Philips DVDR600VR/37, Руководство по обслуживанию

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Circuit Descriptions, Abbreviation List, and Data Sheets
EN 33 VAD8041 9.
9. Circuit Descriptions, Abbreviation List, and Data Sheets
9.1 General
The VAD8041 module, also known as “AV3.5”, is a Video
Recorder Drive with an IDE interface intended for use in a
consumer DVD+RW/+R video recorder.
The video recorder engine performs all basic servo tasks. It
reads data from and writes data to the disc and controls all
functions like tray control, start/stop the disc, tracking, jumping
and communicating to the host.
Mechanically, the module consists of a motorized tray loader
that contains the dual laser optical pickup unit and a PCBA that
contains all the electronics needed to control the drive and
interfacing to the MPEG encoder/decoder back-end
application.
There is a temperature sensor included in the drive that
prevents malfunction or destruction of the drive in case the
temperature inside the drive gets too high.
9.2 Overall Block Diagram DVDM & Frontend
Figure 9-1
9.3 Centaurus
Figure 9-2
The Centaurus, IC7500 is a highly integrated IC that controls all
the functions of the drive. It interfaces via the IDE to the MPEG
back-end and incorporates the following functions:
•
CD/DVD channel decoder/encoder
• CD/DVD data block decoder/encoder
• Buffer Manager
• Digital Servo processor using digital signal processor.
• Drive System microprocessor based on MIPS core.
The MIPS microcontroller uses Flash ROM for the firmware
and SRAM to execute the program. SDRAM is provided for the
encoding/decoding function block of centaurus. 2 MBytes of
data buffer size is available inside the IC for data storage.
9.4 Cheetah
The Cheetah, IC7201 is an analogue pre-processing for the
diode signals coming from the OPU. It contains an amplifier
with programmable gain that amplifies the RF signal to adapt
the output for the different reflectivity of the various discs. The
tracking signals are filtered and normalized. In addition the IC
contains a timing circuit for the sample and hold circuits and for
switching the various blocks between read and write.
Supporting functions such as laser control and offset control
are incorporated. Communication to and from the IC is based
on a fast two-wire serial bus that works according to the I2C
interface protocol.
9.5 Laconic
The main function of the LACONIC, IC7300 is to control the
laser power. The IC forms a closed control loop in combination
with the Elantec located on the OPU. It compensates aging and
temperature of the laser. Furthermore it forms a fingerprint
correction loop. It also acts as bridge between IIC and serial
bus of the Elantec laser driver on the OPU.
9.6 Optical Pick-up Unit
The OPU66 is a dual laser Optical Pick-up Unit for DVD+RW/
+R. It consists of a 3-D actuator for focusing, redial tracking and
tilt correction.
•
650nm laser for DVD
• 780nm laser for CD
On the interconnecting flex several electrical components are
mounted.
•
Elantec programmable laser diode power
driver
Laser
DVD
BA5995FM
Brush-less
Motordriver
EL6915
PAEDIC
SA56202
Laser driver
EEPROM
OPU 66
Stepper
Laser
CD
Digital Backend
CENTAURUS
Flash
ROM
Sync
DRAM
Cheetah
IDE
Laconic
3D
BA5995FM
A
na
logue
Servo
Controller
A
na
logue
Centaurus Basic Functions Block Diagram
Control
Processor
Buffer
Manager
Channel
Codec