LG T710BH Service Manual - Page 3
Safety Precautions - monitor
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SAFETY PRECAUTIONS SAFETY-RELATED COMPONENT WARNING! There are special components used in this color monitor which are important for safety. These parts are marked on the schematic diagram and the replacement parts list. It is essential that these critical parts should be replaced with the manufacturer's specified parts to prevent X-radiation, shock, fire, or other hazards. Do not modify the original design without obtaining written permission from manufacturer or you will void the original parts and labor guarantee. CAUTION: No modification of any circuit should be attempted. Service work should be performed only after you are thoroughly familiar with all of the following safety checks and servicing guidelines. SAFETY CHECK Care should be taken while servicing this color monitor because of the high voltage used in the deflection circuits. These voltages are exposed in such areas as the associated flyback and yoke circuits. FIRE & SHOCK HAZARD An isolation transformer must be inserted between the color monitor and AC power line before servicing the chassis. • In servicing, attention must be paid to the original lead dress specially in the high voltage circuit. If a short circuit is found, replace all parts which have been overheated as a result of the short circuit. • All the protective devices must be reinstalled per the original design. • Soldering must be inspected for the cold solder joints, frayed leads, damaged insulation, solder splashes, or the sharp points. Be sure to remove all foreign materials. X-RADIATION The only potential source of X-radiation is the picture tube. However, when the high voltage circuitry is operating properly there is no possibility of an X-radiation problem. The basic precaution which must be exercised is keep the high voltage at the factory recommended level; the normal high voltage is about 25.5KV. The following steps describe how to measure the high voltage and how to prevent X-radiation. Note : It is important to use an accurate high voltage meter calibrated periodically. • To measure the high voltage, use a high impedance high voltage meter, connect (-) to chassis and (+) to the CDT anode cap. • Set the brightness control to maximum point at full white pattern. • Measure the high voltage. The high voltage meter should be indicated at the factory recommended level. • If the meter indication exceeds the maximum level, immediate service is required to prevent the possibility of premature component failure. • To prevent X-radiation possibility, it is essential to use the specified picture tube. CAUTION: Please use only a plastic screwdriver to protect yourself from shock hazard during service operation. IMPLOSION PROTECTION All used display tubes are equipped with an integral implosion protection system, but care should be taken to avoid damage and scratching during installation. Use only same type display tubes. -3-