LG CF-29F84, CT-29Q46EN, CT-25Q46EN, CT-29Q47E, CT-25Q47E Service Manual

COLOR TV

SERVICE MANUAL

CAUTION

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

CHASSIS : MC-007A

MODEL:CT-25/29Q47E/P/EN/EX

MODEL:CT-25/29Q46EN CF-29F84

website:http://biz.LGservice.com

e-mail:http://www.LGEservice.com/techsup.html

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CONTENTS

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

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

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

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

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

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

Exploded View .................................................................................................. 14

Exploded View Parts List ..............................................................................15

Replacement Parts List ................................................................................ 16

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.

¡ Video input system:

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

¡ 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’)

¡ Power requirement : 110~240V, 50/60Hz

¡ Power consumption : 25”:125W

29”:135W

¡ CPT : True Flat CPT(Flatron)

¡ Tuning system :

FVS 100 Programme memory 200 Programme memory(For CHINA)

Antenna input impedance : VHF/UHF 75 ohm, unbalanced

¡ OSD (On Screen Display) : MENU Type

¡ Voice coil impedance : 8 ohm

¡ Sound output : 12W+12W

Dual/Stereo : A2/NICAM(Option)

¡ External connection :

Head Phone Jack S-VIDEO in A/V in :1 pair Scart 1(Full) A/V in/out Scart 2(Half)+Audio out A/V in/out

¡ 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

¡ Feature : Auto programme/Manual programme

SVM (Scanning Velocity Modulation) Digital Eye Digital Comb Filter Auto Sleep Dynamic Focus Programme Editing PSM (Picture Status Memory) CTI Double Window Teletext (TOP/FLOF) Turbo Search, Picture & Sound ACMS ARC (Zoom 1/ZOOM 2, 16:9¡Œ4:3) 1 TUNER PIP(Double Window PIP)

Child Lock :

¡ 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

In the Lock On state the TV can only be operated by the Remote Controller. If any button on the front panel is pressed, "Child Lock" is displayed on the screen but the button's function is not performed. To cancel of this mode, select lock off with menu button on remote controller only.

(

): SECAM

Front or

Side

Back

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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. MENU

selects a menu.

DD / EE

(Programme Up/Down)

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

FF / GG (Volume Up/Down)

adjusts the volume. adjusts menu settings.

accepts your selection or displays the current mode.

5. VCR BUTTONS (option)

control a LG video cassette recorder.

6. SSM (Sound Status Memory)

recalls your preferred sound setting.

7. PSM (Picture Status Memory)

recalls your preferred picture setting.

8. EYE/*(option)

switches the eye function on or off.

9. TELETEXT BUTTONS (option)

These buttons are used for teletext. For further details, see the ÔTeletextÕ section.

10. MUTE

switches the sound on or off.

11. ARC (Aspect Ratio Control)

changes the picture format.

12. TV/AV

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

13. TURBO PICTURE / SOUND BUTTON

selects Turbo picture / sound.

TEXT/EYE/

Q.VIEW

MIX

TIME

REVEAL SLEEP

(With teletext / Without PIP)

(With teletext / PIP)

TV/AV

SOUND

PICTURE

TURBO

ARC

MUTE

POWER

VOL

PLAY

P/STILL

LIST

STOP

REC

REW FF

I/II

TEXT/ PIPEYE/

PR- PR+ SWAP INPUT

SSM

PSM

1 2 3

4 5 6

7 8 9

MIX

TIME

REVEAL SLEEP

SIZE

STILL

POSITION

9/4PIP

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2 31

5 64

8 97

POWER

LIST

ARC I/II

SSM

SLEEP

PSM

SOUNDPICTURE

Q.VIEW

VOL VOL

TV/AV

MUTE

TURBO

EYE/

14. LIST

displays the programme table.

15. I/II

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

16. 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.

17. SLEEP

sets the sleep timer.

18. SWAP or Q.VIEW returns to the previously viewed programme.

COLOURED BUTTONS

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

Battery installation

The remote control handset is powered by two AAA or AA type 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.

AAA AA

(Without teletext / 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.

