SAMSUNG CX6840W3X-XEG Service Manual

COLOR TELEVISION RECEIVER

Chassis : S51A
Model: CX6840W3X/XEG

COLOR TELEVISION RECEIVER CONTENTS

Precautions

Specifications and IC Data

Disassembly and Reassembly

Alignment and Adjustment

Troubleshooting

Exploded View and Parts List

Electric Parts List

Block Diagram

PCB Layout Diagram

Wiring Diagram

Schematic Diagrams

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

1. Precautions

1-1 Safety Precautions

1. Be sure that all of the built-in protective
devices are replaced. Restore any missing
protective shields.

2. When reinstalling the chassis and its
assemblies, be sure to restore all protective
devices, including: nonmetallic control knobs
and compartment covers.

3. Make sure that there are no cabinet openings
through which peopleÑparticularly
childrenÑmight insert fingers and contact
dangerous voltages. Such openings include
the spacing between the picture tube and the
cabinet mask, excessively wide cabinet

ventilation slots, and improperly fitted back

covers.

If the measured resistance is less than 1.0
megohm or greater than 5.2 megohms, an
abnormality exists that must be corrected
before the unit is returned to the customer.

4. Leakage Current Hot Check (Figure 1-1):
Warning: Do not use an isolation
transformer during this test. Use a leakage­current tester or a metering system that
complies with American National Standards
Institute (ANIS C101.1, Leakage Current for
Appliances), and Underwriters Laboratories
(UL Publication UL1410, 59.7).

5. With the unit completely reassembled, plug
the AC line cord directly into the power
outlet. With the unitÕs AC switch first in the
ON position and then OFF, measure the
current between a known earth ground (metal
water pipe, conduit, etc.) and all exposed
metal parts, including: antennas, handle
brackets, metal cabinets, screwheads and
control shafts. The current measured should
not exceed 0.5 milliamp. Reverse the power­plug prongs in the AC outlet and repeat the
test.

Fig. 1-1 AC Leakage Test

6. Antenna Cold Check:
With the unitÕs AC plug disconnected from the
AC source, connect an electrical jumper across
the two AC prongs. Connect one lead of the
ohmmeter to an AC prong. Connect the other
lead to the coaxial connector.

7. X-ray Limits:
The picture tube is especially designed to pro­hibit X-ray emissions. To ensure continued
X-ray protection, replace the picture tube only
with one that is the same type as the original.
Carefully reinstall the picture tube shields and
mounting hardware; these also provide X-ray
protection.

8. High Voltage Limits:
High voltage must be measured each time ser­vicing is done on the B+, horizontal deflection
or high voltage circuits. Correct operation of
the X-ray protection circuits must be
reconfirmed whenever they are serviced.

(X-ray protection circuits also may be called

Òhorizontal disableÓ or Òhold-downÓ.)

Heed the high voltage limits. These include
the XÐray Protection Specifications Label, and
the Product Safety and X-ray Warning Note on
the service data schematic.

Precautions

Samsung Electronics 1-1

LEAKAGE
CURRENT

TESTER

DEVICE
UNDER

TEST

TEST ALL

EXPOSED METAL

SURFACES

2-WIRE CORD

ALSO TEST WITH

PLUG REVERSED

(USING AC ADAPTER

PLUG AS REQUIRED)

EARTH

GROUND

(READING SHOULD

NOT BE ABOVE

0.5mA)

Follow these safety, servicing and ESD precautions to prevent damage and protect against potential
hazards such as electrical shock and X-rays.

1-1 Safety Precautions (Continued)

9. High voltage is maintained within specified
limits by close-tolerance, safety-related
components and adjustments. If the high
voltage exceeds the specified limits, check
each of the special components.

10. Design Alteration Warning:
Never alter or add to the mechanical or
electrical design of this unit. Example: Do not
add auxiliary audio or video connectors. Such
alterations might create a safety hazard. Also,
any design changes or additions will void the
manufacturerÕs warranty.

11. Hot Chassis Warning:
Some TV receiver chassis are electrically
connected directly to one conductor of the AC
power cord. If an isolation transformer is not
used, these units may be safely serviced only
if the AC power plug is inserted so that the
chassis is connected to the ground side of the
AC source.

