LG OK75 - Section 3: Electrical

SECTION 3
ELECTRICAL
CONTENTS
ONE POINT REPAIR GUIDE ............................................................................................................................ 3-2
1. NO POWER ............................................................................................................................................ 3-2
2. NO BOOTING WHEN POWER ON THE SET........................................................................................ 3-4
3. VFD IS NOT DISPLAYED WHEN POWER ON THE SET ..................................................................... 3-5
4. NO BOOTING (IN CD/USB FUNCTION) ................................................................................................ 3-6
5. NO OPERATION OF MD ........................................................................................................................ 3-9
6. NO SOUND ........................................................................................................................................... 3-14
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................. 3-23
1. POWER (SMPS) ................................................................................................................................... 3-23
2. MCS PART CHECK .............................................................................................................................. 3-26
3. FLD DISPLAY CHECK ......................................................................................................................... 3-27
4. PWM MODULATION CHECK ............................................................................................................... 3-28
5. POWER AMP PART CHECK ............................................................................................................... 3-29
6. TUNER / AUX FUNCTION CHECK ...................................................................................................... 3-30
7. TUNER FUNCTION CHECK................................................................................................................. 3-31
8. CD FUNCTION CHECK ........................................................................................................................ 3-32
9. DOUBLE USB FUNCTION ................................................................................................................... 3-33
WAVEFORMS OF MAJOR CHECK POINT .................................................................................................... 3-34
1. DSP (IC501) .......................................................................................................................................... 3-34
2. SDRAM (IC502) .................................................................................................................................... 3-35
3. SERVO (IC401) ..................................................................................................................................... 3-36
4. MOTOR DRIVER (IC400) ..................................................................................................................... 3-37
5. ADC (IC301) .......................................................................................................................................... 3-38
6. USB (CN502) ........................................................................................................................................ 3-38
7. BLUETOOTH (CN504) .......................................................................................................................... 3-39
WIRING DIAGRAM .......................................................................................................................................... 3-41
BLOCK DIAGRAM .......................................................................................................................................... 3-43
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-45
1. IC VOLTAGE ......................................................................................................................................... 3-45
2. FAN MOTOR VOLTAGE ...................................................................................................................... 3-46
3. SMPS CAPACITOR & ZENER DIODE ................................................................................................. 3-46
4. MAIN CAPACITOR ............................................................................................................................... 3-47
5. CONNECTOR VOLTAGE ..................................................................................................................... 3-48
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-53
1. SMPS P.C.BOARD DIAGRAM ............................................................................................................. 3-53
2. MAIN P.C.BOARD DIAGRAM .............................................................................................................. 3-57
3. TOP P.C.BOARD DIAGRAM ................................................................................................................ 3-61
4. JACK & RMC P.C.BOARD DIAGRAM ................................................................................................. 3-65
5. SPARKLE LED UP P.C.BOARD DIAGRAM ......................................................................................... 3-67
6. SPARKLE LED DOWN P.C.BOARD DIAGRAM .................................................................................. 3-67
7. X-FLASH LED UP LEFT P.C.BOARD DIAGRAM ................................................................................ 3-69
8. X-FLASH LED UP RIGHT P.C.BOARD DIAGRAM .............................................................................. 3-70
9. SPEAKER LED P.C.BOARD DIAGRAM .............................................................................................. 3-70
3-1
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