LG CM8440 Series - Section 3: Electrical

SECTION 3
ELECTRICAL
CONTENTS
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
WAVEFORMS OF MAJOR CHECK POINT ................................................................................................... 3-35
WIRING DIAGRAM ......................................................................................................................................... 3-39
BLOCK DIAGRAMS ........................................................................................................................................ 3-41
1. SMPS BLOCK DIAGRAM..................................................................................................................... 3-41
2. MAIN SYSTEM BLOCK DIAGRAM ...................................................................................................... 3-43
3. MAIN POWER BLOCK DIAGRAM ....................................................................................................... 3-45
CIRCUIT DIAGRAMS ...................................................................................................................................... 3-47
1. SMPS - POWER #1 CIRCUIT DIAGRAM ............................................................................................ 3-47
2. SMPS - POWER #2 CIRCUIT DIAGRAM ............................................................................................ 3-49
3. MAIN - CD DSP CIRCUIT DIAGRAM .................................................................................................. 3-51
4. MAIN - RF / SERVO CIRCUIT DIAGRAM ........................................................................................... 3-53
5. MAIN - ADC / PWM CIRCUIT DIAGRAM ............................................................................................ 3-55
6. MAIN - AMP CIRCUIT DIAGRAM ........................................................................................................ 3-57
7. FRONT VOLUME CIRCUIT DIAGRAM ................................................................................................ 3-59
8. MIC & PORTABLE CIRCUIT DIAGRAM .............................................................................................. 3-61
CIRCUIT VOLTAGE CHART .......................................................................................................................... 3-63
1. CONNECTORS .................................................................................................................................... 3-63
2. CAPACITORS....................................................................................................................................... 3-64
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-65
1. SMPS P.C.BOARD ............................................................................................................................... 3-65
2. MAIN P.C.BOARD ................................................................................................................................ 3-69
3. FRONT VOLUME P.C.BOARD ............................................................................................................ 3-73
4. MIC & PORTABLE P.C.BOARD ........................................................................................................... 3-75
3-1