Philips 900 Series - Page 17

CIRCUIT DESCRIPTION
28
NR NR
Pin configuration TDA1319T
PIN NAME FUNCTION
1 RX auxitiary current adjust resistor
2 “| AD data current adjust resistor |
3 RSENSE | Sense voltage positive input
4 VssS sense voltage ground
5 VssE erase current source ground
6 RE erase current adjust resistor |
ta Vad supply voitage
a GND ground
9 REF reference voltage input
10 STANDBY standby mode contro! input
W WCLK write clock input
[
12
WDATA
write
data
input
_|
13 _| au write pulse output
Qh write pulse output
QH write pulse output
QG write pulse output
write pulse output
supply voltage (write outputs)
write pulse output
write pulse output
21 write pulse output
as write pulse output
3.1.3 Read IC TDA1317
The TDA1317 amplifies and filters the signals
which are coming from the Magneto Resistive
thin film Head (MRH) of the head. The IC
also incorporates the 2 amplifiers to provide
the magnetic feedback to the CC head
elements.
The IC consists of:
0° digital preamplifiers,
multiplexer,
analog preamplifiers,
feedback amplifiers.
ooo
3.1.3.1 digital pre-amplifiers
In DCC the IC employs 8 main data channels
and 1 auxiliary channel. The main data
channels have been equipped, at the input
side, with low-noise pre-amplifiers which
amplify the headsignals by 58dB.
Pre-equalization, for frequencies from 1 kHz
to 50 kHz, is obtained using 1st order
high-pass filters (-3dB at 80 kHz). A second
amplifier amplifies, after that filter, the signal
by 26 dB. Anti-aliasing of the signal, is
achieved by using 2 times 2nd order low-pass
filters (-6dB at 135 kHz). See IC block
Hagrarm figure 12.
22
[as [an
A
The auxiliary channel uses a preamplifier with
a 1st order low-pass filter (-3dB at 400 kHz).
All inputs are external AC coupled.
3.1.3.2 multiplexer
The multiplexer circuit switches the amplified
and filtered digital channel signals,
sequentially, to the output RDMUX (pin 3).
The effective sampling frequency is 1/10 of
the clock frequency at RDCLK (pin 6).
(RDCLK = TCLOCK)
For every cycle of RDSYNC (307,2kHz), the
information of 8 main data tracks, the AUX
track and one random slot is transferred.
When RDSYNC = “1”, the head signals of the
AUX channel are transferred. The data are
read in at each rising edge of RDCLK.
3.1.3.3 analog pre-amplifiers
In case an ACC cassette is inserted the ACC
playback signal is read. The 2 fow-noise
preamplifiers raise the 2 analog track signals
by 44 dB. Also the analog input is AC
coupicd.
es LN ee SS
PCS 83 528
PHILIPS SOUND & VISION, BG AUDIO - Service Training
29
CIRCUIT DESCRIPTION
3.1.3.4 feedback amplifier.
Two feedback amplifiers are provided for
driving a coil in the MRH (magnetic resistor
head). This amplifier provides a feedback
loop in order tc improve the linearity of the
frequency response of the analog audio
REF1
REF2
INAUX
signal. Together with the bias-signa! of the
Barkhausen noise suppression generator on
the Read/Write board, the Barkhausen noise
from the tape, is suppressed too.
3.1.3.5 Block diagram and pin
configuration TDA1317.
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BS
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ER
83 kHz
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z
8 3 LE: =f)
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Bile
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fo)
3 ||| z nn
ale o
3
W
g8
kHz
Dp Q 5
n »]
;
D
oO
zo
fa
a
&
IN2 Hsea8> | | ele _
1B
cell ‘e
IN3 Ss Lp if 26d
Dp a
nn 2 rs) z
nn
aa BO Pe
ER
iN4
Fa
a
t-p—H
RB 8
Eze Batis
:
y
3
3
z
(IS estes tosfeatt
8
& 8 aR
W
88
ga
g
z
&
INS 4 oy
ING LH sea5> i i
J SoS
ini 0 RC LPF |_|RC HPI oeo8 Ac LP So
135 kHz
VREFD TDA
VY
ES
VW
3
35 kHz
1317
READ AMPLIFIER
REFS
REF4
INL
INR
Yoo Veen Yss Vcca
Veea Voom VEEM
Fig. 18 Read amplifier IC TDA1317 and pin configuration
PHILIPS SOUND & VISION, BG AUDIO - Service Training
PCS 83 529