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IMPOTANT 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.
SAFETY PRECAUTIONS
General Guidance
An lsolation Transformer should always be used during
the servicing of a receiver whose chassis is not isolated
from the AC power line. Use a transformer of adequate
power rating as this protects the technician from accidents
resulting in personal injury from electrical shocks.
It will also protect the receiver and it’s components from
being damaged by accidental shorts of the circuitary that
may be inadvertently introduced during the service
operation.
If any fuse (or Fusible Resistor) in this TV receiver is blown,
replace it with the specified.
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.
Due to high vacuum and large surface area of picture tube,
extreme care should be used in handling the picture Tube.
Do not lift the picture tube by it’s Neck.
x-RAY Radiation
Warning:
The source of X-RAY RASIATION in this TV receiver is the
High Voltage section and the picture Tube.
For continude S-RAY RADIATIONprotection , the
replacement tube must be the same type tube as speci-
fied in the Replacement parts List
To determine the presence of high voltage,use an accu-
rate high impedance HV meter.
Adjust brightness, color,contrast controls to minimum.
Measure the high voltage.
The meter reading should indicate 23.5+1.5KV:14-19 inch,
26 +1.5kv:19-21inch,lf the meter indication is out of
tolerance,immediate serviceand correction is required to
prevent the possibility of premature component failure.
Before returning the receiver to the customer
always perform an AC leakag current check on the
exposed metallic parts of the cabinet,such as antennas,
terminals,etc;to be sure the set is safe to operate
without damage of electrical shock.
Leakage current cold check (Antenna cold check )
with the instrument AC plug renoved fron AC source,
connect an electical junper 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 tum to each exposed metallic parts
such as antenna terminals,phone jacks,etc.
If the exposed metallic part has a return path to the chassis,
the measured resistance should be beween1M
Ω
and 5.
2M
Ω
When the exposed metal has no return path to the
chassis the reading must be infinite,An other abnormality
exists that must be corrected before the receiver is returned
to the customer.
Leakage Current Hot Check(See below Figure)
plug the AC cord DIRECTLY into the AC outlet.
Do notuse a line lsolation 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
voltemeter with 1000 ohms/volt or more sensitivity.
Reverse plug the AC cord into the AC outlet and repeat AC
voltage measurements for 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 of the limits specified,
there is possibility of shock hazard and the set must be
checked and repaired before it is retumed to the customer.
Leakage Current-Hot Check circuit
AC Volt-meter
To Instrument’s
exposed
METALLICPARTS
Good Earth Ground
s u c h a s W A T E R
PIPE,CONDUIT EIC
1.5Kohm/10W
0.15 uF
