LG LHD625 Service Manual page 14

DIGITAL DISPLAY & MEDIA TRAINING MASTER ......................................................................................... 2-2
1. DISTORTED PICTURE ........................................................................................................................... 2-2
2. NO PICTURE .......................................................................................................................................... 2-7
3. PICTURE COLOR ................................................................................................................................. 2-12
4. NOISE/AUDIO PROBLEMS .................................................................................................................. 2-14
5. MISCELLANEOUS ................................................................................................................................ 2-17
ONE POINT REPAIR GUIDE .......................................................................................................................... 2-26
1. NO POWER PROBLEM ....................................................................................................................... 2-26
2. NO BOOTING WHEN YOU TURN THE UNIT ON, NO MESSAGE ON FRONT PANEL.................... 2-28
3. BAD HDMI VIDEO / AUDIO OUTPUT .................................................................................................. 2-34
4. NO AUDIO FROM SPEAKER ............................................................................................................... 2-35
5. NO USB ................................................................................................................................................ 2-36
6. BT CONNECTION ERROR .................................................................................................................. 2-37
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................. 2-38
1. SYSTEM POWER SUPPLY ON SMPS BOARD .................................................................................. 2-38
2. POWER SUPPLY ON MAIN BOARD ................................................................................................... 2-41
3. SYSTEM PART ..................................................................................................................................... 2-43
4. NO HDMI OUTPUT ............................................................................................................................... 2-45
5. NO AUDIO OUTPUT ............................................................................................................................ 2-46
DETAILS AND WAVEFORMS ON SYSTEM TEST AND DEBUGGING ....................................................... 2-47
1. SYSTEM PART (MPEG CRYSTAL 27 MHz) ....................................................................................... 2-47
2. SDRAM CLOCK .................................................................................................................................... 2-48
3. VIDEO PART (100% FULL COLOR-BAR) ........................................................................................... 2-48
4. HDMI PART .......................................................................................................................................... 2-49
5. SERVO OPEN/CLOSE SIGNAL ........................................................................................................... 2-50
WIRING DIAGRAM .......................................................................................................................................... 2-59
BLOCK DIAGRAM .......................................................................................................................................... 2-61
CIRCUIT DIAGRAMS ...................................................................................................................................... 2-63
1. SMPS CIRCUIT DIAGRAM .................................................................................................................. 2-63
2. MAIN & AMP - MPEG CIRCUIT DIAGRAM ......................................................................................... 2-65
3. MAIN & AMP - SERVO CIRCUIT DIAGRAM ....................................................................................... 2-67
4. MAIN & AMP - I/O CIRCUIT DIAGRAM ............................................................................................... 2-69
5. MAIN & AMP - MICOM CIRCUIT DIAGRAM........................................................................................ 2-71
6. MAIN & AMP - PWM CIRCUIT DIAGRAM ........................................................................................... 2-73
7. MAIN & AMP - AMP CIRCUIT DIAGRAM ............................................................................................ 2-75
8. JACK CIRCUIT DIAGRAM ................................................................................................................... 2-77
9. FRONT CIRCUIT DIAGRAM ................................................................................................................ 2-79
CIRCUIT VOLTAGE CHART ........................................................................................................................... 2-81
1. ICs ......................................................................................................................................................... 2-81
2. CAPACITORS ....................................................................................................................................... 2-81
3. CONNECTORS ..................................................................................................................................... 2-82
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 2-83
1. SMPS P. C. BOARD ............................................................................................................................. 2-83
2. MAIN & AMP P. C. BOARD .................................................................................................................. 2-85
3. JACK P. C. BOARD .............................................................................................................................. 2-87
4. FRONT P. C. BOARD ........................................................................................................................... 2-87
SECTION 2
ELECTRICAL
CONTENTS
2-1