LG SPD75A Service Manual

3-1
Copyright © 2020 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 .................................................................................................... 3-15
1. CRYSTAL .............................................................................................................................................. 3-15
2. REMOTE CONTROL ............................................................................................................................ 3-16
3. OPTICAL ............................................................................................................................................... 3-17
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-19
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-21
1. MAIN P. C. BOARD DIAGRAM ............................................................................................................ 3-21
2. AMP P. C. BOARD DIAGRAM ............................................................................................................. 3-23
3. FRONT LED P. C. BOARD DIAGRAM ................................................................................................. 3-25
4. MIC & TOUCH P. C. BOARD DIAGRAM ............................................................................................. 3-25

LG SPD75A Specifications

General

Brand	LG
Model	SPD75A
Category	Speaker System
Language	English