LG DP270B, Service Manual

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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 is not delayed until the new service literature is printed.
CAUTION : Do not attempt to modify this product in any way. Never perform
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.
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 A LINE 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.