LG CM9730 Service Manual page 18

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 ..................................................................................................................... 3-11
6. NO SOUND .......................................................................................................................................... 3-16
7. AUDIO OUTPUT IS SMALL OR NO AUDIO OUTPUT ........................................................................ 3-23
8. NO POWER ON (STANDBY LED IS BLINKING) ................................................................................ 3-24
9. SPEAKER NO AUDIO .......................................................................................................................... 3-25
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................ 3-26
1. POWER SUPPLY ON SMPS BOARD ................................................................................................. 3-26
2. SYSTEM PART .................................................................................................................................... 3-30
3. NO AUDIO PART ................................................................................................................................. 3-32
4. NO LIGHTING (WOOFER SPEAKER) ................................................................................................. 3-37
WAVEFORMS ................................................................................................................................................. 3-38
WIRING DIAGRAM ......................................................................................................................................... 3-43
BLOCK DIAGRAMS ........................................................................................................................................ 3-45
1. SMPS BLOCK DIAGRAM..................................................................................................................... 3-45
2. MAIN SYSTEM BLOCK DIAGRAM ...................................................................................................... 3-47
CIRCUIT DIAGRAMS ...................................................................................................................................... 3-49
1. SMPS #1 CIRCUIT DIAGRAM ............................................................................................................. 3-49
2. SMPS #2 CIRCUIT DIAGRAM ............................................................................................................. 3-51
3. MAIN - MICOM CIRCUIT DIAGRAM .................................................................................................... 3-53
4. MAIN - PWM CIRCUIT DIAGRAM ....................................................................................................... 3-55
5. MAIN - AMP CIRCUIT DIAGRAM ........................................................................................................ 3-57
6. MAIN - DSP CIRCUIT DIAGRAM ......................................................................................................... 3-59
7. MAIN - RF SERVO CIRCUIT DIAGRAM ............................................................................................. 3-61
8. MAIN - ADC CIRCUIT DIAGRAM ........................................................................................................ 3-63
9. VFD CIRCUIT DIAGRAM ..................................................................................................................... 3-65
10. MAIN VOLUME CIRCUIT DIAGRAM ................................................................................................... 3-67
11. MIC CIRCUIT DIAGRAM ...................................................................................................................... 3-69
12. MULTI JOG VOLUME CIRCUIT DIAGRAM ......................................................................................... 3-71
13. USB CIRCUIT DIAGRAM ..................................................................................................................... 3-73
14. AUX / TUNER / SPEAKER LIGHT JACK CIRCUIT DIAGRAM ........................................................... 3-75
15. SPEAKER LED_MAIN CIRCUIT DIAGRAM ........................................................................................ 3-77
16. SPEAKER LED CIRCUIT DIAGRAM ................................................................................................... 3-79
CIRCUIT VOLTAGE CHART .......................................................................................................................... 3-81
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-87
1. SMPS P.C.BOARD ............................................................................................................................... 3-87
2. MAIN P.C.BOARD ................................................................................................................................ 3-89
3. VFD P.C.BOARD .................................................................................................................................. 3-93
4. MAIN VOLUME P.C.BOARD ................................................................................................................ 3-95
5. MIC P.C.BOARD .................................................................................................................................. 3-95
6. JOG P.C.BOARD .................................................................................................................................. 3-97
7. USB P.C.BOARD .................................................................................................................................. 3-98
8. TUNER P.C.BOARD ............................................................................................................................. 3-98
9. SPEAKER LED_MAIN P.C.BOARD ..................................................................................................... 3-99
10. SPEAKER LED P.C.BOARD ................................................................................................................ 3-99
SECTION 3 ELECTRICAL
CONTENTS
3-1