Sharp 21FL94 Service Manual - Page 3

21FL94 IMPORTANT SERVICE SAFETY PRECAUTION (Continued) BEFORE RETURNING THE RECEIVER (Fire & Shock Hazard) Before returning the receiver to the user, perform the following safety checks. 1. Inspect all lead dress to make certain that leads are not pinched or that hardware is not lodged between the chassis and other metal parts in the receiver. 2. Inspect all protective devices such as non-metallic control knobs, insulating materials, cabinet backs, adjustment and compartment covers or shields, isolation resistor-capacity networks, mechanical insulators, etc. 3. To be sure that no shock hazard exists, check for leakage current in the following manner. • Plug the AC cord directly into a 110~220 volt AC outlet, (Do not use an isolation transformer for this test). • Using two clip leads, connect a 1.5k ohm, 10 watt resistor paralleled by a 0.15µF capacitor in series with all exposed metal cabinet parts and a known earth ground, such as electrical conduit or electrical ground connected to earth ground. • Use an AC voltmeter having with 5000 ohm per volt, or higher, sensitivity to measure the AC voltage drop across the resistor. • Connect the resistor connection to all exposed metal parts having a return to the chassis (antenna, metal cabinet, screw heads, knobs and control shafts, escutcheon, etc.) and measure the AC voltage drop across the resistor. AII checks must be repeated with the AC line cord plug connection reversed. (If necessary, a nonpolarized adapter plug must be used only for the purpose of completing these check.) Any current measured must not exceed 0.5 milliamp. Any measurements not within the limits outlined above indicate of a potential shock hazard and corrective action must be taken before returning the instrument to the customer. DVM AC SCALE 1.5k ohm 10W TO EXPOSED METAL PARTS CONNECT TO KNOWN EARTH GROUND 111122223333444455556666777788889999000011112222333344445555666677778888999900001111222233334444555566667777888899990000111122221111222233334444555566667777888899990000111122223333444455556666777788889999000011112222333344445555666677778888999900001111222211112222333344445555666677778888999900001111222233334444555566667777888899990000111122223333444455556666777788889999000011112222111122223333 SAFETY NOTICE Many electrical and mechanical parts in television For continued protection, replacement parts must be receivers have special safety-related characteristics. identical to those used in the original circuit. The use of These characteristics are often not evident from visual substitute replacement parts which do not have the same inspection, nor can protection afforded by them be safety characteristics as the factory recommended necessarily increased by using replacement components replacement parts shown in this service manual, may rated for higher voltage, wattage, etc. create shock, fire, X-radiation or other hazards. Replacement parts which have these special safety characteristics are identified in this manual; electrical components having such features are identified by "å" and shaded areas in the Replacement Parts Lists and Schematic Diagrams. 11112222333344445555666677778888999900001111222233334444555566667777888899990000111122223333444455556666777788889999000011112222111122223333444455556666777788889999000011112222333344445555666677778888999900001111222233334444555566667777888899990000111122221111222233334444555566667777888899990000111122223333444455556666777788889999000011112222333344445555666677778888999900001111222211112222 3