SAFETY PRECAUTIONS
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by
△
！
in the
Exploded View.
It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent
Shock, Fire, or other Hazards.
Do not modify the original design without permission of manufacturer.
IMPORTANT SAFETY NOTICE
General Guidance
An other abnormality exists that must be corrected before the
receiver is returned to the customer.
An
isolation Transformer should always be used
during the
servicing of a receiver whose chassis is not isolated from the AC
Leakage Current Hot Check
(See below Figure)
power line. Use a transformer of adequate power rating as this
Plug the AC cord directly into the AC outlet.
protects the technician from accidents resulting in personal injury
from electrical shocks.
Do not use a line Isolation Transformer during this check.
Connect 1.5 K / 10 watt resistor in parallel with a 0.15 uF capacitor
It will also protect the receiver and it's components from being
between a known good earth ground (Water Pipe, Conduit, etc.)
damaged by accidental shorts of the circuitry that may be
and the exposed metallic parts.
inadvertently introduced during the service operation.
Measure the AC voltage across the resistor using AC voltmeter
If any fuse (or Fusible Resistor) in this TV receiver is blown,
with 1000 ohms/volt or more sensitivity.
replace it with the specified.
Reverse plug the AC cord into the AC outlet and repeat AC voltage
measurements for each exposed metallic part. Any voltage
When replacing a high wattage resistor (Oxide Metal Film Resistor,
measured must not exceed 0.75 volt RMS which is corresponds to
over 1 W), keep the resistor 10 mm away from PCB.
0.5 mA.
Keep wires away from high voltage or high temperature parts.
In case any measurement is out of the limits specified, there is
Before returning the receiver to the customer,
possibility of shock hazard and the set must be checked and
repaired before it is returned to the customer.
always perform an
AC leakage current check
on the exposed
metallic parts of the cabinet, such as antennas, terminals, etc., to
Leakage Current Hot Check circuit
be sure the set is safe to operate without damage of electrical
shock.
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Copyright © 2018 LG Electronics Inc. All rights reserved.
Only training and service purposes
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
switch in the on position, connect one lead of ohm-meter to the AC
plug prongs tied together and touch other ohm-meter lead in turn to
each exposed metallic parts such as antenna terminals, phone
jacks, etc.
When 25A is impressed between Earth and 2nd Ground
If the exposed metallic part has a return path to the chassis, the
for 1 second, Resistance must be less than 0.1
*Base on Adjustment standard
measured resistance should be between 1 M
Ω
and 5.2 M
Ω
.
When the exposed metal has no return path to the chassis the
reading must be infinite.
Summary of Contents for 24BL650C
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