LG MC022A Service Manual

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CONTENTS

Contents ................................................................................................................. 2

Safety Precautions ............................................................................................3

Specifications ..................................................................................................... 4

Control Descriptions ........................................................................................ 5

Disassembly Instructions ............................................................................. 8

Adjustment Instructions ............................................................................... 9

Block Diagram .................................................................................................... 16

Trouble Shooting .............................................................................................. 18

Exploded View .................................................................................................. 22

Exploded View Parts List .............................................................................23

Replacement Parts List ............................................................................... 24

SVC. Sheet ................................................................................................................

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SAFETY PRECAUTIONS

Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the Schematic Diagram and Replacement Parts List. It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent X-RADIATION, Shock, Fire, or other Hazards. Do not modify the original design without permission of manufacturer.

General Guidance

An lsolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks.

It will also protect the receiver and it's components from being damaged by accidental shorts of the circuitary that may be inadvertently introduced during the service operation.

If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it with the specified.

When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1W), keep the resistor 10mm away from PCB.

Keep wires away from high voltage or high temperature parts.

Due to high vacuum and large surface area of picture tube, extreme care should be used in handling the Picture Tube. Do not lift the Picture tube by it's Neck.

X-RAY Radiation

Warning:

To determine the presence of high voltage, use an accurate high impedance HV meter.

Adjust brightness, color, contrast controls to minimum. Measure the high voltage. The meter reading should indicate

23.5

¡ 1.5KV: 14-19 inch, 26 ¡ 1.5KV: 19-21 inch,

29.0 ¡ 1.5KV: 25-29 inch, 30.0 ¡ 1.5KV: 32 inch If the meter indication is out of tolerance, immediate service and correction is required to prevent the possibility of premature component failure.

Before returning the receiver to the customer,

always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as antennas, terminals, etc., to be sure the set is safe to operate without damage of electrical shock.

Leakage Current Cold Check(Antenna Cold Check)

With the instrument AC plug removed from AC source, connect an electrical jumper across the two AC plug prongs. Place the AC switch in the on positioin, connect one lead of ohm-meter to the AC plug prongs tied together and touch other ohm-meter lead in turn to each exposed metallic parts such as antenna terminals, phone jacks, etc. If the exposed metallic part has a return path to the chassis, the measured resistance should be between 1MΩ and 5.2MΩ. When the exposed metal has no return path to the chassis the reading must be infinite. An other abnormality exists that must be corrected before the receiver is returned to the customer.

Leakage Current Hot Check (See below Figure)

Plug the AC cord directly into the AC outlet.

Do not use a line Isolation Transformer during this check.

Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor between a known good earth ground (Water Pipe, Conduit, etc.) and the exposed metallic parts. Measure the AC voltage across the resistor using AC voltmeter with 1000 ohms/volt or more sensitivity. Reverse plug the AC cord into the AC outlet and repeat AC voltage measurements for each esposed metallic part. Any voltage measured must not exceed 0.75 volt RMS which is corresponds to 0.5mA. In case any measurement is out of the limits sepcified, there is possibility of shock hazard and the set must be checked and repaired before it is returned to the customer.

Leakage Current Hot Check circuit

The source of X-RAY RADIATION in this TV receiver is the High Voltage Section and the Picture Tube. For continued X-RAY RADIATION protection, the replacement tube must be the same type tube as specified in the Replacement Parts List.

1.5 Kohm/10W

To Instrument's exposed METALLIC PARTS

Good Earth Ground such as WATER PIPE, CONDUIT etc.

AC Volt-meter

IMPORTANT SAFETY NOTICE

0.15uF

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SPECIFICATIONS

Note : Specification and others are subject to change without notice for improvement.