To confirm that the AC power plug is inserted
correctly, do the following: Using an AC
voltmeter, measure the voltage between the
chassis and a known earth ground. If the
reading is greater than 1.0V, remove the AC
power plug, reverse its polarity and reinsert.
Re-measure the voltage between the chassis
and ground.

12. Some TV chassis are designed to operate with
85 volts AC between chassis and ground,
regardless of the AC plug polarity. These units
can be safely serviced only if an isolation
transformer inserted between the receiver and
the power source.

13. Some TV chassis have a secondary ground
system in addition to the main chassis ground.
This secondary ground system is not
isolated from the AC power line. The two
ground systems are electrically separated by
insulating material that must not be defeated
or altered.

14. Components, parts and wiring that appear to
have overheated or that are otherwise
damaged should be replaced with parts that
meet the original specifications. Always
determine the cause of damage or overheat­ing, and correct any potential hazards.

15. Observe the original lead dress, especially
near the following areas: Antenna wiring,
sharp edges, and especially the AC and high
voltage power supplies. Always inspect for
pinched, out-of-place, or frayed wiring. Do
not change the spacing between components
and the printed circuit board. Check the AC
power cord for damage. Make sure that leads
and components do not touch thermally hot
parts.

16. Picture Tube Implosion Warning:
The picture tube in this receiver employs
Òintegral implosionÓ protection. To ensure
continued implosion protection, make sure
that the replacement picture tube is the same
as the original.

17. Do not remove, install or handle the picture
tube without first putting on shatterproof
goggles equipped with side shields. Never
handle the picture tube by its neck. Some
Òin-lineÓ picture tubes are equipped with a
permanently attached deflection yoke; do not
try to remove such Òpermanently attachedÓ
yokes from the picture tube.

18. Product Safety Notice:
Some electrical and mechanical parts have
special safety-related characteristics which
might not be obvious from visual inspection.
These safety features and the protection they
give might be lost if the replacement compo­nent differs from the originalÑeven if the
replacement is rated for higher voltage,
wattage, etc.

Components that are critical for safety are
indicated in the circuit diagram by shading,
( ) or ( ).

Use replacement components that have the
same ratings, especially for flame resistance
and dielectric strength specifications.
A replacement part that does not have the
same safety characteristics as the original
might create shock, fire or other hazards.

Precautions

1-2 Samsung Electronics

!

1-2 Servicing Precautions

1. Servicing precautions are printed on the
cabinet. Follow them.

2. Always unplug the unitÕs AC power cord from
the AC power source before attempting to: (a)
Remove or reinstall any component or
assembly, (b) Disconnect an electrical plug or
connector, (c) Connect a test component in
parallel with an electrolytic capacitor.

3. Some components are raised above the printed
circuit board for safety. An insulation tube or
tape is sometimes used. The internal wiring is
sometimes clamped to prevent contact with
thermally hot components. Reinstall all such
elements to their original position.

4. After servicing, always check that the screws,
components and wiring have been correctly
reinstalled. Make sure that the portion around
the serviced part has not been damaged.

5. Check the insulation between the blades of the
AC plug and accessible conductive parts
(examples: metal panels, input terminals and
earphone jacks).

6. Insulation Checking Procedure: Disconnect the
power cord from the AC source and turn the
power switch ON. Connect an insulation
resistance meter (500V) to the blades of the AC
plug.

The insulation resistance between each blade
of the AC plug and accessible conductive parts
(see above) should be greater than 1 megohm.

7. Never defeat any of the B+ voltage interlocks.
Do not apply AC power to the unit (or any of
its assemblies) unless all solid-state heat sinks
are correctly installed.

8. Always connect a test instrumentÕs ground
lead to the instrument chassis ground before
connecting the positive lead; always remove
the instrumentÕs ground lead last.

Precautions

Samsung Electronics 1-3

Warning1: First read the “Safety Precautions” section of this manual. If some unforeseen circumstance creates a conflict between

the servicing and safety precautions, always follow the safety precautions.

Warning2: An electrolytic capacitor installed with the wrong polarity might explode.

1. Some semiconductor (Òsolid stateÓ) devices
are easily damaged by static electricity. Such
components are called Electrostatically
Sensitive Devices (ESDs); examples include
integrated circuits and some field-effect
transistors. The following techniques will
reduce the occurrence of component damage
caused by static electricity.

