Table Of Contents - NEC LCD1550X Service Manual

1. Circuit description ....................................................................................................................1-1
1.1 Power circuit ......................................................................................................................1-1
1.2 Detailed description of each circuit ................................................................................1-2
1.2.1 Pseudo-resonance circuit method ........................................................................1-2
1.2.2 Switching circuit operation ....................................................................................1-3
1.2.3 Description of operation ........................................................................................1-4
1.2.4 Protection circuit .....................................................................................................1-6
1.2.4.1. Latch circuit ...............................................................................................1-6
1.2.4.2 Overheat protection circuit ......................................................................1-6
1.2.4.3 Overvoltage protection circuit.................................................................1-7
1.3 PWB-MAIN basic specifications ...............................................................................1-8
1.3.1 Basic specifications ................................................................................................1-8
1.3.2 PWB-MAIN circuit block diagram .........................................................................1-9
1.3.3 Input/output connector pin assignment ............................................................. 1-10
1.4 Video input signal specifications .................................................................................. 1-11
1.4.1 Video interface peripheral circuit ....................................................................... 1-12
1.4.2 Horizontal/vertical synchronizing signal input circuit ...................................... 1-13
1.4.3 Composite sync V separation circuit ................................................................. 1-14
1.4.4 Sync On Green synchronization separating circuit ......................................... 1-15
1.4.5 TMDS receiver ...................................................................................................... 1-17
1.4.6 Input signal presence judgment function .......................................................... 1-18
1.4.7 Input signal switching control function .............................................................. 1-21
1.5 DDC interface peripheral circuit ................................................................................... 1-24
1.5.1 DDC switching control function .......................................................................... 1-25
1.5.2 DDC2BI/DDC CI function (only DVI-I connector side) .................................... 1-28
1.5.3 EDID data write protect control function ........................................................... 1-29
1.6 Power peripheral circuit ................................................................................................. 1-30
1.6.1 DC/DC converter and panel power specifications ........................................... 1-31
1.6.2 DC/DC output voltage design sheet .................................................................. 1-32
1.6.3 Power rising/falling edge sequence control function ...................................... 1-37
1.6.4 Reset circuit ........................................................................................................... 1-39
1.7. Panel interface ................................................................................................................ 1-40
1.7.1 Switch substrate interface ................................................................................... 1-41
1.8 Inverter circuit .................................................................................................................. 1-42
1.8.1 Basic configuration ............................................................................................... 1-42
1.8.2.Circuit block diagram ........................................................................................... 1-42
1.8.3.Input/output terminal functions ........................................................................... 1-43
1.8.4.Detailed description of each circuit .................................................................... 1-44
Contents
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