User manual LG HFB-510

[. . . ] 2) The Components used in the unit have a specified conflammability and dielectric strength. When replacing any components, use components which have the same ratings. Components marked in the circuit diagram are important for safety or for the characteristics of the unit. 3) An insulation tube or tape is sometimes used and some components are raised above the printed writing board for safety. [. . . ] The internal wiring is sometimes clamped to prevent contact with heating components. 4) After servicing always check that the removed screws, components and wiring have been installed correctly and that the portion around the service part has not been damaged. Further check the insulation between the blades of attachment plug and accessible conductive parts. - 1-2 - ESD PRECAUTIONS Electrostatically Sensitive Devices (ESD) Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated circuits and some field-effect transistors and semiconductor chip components. The following techniques should be used to help reduce the incidence of component damage caused by static electricity. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed for potential shock reasons prior to applying power to the unit under test. After removing an electrical assembly equipped with ESD devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly. Q371, Q372, IC403 Is u-com IC906 LCD reset circuit normal?Pin74 NO · Reset circuit defective. IC901 Surrounding circuit defective. YES Is u-com IC906 X1, X2 terminal Pin11, 12, 14, 15 input?OSC :19. 2MHz OSC :32. 768kHz YES Is u-com IC906 keyin Pin19, 20 5volt input?YES NO NO Q921, ZD910 PCB pattern defective. NO X101, X102, C101, C102, C103, C104. Is u-com IC906 Pin 74, 75, 76 output waveform normal? IC906, Pin74, 75, 76 front PCB pattern defective. YES NO Is IC901 Com1, Com2, Com3 output waveform normal? IC901, Surrounding circuit PCB pattern defective. YES Display LCD connector defective. - 2-2 - 3. Initial reading is not carried out. Slide motor moves (With disc) YES NO Spindle motor turns WAVEFORM #1 YES (with disc) Does RF waveform appear?IC501 Pin49 WAVEFORM #2 NO Check the Voltage change of CN503 Pin12 (6. 4~6. 8V) YES NO NO Defective connector CN503 Defective IC501 Defective connector CN503 Defective MICOM Check the Voltage IC501 Pin23 (1. 4V~1. 8V) YES Check the Data transmission from CN503 (16, 17, 18) to CD DSP WAVEFORM #5 YES NO Check the Data transmission from CN503 Pin21 to MICOM WAVEFORM #5 YES Defective NO connector CN503 Defective IC503 Check the TRVP Voltage IC501 Pin23 YES NO Defective IC501 Check the change of SL +, SL - Voltage IC503 Pin13, 14 YES NO Defective IC503 Laser light check A ? YES Defective contact CN501 Defective PICK-UP Does FA+ waveform appear at IC501 Pin23?WAVEFORM #3 focus coil drive wareform. YES NO Does TE waveform appear at IC501 Pin24?WAVEFORM #4 TRACKING ERROR wareform YES NO Is rotation normal? NO YES Is there no dropout of RF signal? YES Defective IC501 Defective PICK-UP - 2-3 - A When laser does not light. Is "2. 4V~3. 4V" applied to pin42 of IC501?YES Defective MICOM or CN503. Did pickup return to innermost circular? [. . . ] WAVEFORM #4 TRACKING ERROR wareform YES NO Is rotation normal? NO YES Is there no dropout of RF signal? YES Defective IC501 Defective PICK-UP - 2-3 - A When laser does not light. Is "2. 4V~3. 4V" applied to pin42 of IC501?YES Defective MICOM or CN503. Did pickup return to innermost circular?YES Does voltage appear at IC503 Pin 13, 14? NO Defective IC501. YES Defective slide motor and/or connector. (CN502) Does it stop at inner pick circular after shift? YES Is defect output from LMT SW applied to Pin7 of PN503? [. . . ]