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SERVICE MANUAL
High Definition
Television Receiver
SERVICE MANUAL
MODEL : LST-4100P
MODEL : LST-4100P
CAUTION
BEFORE SERVICING THE UNIT, READ THE "SAFETY PRECAUTIONS"
IN THIS MANUAL.
MAY, 2004
P/NO : 3829RHP028K Printed in Korea
SECTION 1
SUMMARY
CONTENTS
PRODUCT SAFETY SERVICING GUIDELINES FOR VIDEO PRODUCTS............1-2
SPECIFICATIONS .....................................................................................................1-3
1-1
PRODUCT SAFETY SERVICING GUIDELINES FOR VIDEO PRODUCTS
IMPORTANT SAFETY NOTICE A.C. Voltmeter
This manual was prepared for use only by properly trained audio-video service
technicians.
When servicing this product, under no circumstances should the original
design be modified or altered without permission from LG Electronics
Corporation. All components should be replaced only with types identical to
those in the original circuit and their physical location, wiring and lead dress
must conform to original layout upon completion of repairs.
0.15uF
Special components are also used to prevent x-radiation, shock and fire haz- Place this probe
Good Earth Ground
ard. These components are indicated by the letter "x" included in their compo- such as the Water
on each exposed
nent designators and are required to maintain safe performance. No deviations 1500 OHM metal part.
Pipe, Conduit, etc.
are allowed without prior approval by LG Electronics Corporation.
Circuit diagrams may occasionally differ from the actual circuit used. This way, 10 WATT
implementation of the latest safety and performance improvement changes
TIPS ON PROPER INSTALLATION
into the set is not delayed until the new service literature is printed.
1. Never install any receiver in a closed-in recess, cubbyhole, or closely fitting
CAUTION: Do not attempt to modify this product in any way. Never perform
shelf space over, or close to, a heat duct, or in the path of heated air flow.
customized installations without manufacturer's approval. Unauthorized modi-
fications will not only void the warranty, but may lead to property damage or 2. Avoid conditions of high humidity such as: outdoor patio installations where
user injury. dew is a factor, near steam radiators where steam leakage is a factor, etc.
Service work should be performed only after you are thoroughly familiar with 3. Avoid placement where draperies may obstruct venting. The customer
these safety checks and servicing guidelines. should also avoid the use of decorative scarves or other coverings that
might obstruct ventilation.
GRAPHIC SYMBOLS
4. Wall- and shelf-mounted installations using a commercial mounting kit must
The exclamation point within an equilateral triangle is intended to
follow the factory-approved mounting instructions. A product mounted to a
alert the service personnel to important safety information in the
shelf or platform must retain its original feet (or the equivalent thickness in
service literature.
spacers) to provide adequate air flow across the bottom. Bolts or screws
The lightning flash with arrowhead symbol within an equilateral tri- used for fasteners must not touch any parts or wiring. Perform leakage tests
angle is intended to alert the service personnel to the presence of on customized installations.
noninsulated "dangerous voltage" that may be of sufficient magni-
5. Caution customers against mounting a product on a sloping shelf or in a tilt-
tude to constitute a risk of electric shock.
ed position, unless the receiver is properly secured.
The pictorial representation of a fuse and its rating within an equi-
6. A product on a roll-about cart should be stable in its mounting to the cart.
lateral triangle is intended to convey to the service personnel the
Caution the customer on the hazards of trying to roll a cart with small cast-
following fuse replacement caution notice:
ers across thresholds or deep pile carpets.
CAUTION: FOR CONTINUED PROTECTION AGAINST RISK
7. Caution customers against using extension cords. Explain that a forest of
OF FIRE, REPLACE ALL FUSES WITH THE SAME TYPE AND
extensions, sprouting from a single outlet, can lead to disastrous conse-
RATING AS MARKED NEAR EACH FUSE.
quences to home and family.
SERVICE INFORMATION
While servicing, use an isolation transformer for protection from AC line shock.
After the original service problem has been corrected, make a check of the fol-
lowing:
FIRE AND SHOCK HAZARD
1. Be sure that all components are positioned to avoid a possibility of adjacent
component shorts. This is especially important on items trans-ported to and
from the repair shop.
