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 lsolation Transformer should always be used duringalways perform an AC leakage current check on the exposed
the servicing of a receiver whose chassis is not isolated frommetallic parts of the cabinet, such as antennas, terminals, etc.,
the AC power line. Use a transformer of adequate power ratingto be sure the set is safe to operate without damage of
as this protects the technician from accidents resulting inelectrical shock.
personal injury 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,
damaged by accidental shorts of the circuitary that may beconnect an electrical jumper across the two AC plug prongs.
inadvertently introduced during the service operation.Place the AC switch in the on positioin, connect one lead of
ohm-meter to the AC plug prongs tied together and touch other
If any fuse (or Fusible Resistor) in this TV receiver is blown,ohm-meter lead in turn to each exposed metallic parts such as
replace it with the specified.antenna terminals, phone jacks, etc.
If the exposed metallic part has a return path to the chassis, the
When replacing a high wattage resistor (Oxide Metal Filmmeasured resistance should be between 1M1 and 5.2M1.
Resistor, 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.Leakage Current Hot Check (See below Figure)
Do 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
Reverse plug the AC cord into the AC outlet and repeat ACHigh Voltage Section and the Picture Tube.
voltage measurements for each esposed metallic part. Any
For continued X-RAY RADIATION protection, the
voltage measured must not exceed 0.75 volt RMS which isreplacement tube must be the same type tube as specified in
corresponds to 0.5mA.
the Replacement Parts List.
In case any measurement is out of the limits sepcified, there is
possibility of shock hazard and the set must be checked and
repaired before it is returned to the customer.
To determine the presence of high voltage, use an accurate
high impedance HV meter.Leakage Current Hot Check circuit
Adjust brightness, color, contrast controls to minimum. AC Volt-meter
Measure the high voltage.
The meter reading should indicate
23.5 ! 1.5KV: 14-19 inch, 26 ! 1.5KV: 19-21 inch,
29.0 ! 1.5KV: 25-29 inch, 30.0 ! 1.5KV: 32 inch
If the meter indication is out of tolerance, immediate serviceGood Earth Ground
such as WATER PIPE,
and correction is required to prevent the possibility of
premature component failure.To Instrument'sCONDUIT etc.0.15uF
exposed
METALLIC PARTS
1.5 Kohm/10W
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ACEC
