Philips 28PW9528, Service Manual

Page: 114 / 134

Circuit Descriptions, Abbreviation List, and IC Data Sheets
EN 114 EM5.1E 9.
The Scavem circuit modulates transitions of the Luminance (Y)
signal on the horizontal deflection current, giving a sharper
picture.
The sound part is built around the MSP34xx (Multi-channel
Sound Processor) for IF sound detection, sound control and
source selection. Dolby decoding is also done by the MSP.
Amplification is done via a 'class D' integrated power amplifier
IC, the TDA7490.
The microprocessor, called OTC (OSD, Teletext and Control)
takes care of the analogue TXT input- and output processing.
The OTC, ROM, and RAM are supplied with 3.3 V, which is
derived from the +5V2.
The NVM (Non Volatile Memory) is used to store the settings,
one Flash-RAM contains the set software, the other Flash-
RAM (7012) is for EPG, and the DRAM is used for storing the
Teletext pages.
There is a separate Standby Supply, in order to reduce the
Standby power consumption. During Standby, the Main Supply
is switched 'off' (via TS7529).
A relay (1550) is used to switch the degaussing circuit. It is
switched 'on' after set start-up and switched 'off' by the P after
12 s.
The Main Supply, an SMPS based on the 'down-converter'
principle, generates the 141 V (V_BAT) and the +/- 16 V for the
audio part.
Note: Voltage V_BAT is not mains isolated ('hot'), but is
alignment free.
9.3
Double Window
9.3.1
Introduction
The Double Window (DW) panel provides the option for viewer
to see two pictures or programs on the displayed area of a TV
screen. The displayed pictures can be in PIP or DW mode. The
viewer can also select the size and position of the "second"
picture.
There are basically two types of configurations. One with one
(main) tuner and one with an additional tuner on the DW panel.