Electronic Circuit Description - Polaroid V23D series Service Manual

9. Electronic Circuit Description

9.1 Main Board Circuit
(1) DVI-I signal
Refer to circuit diagram of PWB-0812
The analog RGB video input signals are supplied through the DVI-I cable which is
terminated at P022. These three input signals are approximately 0.7Vpp in amplitude.
R374、R301 and R327 give resistance of 75Ω respectively for impedance matching. These
R、G、B video signals are ac coupled via 0.047U capacitor C021、C016 、C013 and then
fed into the I001 AD converter (MST9883C) at Pin54、49 and 43 respectively. These analog
R、G、B video signals are converted to the their digital forms in I001. The outputs of digital
data including 8 bits red、8 bits green、8b bits blue signals are assigned at Pin70 ~ 77、Pin
2 ~ 9 and Pin 12 ~ 19 of I001，and applied to Port A of I019 (Scaler：TP6761 ) Hsync &
Vsync are applied to I001 (MST9883C) #30 & #31 and the processed signal taken from #66
& #64 are fed into I019 (TP6761) #18、#19..
CLK signal is taken from I001 (MST9883C) #67 and applied to I019 (TP6761) #156.The
LCD-TV is designed to have the DDC/2B FUNCTIONS. Communication between the
LCD-TV and computer for DDC is via P022 (DVI-I connector ) #20、#21 which are defined
as SCL、SDA signals. The computer will read out the EDID from the I011 (EEPROM) and
the EDID data is written into the EEPROM in the factory during production.
The digital input signal through DVI-I cable which is terminated at P022. Input signal from
TMDS low voltage differential signal input data pairs Pin 80、 81、 85、 86、 90、 91 and TMDS
signal input clock pairs 93、94 are fed into I040 (SiI 169).
The I040 (SiI 169) supports High-bandwidth Digital Content Protection (HDCP) by
decrypting the pixel data stream received from an HDCP transmitter in the video host
system. HDCP provides a secure method of delivering high-definition content between a
host (such as a set-top box, DVD player, or D-VHS player) and display (such as an HDTV,
projector, or A/V receiver).
The SiI 169 comes pre-programmed with a production set of HDCP keys in its internal
EEPROM. In this way the keys are provided the highest level of protection as required by
the HDCP specification.
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