LG CT-25Q40RQ, CT-29Q40RE, CF-29F84V Service manual

COLOR TV

SERVICE MANUAL

CAUTION

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

CHASSIS : MC-022A

MODEL:CT-25Q40RQ/VB/VE/VQ

MODEL:CT-29Q40RE/RQ/VB/VE/VQ
MODEL:CF-29F84V

website:http://biz.LGservice.com

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

- 2 -

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

- 3 -

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

- 4 -

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)

O

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

- 5 -

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.

5.

/

(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.

OK

PR

VOL

PR

VOL

PLAY

P/STILL STOP

REC

REW

FF

I/II SSM LIST

PSM

SLEEP

PIP

Q.VIEW

?

MIX

TIME

SWAP

INPUT

REVEAL MODE

SIZE

STILL

POSITION

9/4 PIP

i

M

0

ARC

TV/AV

MENU

PICTURE

SOUND

1

2 3

4

5 6

7

8 9

POWER

MUTE

TEXT

PR

PR

T U R B O

EYE/

( )

( )

2

1

3

5

6

8

10

4

9

7

( )

( )

11

12

15
16

13

18

14

17

19

(With TELETEXT / PIP)

TEXT

Q.VIEW

?

MIX

TIME

REVEAL MODE

SIZE

HOLD

UPDATE

INDEX

i

M

(With TELETEXT / Without PIP)

10

- 6 -

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.

+

-

OK

PR

VOL

PR

VOL

PLAY

P/STILL STOP

REC

REW

FF

I/II SSM LIST

PSM

SLEEP

Q.VIEW

0

ARC

TV/AV

MENU

PICTURE

SOUND

1

2 3

4

5 6

7

8 9

POWER

MUTE

T U R B O

EYE/

( )

( )

2

1

3

5

6

8

4

9

7

11

12

15
16

13

18

14

17

(Without TELETEXT / PIP)

PIP

Q.VIEW

SWAP

INPUT

SIZE

STILL

POSITION

9/4 PIP

PR

PR

EYE/

(Without TELETEXT / With PIP)

19

- 7 -

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.

5.

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

11

12

1

3

4

2 6

10

5

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-29FA33 series models..

ON/OFF

MENU OK VOL PR

RT-28FZ10 series

1

2

4

3

6

5

ON/OFF

MENU OK VOL PR

1

RT-29FA33 series

2

34

5 12

10

6 11

ON/OFF

MENU

O K

VOL VOL

PR

CT-25/29Q40 series

1

3

2 6

4

10

5

L/MONO R

AUDIO

VIDEO

AV3

S-VIDEO

11

12

- 8 -

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

- 9 -

1. 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.

6. The adjustment of TVshould be performed after warming up

for 15 minutes.

2. Test Equipment required

1. RF signal generator (with pattern generator)

2. DC Power Supply

3. Multimeter (volt meter)

4. Oscilloscope

5. Color analyzer

3.

DVCO

Adjustment

1) This is for adjustment of VCT38XX,crystal oscillator

frequency after receiving a company Digital
pattern.(PAL:EU05CH,NTSC:13CH)

2) When entering adjustment mode by pressing IN-START

button,DVCO adjustment is operating automatically.
(T/X doesn’t operating occassionally during DVCO
adjustment.)

4. Focus Adjustment

4-1. Preparation for Adjustment

Tune the TV set to receive a digital pattern.

4-2. Adjustment Method

1) Single Focus CPT

Adjust the upper Focus volume of FBT for the best focus of
horizontal line A,vertical line B.

2) Double Focus CPT

1) Adjust the lower Focus volume of FBT for the best focus of
vertical line B.

2) Adjust the upper Focus volume of FBT for the best focus of
area A.

3) Repeat above step 1) and 2) for the best overall focus.

5.

Screen Voltage & White Balance Adjustment

5-1. Adjustment of screen manually

(Using ADJ.Remote Control)

1) Receive the PAL or SECAM(NTSC) signal into RF mode
regardless of channel.