F / G (Volume Up/Down)

adjusts the volume. adjusts menu settings.

D / E

(Programme Up/Down)

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

5. EYE

adjusts picture according to the surrounding conditions.

6. REMOTE CONTROL SENSOR

7. AUDIO/VIDEO IN SOCKETS (AV2)

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

8. HEADPHONE SOCKET

Connect the headphone plug to this socket.

VIDEO

MONO

AUDIO

AV2

1 3 4 2 6 5

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Fig. 2-1

Fig. 2-2

CPT board

Remove Screws

STEREO PCB

Main PCB

A/V PCB

VCD PCB

POWER 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.

Speaker Assy Removal

Remove P1651 and P1652 connector from Main2 (Power/Def./ Sound-Amp) Board.

2. Remove respective 6 screws for speaker on the front cabinet. (Fig. 2-2).

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.

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¡ Safety Precautions

1. It is safe to adjust after using insulating transformer between

the power supply line and chassis input to prevent the risk of electric shock and protect the instrument.

2. Never disconnect leads while the TV receiver is on.

3. Don't short any portion of circuits while power is on.

4. The adjustment must be done by the correct appliances.

5. Unless otherwise noted, set the line voltage to 230Vac¡

10%, 50Hz.

5. The adjustment of TVshould be performed after warming up

for 15 minutes.

¡ Test Equipment required

1. RF signal generator (with pattern generator)

2. DC Power Supply

3. Multimeter (volt meter)

4. Oscilloscope

5. Color analyzer

PIF (Picture Intermediate Frequency) Adjustment

1) Connect the measuring equipment to the Main Board as

shown in Fig.1.

2) Set RF frequency and output level of RF SIGNAL

GENERATOR as shown Table 1.

3) Turn off S1 and S3 and on S2.

4) Adjust L104 so that the DC voltage may be 2.4¡ 0.05Vdc.

(Table 1)

¡ LÕ VCO Adjustment (For SECAM-LÕ MODEL)

1) Connect the measuring equipment to the Main Board as shown in Fig.1.

2) Set RF frequency and output level of RF SIGNAL GENERATOR as shown Table 1.

3) Turn on S1,S3 and off S2.

2) Adjust VR122 so that the DC Voltage may be 2.4¡ 0.05Vdc.

RF AGC (Automatic Gain Control) Adjustment

1) Input PAL-B/G 05 CH.

2) Connect Multimeter to TP2(J15),AGC adjustment point.

3) Adjust VR121 until the voltage of Multimeter becomes

2.5¡ 0.1V.

¡ Screen Voltage Adjustment

1) Tune the RF Modulator to receive a PAL or SECAM signal.

2) Press MIX button on remote controller for Service to get into the Screen Adjust Mode.

3) Adhere the Color Analyzer on the White window of CPT face.

4) Adjust Screen Volume of FBT so that the luminance of White window is 12¡ 1 FL.

¡ Focus Adjustment

1) Tune the TV set to receive a digital pattern.

2) Adjust the upper Focus volume of FBT for the best focus of vertical line B.

3) Adjust the lower Focus volume of FBT for the best focus of area A.

4) Repeat above step 2) and 3) for the best overall focus.

IC101

TDA4470

TP1(VCO)

IC102(KI7805)

13  14

0.01uF

JP1

L104

Power- Supply

V Multimeter or Oscilloscope

JP2

38.9MHz

34.25MHz

(B/G,D/K,I,L) (SECAM-L')

100 ohm

4.7 Kohm

JP3

100 ohm



Q122

VR122

R108

R144

Test Point : TP1

Adjust : L104

Test Point : TP1

Adjust : VR122

Frequency

38.9MHz

34.25MHz

System

B/G,D/K/I,SECAM-L

SECAM-LÕ

Modulation

OFF

Output level

10mVp-p

Adjust

L104

VR122

Fig. 1 : Connection Diagram of Equipment for PIF Adjustment

ADJUSTMENT INSTRUCTIONS

Test Point : TP 2(J15)

Adjust : VR121

Test Point : CPT Face

Adjust : Screen Control of FBT

Test Point : Observing Display

Adjust : Focus control of FBT

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