LG LAS551H - USB connection

3-1
SECTION 3
ELECTRICAL
CONTENTS
ONE POINT REPAIR GUIDE ............................................................................................................................ 3-2
1. NO POWER PROBLEM (PVDD) ............................................................................................................ 3-2
2. POWER ON ERROR .............................................................................................................................. 3-3
3. NO SOUND (PORTABLE FUNCTION) .................................................................................................. 3-4
4. NO WIRELESS ....................................................................................................................................... 3-5
5. NO BLUETOOTH .................................................................................................................................... 3-6
6. NO SOUND (USB) .................................................................................................................................. 3-7
7. NO SOUND (OPTICAL) .......................................................................................................................... 3-8
8. HDMI PROBLEM .................................................................................................................................... 3-9
WAVEFORMS OF MAJOR CHECK POINT .................................................................................................... 3-10
1. CRYSTAL .............................................................................................................................................. 3-10
2. FLASH MEMORY ................................................................................................................................. 3-11
3. TACT KEY ............................................................................................................................................. 3-12
4. USB ....................................................................................................................................................... 3-13
5. REMOTE CONTROL ............................................................................................................................ 3-14
6. OPTICAL ............................................................................................................................................... 3-15
7. PORTABLE ........................................................................................................................................... 3-16
8. AUDIO PWM ......................................................................................................................................... 3-17
9. AUDIO AMP .......................................................................................................................................... 3-19
WIRING DIAGRAM .......................................................................................................................................... 3-21
BLOCK DIAGRAM .......................................................................................................................................... 3-23
CIRCUIT DIAGRAMS ...................................................................................................................................... 3-25
1. SMPS CIRCUIT DIAGRAM .................................................................................................................. 3-25
2. MAIN - DSP CIRCUIT DIAGRAM ......................................................................................................... 3-27
3. MAIN - PWM & AMP CIRCUIT DIAGRAM ........................................................................................... 3-29
4. MAIN - POWER CIRCUIT DIAGRAM ................................................................................................... 3-31
5. HDMI & JACK CIRCUIT DIAGRAM ...................................................................................................... 3-33
6. FRONT CIRCUIT DIAGRAM ................................................................................................................ 3-35
7. TACT KEY CIRCUIT DIAGRAM ........................................................................................................... 3-37
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-39
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-41
1. SMPS P. C. BOARD DIAGRAM ........................................................................................................... 3-41
2. MAIN P. C. BOARD DIAGRAM ............................................................................................................ 3-43
3. HDMI & JACK P. C. BOARD DIAGRAM .............................................................................................. 3-45
4. FRONT P. C. BOARD DIAGRAM ......................................................................................................... 3-45
5. TACT KEY P. C. BOARD DIAGRAM .................................................................................................... 3-45