Philips 900 Series - Frequently Asked Questions

CIRCUIT DESCRIPTION
3 TAPE DRIVE PART ELECTRICAL
The electrical functions of the tape drive part
are carried out by:
+ Read/Write board
* Digital board
* Tape drive contro! board
3.1 Read/Write board
The Read/Write board contains the record
and playback amplifiers for the DCC head.
The recording (write) current is adjustable
with one potentiometer. The RDMUX signal is
electrical controlled for optimal output level.
The ACC playback circuit includes an
equalizer (70/120us circuit) which enables
optimal interfacing for the external connected
analog circuits like Dolby noise reduction.
The board contains the following functions:
« Read and Write amplifier for DCC head,
¢« Read amplifier for ACC
« ACC equalizer 70/120us circuit.
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Described in next paragraphs are:
0 the block diagram of the Read/Write
board in Write and in Read Mode.
Write IC TDA1319T
Read IC TDA1317
Pin configuration of RAW Connectors
Circuit diagram R/W board
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The write part done by IC TDA1319T:
- It generates the write pulses for the head.
The read part is done via IC TDA1317:
- Amplifies and multiplexes the head read
signals from DCC tapes.
- Amplifies the head signals with ACC
playback.
ACC equalization (70/120usec) is done by
separate circuits on the board.
3.1.1. Block diagrams of the Read/Write
board
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Fig. 15 Block diagram Read/Write board. Write mode
First look to the Write Mode. In figure 15 the
block diagram is drawn in Write Mode. The
write function is on top of it. The signal flow is
from left to right. The input signal WDATA is
led to the input amplifiers and via
de-multiplexing the serial data are split up
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PCS 83 524
auxiliary channel. The record current can be
adjusted via an adjustment of the amplifiers.
All signals are clocked via the TCLOCK
signal.
The Read Mode is shown on next block
Gagram, in figure 19, Again the Signal fiows
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25 CIRCUIT DESCRIPTION
READWRITE board
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Fig. 16. Block diagram Read/Write board. Read Mode
from left to right and on top of this drawing It contains:
the Digital read amplifier and the Analog © decoder
amplifier are drawn. : oO current amplifier .
The by head elements read DCC signal is led 0 voltage reference
to the 9 digital read amplifiers. After © outputs
multiplexing the RDMUX signal is composed © clamp circuit
from the 9 digital input channels. o standby mode
In the next paragraphs the Write and Read oO protection
ICs are described.
3.1.2.1 decoder part
3.1.2 Write IC TDA1319T The DCC write IC is controlled by the 32-bit
wide serial dataword which is clocked in at
WDATA (pin 12). The clock frequency
(WCLK, pin 11) is 3.072 MHz with a clock
period of 325 ns. The write pulses are made
available at the outputs QA to Qu (pin 13 to
17 and 19 to 23). The dataword also contains
The TDA1319T drives the 9 elements of
multichannel DCC recording head. The IC
forces a current through the selected path.
The IC consists of a decoder part, a current
amplifier, a Voltage reference, outputs, clamp
Circuit, standby mode. in figure 17 the control bits, which set the mode of the write
contents of the IC is shown in a block amplifier. Control bits TDAPLB, TAUPLB,
diagram. TERAUX have the following meanings:
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