PRODUCT SAFETY SERVICING GUIDELINES FOR VIDEO PRODUCTS
IMPORTANT SAFETY NOTICE
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 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.
Special components are also used to prevent x-radiation, shock and fire hazard.
These components are indicated by the letter “x” included in their component
designators and are required to maintain safe performance. No deviations are allowed
without prior approval by LG Corporation.
Circuit diagrams may occasionally differ from the actual circuit used. This way,
implementation of the latest safety and performance improvement changes into the set
are not delayed until the new service literature is printed.
CAUTION
customized installations without manufacturer’s approval. Unauthorized modifications
will not only void the warranty, but may lead to property damage or user injury.
Service work should be performed only after you are thoroughly familiar with these
safety checks and servicing guidelines.
: Do not attempt to modify this product in any way. Never perform
GRAPHIC SYMBOLS
The exclamation point within an equilateral triangle is intended to alert
the service personnel to important safety information in the service
literature.
The lightning flash with arrowhead symbol within an equilateral triangle
is intended to alert the service personnel to the presence of noninsulated
“dangerous voltage” that may be of sufficient magnitude to constitute a
risk of electric shock.
The pictorial representation of a fuse and its rating within an equilateral
triangle is intended to convey to the service personnel the following fuse
replacement caution notice:
CAUTION: FOR CONTINUED PROTECTION AGAINST RISK OF
FIRE, REPLACE ALL FUSES WITH THE SAME TYPE AND RATING
AS MARKED NEAR EACH FUSE.
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 following:
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 particles.
4. Check for physical evidence of damage or deterioration to parts and components,
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 ALINE ISOLATION TRANSFORMER 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 metallic 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 constitutes a potential
shock hazard and must be corrected immediately.
TIPS ON PROPER INSTALLATION
1. Never install any receiver in a closed-in recess, cubbyhole, or closely fitting shelf
space over, or close to, a heat duct, or in the path of heated air flow.
2. Avoid conditions of high humidity such as: outdoor patio installations where dew is a
factor, near steam radiators where steam leakage is a factor, etc.
3. Avoid placement where draperies may obstruct venting. The customer should also
avoid the use of decorative scarves or other coverings that might obstruct ventilation.
4. Wall- and shelf-mounted installations using a commercial mounting kit must follow
the factory-approved mounting instructions. A product mounted to a shelf or platform
must retain its original feet (or the equivalent thickness in spacers) to provide
adequate air flow across the bottom. Bolts or screws used for fasteners must not
touch any parts or wiring. Perform leakage tests on customized installations.
5. Caution customers against mounting a product on a sloping shelf or in a tilted
position, unless the receiver is properly secured.
6. A product on a roll-about cart should be stable in its mounting to the cart.
Caution the customer on the hazards of trying to roll a cart with small casters across
thresholds or deep pile carpets.
7. Caution customers against using extension cords. Explain that a forest of
extensions, sprouting from a single outlet, can lead to disastrous consequences to
home and family.
CAUTION: Before servicing the PORTABLE DVD covered by
this service data and its supplements and addends, read and
follow the SAFETY PRECAUTIONS. NOTE: if unforeseen
circumstances create conflict between the following servicing
precautions and any of the safety precautions in this
publication, always follow the safety precautions.
Remember Safety First :
General Servicing Precautions
1. Always unplug the PORTABLE DVD AC power cord from
the AC power source before:
(1) Removing or reinstalling any component, circuit board,
module, or any other assembly.
(2) Disconnecting or reconnecting any internal electrical
plug or other electrical connection.
(3) Connecting a test substitute in parallel with an
electrolytic capacitor.
Caution: A wrong part substitution or incorrect polarity
installation of electrolytic capacitors may result in an
explosion hazard.
2. Do not spray chemicals on or near this PORTABLE DVD or
any of its assemblies.
3. Unless specified otherwise in this service data, clean
electrical contacts by applying an appropriate contact
cleaning solution to the contacts with a pipe cleaner, cottontipped swab, or comparable soft applicator.
Unless specified otherwise in this service data, lubrication of
contacts is not required.
4. Do not defeat any plug/socket B+ voltage interlocks with
which instruments covered by this service manual might be
equipped.
5. Do not apply AC power to this PORTABLE DVD and / or any
of its electrical assemblies unless all solid state device heat
sinks are correctly installed.
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
lead last.
Insulation Checking Procedure
Disconnect the attachment plug from the AC outlet and turn
the power on. Connect an insulation resistance meter (500V)
to the blades of the attachment plug. The insulation resistance
between each blade of the attachment plug and accessible
conductive parts (Note 1) should be more than 1Mohm.
Note 1: Accessible Conductive Parts include Metal panels,
Input terminals, Earphone jacks,etc.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid state) devices can be damaged
easily by static electricity. Such components commonly are
called Electrostatically Sensitive (ES) Devices. Examples of
typical ES devices are integrated circuits and some field effect
transistors and semiconductor chip components.
The following techniques should be used to help reduce the
incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor component
or semiconductor-equipped assembly, drain off any
electrostatic charge on your body by touching a known earth
ground. Alternatively, obtain and wear a commercially
available discharging wrist strap device, which should be
removed for potential shock reasons prior to applying power
to the unit under test.
2. After removing an electrical assembly equipped with ES
devices, place the assembly on a conductive surface such
as aluminum foil, to prevent electrostatic charge buildup or
exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder
ES devices.
4. Use only an anti-static solder removal device. Some solder
removal devices not classified as “anti-static” can generate
electrical charges sufficient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate
an electrical charge sufficient to damage ES devices.
6. Do not remove a replacement ES device from its protective
package until immediately before you are ready to install it.
(Most replacement ES devices are packaged with leads
electrically shorted together by conductive foam, aluminum
foil, or comparable conductive material).
7. Immediately before removing the protective material from
the leads of a replacement ES device, touch the protective
material to the chassis or circuit assembly into which the
device will be installed.
Caution: Be sure no power is applied to the chassis or
circuit, and observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged
replacement ES devices. (Normally harmless motion such
as the brushing together of your clothes fabric or the lifting
of your foot from a carpeted floor can generate static
electricity sufficient to damage an ES device.)
LCD PART ...................................................................................................................................................3-2
MAIN PART ...............................................................................................................................................3-11
MAIN ELECTRICAL TROUBLESHOOTING GUIDE .....................................................................3-11
1. POWER (DC-DC CONVERTER) CIRCUIT..........................................................................................3-11