LG DR-7400 Service Manual page 11

VDR PART
ELECTRICAL TROUBLESHOOTING GUIDE...................................................................................3-2
1. POWER (SMPS) CIRCUIT ........................................................................................................3-2
2. SYSTEM CIRCUIT ......................................................................................................................3-5
BLOCK DIAGRAMS ........................................................................................................................3-10
1. SMPS BLOCK DIAGRAM ........................................................................................................ 3-10
2. VIDEO & AUIDO BLOCK DIAGRAM ........................................................................................3-12
CIRCUIT DIAGRAMS ......................................................................................................................3-14
1. POWER CIRCUIT DIAGRAM ...................................................................................................3-14
2. MPEG CIRCUIT DIAGRAM ......................................................................................................3-16
3. DSP CIRCUIT DIAGRAM..........................................................................................................3-18
4. RF CIRCUIT DIAGRAM ............................................................................................................3-20
5. TUNER/MPX/ADC/DAC/JACK CIRCUIT DIAGRAM ................................................................3-22
6. FRONT JACK CIRCUIT DIAGRAM ..........................................................................................3-24
7. KEY CIRCUIT DIAGRAM..........................................................................................................3-26
8. TIMER CIRCUIT DIAGRAM......................................................................................................3-28
• WAVEFORMS .............................................................................................................................3-30
• CIRCUIT VOLTAGE CHART.......................................................................................................3-32
PRINTED CIRCUIT DIAGRAMS......................................................................................................3-38
1. MAIN P.C.BOARD(TOP SIDE) .................................................................................................3-38
2. MAIN P.C.BOARD(BOTTOM SIDE)..........................................................................................3-40
3. I/O P.C.BOARD .........................................................................................................................3-42
4. JACK P.C.BOARD.....................................................................................................................3-42
5. KEY P.C.BOARD.......................................................................................................................3-44
6. FRONT P.C.BOARD..................................................................................................................3-44
7. POWER P.C.BOARD ................................................................................................................3-45
SECTION 3
ELECTRICAL
CONTENTS
3-1