- 3 - LGE Internal Use OnlyCopyright ©2010 LG Electronics Inc. All rights reserved.
Only or training and service purposes
SAFETY PRECAUTIONS
Many electrical and mechanical parts in this chassis have special sa ety-related characteristics. These parts are identi ied by in
the Schematic Diagram and Exploded View.
It is essential that these special sa ety parts should be replaced with the same components as recommended in this manual to
prevent X-RADIATION, Shock, Fire, or other Hazards.
Do not modi y the original design without permission o manu acturer.
General Guidance
An isolation Transformer should always be used during the
servicing o a receiver whose chassis is not isolated rom the AC
power line. Use a trans ormer o adequate power rating as this
protects the technician rom accidents resulting in personal injury
rom electrical shocks.
It will also protect the receiver and it's components rom being
damaged by accidental shorts o the circuitry that may be
inadvertently introduced during the service operation.
I any use (or Fusible Resistor) in this monitor is blown, replace it
with the speci ied.
When replacing a high wattage resistor (Oxide Metal Film
Resistor, over 1W), keep the resistor 10mm away rom PCB.
Keep wires away rom high voltage or high temperature parts.
Due to high vacuum and large sur ace area o picture tube,
extreme care should be used in handling the Picture Tube.
Do not li t the Picture tube by it's Neck.
Leakage Current Cold Check(Antenna Cold Check)
With the instrument AC plug removed rom AC source, connect
an electrical jumper across the two AC plug prongs. Place the
AC switch in the on position, connect one lead o 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.
I the exposed metallic part has a return path to the chassis, the
measured resistance should be between 1MΩ and 5.2MΩ.
When the exposed metal has no return path to the chassis the
reading must be in inite.
An other abnormality exists that must be corrected be ore the
receiver is returned to the customer.
Leakage Current Hot Check (See below Figure)
Plug the AC cord directly into the AC outlet.
Do not use a line Isolation Transformer during this check.
Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor
between a known good earth ground (Water Pipe, Conduit, etc.)
and the exposed metallic parts.
Measure the AC voltage across the resistor using AC voltmeter
with 1000 ohms/volt or more sensitivity.
Reverse plug the AC cord into the AC outlet and repeat AC
voltage measurements or each exposed metallic part. Any
voltage measured must not exceed 0.75 volt RMS which is
corresponds to 0.5mA.
In case any measurement is out o the limits speci ied, there is
possibility o shock hazard and the set must be checked and
repaired be ore it is returned to the customer.
Leakage Current Hot Check circuit