2. Immediately before handling any semicon
ductor components or assemblies, drain the
electrostatic charge from your body by
touching a known earth ground. Alternatively,
wear a discharging wrist-strap device. (Be
sure to remove it prior to applying powerÑ
this is an electric shock precaution.)

3. After removing an ESD-equipped assembly,
place it on a conductive surface such as
aluminum foil to prevent accumulation of
electrostatic charge.

4. Do not use freon-propelled chemicals. These
can generate electrical charges that damage
ESDs.

5. Use only a grounded-tip soldering iron when
soldering or unsoldering ESDs.

6. Use only an anti-static solder removal device.
Many solder removal devices are not rated as
Òanti-staticÓ; these can accumulate sufficient
electrical charge to damage ESDs.

7. Do not remove a replacement ESD from its
protective package until you are ready to
install it. Most replacement ESDs are
packaged with leads that are electrically
shorted together by conductive foam,
aluminum foil or other conductive materials.

8. Immediately before removing the protective
material from the leads of a replacement ESD,
touch the protective material to the chassis or
circuit assembly into which the device will be
installed.

9. Minimize body motions when handling
unpackaged replacement ESDs. Motions such
as brushing clothes together, or lifting a foot
from a carpeted floor can generate enough
static electricity to damage an ESD.

Precautions

1-4 Samsung Electronics

1-3 Precautions for Electrostatically Sensitive Devices (ESDs)

Specifications and IC Data

Samsung Electronics 2-1

2. Specifications and IC Data

2-1 Specifications

Televisio n System:

C hann els:

Interm ediate-F requ en cies(MHz ):

P icture T ub e:

Power Requirements: AC 230 V, 50Hz or AC 220 ~ 240 V, 50Hz

Antenna Input Impedan ce :

VHF ,UHF: Telesc opic dipo le antenna (75Wunb alanced type)

Speak er Im ped ance :

8

W

,

10W + 10W or 16

W , 5W + 5W (533C only)

MODEL SYSTEM

CI PAL-I (UHF)

CII PAL-I (VHF/UHF)
CX P AL -B/G,SEC AM-B/G
CK PAL-B/G,D/K,SE CAM-B/G ,D/K
CB PAL-B/G
CF SECAM-L/L' , PAL/SECAM-B/G

SYSTEM

BAND

PAL/SECAM

-B/G,I

PAL/SECAM

-D/K

SECAM-K1,

PAL-D
VHF 2-12 1-13 2-9
UHF 21-69 21-69 13-57

SYSTEM

BAND

PAL/SECAM

-B/ G

PAL/SECAM

-D/K,K1

PAL-I SECAM-L

Picture IF Carrier 38.90 38.90 38.90 38.90

Sound IF C arrier 33.40 32.40 32.90 34.40

Color Sub Carrier 34.47 34.47 34.47 34.47

25 Inch

A51EER131X31

Quick start,in-line-gun,
Black stripe,90¡degree d eflection

28 Inch
30 Inch

A66EAK071X01 (Normal)

A70QBZ791X

SECAM-L'

34.50

41.00

38.93

A66EAK552X21 (Invar)

A59EAK071X01 (Normal)
A59EAK552X21 (Invar)

21 Inch

2-2 IC Line Up

Specifications and IC Data

2-2 Samsung Electronics

LOC NO NO Specification Description Remarks

HIC101 1 PAP103T IF PRE-AMP

IC201 2

TDA8844 PAL/SEC AM/NTSC/SEC AM-L

TDA8843 PAL/NTSC
IC301 3 LA7845 VER TICAL DEF LE C TION AMP
IC501 4 TDA6108 RGB DRIVE AMP

IC601 5

TDA7297 SOUND AMP(10W/CH)

TDA7266S SOUND AMP(5W/C H)
IC701 6 TDA9859 AUDIO PROCESSOR
IC801 7 KA3S1265R SMPS IC( 12A)
IC802 8 PC123Y PHOTO C OUP LE R
IC803 9 78R05 SWITCHING RE GULATOR
IC804 10 K A7630 SWITCHING RE GULATOR(5,8V)
IC901 11 SPM171EE MICOM
IC902 12 24W16 EEPROM
ICE01 13 455 8 EW DR IVE AMP
ICN01 14 TDA9814T SIF DETECTOR (SECAM-L)

