Philips DVDR615 Service Manual page 135

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Circuit-, IC descriptions and list of abbreviations
A matrix switch STV6618 [7402] controlled by the slave µP via
I2C-bus is used for Video I/O switching. All used outputs
excluding pin 21 (Y/CVBS-REC) have a 6dB-amplification and
a 75 ohms-driver-stage inside. This IC also includes several
digital outputs, which are used for switching purposes on the
MOBO (analog) board.
The record selector inside the switch selects between the
inputs from Tuner Frontend (VFV), CVBS Rear Ext 2
(CVBSR_IN) or S-Video Rear Ext 2 (YR_IN). Afterwards the
signal passes another switch [7401] in which a selection
between signals (CVBSFIN or YFIN) from the front or the pre-
selected one is done. Likewise another switch selects between
Rear Ext 2 (CRIN) or Front in (CFIN). The output signals of
[7401] are fed as A_YCVBS- and A_C-line to the FEBE board
for further processing.
To reduce the number of external presets there is only one
station for CVBS or Y/C (front and rear). The set automatically
detects between the two inputs depending on the presence of
a video signal where Y/C has higher priority.
The signals D_C and D_Y are fed through [7402] (6dB
amplification) and via [7400] and [7403] as driver to the S-
Video output connector.
The D_CVBS signal is fed directly to the modulator of the Tuner
Frontend and [7402] (6dB amplification) and via [7404] as
driver to the CVBS output connector.
The Y/U/V signals from the FEBE board are also passing
[7402] for 6dB amplification and driving purposes.
The detection of the picture ratio information on the Y/C inputs
(Rear or Front) is done by measuring the DC-level on the
Chroma signal via an analog input of the slave µP (WSRI- and
WSFI-line). In case the level is higher than 3.5V the input
signal is a 16:9 source, if the level is lower than 2.4V the picture
ratio is 4:3
For generation of the appropriate DC-voltage on the Y/C output
the WSRO-line is controlled via pin 18 of [7402] by the slave µP
(pin 18 set to low means 4:3, pin 18 set to high determines
16:9).
During Standby there is no loop-through of any input to any
output performed.
9.2 VAU8041 (FEBE / AV3.5) Module
9.2.1 General
The Video Recorder Drive VAU8041 module known as FEBE
1.0 with AV3.5 drive is actually the Video Recorder Drive
VAD8041 module with and extended board. The new FEBE
board contains both the frontend Servo and backend Digital
portion. Being physically on the same board the IDE connector
is no longer required.
The recorder engine performs all basic servo tasks - reading
and writing data on 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 board that
contains all the electronics needed to control the drive and
interfacing to the MPEG encoder/decoder backend Digital
portion
The backend Digital portion encodes and multiplexes analogue
video and digital uncompressed audio (I
stream. This MPEG2 stream is formatted, to be recorded by
the DVD+RW/+R engine. In playback, it decodes the MPEG2
stream into analogue and digital audio and into analogue video.
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.
9.2.2 Power Supply
The +3V3, +5V, -5V and +12V come from the PSU of the
MOBO analog board via connector [1905] while the +1V8 core
voltage is generated on the board by a low voltage buck
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2
S) into an MPEG2
DVDR615/69
controller [7929]. It provides the control for DC-DC power
solution producing a +1.8V output power over a wide current
range. The NCP1570-based solution is powered from +12V
with the output derived from the +3V3 supply. It contains all
required circuitry for a synchronous NFET [7927-1] and [7928-
2] buck regulator.
9. EN 135