LG 12.8 Service Manual free download

File name 12.8 Service Manual.pdf

CONTENTS PAGE Safety Instructions 1 Technical Specifications 2 Instructions Manual 3 Block Diagram 7 Pin Voltages of IC's 8 Oscillograms 11 Electrical and Service Adjustments 15 Channel Frequency Tables 18 Part List 22 Circuit Diagrams Attached SAFETY INSTRUCTIONS GENERAL GUIDELINES connectors, control shafts etc. When the exposed metallic part a return path to the 1. It is advised to insert an isolation transformer chassis the reading should be between in the AC supply before servicing a hot 4Mohm and the 20Mohm. When the chassis. exposed metal does not have a return path to the chassis, the reading must be infinite. 2. Potentials as high as 33KV are present when this receiver is in operation. Operation of the LEAKAGE CURRENT HOT CHECK receiver without the rear cover involves the danger of a shock hazard from the receiver 1. Plug the AC cord directly in to the AC power supply. Servicing should not be outlet. Do not use an isolation transformer attempted by any one who is not for this check. competent with the precautions necessary 2. Connect a 2Kohm 10W resistor in series with when working on the high voltage an exposed metallic part on the receiver equipment. Always discharge the anode of and an earth, such as a water pipe. the tube. 3. Use an AC voltmeter with high impedance to measure the potential across the resistor. 3. When servicing observe the original lead 4. Check each exposed metallic part and dress in the high voltage circuits. If a short check the voltage at the each point. circuit is found, replace all the parts which 5. Reverse the AC plug at the outlet and have been overheated or damaged by the repeat each of the above measurements. short circuit. 6. The potential at the any point should not exceed 1.4 Vrms. In case a measurement is 4. Always use the manufacturer's replacement outside the limits specified, there is the safety components. The critical safety possibility of a shock hazard, and the components marked with on the