O Video input system:

PAL-B/G, D/K, I/I SECAM-B/G, D/K/L/L’ NTSC M NTSC 4.43(AV) NTSC- M/PAL M-N

O Intermediate Frequency (Unit : MHz)

VISION IF : 38.9MHz,33.9MHz(SECAM-L’) COLOR IF : 34.47MHz(4.43)

35.32MHz(3.58) : NTSC-M VIF-4.25000MHz VIF-4.40625MHz

SOUND IF : 33.4MHz (B/G)

32.9MHz (I/I)

32.4MHz (D/K,L)

34.4MHz (M)

40.4MHz (L’)

O Power requirement : 110~240V, 50/60Hz(NON-EU)

230V, 50Hz(EU)

O Power consumption : 25”:125W

29”:135W

O Tuning system :

FVS 100 Programme memory 200 Programme memory(W/O TXT Model)

Antenna input impedance : VHF/UHF 75 ohm, unbalanced

O Voice coil impedance : 8 ohm

O External In/Output

Audio-In:0.5Vrms

± 3db,over 10Kohm

Audio-Out:0.5Vrms

± 3db,below 1Kohm

Video-In/Out:1Vp-p

± 3db,75ohm

R,G,B In:0.7Vp-p

± 3db

O Feature & Funtion

Teletext(TOP/FLOF/LIST) AV Input : Side or Front(1),Rear(2) Component Input : Rear(Opt.) PERI TV Connector(AV Input,SCART Opt.) RGB INput 2 Carrier Stereo : BG/DK NICAM Stereo : BG/I/L 2 Carrier Dual : BG/DK NICAM Dual : BG/I/L SSC(Split Screen) Mode Multi Picture Display Mode(1:4:9 PIP) DBS

O Tuning range

Band

VHF-Low

VHF-High

Hyper UHF

S1'-S3', S1

S2-S10, S11-S20 S21-S41

For TV

For CATV

B/G

Ch2-4

Ch5-12

D/K

Ch1-5

Ch6-12

I/I

Ch4-13

NTSC

Ch2-13

Ch21-69 Ch14-69

( ): SECAM

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DESCRIPTION OF CONTROLS

All the functions can be controlled with the remote control handset. Some functions can also be adjusted with the buttons on the front panel of the set.

Remote control handset

Before you use the remote control handset, please install the batteries. See the next page.

1. POWER

switches the set on from standby or off to standby.

2. NUMBER BUTTONS

switches the set on from standby or directly select a number.

3. ARC (Aspect Ratio Control)

changes the picture format.

4. TURBO PICTURE / SOUND BUTTON

selects Turbo picture / sound.

(Programme Up/Down)

selects a programme or a menu item. switches the set on from standby. scans programmes automatically.

FF / GG

(Volume Up/Down)

adjusts the volume. adjusts menu settings.

6. VCR BUTTONS (option)

control a LG video cassette recorder.

7. SSM (Sound Status Memory)

recalls your preferred sound setting.

8. I/II (option)

selects the language during dual language broadcast (option). selects the sound output.

9. PSM (Picture Status Memory)

recalls your preferred picture setting.

10. TELETEXT BUTTONS (option)

These buttons are used for teletext. For further details, see the ‘Teletext’ section.

11. MUTE

switches the sound on or off.

12. TV/AV

selects TV or AV mode. switches the set on from standby.

13. MENU

selects a menu.

VOL

PLAY

P/STILL STOP

REC

REW

I/II SSM LIST

PSM

SLEEP

PIP

Q.VIEW

MIX

TIME

SWAP

INPUT

REVEAL MODE

SIZE

STILL

POSITION

9/4 PIP

ARC

TV/AV

PICTURE

SOUND

2 3

5 6

8 9

POWER

MUTE

TEXT

T U R B O

EYE/

( )

15 16

(With TELETEXT / PIP)

TEXT

Q.VIEW

MIX

TIME

REVEAL MODE

SIZE

HOLD

UPDATE

INDEX

(With TELETEXT / Without PIP)

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14. OK

accepts your selection or displays the current mode.

15. LIST

displays the programme table.

16. EYE/*(option)

switches the eye function on or off.

17. SLEEP

sets the sleep timer.

18. Q.VIEW

returns to the previously viewed programme. selects a favorite programme.

19. PIP BUTTONS (option) PIP

switches the sub picture on or off.

PR +/

selects a programme for the sub picture.

SWAP

alternates between main and sub picture.

INPUT

selects the input mode for the sub picture.

SIZE

adjusts the sub picture size.

STILL

freezes motion of the sub picture.

POSITION

relocates the sub picture in clockwise direction.

