LG CM9550 Service Manual page 22

ONE POINT REPAIR GUIDE ............................................................................................................................3-2
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 BOOTING IN CD/USB FUNCTION ..................................................................................................3-6
5. NO OPERATION OF MD (DRIVING THE SERVO MOTORS) ............................................................3-11
6. NO SOUND ...........................................................................................................................................3-16
7. AUDIO OUTPUT IS SMALL OR NO AUDIO OUTPUT ........................................................................3-22
8. NO POWER ON (STANDBY LED IS BLINKING) .................................................................................3-23
9. SPEAKER NO AUDIO ..........................................................................................................................3-24
ELECTRICAL TROUBLESHOOTING GUIDE .................................................................................................3-25
1. POWER SUPPLY ON SMPS BOARD ..................................................................................................3-25
2. SYSTEM PART .....................................................................................................................................3-29
3. NO AUDIO PART ..................................................................................................................................3-30
4. NO LIGHTING (WOOFER SPEAKER) .................................................................................................3-35
WAVEFORMS OF MAJOR CHECK POINT ....................................................................................................3-36
WIRING DIAGRAM ..........................................................................................................................................3-41
BLOCK DIAGRAMS ........................................................................................................................................3-43
1. SMPS BLOCK DIAGRAM .....................................................................................................................3-43
2. MAIN SYSTEM BLOCK DIAGRAM ......................................................................................................3-45
3. MAIN POWER BLOCK DIAGRAM .......................................................................................................3-47
CIRCUIT DIAGRAMS ......................................................................................................................................3-49
1. SMPS - POWER #1 CIRCUIT DIAGRAM ............................................................................................3-49
2. SMPS - POWER #2 CIRCUIT DIAGRAM ............................................................................................3-51
3. MAIN - CD DSP CIRCUIT DIAGRAM ...................................................................................................3-53
4. MAIN - RF / SERVO CIRCUIT DIAGRAM ............................................................................................3-55
5. MAIN - ADC / PWM CIRCUIT DIAGRAM .............................................................................................3-57
6. MAIN - AMP CIRCUIT DIAGRAM.........................................................................................................3-59
7. FRONT VOLUME CIRCUIT DIAGRAM ................................................................................................3-61
8. MIC & PORTABLE CIRCUIT DIAGRAM ..............................................................................................3-63
9. FRONT SPEAKER MAIN CIRCUIT DIAGRAM ....................................................................................3-65
10. FRONT SPEAKER SUB CIRCUIT DIAGRAM ......................................................................................3-67
11. WOOFER SPEAKER MAIN CIRCUIT DIAGRAM ................................................................................3-69
12. WOOFER SPEAKER SUB CIRCUIT DIAGRAM ..................................................................................3-71
CIRCUIT VOLTAGE CHART ...........................................................................................................................3-73
1. CONNECTORS .....................................................................................................................................3-73
2. CAPACITORS .......................................................................................................................................3-74
PRINTED CIRCUIT BOARD DIAGRAMS .......................................................................................................3-75
1. SMPS P.C.BOARD (TOP VIEW) ..........................................................................................................3-75
2. SMPS P.C.BOARD (BOTTOM VIEW) ..................................................................................................3-77
3. MAIN P.C.BOARD (TOP VIEW) ...........................................................................................................3-79
4. MAIN P.C.BOARD (BOTTOM VIEW) ...................................................................................................3-81
5. FRONT VOLUME & MIC & PORTABLE P.C.BOARD (TOP VIEW).....................................................3-83
6. FRONT VOLUME & MIC & PORTABLE P.C.BOARD (BOTTOM VIEW).............................................3-85
7. FRONT SPEAKER MAIN/SUB & WOOFER SPEAKER MAIN/SUB P.C.BOARD (TOP VIEW) ..........3-87
8. FRONT SPEAKER MAIN/SUB & WOOFER SPEAKER MAIN/SUB P.C.BOARD (BOTTOM VIEW) ..3-87
SECTION 3
ELECTRICAL
CONTENTS
3-1