2. Verify that all protective devices such as insulators, barriers, covers, shields,
strain reliefs, power supply cords, and other hardware have been reinstalled
per the original design. Be sure that the safety purpose of the polarized line
plug has not been defeated.
3. Soldering must be inspected to discover possible cold solder joints, solder
splashes, or sharp solder points. Be certain to remove all loose foreign par-
ticles.
4. Check for physical evidence of damage or deterioration to parts and compo-
nents, for frayed leads or damaged insulation (including the AC cord), and
replace if necessary.
5. No lead or component should touch a high current device or a resistor rated
at 1 watt or more. Lead tension around protruding metal surfaces must be
avoided.
6. After reassembly of the set, always perform an AC leakage test on all
exposed metallic parts of the cabinet (the channel selector knobs, antenna
terminals, handle and screws) to be sure that set is safe to operate without
danger of electrical shock. DO NOT USE A LINE ISOLATION TRANS-
FORMER DURING THIS TEST. Use an AC voltmeter having 5000 ohms per
volt or more sensitivity in the following manner: Connect a 1500 ohm, 10
watt resistor, paralleled by a .15 mfd 150V AC type capacitor between a
known good earth ground water pipe, conduit, etc.) and the exposed metal-
lic parts, one at a time. Measure the AC voltage across the combination of
1500 ohm resistor and .15 mfd capacitor. Reverse the AC plug by using a
non-polarized adaptor and repeat AC voltage measurements for each
exposed metallic part. Voltage measured must not exceed 0.75 volts RMS.
This corresponds to 0.5 milliamp AC. Any value exceeding this limit consti-
tutes a potential shock hazard and must be corrected immediately.
1-2
SPECIFICATIONS
Television System DVB-T Austraalian Standard Compliant
Frequency Range VHF : 48.5 to 219.5MHz
UHF : 529.5 to 816.5MHz
Input/Output
RF Inputs ANT IN (1) 75 ohm unbalanced
ANT Loop Out Out To TV (1)
DVI Output DVI-HDTV Out (1), DVI-D Single Link connector
1080i, 720p, 576p digital RGB
Component Video Output Component Out (1 Set), Typical RCA type Jack connectors
1080i, 720p, 576p, 576i YPbPr
RGB Output RGB Out (1), 15-pin connector
1080i, 720p, 576p RGB
S-Video Output S-Video Out (1), 4-pin Mini-DIN
576i Y/C
Video Output Video Out (1), Typical RCA type Jack connector
576i Composite
Digital Audio Output Coaxial, Optical (Dolby Digital output)
Analog Audio Output Audio Out (2) (Variable Output Level)
Authorized Service Port 9-pin Serial Port (1)
Dimension (W x H X D) 370 x 60 x 262 mm
Weight 3.5 kg
Power Requirements AC 90-250V, 50/60Hz
Power Consumption 18W
Environment
Humidity 0 to 99 percent non condensing
Storage Temperature -20 to 60 degrees Celsius
Operating Temperature 0 to 40 degrees Celsius
Accessories
RF cable 1
Video cable 1
Audio (L/R) cable 1
Component (YPbPr) cable 1
Remote Control 1
Batteries (size AAA) 2
1-3
SECTION 2
CABINET & MAIN CHASSIS
CONTENTS
EXPLODED VIEWS .....................................................................................................................2-2
1. Cabinet and Main Frame Section ...........................................................................................2-2
2-1
EXPLODED VIEWS
1. Cabinet and Main Frame Section
NOTE) Refer to "SECTION 4 REPLACEMENT
PARTS LIST" in order to look for the
part number of each part.
