Sharp XL-UH260 Service Manual - Page 3

CHAPTER 1. GENERAL DESCRIPTION XL-UH260 FOR A COMPLETE DESCRIPTION OF THE OPERATION OF THIS UNIT, PLEASE REFER TO THE OPERATION MANUAL. BEFORE RETURNING THE AUDIO PRODUCT (Fire & Shock Hazard) Before returning the audio product 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 audio product. VTVM AC SCALE 2. Inspect all protective devices such as insulating materials, cabinet, terminal board, adjustment and compartment covers or shields, mechanical insulators etc. 1.5k ohms 10W 3. To be sure that no shock hazard exists, check for leakage current in the following manner. 0.15 µ F * Plug the AC line cord directly into a 120 volt AC outlet. * 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 conduit or electrical ground connected to earth ground. * Use a VTVM or VOM with 1000 ohm per volt, or higher, sensitivity to measure the AC voltage drop across the resistor (See diagram). * Connect the resistor connection to all exposed metal parts having a return path to the chassis (antenna, metal cabinet, screw heads, knobs and control shafts, escutcheon, etc.) and measure the AC voltage drop across the resistor. TEST PROBE TO EXPOSED METAL PARTS CONNECT TO KNOWN EARTH GROUND All check must be repeated with the AC line cord plug connection reversed. Any reading of 0.3 volt RMS (this corresponds to 0.2 milliamp. AC.) Or more is excessive and indicates a potential shock hazard which must be corrected before returning the audio product to the owner. 1 - 31