN MOTOR

TABLE

RELAY

MONITOR

SWITCH

(NC)(C)

CONTROL MODULE

(9 PIN )

CONNECTOR

BK BL BN

CHOKE FILTER(Optional)

CAPACITOR

H.V.DIODE

MAGNETRON

H.V.

FAN

RELAY

MOTOR

HEATER

POWER RELAY

MAIN

THERMISTOR

C.M

PRIMARY SWITCH

MGT

THERMOSTAT

CIRC. MOTOR RELAY

CONVECTION

HEATER

CONVECTION

MOTOR

YLBL

YLWH PK PK

(RY5)

(RY2)

(RY1)

(RY4)

(RY6)

(CN1)

MAIN PCB

(CN2)

(CN4)

BNWHRD

SENSOR

1756

FUSE

G-Y

NOISE

FILTER

INPUT

POWER

4-5

CIRCUIT DESCRIPTION

FUSE

H.V.

TRANS-

FORMER

RELAY 2

MICOM CONTROLLER

SECONDARY SWITCH

PRIMARY

SWITCH

MONITOR

SWITCH

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 the primary switch and relay 2.

• Turntable rotates.

WHEN THE DOOR IS OPENED DURING COOKING

• Both the primary switch and relay 2 cut off the primary winding voltage of the high voltage transformer.

• ON-OFF of relay 2 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 primary switch

and relay 2 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.

H.V.

TRANS-

FORMER

SECONDARY SWITCH

FUSE

PRIMARY

SWITCH

RELAY 2

MONITOR

SWITCH

• The fan motor rotates and cools the magnetron by blowing the air.

• The air is also directed into the oven to exhaust the vapor in the oven through the upper plate.

• Cooking time starts counting down.

• 3.15 volts AC is generated from the filament winding of

the high voltage transformer. This 3.15 volts is applied to the magnetron to heat the magnetron filament through two noise-preventing choke coils.

• A high voltage of approximately 2,210 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 2 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 2 is 22 seconds.

MICOM CONTROLLER

WHEN TOUCHING THE START KEY WITH THE CONVECTION COOKING.

• The contacts of the primary switch and the secondary switch close the circuit.

• Damper close.

• Turntable rotate.

• Fan Motor, Circulation Motor rotate.

4-6

OVEN THERMOSTAT

G-Y

RELAY 4

CONVECTION

HEATER

+ 28 hidden pages