Signal Flow - Philips PTV500 series Service Manual

Signal Flow
The Signal/Deflection/High Voltage Module features split Audio
and Video IF processing. The TV signal is.applied to the U/V
Tuner, or through an optional RF Switch then to the UN Tuner.
The IF signal is developed in the UN Tuner and sent through a
dual output SAW Filter to the Audio and Video IF inputs of
IC200. The detected Baseband Audio signal exits IC200 and is
sent to the Stereo Decoder IC, IC120. Left and Right channel
audio signals exit the Stereo Decoder and are sent to the Jack
Panel for distribution. Some Models feature an Automatic
Volume Level control Module that is located on the frame of the
AVIO Jack Panel. This module acts like an AGC circuit for both
channels of audio.
The Video signal is developed by IC200 and is applied directly
to the Color MDPIP Module and also to the AVIO Jack Panel for
switching. The MDPIP Module is mounted on the Main Chassis
PCB next to the U/V Tuner. If an optional, chassis mounted,
Color MDPIP Module is used in the set, the composite video is
routed from the Jack Panel to the Color MDPIP Module to be
used as the PIP Picture. ReModulated Video (RMV) is sent
from the Color MDPIP Module to the S-VHS Switch IC, IC670.
External Video input from an External Video source can be
applied through the Jack Panel to the Color MDPIP Module.
Control of the Color MDPIP Module is via the 12C Bus.
The S-VHS Switch IC selects either the tuner signal or the
Super VHS signals from the Jack Panel. This composite video
is applied to the CCD Comb Filter, Closed-Caption Decoder
Module, and the NTSC Signal Processor. The combed
Chrominance signal is sent from the CCD Comb Filter Module
through the S-VHS Switch IC before being applied to IC600.
The combed Luminance is applied directly to IC600. The RGB
and Fast Blanking signals from the Character Generator, IC308,
are applied to the Closed-Caption Decoder before being applied
to IC600. These signals are matrixed when Closed-Caption or
On-Screen Graphics are needed and the product is output via
RGB lines to the Green CRT Board. Without RGB input from
IC308 or data from the Closed Caption Module, normal program
material is presented to the Green CRT Board. Both the Red
and Blue video information go through the Green CRT Board
before going to their respective boards.
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