4
250
A44
300
3
A46
A43
2
A47
A50
1
A B C D
2-2
SECTION 3
ELECTRICAL
CONTENTS
ELECTRICAL TROUBLESHOOTING GUIDE........3-2 16. EXTERNAL CON CIRCUIT DIAGRAM .....3-51
1. SYSTEM REPAIR FLOW ..............................3-2 17. DVB-T TUNER CIRCUIT DIAGRAM .........3-53
2. BASIC OPERATION ......................................3-4 18. DVB-T CHANNEL DEC
CIRCUIT DIAGRAM ..................................3-55
3. SYSTEM OPERATION ..................................3-9
19. DVI I/F CIRCUIT DIAGRAM ......................3-57
4. MPEG & A/V OPERATION ..........................3-11
20. VIDEO HD OUT & UART
5. CHANNEL OPERATION..............................3-19 CIRCUIT DIAGRAM ..................................3-59
21. VIDEO OUT CVBS/S-VHS
CIRCUIT DIAGRAM ..................................3-61
BLOCK DIAGRAM ...............................................3-20
22. AUDIO DAC & SPDIF
CIRCUIT DIAGRAM ..................................3-63
CIRCUIT DIAGRAMS ...........................................3-21
23. SPDIF & COAXIAL CIRCUIT DIAGRAM..3-65
1. DDR SDRAM0 CIRCUIT DIAGRAM ...........3-21
24. RCA CONNECTOR CIRCUIT DIAGRAM .3-67
2. DDR SDRAM1 CIRCUIT DIAGRAM ...........3-23
25. RS232 CIRCUIT DIAGRAM ......................3-69
3. SIO I/F CIRCUIT DIAGRAM .......................3-25
PRINTED CIRCUIT DIAGRAMS ..........................3-71
4. LOCAL BUS & PCI I/F
1. MAIN PRINTED CIRCUIT DIAGRAMS .......3-71
CIRCUIT DIAGRAM.....................................3-27
5. BOOTROM & FLASH I/F
CIRCUIT DIAGRAM.....................................3-29
6. IDE I/F CIRCUIT DIAGRAM ........................3-31
7. TRANSPORT IN/OUT PORT
CIRCUIT DIAGRAM.....................................3-33
8. AUDIO I2S IN/OUTPUT
CIRCUIT DIAGRAM.....................................3-35
9. HD DVI VIDEO CIRCUIT DIAGRAM3-37
10. AUX VIDEO CIRCUIT DIAGRAM..............3-39
11. POWER FOR CPU & MEMORY
CIRCUIT DIAGRAM...................................3-41
12. POWER & GND FOR TL955
CIRCUIT DIAGRAM ..................................3-43
13. POWER & GND FOR MEMORY
CIRCUIT DIAGRAM ..................................3-45
14. CLOCK CIRCUIT DIAGRAM.....................3-47
15. POWER CON CIRCUIT DIAGRAM...........3-49
3-1
ELECTRICAL TROUBLESHOOTING GUIDE
1. SYSTEM REPAIR FLOW
It is recommended that the repair of a failed or poor set should basically comply with the following steps:
1. Appearance inspection
Check the appearance of the set for poor assembly, imperfect connector connection, bending or breakage of
the front/main PCBs, poor soldering of parts, short circuits, and shortage of parts.
2. Basic inspection
1) Check the output voltages of connector JP271 rise to +3.3V, +5V, +5V, -5V, +12V, +7.5V and JP272 stand
by +5V, -28V and 3.9Vac he main power.
2) Check that the front keys and IR sensor function properly.
3. System inspection
1) Check that the reset signal, indicating that the MICOM which is located in the front board (AT89C51RB2,
U901) has been activated.
2) Check that the main clock is being applied to the TL955(U2).
4. MPEG and A/V inspection
Inspect all the processes from the MPEG decoding to the A/V output and then inspect each output of the
back-end terminals.
5. Channel inspection
Inspect the operation of the tuner and regulator, including locking status, AGC (Automatic Gain Control), and
the DC power.
Waveforms shown in this instruction manual are typical examples and may differ depending upon the operat-
ing environments. It is recommended, therefore, that you refer to the figures as illustrative examples to identify
the cause of any problem.
3-2
PCB LAYOUT FUNCTION BLOCKS
Channel OFDM
Analog A/V & DVI
CPU MPEG & VIDEO
AUDIO process
3-3
2. BASIC OPERATION
ITEM: POWER SUPPLY
SYMPTOM: A PART OR THE WHOLE OF A SYSTEM DOES NOT WORK.
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