LG SN4A - SECTION 3 ELECTRICAL

3-1
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SECTION 3
ELECTRICAL
CONTENTS
WIRING DIAGRAM ............................................................................................................................................ 3-2
BLOCK DIAGRAMS .......................................................................................................................................... 3-3
1. SYSTEM BLOCK DIAGRAM .................................................................................................................. 3-3
2. POWER BLOCK DIAGRAM ................................................................................................................... 3-4
ONE POINT REPAIR GUIDE ............................................................................................................................ 3-5
1.
NO BOOTING WHEN YOU TURN THE UNIT ON, NO MESSAGE OR “HELLO” ON FRONT PANEL ........ 3-5
2. NO SOUND ............................................................................................................................................. 3-9
3. PROTECTION ERROR ......................................................................................................................... 3-13
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................. 3-15
1. ADAPTER POWER CIRCUIT ............................................................................................................... 3-15
2. KEY PART ............................................................................................................................................ 3-24
3. USB FUNCTION ................................................................................................................................... 3-25
4. OPTICAL FUNCTION ........................................................................................................................... 3-26
WAVEFORMS OF MAJOR CHECK POINT .................................................................................................... 3-27
1. CRYSTAL .............................................................................................................................................. 3-27
2. FLASH MEMORY ................................................................................................................................. 3-27
3. TACT KEY ............................................................................................................................................. 3-28
4. USB ....................................................................................................................................................... 3-29
5. REMOTE CONTROL ............................................................................................................................ 3-30
6. OPTICAL ............................................................................................................................................... 3-31
7. FM ......................................................................................................................................................... 3-32
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-33
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-35
1. MAIN P. C. BOARD DIAGRAM ............................................................................................................ 3-35
2. KEY P. C. BOARD DIAGRAM .............................................................................................................. 3-37