LG CT-14T35M,CT-14T35V Service manual

COLOR TV

SERVICE MANUAL

CAUTION

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

CHASSIS : MC-049B

MODEL: CT-14T35M/V

website:http://biz.LGservice.com

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

- 2 -

CONTENTS

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

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

Control Descriptions..........................................................................................4

Specifications........................................................................................................7

Adjustment Instructions .................................................................................8

Trouble Shooting.................................................................................................12

Printed circuit board.........................................................................................16

Block Diagram......................................................................................................19

Exploded View....................................................................................................20

Exploded View Parts List ..............................................................................21

Replacement Parts List .................................................................................22

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 isolation 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 circuitry 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 position, 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 exposed 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 specified, 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 -

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 (or INDEX)

selects a menu.
selects an index page in the teletext mode (only TELETEXT
models). (option)

4. EYE/*(option)

switches the eye function on or off.

5.

D/ E

(Programme Up/Down)

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

F / G

(Volume Up/Down)

adjusts the volume.
adjusts menu settings.

OK

accepts your selection or displays the current mode.

6. Q.VIEW

returns to the previously viewed programme.

7. TELETEXT BUTTONS (option)

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

8. PSM (Picture Status Memory)

recalls your preferred picture setting.

9. FAVOURITE

selects a favorite programme.

10. TURBO PICTURE / SOUND BUTTON (option)

selects Turbo picture and sound.

11. MUTE

switches the sound on or off.

12. TV/AV

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

OK

PR

VOL

PR

VOL

PLAY

P/STILL STOP

REC

REW

FF

I/II/ SSM/ LIST

PSM

PIP

FAVOURITE

Q.VIEW

SLEEP

?

MIX

TIME

SWAP

INPUT

REVEAL MODE

SIZE

STILL

POSITION

9/4PIP

i

M

0

TV/AV

MENU

PICTURE

SOUND

1

2 3

4

5 6

7

8 9

POWER

MUTE

EYE/

PR

PR

T U R B O /

TEXT/

( )

( )

1

2

10

5

18

13
15

11

12

3

14

6

4

16

9

8

19

7

- 5 -

13. I/II/*(option)

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

14. LIST

displays the programme table.

15. SLEEP

sets the sleep timer.

16. SSM/

*

(option) (Sound Status Memory)

recalls your preferred sound setting.

17. SURROUND (

ºº

/

*

) (option)

selects surround sound.

18. VCR BUTTONS

control a LG video cassette recorder.

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.

*

: No function

COLOURED BUTTONS : These buttons are used for teletext (only

TELETEXT models) or programme edit.

(Without TELETEXT / PIP)

POWER MUTE

123

456

789

MENU/INDEX

TV/AV

0

EYE/

Q.VIEW

LIST

I / II /

( )

PR

( )

PR

OK

VOLVOL

PSM SSM/ SLEEP

PICTURE SOUND

/

TURBO/

FAVOURITE

TV

1

2

3
4

5

6

8

10

11

12
13

14

15
17

16

9

TEXT/MIX/ SIZE/ HOLD/

Q.VIEW

LIST

UPDATE/

PSM SSM/ SLEEP/ M

X

TIME/ REVEAL/

?

PICTURE SOUND

/

TURBO/

FAVOURITE

7

(With TELETEXT / Without PIP)

- 6 -

Front panel

Shown is a simplified representation of front or side panel.
Here shown may be somewhat different from your set.

1. MAIN POWER (ON/OFF)

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.
blinks when signal is input from the remote control.

3. REMOTE CONTROL SENSOR

4. MENU

selects a menu.

5. OK

accepts your selection or displays the current mode.

FF / GG

(Volume Up/Down)

adjusts the volume.
adjusts menu settings.

DD / EE

(Programme Up/Down)

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

6. AUDIO(or AUDIO-L/R)/VIDEO IN SOCKETS (AV2) (option)

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

7. HEADPHONE SOCKET (option)

Connect the headphone plug to this socket.

8. TURBO SOUND/PICTURE (option)

switches Turbo sound or Turbo picture on or off.

9. EYE (option)

adjusts picture according to the surrounding conditions.

! !

6

7

VIDEO

(L/MONO)

I

AUDIO

I

(R)

VIDEO

AUDIO

! !

6

VIDEO

(L/MONO)

I

AUDIO

I

(R)

VIDEO

AUDIO

7

ON/OFFrMENU OK F VOL

G E PRD

VIDEO (L/MONO)-AUDIO-(R)!P-TURBO-S

1 2 3 4 5 6 7 8 9

TURBO

ON/OFF

r

MENU OK F VOL

G E PRD

VIDEO AUDIO!SOUND PICTURE

1 2 3 4 5 6 7 8 9

1 2 3 4 5 9

PR

D

ON/OFF

r

MENU F VOL VOL

G

OK

PR

E

(Side panel)

ON/OFFrMENU OK F VOL

G E PRD

VIDEO (L/MONO)-AUDIO-(R)!S-TURBO-P

1 2 3 4 5 6 7

8

9

- 7 -

SPECIFICATIONS

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

F Scope

This specification can be applied to all the television related to
MC-049B Chassis.

