Electronic Circuit Description; Main Board Circuit - Hitachi CML151XW Service Manual

6. Electronic Circuit Description

The block diagram of CML151X LCD monitor is shown in Appendix A.

6.1 Main Board Circuit

The circuit diagrams of main board that labeled with PWB-0273-B are shown in Appendix
B. The circuit diagrams of keyboard and inverter are shown in Appendix C and D, respectively.
(1) RGB INTERFACE ADC
Refer to circuit diagrams Sheet 1 of PWB-0273-B in Appendix B.
The analog R, G, B video input signals are supplied through the cable which is terminated
at P001. These input signals are approximately 0.7 V
R006, R007 and R008 give a resistance of 75O for impedance matching. These R, G, B
video signals are AC coupled via 0.01uF capacitors C019, C017 and C016 and then fed into the
video signal processor I007.A at pin-95, pin-91 and pin-87 respectively. These analog R, G and
B video signals are converted to their digital forms in I007.A.
RESETN signal comes from Sheet 4 and is fed into pin-100 of I007.A. It provides the
necessary reset signal for the proper operation of I007.A.
VGA_CON from pin-5 of P001 is fed to I007.C also. (Refer to Sheet 2).
I001 provides the necessary plug and play function with PC via its pin-5 and pin-6.
D003~D016 provide ESD protection for I001, I007.A and the associated components.
(2) PLL/OSD INTERFACE
Refer to circuit diagrams Sheet 2 of PWB-0273-B in Appendix B.
The H. and V. sync signals from P001 (in Sheet 1) are fed into I007.B at pin-150 and
pin-148 via I005.B and I005.A respectively. I007.B utilize this H. sync to generate the
necessary pixel clock for further processing internally.
There is a 50MHz crystal (X002), which is used to generate clock source input to I007.B at
TCLK (pin-141).
The signals designated HDATA0~HDATA3 (pin-99, -105, -104 and -102 of I007.C) and
HFS (pin-98), HCLK (pin-103) and IRQ (pin-101) are signals used for transferring control
message and data between I007.C and I003 (in Sheet 4).
VGA_CON from pin-5 of P001 (in Sheet 1) is fed to pin-111 of I007.C for the connectivity
test of the signal cable. Another signal designed as LVDET (from I008.A in Sheet 5) is used as
the indicator of power source drop, and is fed into pin-110 of I007.C.
Hitachi CML151X LCD Monitor Service Manual
in amplitude.
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