Samsung CS20F10MJ0XBWT Service Manual

Contents

1. Precautions1-1 Safety Precautions1. Be sure that all of the built-in protectivedevices are replaced. Restore any missingprotective shields.2. When reinstalling the chassis and itsassemblies, be sure to restore all protectivedevices, including: nonmetallic control knobsand compartment covers.3. Make sure that there are no cabinet openingsthrough which people—particularlychildren—might insert fingers and contactdangerous voltages. Such openings includethe spacing between the picture tube and thecabinet mask, excessively wide cabinetventilation slots, and improperly fitted backcovers.If the measured resistance is less than 1.0megohm or greater than 5.2 megohms, anabnormality exists that must be correctedbefore the unit is returned to the customer.4. Leakage Current Hot Check (Figure 1-1):Warning: Do not use an isolationtransformer during this test. Use a leakage-current tester or a metering system thatcomplies with American National StandardsInstitute (ANIS C101.1, Leakage Current forAppliances), and Underwriters Laboratories(UL Publication UL1410, 59.7).5. With the unit completely reassembled, plugthe AC line cord directly into the poweroutlet. With the unit’s AC switch first in theON position and then OFF, measure thecurrent between a known earth ground (metalwater pipe, conduit, etc.) and all exposedmetal parts, including: antennas, handlebrackets, metal cabinets, screwheads andcontrol shafts. The current measured shouldnot exceed 0.5 milliamp. Reverse the power-plug prongs in the AC outlet and repeat thetest.Fig. 1-1 AC Leakage Test6. Antenna Cold Check:With the unit’s AC plug disconnected from theAC source, connect an electrical jumper acrossthe two AC prongs. Connect one lead of theohmmeter to an AC prong. Connect the otherlead to the coaxial connector.7. X-ray Limits:The picture tube is especially designed to pro-hibit X-ray emissions. To ensure continuedX-ray protection, replace the picture tube onlywith one that is the same type as the original.Carefully reinstall the picture tube shields andmounting hardware; these also provide X-rayprotection.8. High Voltage Limits:High voltage must be measured each time ser-vicing is done on the B+, horizontal deflectionor high voltage circuits. Correct operation ofthe X-ray protection circuits must bereconfirmed whenever they are serviced.(X-ray protection circuits also may be called“horizontal disable” or “hold-down”.)Heed the high voltage limits. These includethe X–ray Protection Specifications Label, andthe Product Safety and X-ray Warning Note onthe service data schematic.Precautions1-1LEAKAGECURRENTTESTERDEVICEUNDERTESTTEST ALLEXPOSED METALSURFACES2-WIRE CORDALSO TEST WITHPLUG REVERSED(USING AC ADAPTERPLUG AS REQUIRED) EARTHGROUND(READING SHOULDNOT BE ABOVE0.5mA)Follow these safety, servicing and ESD precautions to prevent damage and protect against potentialhazards such as electrical shock and X-rays.