NICAM

MODULE

ICN02 15 TDA9874H NIC AMDE MODULATOR
ICA01 16 LA7567N SIF DE TEC TOR

A2 STEREO

MODULE

ICA02 17 TDA9873H A2 DEMODULATOR

ICM01 18 LA7566 SIF & FM DETECTOR MONO
ICS01 19 TEA5114 VIDE O SWITC H

16K

RGB -S/W

2-3 Semiconductor Base Diagrams

Specifications and IC Data

Samsung Electronics 2-3

ELECTROLYTIC­CONDENSER

IC

DIODE

TDA884X(Pin 56)
SPM171EX(Pin 52)
24W16(Pin 8)
TDA9859(Pin 32)

IC

TRANSISTOR TRANSISTOR

KA7630

KA7812

IN

G

OUT

TRANSISTOR

TRANSISTOR

2SD1651
2SD1650
KSD5072
KSD5071
KSD1711

B

C

E

E B C

KSA815-Y
KSA539-Y

IC

UPC574J

or

KA33V

G1962
K2950M
K9253M
G3956M

SAW-FILTER

1

E C B

KSR1012
KSR1010
KSR2010

Fig. 2-1 Semiconductor Base Diagrams

2-4 Samsung Electronics

MEMO

Disassembly and reassembly

Samsung Electronics 3-1

3. Disassembly and Reassembly

3-1 Back Cover Removal

1. After removing the 7 screws, pull the cabinet backwards.

3-2 Main Board Removal

Disassembly and reassembly

3-2 Samsung Electronics

1

2

3

4

5

6

7

8

9

10

11

12

13

1. Separate the TBC-wire 2P connector from GT501,GT502.

2. Separate the CRT Assembly from the CRT socket.

3. Remove the Anode Cap from the CRT.

4. Separate the D-Coil Connector from CN802.

5. Separate the AC cord from CN801.

6. Separate the DC connector from CN401.

7. Separate the CN501B 8P CRT connector from CN501.

8. Separate the CNA05 5P A/V side connector from CN602.

9. Separate the CNA01 8P CRT connector from CN701.

10. Separate the Focus Screen Wire from the FBT clamper.

11. Separate the TBC wire 2P, speaker wires from the wire clamper.

12. Separate the CN701, CN602 connector from the wire clamper.

13. Separate the AC cord from the wire clamper.

14. Remove the main board by pulling it with both hands.

3-3 Speaker Removal

Disassembly and reassembly

Samsung Electronics 3-3

1. Remove the speaker by
pressing the tension rib.

1. Separate the speaker wires from D-coil

(located on the bottom to the right side).

2. Remove the screws.

7

Disassembly and reassembly

3-4 Samsung Electronics

3-4 CRT Removal

1. Remove the 4 nuts that mount the CRT to the front cabinet.
Pull the CRT backwards.

2. Caution: Because of the high vacuum and large surface area of the picture
tube, be careful while handling it: (1) Always lift the picture tube by
grasping it firmly around the faceplate, (2) Never lift the tube by its neck.
(3) Do not scratch the picture tube or apply excessive pressure. Fractures
of the glass may cause an implosion.

Alignment and Adjustments

Samsung Electronics 4-1

4. Alignment and Adjustments

4-1 Preadjustment

4-1-1 Factory Mode

1. Do not attempt these adjustments in the Video
Mode.

2. The Factory Mode adjustments are necessary
when either the EEPROM (IC902) or the CRT
is replaced.

3. Do not tamper with the ÒAdjustmentÓ screen
of the Factory Mode menu. This screen is
intended only for factory use.

4-1-2 When EEPROM (IC902) Is Replaced

1. When IC902 is replaced all adjustment data
revert to initial values. It is necessary to
re-program this data.

2. After IC902 is replaced, warm up the TV for
10 seconds.

4-1-3 When CRT Is Replaced

1. Make the following adjustments AFTER set­ting up after setting up purity and conver­gence :

White Balance
Sub-Brightness, Sub-Contrast
Vertical Center
Vertical Size
Horizontal Size
Fail Safe (This adjustment must be the last
step).

4-2 Factory/Service Mode

4-2-1 Procedure for the “Adjustment” Mode

1. This mode uses the standard remote control.
The Service Mode is activated by entering the
following remote-control sequence :

(1) STAND-BY® DISPLAY® MENU® MUTE

®POWER ON.

