Philips EM7U LCOS, Руководство по обслуживанию

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NTSC COMB FILTER CIRCUIT (Figure 36)
The Comb Filter circuit separates the Chrominance and Luminance, YC, from the composite
video. This is a separate PC board that plugs into the System board. The video signal is
amplified by Transistors 7008 and 7009. Transistors 7010, 7015, 7016, and 7017 separate
the Sync from the composite video. The Sync is fed to Pin 76 of 7023. If non-standard Sync
is detected, as with a video game, 7023 performs a 3-line sync separation. The composite
video is buffered by 7011 and fed to a 6MHz filter, 5006. This prevents any high frequency
signals from causing problems with the A/D conversion. The signal from 5006 is buffered by
Transistor 7012 and fed to Pin 88 of 7023. A Clamp circuit sets the sampling range of the
A/D converter. A full frame 3D YC separation is performed by the YCS circuit. The YC signal
is then output to two D/A converters that output C on Pin 83 and Y on Pin 84. The Y signal is
buffered by 7003 before being fed to a 6MHz filter to remove any high frequency components
generated by the D/A conversion. The signal is then buffered by Transistors 7002, 7001, and
7000 before being fed back to the SSB via the System board. A similar circuit also filters the
C signal.
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COMB FILTER INSERTED INTO SYSTEM BOARD