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 Replacement Parts List.
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 GuidanceBefore returning the receiver to the customer,
An isolation Transformer should always be usedduring thealways perform an AC leakage current checkon the exposed
servicing of a receiver whose chassis is not isolated from the ACmetallic parts of the cabinet, such as antennas, terminals, etc., to
power line. Use a transformer of adequate power rating as thisbe sure the set is safe to operate without damage of electrical
protects the technician from accidents resulting in personal injuryshock.
from electrical shocks.
Leakage Current Cold Check(Antenna Cold Check)
It will also protect the receiver and it's components from beingWith the instrument AC plug removed from AC source, connect an
damaged by accidental shorts of the circuitry that may beelectrical jumper across the two AC plug prongs. Place the AC
inadvertently introduced during the service operation.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
If any fuse (or Fusible Resistor) in this TV receiver is blown,each exposed metallic parts such as antenna terminals, phone
replace it with the specified.jacks, etc.
If the exposed metallic part has a return path to the chassis, the
When replacing a high wattage resistor (Oxide Metal Film Resistor,measured resistance should be between 1M& and 5.2M&.
over 1W), keep the resistor 10mm away from PCB.When the exposed metal has no return path to the chassis the
reading must be infinite.
Keep wires away from high voltage or high temperature parts.An other abnormality exists that must be corrected before the
receiver is returned to the customer.
Due to high vacuum and large surface area of picture tube,
extreme care should be used in handling the Picture Tube.DoLeakage Current Hot Check(See below Figure)
not lift the Picture tube by it's Neck.Plug the AC cord directly into the AC outlet.
Do not use a line Isolation Transformer during this check.
X-RAY RadiationConnect 1.5K/10watt resistor in parallel with a 0.15uF capacitor
between a known good earth ground (Water Pipe, Conduit, etc.)
Warning: and the exposed metallic parts.
Measure the AC voltage across the resistor using AC voltmeter
with 1000 ohms/volt or more sensitivity.
The source of X-RAY RADIATION in this TV receiver is the HighReverse plug the AC cord into the AC outlet and repeat AC voltage
Voltage Section and the Picture Tube.measurements for each exposed metallic part. Any voltage
For continued X-RAY RADIATION protection, the replacementmeasured must not exceed 0.75 volt RMS which is corresponds to
tube must be the same type tube as specified in the0.5mA.
Replacement Parts List.In case any measurement is out of the limits specified, there is
possibility of shock hazard and the set must be checked and
To determine the presence of high voltage, use an accurate highrepaired before it is returned to the customer.
impedance HV meter.
Leakage Current Hot Check circuit
Adjust brightness, color, contrast controls to minimum.
Measure the high voltage.
The meter reading should indicate AC Volt-meter
23.5 ý}1.5KV: 14-19 inch, 26 ý}1.5KV: 19-21 inch,
29.0 ý}1.5KV: 25-29 inch, 30.0 ý}1.5KV: 32 inch
If the meter indication is out of tolerance, immediate service and
correction is required to prevent the possibility of premature
component failure.Good Earth Ground
such as WATER PIPE,
To Instrument'sCONDUIT etc.0.15uF
exposed
METALLIC PARTS
1.5 Kohm/10W
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ACEC
LG-GOLDSTAR
