Prima PS-42D8 B Service Manual page 14

picture effect is better than that of sub-picture. The adjustment of brightness, contrast, definition and
chroma is performed by N302.
The decoding of CCD/V-CHIP in this channel is specially performed by 21 line decoder N301
Z86229. The decoded information is superposed onto the image in N302 also in the form of R, G, B and
FB.
For VGA and YPRPB, after the selection in N1 YPRPB1 and YPRPB2 are fed together with N402
for channel selection. The selected signal is fed into the ADC part of N403 AD9887 for A/D conversion
so as to produce 24 bit digital RGB signal to be fed into the G PORT of PW181. The line and field
synchronous signal of VGA is directly fed into N403 whereas The line and field synchronous signal of
YPRPB is obtained after synchronous separation of Y signal of SOGIN
in AD9887 (This signal is input to N403 pin 108).
Synchronous switching device is shown in the following figure:
AD9887 is also provided with DVI input port. The DVI input signal is converted into 48 bit digital
RGB signal and sent to G PORT of PW181 for processing. The selection from DVI and VGA/YPRPB is
performed by AD9887.Certain organizations for the oversea sales of this TV series have been equipped
with the capability to decode HDCP. PORTA4 and PORTA5 of PW181 verify the password (cipher key)
through bus line with broadcast equipment. Each TV set has its own independent password, which is
stored in EEPROM.
The mode identification of VGA or YPRPB is performed by PW181. The identification process is :
When selecting channel signal input PW181 presets the synchronous selection of AD9887 so that it
can directly output the required synchronous signal for direct feeding to PW181. The synchronous signal
format is identified inside PW181. By making cross-reference with the format table pre-stored inside a
most similar format is obtained. Then the parameters of this format are called for use in setting up the
parameters for modular conversion so that it is optimized. At the same time the conversion coefficient of
SCALER is confirmed.
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