LG CJ44 - 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 OPERATION OF MD ........................................................................................................................3-6
5. NO SOUND ...........................................................................................................................................3-11
ELECTRICAL TROUBLESHOOTING GUIDE .................................................................................................3-17
1. POWER (SMPS) ...................................................................................................................................3-17
2. MCS PART CHECK ..............................................................................................................................3-20
3. IC503(GD25Q80) CHECK ....................................................................................................................3-20
4. FLD DISPLAY CHECK .........................................................................................................................3-21
5. PWM MODULATION CHECK ...............................................................................................................3-22
6. POWER AMP PART CHECK ...............................................................................................................3-23
7. TUNER / AUX FUNCTION CHECK ......................................................................................................3-24
8. TUNER FUNCTION CHECK.................................................................................................................3-24
9. CD FUNCTION .....................................................................................................................................3-25
10. DOUBLE USB FUNCTION ...................................................................................................................3-26
WAVEFORMS OF MAJOR CHECK POINT ....................................................................................................3-27
WIRING DIAGRAM ..........................................................................................................................................3-29
BLOCK DIAGRAMS ........................................................................................................................................3-31
1. SYSTEM BLOCK DIAGRAM ................................................................................................................3-31
2. SMPS BLOCK DIAGRAM .....................................................................................................................3-33
3. POWER BLOCK DIAGRAM .................................................................................................................3-35
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-37
1. INPUT VOLTAGE OF ICs .....................................................................................................................3-37
2. INPUT VOLTAGE OF CONNECTORS .................................................................................................3-37
3. VOLTAGE OF CAPACITORS ...............................................................................................................3-38
PRINTED CIRCUIT BOARD DIAGRAMS .......................................................................................................3-39
1. SMPS P.C.BOARD ...............................................................................................................................3-39
2. MAIN P.C.BOARD ................................................................................................................................3-41
3. FRONT P.C.BOARD .............................................................................................................................3-43
4. MIC P.C.BOARD DIAGRAM .................................................................................................................3-45
3-1