LG SoundPlate LAP250H, Service Manual

Page: 12 / 51

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) .................................................................................................. 3-5
4. NO BLUETOOTH .................................................................................................................................... 3-6
5. NO SOUND (USB) .................................................................................................................................. 3-7
6. NO SOUND (OPTICAL) .......................................................................................................................... 3-8
7. HDMI PROBLEM .................................................................................................................................... 3-9
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................. 3-10
1. DSP OPERATING CHECK ................................................................................................................... 3-10
2. OPTICAL CHECK ................................................................................................................................. 3-10
3. PORTABLE PART CHECK ................................................................................................................... 3-11
4. USB FUNCTION CHECK ..................................................................................................................... 3-11
5. HDMI PART CHECK ............................................................................................................................. 3-12
6. AMP PART CHECK .............................................................................................................................. 3-12
7. LCD DISPLAY CHECK ......................................................................................................................... 3-13
WAVEFORMS OF MAJOR CHECK POINT .................................................................................................... 3-14
1. CRYSTAL .............................................................................................................................................. 3-14
2. FLASH MEMORY ................................................................................................................................. 3-15
3. TACT KEY ............................................................................................................................................. 3-16
4. USB ....................................................................................................................................................... 3-17
5. REMOTE CONTROL ............................................................................................................................ 3-18
6. OPTICAL ............................................................................................................................................... 3-19
7. PORTABLE ........................................................................................................................................... 3-21
8. AUDIO PWM ......................................................................................................................................... 3-22
9. AUDIO AMP .......................................................................................................................................... 3-23
WIRING DIAGRAM .......................................................................................................................................... 3-25
BLOCK DIAGRAMS ........................................................................................................................................ 3-27
1. BLOCK DIAGRAM #1 ........................................................................................................................... 3-27
2. BLOCK DIAGRAM #2 ........................................................................................................................... 3-29
3. VOLTAGE BLOCK DIAGRAM .............................................................................................................. 3-31
CIRCUIT DIAGRAMS ...................................................................................................................................... 3-33
1. SMPS CIRCUIT DIAGRAM .................................................................................................................. 3-33
2. MAIN - DSP CIRCUIT DIAGRAM ......................................................................................................... 3-35
3. MAIN - AMP CIRCUIT DIAGRAM......................................................................................................... 3-37
4. MAIN - POWER CIRCUIT DIAGRAM ................................................................................................... 3-39
5. MAIN - HDMI CIRCUIT DIAGRAM ....................................................................................................... 3-41
6. FRONT CIRCUIT DIAGRAM ................................................................................................................ 3-43
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-45
1. ICs ......................................................................................................................................................... 3-45
2. CAPACITORS ....................................................................................................................................... 3-46
3. CONNECTORS ..................................................................................................................................... 3-47
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-49
1. SMPS P. C. BOARD DIAGRAM ........................................................................................................... 3-49
2. MAIN P. C. BOARD DIAGRAM ............................................................................................................ 3-51
3. FRONT P. C. BOARD ........................................................................................................................... 3-53