9/4 PIP

switches on or off the 9 or 4 sub pictures.

COLOURED BUTTONS

These buttons are used for teletext (only TELETEXT models) or programme edit.

Battery installation

The remote control handset is powered by two AAtype batteries. To load the batteries, turn the remote control handset over and open the battery compartment. Install two batteries as indicated by the polarity symbols ( and ) marked inside the compartment.

Note : To avoid damage from possible battery leakage, remove the batteries if you do not plan to use the remote control handset for an extended period of time.

VOL

PLAY

P/STILL STOP

REC

REW

I/II SSM LIST

PSM

SLEEP

Q.VIEW

ARC

TV/AV

PICTURE

SOUND

2 3

5 6

8 9

POWER

MUTE

T U R B O

EYE/

( )

15 16

(Without TELETEXT / PIP)

PIP

Q.VIEW

SWAP

INPUT

SIZE

STILL

POSITION

9/4 PIP

EYE/

(Without TELETEXT / With PIP)

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1. MAIN POWER

switches the set on or off.

2. POWER/STANDBY INDICATOR

illuminates brightly when the set is in standby mode. dims when the set is switched on.

3. MENU

selects a menu.

4. OK

accepts your selection or displays the current mode.

DD / EE

(Programme Up/Down)

selects a programme or a menu item. switches the set on from standby.

FF / GG

(Volume Down/Up)

adjusts the volume. adjusts menu settings.

6. REMOTE CONTROL SENSOR

Note : Only use the supplied remote control handset.

(When you use others, they’ll be not able to function.)

7. TV/AV

selects TV or AV mode. clears the menu from the screen. switches the set on from standby.

8. (Function)

selects volume, EYE (option), picture items or brief auto programme while the menus not display.

Front panel

ON/OFF

MENU OK VOL PR

CT-25/29Q20 series

S-VIDEO

VIDEO

L/MONO RAUDIO

AV3

2 6

9. +/- (

DD/EE

)

adjusts the function or selects a programme. switches the set on from standby.

10. EYE (option)

adjusts picture according to the surrounding conditions.

11.HEADPHONE SOCKET (option)

Connect the headphone plug to this socket.

12.AUDIO/VIDEO IN SOCKETS (AV3)

Connect the audio/video out sockets of external equipment to these sockets.

S-VIDEO/AUDIO IN SOCKETS (S-AV) (option)

Connect the video out socket of an S-VIDEO VCR to the S-VIDEO socket. Connect the audio out sockets of the S-VIDEO VCR to the audio sockets as in AV3.

Note : Do not place any heavy objects (over 4Kg) on the RT-29F A33 series models..

ON/OFF

MENU OK VOL PR

RT-28FZ10 series

ON/OFF

MENU OK VOL PR

RT-29FA33 series

5 12

6 11

ON/OFF

O K

VOL VOL

CT-25/29Q40 series

2 6

L/MONO R

AUDIO

VIDEO

AV3

S-VIDEO

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Fig. 2-1

Fig. 2-2

CPT PCB

Remove Screws

PIP PCB

MAIN PCB

CNTROL PCB

DISASSEMBLY INSTRUCTIONS

Important note

This set is disconnected from the power supply through the converter transformer. An isolating transformer is necessary for service operations on the primary side of the converter transformer.

Back Cabinet Removal

Remove the screws residing on the back cabinet and carefully separate the back cabinet from the front cabinet. (Fig. 2-1).

Chassis Assy Removal

Grasp both side of Frame and pull it backward smoothly.

CPT Removal

1. Pull out the CPT board from the CPT neck.

2. Place the front cabinet on soft material not to mar the front surface or damage control knobs.

3. Remove 4 screws securing the picture tube mounting brackets to the front cabinet.

4. Carefully separate CPT from the front cabinet.

PICTURE TUBE HANDLING CAUTION

Due to high vacuum and large surface area of picture tube, great care must be exercised when handling picture tube. Always lift picture tube by grasping it firmly around faceplate. NEVER LIFT TUBE BY ITS NECK! The picture tube must not be scratched or subjected to excessive pressure as fracture of glass may result in an implosion of considerable violence which can cause personal injury or property damage.

POWER PCB

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