LG SL7Y, Service Manual

Page: 26 / 75

3-1 Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
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 ............................................................................................................................................. 3-8
3. PROTECTION ERROR ......................................................................................................................... 3-12
WAVEFORMS OF MAJOR CHECK POINT .................................................................................................... 3-14
1. CRYSTAL .............................................................................................................................................. 3-14
2. FLASH MEMORY ................................................................................................................................. 3-14
3. TACT KEY ............................................................................................................................................. 3-15
4. USB ....................................................................................................................................................... 3-16
5. REMOTE CONTROL ............................................................................................................................ 3-17
6. OPTICAL ............................................................................................................................................... 3-18
7. FM ......................................................................................................................................................... 3-19
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-21
1. IC VOLTAGE ......................................................................................................................................... 3-21
2. CAPACITOR VOLTAGE ....................................................................................................................... 3-23
3. CONNECTOR VOLTAGE ..................................................................................................................... 3-23
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-25
1. MAIN P. C. BOARD DIAGRAM ............................................................................................................ 3-25
2. MPEG / JACK P. C. BOARD DIAGRAM .............................................................................................. 3-27
3. AMP P. C. BOARD DIAGRAM ............................................................................................................. 3-29
4. KEY P. C. BOARD DIAGRAM .............................................................................................................. 3-30