2) If you press the “ADJ”button in LINE SVC mode(IN-START
button),the LINE SVC mode changes to screen adjustment
mode.

3) Turn the Sreen Volume of FBT to change luminance of
White signal center as shown below.(Deviation ! 1FL)

4) Press the EXIT button (Like TV/AV) to exit SVC mode.

5-2.

Adjustment of white balance manually(LIne-SVC 1)

1) Tune the TV set to receive an 100% white pattern.

2) Adjust LOW LIght status of CUT R,CUT B at CUT G:50.

3) Adjust HIGH LIght status of WDR R,WDR B at WDR G:380.

4) Repeat above step 2) and 3) for the best condition each
status of High Light and Low Light.

NOTE : When adjusting white balance automatically,connect the

adjustment JIG in SVC mode.(When pressing IN­START,MUTE button on remote control for adjustment
orderly,it changes to SVC mode and screen displays
SVC.)

Luminance(Manual)

6

!

1FL

8

!

1FL

5

!

1FL

6

!

1FL

8

!

1FL

CPT & INCH

29” FLAT

25” FLAT
29” NORMAL
25” NORMAL
28” NORMAL

Note

Single Focus

ADJUSTMENT INSTRUCTIONS

b

A

B

Fig. 1

Menu

X
Y

Color Temperature

288
295

9000

o

K

268
273

13000

o

K

EU

N-EU

Menu

CUR R

CUR G

CUR B

WDR R
WDR G
WDR B

0 ~ 511
0 ~ 511
0 ~ 511
0 ~ 511
0 ~ 511
0 ~ 511

50
50

50
380
380
380

Range

DATA

White Balance Color analyzer

White Balance Initial Data

- 10 -

6.Deflection Data Adjustment (Line SVC-2)

NOTE : How to enter into the Line Service Mode with a remocon.

1.Power off.

2.Press the Red button.

3.Press the Green button.

4.Press the Yellow button.

5.Press the Cyan button.

6.Press the OK button.

7.Power On.

6-1. Preparation for Deflection Adjustment

1) At adjustment mode(IN-START button on remote control of
adjustment),changed to LINE SVC 2 mode to adjust the
deflection.

2) Press Channel UP/DOWN button for desirous function
Adjustment.

3) Press Volume UP/DOWN button to adjust the data.

4) Tune the TV set to receive a Digital pattern.(PAL:05CH)

NOTE : If production line doesn’t the production line of LG

TV,receive available deflection adjustment pattern.

6-2. Adjustment Method

NOTE : First,adjust deflection at N50Hz,W50Hz,Z50Hz of PAL

signal.Then adjust deflection at N60Hz,W60Hz,Z60Hz of
NTSC signal.
In case of NTSC only model,adjust deflection of
N60Hz,W60Hz,Z60Hz of NTSC signal.

Store the deflection adjustment data in EEPROM by
using ENTER button before adjusting PIP position.

1) When adjusting a deflection,adjust N50Hz of PAL signal first and
adjust a deflection at W50Hz,Z50Hz,N60Hz,W60Hz,Z60Hz of PAL
signal.

2) Adjust a deflection as shown below
PAL 4:3=> PAL 16:9=>PAL ZOOM=>NTSC 4:3=>NTSC
16:9=>NTSC ZOOM.

3) After finishing deflection adjustment,press the ENTER button
to enter or exit in SVC mode.

VL (Vertical Linearity)

Adjust so that the boundary line between upper and lower half is in
accord with geometric horizontal center of the CPT.

VA (Vertical Amplitude)

Adjust so that the circle of a digital circle pattern may be
located within the effective screen of the CPT.

SC (Vertical “S” Correction)

Adjust so that all distance between each horizontal lines are to
be the same.

VS (Vertical Shift)

Adjust so that the horizontal center line of a digital circle pattern
is in accord with geometric horizontal center of the CPT.

HS (Horizontal Shift)

Adjust so that the vertical center line of a digital circle pattern is in
accord with geometric vertical center of the CPT.

EW (Horizontal Width)

Adjust to that a digital circle pattern looks like exact circle.

