Service Manuals, User Guides, Schematic Diagrams or docs for : LG DVD LST-3510A hfe_lg_electronics_lst-3510a_service_en
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SET-TOP BOX
SERVICE MANUAL
MODEL : LST-3510A
CAUTION
BEFORE SERVICING THE UNIT, READ THE "SAFETY PRECAUTIONS"
IN THIS MANUAL.
SECTION 1
SUMMARY
CONTENTS
OVERVIEW................................................................................................................1-2
PRODUCT SAFETY SERVICING GUIDELINES FOR VIDEO PRODUCTS............1-3
SERVICING PRECAUTIONS....................................................................................1-4
SPECIFICATIONS .....................................................................................................1-5
LOCATION OF CUSTOMER CONTROLS ...............................................................1-6
1-1
OVERVIEW
1 Description
- Digital HDTV receiver/DVD player can receive a ground HD digital broadcasting signal and play a DVD.
- Configuration
LST3500 largely consists of 4 boards - ATSC board, Front Panel board, SMPS board, and DVD board.
Each board consists of the followings:
ATSC board
- System part
It consists of CPU, Flash Memory, System Memory, MPEG-II Decoder, and EPLD. It controls the operation of
the entire system, and handles MPEG A/V data.
- Tuner part
It generates TP signal by transmitting IF of the desired channel from the RF signal to the VSB receiver.
- A/V signal output part
It processes the A/V signal handled by the DAC to output.
Front Panel board
- Front part
It is located at the front, which receives various key inputs of users and displays the state of the set-top box
at the VFD.
SMPS board
- Power part
It supplies the DC power to the main digital board based on AC 110~220V as an input.
DVD board
- DVD part
It plays a disc and transmits the A/V data to the MPEG Decoder IC.
1-2
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.
1-3
SERVICING PRECAUTIONS
CAUTION: Before servicing the SET-TOP BOX covered by Electrostatically Sensitive (ES) Devices
this service data and its supplements and addends, read and Some semiconductor (solid state) devices can be damaged
follow the SAFETY PRECAUTIONS. NOTE: if unforeseen easily by static electricity. Such components commonly are
circumstances create conflict between the following servic- called Electrostatically Sensitive (ES) Devices. Examples of
ing precautions and any of the safety precautions in this pub- typical ES devices are integrated circuits and some field
lications, always follow the safety precautions. effect transistors and semiconductor chip components.
Remember Safety First: The following techniques should be used to help reduce the
incidence of component damage caused by static electricity.
General Servicing Precautions
1. Always unplug the SET-TOP BOX AC power cord from the 1. Immediately before handling any semiconductor compo-
AC power source before: nent or semiconductor-equipped assembly, drain off any
(1) Removing or reinstalling any component, circuit board, electrostatic charge on your body by touching a known
module, or any other assembly. earth ground. Alternatively, obtain and wear a commer-
(2) Disconnecting or reconnecting any internal electrical cially available discharging wrist strap device, which
plug or other electrical connection. should be removed for potential shock reasons prior to
(3) Connecting a test substitute in parallel with an elec- applying power to the unit under test.
trolytic capacitor.
Caution: A wrong part substitution or incorrect 2. After removing an electrical assembly equipped with ES
polarity installation of electrolytic capacitors may result devices, place the assembly on a conductive surface such
in an explosion hazard. as aluminum foil, to prevent electrostatic charge buildup or
exposure of the assembly.
2. Do not spray chemicals on or near this SET-TOP BOX or
any of its assemblies. 3. Use only a grounded-tip soldering iron to solder or unsolder
ES devices.
3. Unless specified otherwise in this service data, clean
electrical contacts by applying an appropriate contact 4. Use only an anti-static solder removal device. Some
cleaning solution to the contacts with a pipe cleaner, solder removal devices not classified as "anti-static" can
cotton-tipped swab, or comparable soft applicator. generate electrical charges sufficient to damage ES
Unless specified otherwise in this service data, lubrication devices.
of contacts is not required.
5. Do not use freon-propelled chemicals. These can
4. Do not defeat any plug/socket B+ voltage interlocks with generate an electrical charge sufficient to damage ES
which instruments covered by this service manual might devices.
be equipped.
6. Do not remove a replacement ES device from its protec-
5. Do not apply AC power to this SET-TOP BOX and / or any tive package until immediately before you are ready to
of its electrical assemblies unless all solid-state device install it. (Most replacement ES devices are packaged with
heat sinks are correctly installed. leads electrically shorted together by conductive foam,
aluminum foil,or comparable conductive material).
6. Always connect the test instrument ground lead to an
appropriate ground before connecting the test instrument
positive lead. Always remove the test instrument ground 7. Immediately before removing the protective material from
lead last. the leads of a replacement ES device, touch the protective
material to the chassis or circuit assembly into which the
Insulation Checking Procedure device will be installed.
Disconnect the attachment plug from the AC outlet and turn
the power on. Connect an insulation resistance meter (500V) Caution: Be sure no power is applied to the chassis or
to the blades of the attachment plug. The insulation resis- circuit, and observe all other safety precautions.
tance between each blade of the attachment plug and acces-
sible conductive parts (Note 1) should be more than 1M- 8. Minimize bodily motions when handling unpackaged
ohm. replacement ES devices. (Normally harmless motion such
Note 1: Accessible Conductive Parts include Metal panels, as the brushing together of your clothes fabric or the lifting
Input terminals, Earphone jacks,etc. of your foot from a carpeted floor can generate static elec-
tricity sufficient to damage an ES device.)
1-4
SPECIFICATIONS
System Specifications Front Panel
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