Philips L01.1L AC Service Manual Download

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Circuit Description

EN 71

L01.1L AC

Circuit Description

Index of this chapter:
1.

Introduction

Audio Signal Processing

Video Signal Processing

Synchronization

Deflection

Power Supply

Control

Abbreviations

IC Data Sheets

Notes:
•

For a good understanding of the following circuit
descriptions, please use the block diagram in section
'Wiring Diagram, Block Diagrams, and Overviews' and/or
the electrical diagrams in section 'Circuit Diagrams and
PWB Layouts'. Where necessary, you will find a separate
drawing for clarification.

•

Figures below can deviate slightly from the actual situation,
due to different set executions.

9.1

Introduction

The 'L01.1L AC' chassis is a global TV chassis for the model
year 2003 and is used for TV sets with screen sizes from 20" to
36", in Super Flat, Real Flat, and Wide Screen executions. In
comparison to its predecessor (the 'L01.1L AB'), the chassis
has enhanced features like 'Virtual Dolby', 'Sub Woofer out',
and 'Active Control'.

The standard architecture consists of a Main panel, a Picture
Tube panel, a Side I/O panel, and a Top Control panel.
The Main panel consists primarily of conventional components
with hardly any surface mounted devices.

Figure 9-1 Block diagram

The functions for video processing, microprocessor (uP), and
teletext (TXT) decoder are combined in one IC (TDA958xH),
the so-called Ultimate One Chip (UOC). This chip is (surface)
mounted on the copper side of the LSP.

The 'L01.1L AC' is divided into 2 basic audio systems, i.e. mono
and stereo sound. While the audio processing for the mono
sound is done in the audio block of the UOC, an external audio
processing IC is used for stereo sets.

The tuning system features 181 channels with on-screen
display. The main tuning system uses a tuner, a
microcomputer, and a memory IC mounted on the main panel.
The microcomputer communicates with the memory IC, the
customer keyboard, remote receiver, tuner, signal processor IC
and the audio output IC via the I

C bus. The memory IC retains

the settings for favorite stations, customer-preferred settings,
and service / factory data.
The on-screen graphics and closed caption decoding are done
within the microprocessor, and then sent to the signal
processor IC to be added to the main signal.

The chassis utilizes a Switching Mode Power Supply (SMPS)
for the main voltage source. The chassis has a 'hot' ground
reference on the primary side and a cold ground reference on
the secondary side of the power supply and the rest of the
chassis.

9.2

Audio Signal Processing

9.2.1

Stereo

In stereo sets, the signal goes via the SAW filter (position 1002/
1003), to the audio demodulator part of the UOC IC 7200. The
audio output on pin 33 goes to the stereo decoder 7831/ 7861.
The switch inside this IC selects either the internal decoder or
an external source (see also ‘block diagram’).

There are two stereo decoder versions used:
1.

A BTSC Stereo/SAP decoder (MSP34X5 at position 7831)
for the highest specified sets, and

A BTSC non-dbx stereo decoder (TDA9853 at position
7861) for BTSC Economic.

The built-in stereo decoder can receive both TV stereo and
Separate Audio Program (SAP) telecasts where available. A
dbx noise reduction system helps provide clear, crisp sound
with proper stereo separation.

The output is fed to the to the audio amplifier (AN7522 at
position 7901). The volume level is controlled at this IC (pin 9)
by a 'Volume|Mute' control line from the microprocessor. The
audio signal from 7901 is then send to the speaker and
headphone output panel.

9.2.2

Mono

In mono sets, the signal goes via the SAW filter (position 1002/
1003), to the audio demodulator part of the UOC IC 7200. The
audio output on pin 48 goes to the audio amplifier (AN7523 at
position 7902).
The volume level is controlled at this IC (pin 9) by a
'Volume|Mute' control line from the microprocessor.
The audio signal from IC 7902 is then send to the speaker and
headphone output panel.

Figure 9-2 Mono audio signal processing

TUNER

VBAT

AUDIO

12V

3.9V

3.3V

FM IF

BUFFER

NOT FOR

NAFTA

VIDEO SOURCE