F Test and Inspection Method

1) Capacity : Follow LG electronics TV testing Standard.

2) Another Required Standard

- EMI : Following CE Standard (EN55020, EN55013)

- Safety : Following CB Standard (EN55013)

F Requirement for Test

Testing for standard of each par must be followed in below
condition

1) Temperature : 20

± 5°C

(CST must be tested 40

± 5°C . Humidity : 50%)

2) Relative Humidity : 65

± 10%

3) Power : Standard input Voltage (110-240V~, 50/60Hz)

4) Measurement must be performed after heat-run more than
20min.

5) Adjusting Standard for this chassis is followed a special
standard.

No

1

2

3

4
5
6
7

8

Item

Receiving System

Receiving Channel

Input Voltage

Market
Screen Size
Tuning System
Operating Environment

Storage Environment

Remark

For EU/ For Non EU

For EU/ For Non EU

NTSC-M (Multi - model)

Non EU

EU

FLAT / CONVENTIONAL

200 PR. (OPTION)

Specification

1) PAL/SECAM BG

2) PAL/SECAM DK

3) PAL I/I

4) NTSC M

5) SECAM-L/L’

6) NTSC 4.43(AV)

1) VHF : E2 ~ E12
UHF : E21 ~ E69
CATV : S1 ~ S20
HYPER : S21 ~ S41

2) L/L’ : B,C,D

3) VHF : 02 ~ 13
UHF : 14~ 69
CATV : 02 ~ 71

110-240V~, 50/60Hz
240V~, 50Hz
EU,CIS, China, Asia, Africa
14” ~ 21”
FVS 100Program

1) Temp. : 0 ~ 45 deg

2) Humidity: 85% under

1) Temp. : -20 ~ 60 deg

2) Humidity: 85% under

F General Specification

1. Application Object

These instructions are applied to all of the color TV, MC-049B.

2. Notes

(1) Because this is not a hot chassis, it is not necessary to use

an isolation transformer. However, the use of isolation
transformer will help protect test instrument.

(2) Adjustment must be done in the correct order.But the

adjustment can be changed by consideration of mass
production.

(3) The adjustment must be performed in the circumstance of

25±5°C of temperature and 65±10% of relative humidity if
there is no specific designation.

(4) The input AC voltage of the receiver must keep rating

voltage in adjusting.

(5) The receiver must be operated for about 15 minutes prior

to the adjustment.

3. Focus adjustment

3.1. Preliminary steps

Tune the TV set to receive a digital pattern.
(SVC mode:Automatically mode change the STANDARD
MODE)

3.2. Adjustment Method

1) Single Focus CPT

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

4. Purity & Convergence adjustment

4.1. Color purity adjustment

(1) It makes CPT enough to demagnetization.
(2) Receive the signal of red raster.
(3) Loosen fixed screw of DY and closely to CPT funnel part.
(4) Check the center of screen that PURITY MAGNET of CPT

by crossing adjustment. At this time, 4 & 6 pole magnet is
located to magnet of nothing.

(5) Move the DY to make equal red on whole screen and it

does not to make the DY by fixed screw after check a
simple color of Red/Green/Blue and white raster whether or
not it is a pollution of color.
(At this time, take care raster of screen and DY must fixing
in the condition which maintains a horizontality.)

(6) Check the receiver by move direction. When adjustment is

not working, adjust with the assisted MAGNET.

4.2. Convergence adjustment

These adjustments can the best condition of focus after
finished purity adjustment.

(1) Receive the signal of CROSS HATCH that BACK RASTER

is black.
(2) Adjust brightness and luminosity till dot appear 9 ~12.
(3) Open angle of the two tab of 4 pole MAGNET by isogonic

angle and accord with vertical line of red and blue color in

the middle of screen.

- 8 -

ADJUSTMENT INSTRUCTIONS

A

B

<Fig 1. PAL Digital Pattern(EU05CH)>

Assembling DY to

CPT

CPT Assembling

As preparatory operations before
assembling CPT, wind cotton Tape for
protecting to CPT NECK and DY, CPT
connection parts. At this moment, end
of tape should be over-lapped and
wound in direct route to the NECK.

Let the screen Standard condition.
Operate Heat-Run at least 15
minutes.

Torque is to be 9-11 kg f.cm when
fixing DY.

Fix the Magnet to the position as
shown picture below. Be careful not to
make CPT neck shadow while
adjusting DY.

HEAT RUN

Degaussing

STC Adjustment

PURITY Adjustment

DY Fixing

SCREEN Voltage adj.

W/B Fixing

FOCUS not yet ADJ.

STC not yet ADJ.

DYC not yet ADJ.

Convergence Magnet

¢‚

15 ~ 20mm

6Pole

¢‚

4

2