Philips 900 Series - Using Your Sonicare; Brushing Techniques and Personalization

CIRCUIT DESCRIPTION 12
1.2 Block diagram of the DCC Digital Unit:
Module (DDU)
LOADER READMWRITE board DIGITAL board
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OL motor
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Sree! & Treel + Switches
Fig. 3. General Block diagram of the DCC Digital Unit DDU
In the diagram of figure 3 the DDU Module
has been drawn in functional blocks. Also the
connections to the rest of the set (the
interface part) are gathered and shown.
These are:
* Power supply.
* — Digital 1/O (IEC958 in- and outputs to the
optical and coaxial units)
* Analog 1/0 (ADC input; DAC output)
* Control bus; a bidirectional synchronous
serial communication between the
apparatus (master) and the processor on
the digital board (slave).
* ACC playback output (L + R).
Other blocks in figure 3 are
* Digital board with uP,
* Read/Write board,
* Loader with CMRD deck,
* Tape Drive board with pP.
In general the signal flow can be described
as follows:
When the module is in Recording mode:
In the digital board the input signal (Digital 1/0
or Analog I/O) is converted into digital format
of WDATA and clocked by TCLOCK. This
signal is fed to the write part of the
Read/Write board, where the signal is split up
into 9 channels for the DCC head.
In Read Mode and a DCC cassette is
inserted, the 9 DCC head tracks deliver digital
signals to the read part of the Read/Write
board. After amplification, the signals are
multiplexed into the RDMUX (Read
multiplexed) signal, which is fed to the Digital
board to be converted into the Digital- and
Analog I/O output devices. The read multiplex
operation is synchronized by the RDSYNC
signal delivered by the digital Board.
CS 83 512
PHILIPS SOUND & VISION. BG AUDIO - Service Training
13
When in Read Mode an analog compact
cassette (ACC) is inserted, than the analog
head tracks deliver the Left and Right analog
signals to the ACC Play Back part of the
ReadMrite board and the analog is
forwarded to the ACC PlayBack output
devices.
The Tape Drive board actuates a.o. the
capstan- and reel motor. The pulses of the
Sree! (Supply reel) and Treel (Take up reel)
indicate the turning speed of each reel. With
the deck and loader switches, the various
positions and cassette variations are defined
to tape drive processor.
1.3 Block diagram DCC951
On the more extended block diagram of
DCC951 (see figure 4 on next page) the
various blocks and their interconnections are
shown.
These blocks belong to the electrical interface
part or to the tape drive part (DDU Module).
To the electrical interface part belongs:
* Front panel with the Control and Display
functions;
* — Input/output panel with Power supply and
Analog output stage;
+ Microphone and Headphone panel with
the Microphone pre-amplifier and the
headphone amplifier.
In the tape drive part is found:
+ _CMRD tape deck mechanism and Loader;
* Read/Write panel with read/write
functions;
* — Digital panel with the function to control
the digital signal (DCC signal processing);
* Tape drive panel with the function to
control the tape deck mechanism.
The signals between the various boards are
found more detailed. Notice the heart beating
function of the 3 pP’s:
+ Main uP (Digital board uP)
* Control & Display pP,
* Tape Drive pP.
These 3 processors are connected with each
other via bus systems.
An important bus structure is the L3-bus. This
bus is found between DRP, ADAS3, Port
expander IC, SFC3, DAIO and Main «P. This
is the contro! bus concerning the main
activities of the DCC signal.
The DCC data are forwarded via the SB-I’S
and IS bus.
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CIRCUIT DESCRIPTION
* DRP = DRive Processor. In the drive
processor Digital read signal is EQualised
(DEQ) and the read and write signals are
both realized via Tape Formatting & Error
correction (TFE).
* ADAS3 = ADaptive Allocation & Scaling
for PASC coding of the DCC signal (only
in Write mode active).
+ SFC3 = Stereo Filter and Codec IC for
PASC coding and decoding (in read and
write mode). Sub-band filtering and audio
frame coding in the PASC system are
processed in this integrated circuit.
* DAIO = Digital Audio Input Output circuit.
1.3.1 Operation modes
There are four (basically different) operating
modes in the DCC recorder:
+ Data playback, Aux playback
¢« Data record, Aux record
* Data playback, Aux record
* ACC playback
in the next paragraphs these modes and their
actions are explained.
1.3.1.1 Data playback, Aux playback
The head signals are first fed to the read
amplifier (TDA1317), where they are
amplified, filtered and supplied to a
multiplexer. The output signal of the
multiplexer (RDMUX) contains the information
of the 8 main data tracks and the ninth AUX
channel, and is passed on to the DRP
(SAA2023). The DCC Drive Processor (DRP)
reconstructs the original digital head signals,
and after digital equalizing and Error
correction procedures, together with DRAM IC
MN4C4256, the digital data are recovered
and demodulated from 10-to-8 bits. Via the
sub-band interface all signals are formatted to
the subband serial PASC data bus. This
‘SB-!?S-Bus’ forwards the signal to the SFC3
(SAA2003). The Stereo Filter and Codec IC
recovers the frames of data from the DRP.
The PASC decoded sub-band samples are
reconstructed by the sub-band filters into a
single complete digital audio signal (SDA2).
Sub-code information (Sub-code = System
information + Auxiliary information) goes to
the main microprocessor via the L3-Bus, (also
connected to SFC3). The ADAS3 IC is
inactive in this operating mode. The audio
broadband signal is transferred via ?S-
interface to the DAIO (TDA1315), and via a
port extender to the DAC (TDA1305T). The
DAIO, together with sub-code information of
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