LG RN7 - 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 USB FUNCTION ........................................................................................................ 3-6
5. NO SOUND ........................................................................................................................................... 3-10
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................. 3-16
1. POWER (SMPS) ................................................................................................................................... 3-16
2. MCS PART CHECK .............................................................................................................................. 3-19
3. PWM MODULATION CHECK ............................................................................................................... 3-20
4. POWER AMP PART CHECK ............................................................................................................... 3-21
5. TUNER / DAB FUNCTION CHECK ...................................................................................................... 3-22
6. TUNER FUNCTION CHECK................................................................................................................. 3-23
7. DOUBLE USB FUNCTION ................................................................................................................... 3-24
WAVEFORMS OF MAJOR CHECK POINT .................................................................................................... 3-25
1. DSP (IC501) .......................................................................................................................................... 3-25
2. SDRAM (IC502) .................................................................................................................................... 3-26
3. SERVO (IC401) ..................................................................................................................................... 3-27
4. MOTOR DRIVER (IC400) ..................................................................................................................... 3-28
5. ADC (IC301) .......................................................................................................................................... 3-29
6. USB (CN502) ........................................................................................................................................ 3-29
7. BLUETOOTH (CN504) .......................................................................................................................... 3-30
WIRING DIAGRAM .......................................................................................................................................... 3-31
BLOCK DIAGRAM .......................................................................................................................................... 3-33
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-35
1. IC VOLTAGE ......................................................................................................................................... 3-35
2. SMPS CAPACITOR & ZENER DIODE VOLTAGE ............................................................................... 3-36
3. MAIN CAPACITOR VOLTAGE ............................................................................................................. 3-36
4. CONNECTOR VOLTAGE ..................................................................................................................... 3-37
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-39
1. SMPS P.C.BOARD DIAGRAM ............................................................................................................. 3-39
2. MAIN P.C.BOARD DIAGRAM .............................................................................................................. 3-41
3. TOP KEY P.C.BOARD DIAGRAM ........................................................................................................ 3-45
4. LIGHTING LED P.C.BOARD DIAGRAM .............................................................................................. 3-49
5. DAB MODULE P.C.BOARD DIAGRAM ................................................................................................ 3-49
3-1
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