EP (East-west Parabolar)

Adjust so that middle portion of the outermost left and right vertical
line looks like parallel with vertical lines of the CPT.

EC (East-west Coner)

Adjust so that the vertical line at every 4 corners of the screen
looks like parallel with the vertical lines of the CPT.

ET (East-west Trapezium)

Adjust to make the length of top horizontal line same with it of
the bottom horizontal line.

PIP (PIP Position)

Adjust until the distance between PIP and main picture
becomes about 1~2mm.

Fig. 2

- 11 -

ITEM

RANGE

Z60Hz

W60Hz

N60HzZ50Hz

W50Hz

25” 29” 25” 29” 29” 29” 29”

29”

25” 25” 25” 25”

N50Hz

VA
VL
SC
VS
HS

EW

ET
EP
ES
EC

PIP P

008A

00F8

00E1

0733
001C
0C59

07F3
07BF

085F
073E

0009

-22
0
0
0
0
0
0

25
29

0
0

-22
0
0
0
0
0
0

25
29

0
0

14

0
0
0
0
0
0

-16
29

0
0

14

0
0
0
0
0
0

-16
29

0
0

0

-5
0

43

4

15

-6

-2
0

12

0

0

-5
0

43

4

15

-6

-2
0

12

0

-22

-5
0

43

4

15

-6

15
44
12

0

-22

-5
0

43

4

15

-6

15
44
12

0

-5
0
0

43

4

15

-16

-16
44
12

0

-5
0
0

43

4

15

-16

-16
44
12

0

0092
00FF
00E1
07FF

0016
0C36
07FC
07B3

0864
083F

0009

0050~00CF
0025~00BF
0000~009F

0600~0900
0000~003F
0400~0EFF
0700~08FF
06E0~0840

06A0~0AFF

0790~08E0
0790~08E0

25/29” FST CPT

ITEM

RANGE

Z50Hz

N50Hz

W50Hz

VA
VL
SC
VS
HS

EW

ET
EP
ES
EC

PIP P

11

0
0
0
0
0
0

-14
0
0
0

-22
0
0
0
0
0
0

22

0
0
0

00A3
00F5
00D0
0744
0016
0E40
07E9
07B4
0840
0840

0000B

0050~00CF

0025~00BF
0000~009F

0600~0900

0000~003F

0400~0EFF

0700~08FF
06E0~0840

06A0~0AFF

0790~08E0
0790~08E0

ITEM

RANGE

Z50Hz

N50Hz

W50Hz

VA
VL
SC
VS
HS

EW

ET
EP
ES
EC

PIP P

11

0
0
0
0
0
0

-14
0
0
0

22

3
0
0
0

22

0

19

0
0
0

009A
00F3
00D0
0774
0019

0B96
07DE
07BF
085C

082B

0007

0050~00CF
0025~00BF

0000~009F
0600~0900

0000~003F
0400~0EFF
0700~08FF
06E0~0840
06A0~0AFF
0790~08E0
0790~08E0

25/29” LG FLAT CPT(CT-25Q20RB) 29” S/S SEB FLAT CPT

ITEM

RANGE

50Hz 50Hz 50Hz 50Hz60Hz 60Hz 60Hz60Hz

16: 9 14: 9

ZOOM STANDARD

VA
VL
SC
VS
HS

EW

ET
EP

0083

00FA

00F0
0753

0014
0A62
07FD
07B6

0083
00FD
00F0

0729

0016
0A6E
07FF
07B7

008F

00FD

00F0
0732

0016
0A6E
07FF
07A9

00A7
00FD
00F0
073B
0016
0A6E
07FF
078E

0083

00FD

00F0
0741

0016
0A6E
07FD
07B3

0084
00F9
00F0
0753
0014
0A68

07EA

07B6

00A7
00F8
00F0
075D

0014
0A68
07EA
078B

008E

00A
00F0
0756
0014
0A68
07E8
07AB

0050~00CF

0025~00BF
0000~009F

0600~0900

0000~003F

0400~0EFF

0700~08FF
06E0~0840

28” LGPD FLAT CPT