LG 42LB4D KL-EX-SI 1387179746 free download

File name 42LB4D_KL-EX-SI_1387179746.pdf

Troubleshooting 42LB4D LCD Flat Panel LCD TV - 2007 General Guidance An isolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks. It will also protect the receiver and it's components from being damaged by accidental shorts of the circuitry that may be inadvertently introduced during the service operation. If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it with the specified. When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1W), keep the resistor 10 mm away from PCB. Keep wires away from high voltage or high temperature parts. Before returning the receiver to the customer, always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as antennas, terminals, etc., to be sure the set is safe to operate without danger of electrical shock. Leakage Current Cold Check (Antenna Cold Check) With the instruments AC plug removed from power source, connect an electrical jumper across the two AC plug prongs. Place the AC switch in the on position, connect one lead of ohm-meter to the AC plug prongs tied together and touch other ohm-meter lead in turn to each exposed metallic parts such as antenna terminals, phone jacks, etc. If the exposed metallic part has a return path to the chassis, the measured resistance should be between 1M and 5.2M. When the expose d metal has no return path to the chassis the reading must be infinite. An other abnormality exists that must be corrected before the receiver is returned to the customer. LCD TV - 2007 SERVICING PRECAUTIONS CAUTION: Before servicing receivers covered by this service manual and its supplements and addenda, read and follow the SAFETY PRECAUTIONS on page in this publication. NOTE: If unforeseen circumstances create conflict between the following servicing precautions and any of the safety precautions in this publication, always follow the safety precautions. Remember: Safety First. General Servicing Precautions 1. Always unplug the receiver AC power cord from the AC power source before; a. Removing or reinstalling any component, circuit board module or any other receiver assembly. b. Disconnecting or reconnecting any receiver electrical plug or other electrical connection. c. Connecting a test substitute in parallel with an electrolytic capacitor in the receiver. CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explosion hazard. 2. Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM, FETVOM, etc) equipped with a suitable high voltage probe. Do not test high voltage by "drawing an arc". 3. Do not spray chemic