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PLASMA TV
SERVICE MANUAL
CHASSIS : PU92A
MODEL : 50PQ20 50PQ20-UA
CAUTION
BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
SAFETY PRECAUTIONS
IMPORTANT SAFETY NOTICE
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the
Schematic Diagram and Exploded View.
It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent
X-RADIATION, Shock, Fire, or other Hazards.
Do not modify the original design without permission of manufacturer.
General Guidance Leakage Current Hot Check (See below Figure)
Plug the AC cord directly into the AC outlet.
An lsolation Transformer should always be used during the Do not use a line Isolation Transformer during this check.
servicing of a receiver whose chassis is not isolated from the AC Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor
power line. Use a transformer of adequate power rating as this between a known good earth ground (Water Pipe, Conduit, etc.)
protects the technician from accidents resulting in personal injury and the exposed metallic parts.
from electrical shocks. Measure the AC voltage across the resistor using AC voltmeter
with 1000 ohms/volt or more sensitivity.
It will also protect the receiver and it's components from being Reverse plug the AC cord into the AC outlet and repeat AC voltage
damaged by accidental shorts of the circuitary that may be measurements for each esposed metallic part. Any voltage
inadvertently introduced during the service operation. measured must not exceed 0.75 volt RMS which is corresponds to
0.5mA.
If any fuse (or Fusible Resistor) in this monitor is blown, replace it In case any measurement is out of the limits sepcified, there is
with the same specified type. possibility of shock hazard and the set must be checked and
repaired before it is returned to the customer.
When replacing a high wattage resistor (Oxide Metal Film Resistor,
over 1W), keep the resistor 10mm away from PCB.
Keep wires away from high voltage or high temperature parts. Leakage Current Hot Check circuit
AC Volt-meter
Leakage Current Cold Check(Antenna Cold Check)
With the instrument AC plug removed from AC source, connect an
electrical jumper across the two AC plug prongs. Place the AC
Good Earth Ground
switch in the on positioin, connect one lead of ohm-meter to the AC such as WATER PIPE,
plug prongs tied together and touch other ohm-meter lead in turn to CONDUIT etc.
To Instrument's
each exposed metallic parts such as antenna terminals, phone 0.15uF
exposed
jacks, etc. METALLIC PARTS
If the exposed metallic part has a return path to the chassis, the
measured resistance should be between 1M and 5.2M.
When the exposed metal has no return path to the chassis the 1.5 Kohm/10W
reading must be infinite.
An other abnormality exists that must be corrected before the
receiver is returned to the customer.
CANADA: LG Electronics Canada, Inc. 550 Matheson
Boulevard East Mississauga, Ontario L4Z 4G3
USA : LG Customer Interactive Center
P.O.Box 240007, 201 James Record Road Huntsville,
AL 35824
Digital TV Hotline 1-800-243-0000
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