LG OM5541 Service Manual page 16

ONE POINT REPAIR GUIDE
1. NO POWER ............................................................................................................................................ 3-2
2. NO BOOTING WHEN POWER ON THE SET ....................................................................................... 3-4
3. VFD IS NOT DISPLAYED WHEN POWER ON THE SET ..................................................................... 3-5
4. NO SOUND ............................................................................................................................................ 3-6
ELECTRICAL TROUBLESHOOTING GUIDE
1. POWER (SMPS) ................................................................................................................................... 3-12
2. MCS PART CHECK.............................................................................................................................. 3-15
3. IC504(M24C16) CHECK ....................................................................................................................... 3-15
4. DOUBLE USB FUNCTION ................................................................................................................... 3-16
5. FLD DISPLAY CHECK ......................................................................................................................... 3-17
6. PWM MODULATION CHECK .............................................................................................................. 3-18
7. POWER AMP PART CHECK ............................................................................................................... 3-20
8. TUNER / AUX FUNCTION CHECK ...................................................................................................... 3-21
9. MIC FUNCTION CHECK ...................................................................................................................... 3-22
WAVEFORMS OF MAJOR CHECK POINT
1. SDRAM ................................................................................................................................................. 3-23
2. AUDIO PATH ........................................................................................................................................ 3-23
3. USB....................................................................................................................................................... 3-23
WIRING DIAGRAM
................................................................................................................................... 3-25
BLOCK DIAGRAMS
1. SYSTEM BLOCK DIAGRAM_1 ............................................................................................................ 3-27
2. SYSTEM BLOCK DIAGRAM_2 ............................................................................................................ 3-29
3. SMPS BLOCK DIAGRAM_1................................................................................................................. 3-31
4. SMPS BLOCK DIAGRAM_2................................................................................................................. 3-33
CIRCUIT DIAGRAMS
1. SMPS CIRCUIT DIAGRAM .................................................................................................................. 3-35
2. MAIN_DSP CIRCUIT DIAGRAM .......................................................................................................... 3-37
3. MAIN_ADC/PWM CIRCUIT DIAGRAM ................................................................................................ 3-39
4. MAIN_AMP CIRCUIT DIAGRAM .......................................................................................................... 3-41
5. FRONT_KEY/USB CIRCUIT DIAGRAM .............................................................................................. 3-43
6. FRONT_VFD CIRCUIT DIAGRAM ....................................................................................................... 3-45
7. FRONT_KEY/PTB CIRCUIT DIAGRAM ............................................................................................... 3-47
8. FRONT_MIC CIRCUIT DIAGRAM ....................................................................................................... 3-49
9. SPK_LED CIRCUIT DIAGRAM ............................................................................................................ 3-51
10. X_LED/RCU2 CIRCUIT DIAGRAM ...................................................................................................... 3-53
CIRCUIT VOLTAGE CHART
1. ICs......................................................................................................................................................... 3-55
2. CAPACITORS....................................................................................................................................... 3-56
3. CONNECTORS .................................................................................................................................... 3-57
PRINTED CIRCUIT BOARD DIAGRAMS
1. SMPS P.C.BOARD ............................................................................................................................... 3-59
2. MAIN P.C.BOARD ................................................................................................................................ 3-61
3. FRONT_KEY/USB P.C.BOARD ........................................................................................................... 3-63
4. FRONT_VFD P.C.BOARD ................................................................................................................... 3-63
5. FRONT_KEY/PTB P.C.BOARD ........................................................................................................... 3-65
6. FRONT_MIC P.C.BOARD .................................................................................................................... 3-65
7. SPK_LED P.C.BOARD ......................................................................................................................... 3-67
8. X_LED/RCU2 P.C.BOARD ................................................................................................................... 3-67
SECTION 3 ELECTRICAL
CONTENTS
................................................................................................................... 3-2
................................................................................................................................. 3-27
............................................................................................................................... 3-35
................................................................................................................. 3-55
.................................................................................. 3-12
..................................................................................... 3-23
......................................................................................... 3-59
3-1