Download: Precautions

Precautions 1. Be sure that all of the built-in protective devices are replaced. Restore any missing protective shields. (Reading should not be above 0.5mA) 2. When reinstalling the chassis and its assemblies, be Device Under Leakage sure to restore all pretective devices, including : Test Currant control knobs and compartment covers. Tester Test all exposed metal 3. Make sure that there are no cabinet openings surfaces through which people-particularly children 2-Wire Cord -might insert fingers and contact dangerous Also test with voltages. Such openings include the spacing plug reversed Earth between the picture tube and the cabinet mask, (using AC adapter Ground excessively wide cabinet ventilation slots, and plug as required) improperly fitted back covers. Fig. 1 AC Leakage Test If the measured resistance is less than 1.0 megohm or greater than 5.2 megohms, an abnormality exists 7. Antenna Cold Check : that must be corrected before the unit is returned With the unit’s AC plug disconnected from the to the customer. AC source, connect an electrical jumper across the two AC prongs. Connect one lead of the ohmmeter 4. Leakage Current Hot Check (See Fig. 1) : to an AC prong. Warning : Do not use an isolation transformer Connect the other lead to the coaxial connector. during this test. Use a leakage current tester or a metering system that complies with American 8. High Voltage Limit : National Standards Institute (ANSI C101.1, High voltage must be measured each time Leakage Current for Appliances), and Underwriters servicing is done on the B+, horizontal deflection Laboratories (UL Publication UL1410, 59.7). or high voltage circuits. 5. With the unit completely reassembled, plug the AC Heed the high voltage limits. These include the line cord directly the power outlet. With the unit’s X-ray protection Specifications Label, and the AC switch first in the ON position and then OFF, Product Safety and X-ray Warning Note on the measure the current between a known erath service data schematic. ground (metal water pipe, conduit, etc.) and all exposed metal parts, including : antennas, handle 9. Some semiconductor (“solid state”) devices are brackets, metal cabinets, screwheads and control easily damaged by static electricity. shafts. The current measured should not exceed Such components are called Electrostatically 0.5 milliamp. Reverse the power-plug prongs in the Sensitive Devices (ESDs); examples include AC outlet and repeat the test. integrated circuits and some field-effect transistors. The following techniques will reduce the 6. X-ray Limits : occurrence of component damage caused by static The picture tube is designed to prohibit X-ray electricity. emissions. To ensure continued X-ray protection, replace the picture tube only with one that is the 10. Immediately before handling sny semiconductor same type as the original. components or assemblies, drain the electrostatic charge from your body by touching a known earth ground. Alternatively, wear a discharging Wrist-strap device. (Be sure to remove it prior to applying power-this is an electric shock precaution.) Samsung Electronics 1-1, Precautions 11. High voltage is maintained within specified limits 18. Picture Tube Implosion Warning : by close-tolerance, safety-related components and The picture tube in this receiver employs adjustments. If the high voltage exceeds the “integral implosion” protection. To ensure specified limits, check each of the special continued implosion protection, make sure that components. the replacement picture tube is the same as the original. 12. Design Alteration Warning : Never alter or add to the mechanical or electrical 19. Do not remove, install or handle the picture tube design of this unit. Example : Do not add without first putting on shatterproof goggles auxiliary audio or video connectors. Such equipped with side shields. Never handle the alterations might create a safety hazard. Also, any picture tube by its neck. Some “in-line” picture design changes or additions will void the tubes are equipped with a permanently attached manufacturer’s warranty. deflection yoke; do not try to remove such “permanently attached” yokes from the picture 13. Hot Chassis Warning : tube. Some TV receiver chassis are electrically connected directly to one conductor of the AC 20. Product Safety Notice : power cord. If an isolation transformer is not Some electrical and mechanical parts have special used, these units may be safely serviced only if safety-related characteristics which might not be the AC power plug is inserted so that the chassis obvious from visual inspection. These safety is connected to the ground side of the AC source. features and the protection they give might be lost if the replacement component differs from the To confirm that the AC power plug is inserted original-even if the replacement is rated for correctly, do the following : Using an AC higher voltage, wattage, etc. voltmeter, measure the voltage between the chassis and a known earth ground. If the reading Components that are critical for safety are is greater than 1.0V, remove the AC power plug, indicated in the circuit diagram by shading, reverse its polarity and reinsert. Re-measure the ( or ). voltage between the chassis and ground. Use replacement components that have the same ratings, especially for flame resistance and 14. Some TV chassis are designed to operate with 85 dielectric strength specifications. A replacement volts AC between chassis and ground, regardless part that does not have the same safety of the AC plug polarity. These units can be safely characteristics as the original might create shock, serviced only if an isolation transformer inserted fire or other hazards. between the receiver and the power source. 15. Never defeat any of the B+ voltage interlocks. Do not apply AC power to the unit (or any of its assemblies) unless all solid-state heat sinks are correctly installed. 16. Always connect a test instrument’s ground lead to the instrument chassis ground before connecting the positive lead; always remove the instrument’s ground lead last. 17. Observe the original lead dress, especially near the following areas : Antenna wiring, sharp edges, and especially the AC and high voltage power supplies. Always inspect for pinched, out- of-place, or frayed wiring. Do not change the spacing between components and the printed circuit board. Check the AC power cord for damage. Make sure that leads and components do not touch thermally hot parts. 1-2 Samsung Electronics]

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