Philips A02E Service Manual page 62

EN 94 9.
9.2
Block Diagrams
IF/
Tuner/SAW
Mono Sound
2nd tuner
PIP-channel
Tuner/SAW
MPIF
Figure 9-3 Chassis block diagram
The tuner is a PLL tuner and delivers the IF-signal, via audio
and video SAW-filters, to the MPIF IC (Multi Platform
InterFace). This is an analogue video and audio pre-processing
unit for the ADOC TV processor. It contains the high frequent
IF part and all the analogue video and audio source switching
for external in- and outputs. The MPIF can handle CVBS, Y/C,
RGB (1fH/2fH) and YPbPr (1fH/2fH) video signals as well as
stereo, I2S, and second sound IF audio signals. The MPIF
converts the selected video and audio streams from the
analogue to the digital domain. Via three high-speed serial data
links (I2D), the digitised audio and video signals are streamed
to the ADOC IC for further processing.
The ADOC (Analogue Digital One Chip) is a fully integrated,
digitally implemented TV processor for audio, video, Vertical
Blank Interval services, graphics, and control. It is a global,
multi-standard system primarily designed for the reception and
processing of analogue broadcast signals.
Internal video processing is done in the ADOC with YUV-
signals. It also handles the video control, geometry part, and
the insertion of the TXT/OSD RGB-signals. The video part
delivers the RGB signals to the CRT-panel and the geometry
part delivers the H-drive, V-drive (differential output), and E/W-
drive.
An integrated MIPS 1910 processor runs the chassis software
and takes care of the set control, error generation TXT/OSD
input-, and output processing. The NVM (Non Volatile Memory)
is used to store the settings, the Flash-RAM contains the set
software, and the SDRAM stores the Teletext pages (in some
versions, this is stored in the internal memory of the ADOC).
Both deflection circuits are located on the LSP and are driven
by the ADOC. The horizontal output stage generates also
some supply voltages and the EHT-, focus- and Vg2-voltages.
The RGB amplifiers on the CRT-panel are integrated in one IC
and are supplied with 200 V from the LOT. The SCAVEM circuit
modulates transitions of the Luminance (Y) signal on the
horizontal deflection current, giving a sharper picture.
Sound IF processing, audio source selection, and audio
analogue-digital signal conversions are done in the MPIF IC.
The ADOC contains a digital TV sound processor for analogue
and digital multi-channel sound systems in TV sets. By
hardware programming, several applications can be scaled.
The audio output stage is built around a balanced amplifier,
and is located on the LSP. It uses a monolithic integrated power
amplifier IC, the TDA7497. The gain of the amplifier is constant.
This means that volume control is done via the ADOC.
The power supply is a Switch Mode Power Supply (SMPS) with
minimum voltage switch. It is a flyback converter with primary
current sensing, secondary voltage sensing, and mains input
measuring. It is built around IC7921 (which has a built-in
MOSFET and control circuit) and generates a.o. the 140 V (V-
BAT) and the 27 V (for the audio part).
A02E Circuit Descriptions, Abbreviation List, and IC Data Sheets
7730 7790 7525
SDRAM FLASH NVM
(TXT) (SET SW) (SETTINGS)
R
G
RGB
Amp. B
ADOC
Audio
Amp.
IR
Local
CL 36532058_064.eps
keyboard
During Standby, the power supply is switched to a 'low power
burst mode' via TS7946 and the following burst mode
generator, in order to reduce the power consumption.
A relay is used to switch the degaussing circuit for several
seconds during switching 'ON' of the set.
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
microprocessor after 12 s.
The Main Supply, a SMPS based on the "boost converter"
principle, generates the 141 V (V_BAT) and the +/- 16 V for the
audio part.
281003
9.3
Power Supply
9.3.1
Introduction
The power supply circuitry is located on the large signal PWB,
together with the audio amplifier and the deflection. It
comprises of:
•
Mains entrance with fuse.
•
Separate standby -supply.
•
Mains harmonic circuit.
•
Mains rectifier.
•
Main-supply: is able to deliver a continuous power between
100 W and 160 W.
•
Degaussing.
For a detailed circuit description, see the EM5E Service
Manual.
9.3.2
Power Supply architecture
The A02 SSB is supplied by +5V, +5.2V, +3.3V and +8V supply
lines from the LSP. The SSB contains:
•
A DC/DC converter which steps down +5.2V to +1V8,
•
A switch to cut off the 3V3 supply to the 3D Comb in
"Standby" mode, and
•
A regulator to generate the 2V5.
When the set is in "Power STANDBY" mode, the +5.2V, +3.3V
supply lines are present. Consequently, only the ADOC IC
(+3V3 and +1V8), the SDRAM (+3V3), the Flash memory
(+3V3), and the NVM memory (+3V3) are supplied. Other than
NVM, all the other devices are powered down in "Standby"
mode. See section below for more details on the power modes.
OFF Mode
The set is completely switched "off" from the mains. This is
done with the mains switch for Europe and AP (for NAFTA it
would mean disconnecting the TV from the mains by pulling out
the mains cable). Depending upon the last Standby Status
(stored in NVM), this mode can transit to "ON' mode or
"STANDBY" mode.
The transition timing for a Cold start from "OFF" state to "ON"
shall be such that from the instance the ADOC gets a hard
reset, within 3 seconds one will hear the audio and within 7
seconds one will see the picture.
ON Mode
This is the normal operating mode. All the power supply lines
on the A02 SSB and LSP are available. All the circuits in the set
are active. From this mode, it is possible to transit to
"STANDBY", "SEMI-STANDBY", "PROTECTION", or "OFF"
mode.
STANDBY Mode
The total power consumption of the TV set in this mode is equal
or less than 1 W. The Standby state will be indicated by the
LED. In this state only the ADOC, SDRAM, Program Memory,
NVM, and all means to wake-up the set are powered. Rest of