2. The ÒSERVICE (FACTORY)Ó message will be
displayed. The Service Mode has three compo­nents: Adjustment, Option and Reset.

3. Access the Adjustment Mode by pressing the
ÒVOLUMEÓ keys ( Up or Down). The adjust­ment parameters are listed in the accompany­ing table, and selected by pressing the

CHANNEL keys (▲ ,▼).

4. Selection sequences for the PAL system:

DOWN or UP key:

AGC↔VCO↔SBT↔SCT↔SCR↔SC↔RG↔

BG↔CDL↔STT↔LCO↔VOL↔PSL↔PVS↔
PVA↔PHS↔PEW↔PEP↔PEC↔PET↔VSC↔
TSC↔SA↔QEW↔PCT↔PTT↔PHM↔PVP↔

PHP↔NSR↔PDL↔AGC.

5. The VOLUME keys increase or decrease the
adjustment values (stored in the
non-volatile memory) when Adjustment Mode
is cancelled.

6. Cancel the Adjustment Mode by re-pressing
the ÒHIDDENÓ or ÒPower OFF/ONÓ keys.

7. After adjustments are completed, re-start

the TV set.

4-2-2 Main Adjustment Parameters

Alignment and Adjustments

4-2 Samsung Electronics

OSD FUNCTION RANGE
AGC AUTO GAIN CONTROL 0-63
VCO VOLTAGE CONTROLLED OSCILLATOR 0 - 127
SBT SUB BRIGHTNESS 0-23
SCT SUB CONTRAST 0-23
SCR SUB COLOUR 0-23
SC S-CORRECTION 0-63
RG RED DRIVE GAIN 0-63
BG BLUE DRIVE GAIN 0-63
CDL CATHODE DRIVE LEVEL 0-7
STT SUB TINT ( FOR NTSC ) 0-7
LCO SECAM-L VOLTAGE CONTROLLED OSCILLATOR 0-1
VOL VOLUME INITIAL LEVEL 0-63
PSL PAL VERTICAL SLOPE 0-63
PVS PAL VERTICAL SHIFT 0-63
PVA PAL VERTICAL AMPLITUDE 0-63
PHS PAL HORIZONTAL SHIFT 0-63
PEW PAL E-W WIDTH 0-63
PEP PAL E-W PALABOLA 0-63
PEC PAL E-W CORNER 0-63
PET PAL E-W TRAPEZIUM 0-63
VSC VERTICAL SCROLL 0-63
TSC TELETEXT SUB CONTRAST 0-63
SA SEPARATION ADJUSTMENT (STEREO) 0-15
QEW Q(12.8:9)MODEL E-W WIDTH 0-7
PCT PIP CONTRAST 0-15
PTT PIP TINT 0-63
PHM PIP HORIZONTAL MOVE 0-15
PVP PIP VERTICAL POSITION 0-63
PHP PIP HORIZONTAL POSITION 0-63
NSR NTSC SUB COLOUR 0-23
PDL PAL DELAYTIME 0-15

Alignment and Adjustments

Samsung Electronics 4-3

4-2-3 AGING Mode (Reference Only)

This pattern is used for pre-heating the CRT during manufacturing--it is accessed in the factory by
twice pressing the ÒFACTORY Ò key.

Even if the TV power is cut off, the Aging Mode is not cancelled, The AGING mode is cancelled by
repressing the ÒHIDDENÓ or any key on the front pannel.

FACTORY MODE VALUE

OSD INITIAL OSD INITIAL OSD INITIAL
2 (CH) LCO 1 (FIXED) TSC 20(FIXED)
AGC 10 VOL 25 SA 7
VCO 80(FIXED) PSL 31(FIXED) QEW 5
SBT 7 PVS 31 PCT 7(FIXED)
SCT 16 PVA 31 PTT 31(FIXED)
SCR 5(FIXED) PHS 40 PHM 8(FIXED)
SC 11(FIXED) PEW 38 PVP 31(FIXED)
RG 31 PEP 22 PHP 31(FIXED)
BG 31 PEC 22 NSR 3 (FIXED)
CDL 5 PET 30 PDL 0 (FIXED)
STT 10(FIXED) VSC 31(FIXED)