Teac TASCAM 32 - Page 72

1-16-3 Reproduce Amplifier Circuit
See Fig. 1-17 (A) and (B).
1. The reproduce amplifier consists of an 18 dB
Step-up Transformer, a Reproduce EQ
Amplifier, a Meter Amplifier and FET
switching transistors which controls the
function of the reproduce amplifier: depend-
ing. on the mode of operation and the tape
the input terminal (pin 3) of U101(2/2)
through the OUTPUT VR for final routing
to the LINE OUT jack.
. Then, because the play mode operation has
been selected, the muting inhibit-signal (ca.
-6.5 V) is applied to the gate of 0107 from
pin 8 of the power supply unit PC board,
head and is connected to one of the terminals
of the REC relay circuit on the K103 side.
Under this condition, the SYNC head will be
connected through K103 to the input
terminal of the primary side of T101 and the
audio signals which are picked up by the
SYNC head are reproduced through the
the gate potential of Q103 to zero, turning it
on. This allows the reproduced frequency
response to be modified to precisely match
the tape speed and the reproduce head used.
When the low speed is selected, Q104 is
turned on to obtain this modifying and
matching result in the same way.
speed
selected.
which
in
turn,
cuts
off
0107.
By
Q107
being
reproduce
amplifier
if
the
REC
mode
is
not
12.When
OUTPUT
SELECT
has
been
set
to
2.
Let’s
assume
that
the
SPEED
selector
has
cut
off,
muting
is
inhibited
and
the
audio
selected.
However,
if
the
REC
mode
is
SYNC,
Q106
is
turned
on
and
the
reproduce
been
set
to
HIGH
(15
ips
—
38
cm/sec.)
and
signals
are
transmitted
to
the
next
stage.
selected,
the
SYNC
head
will
be
connected
EQ
amplifier
output
signals
are
fed
to
pin
3
that
the
play
button
is
on.
10.When
OUTPUT
SELECT
has
been
set
to
through
K103
to
the
record
amplifier
output
of
U101(2/2)
through
OUTPUT
VR
to
be
3.When
OUTPUT
SELECT
is
set
to
INPUT,
SYNC,
0204
is
turned
on
and
the
SYNC
circuit
as
described
in
‘‘1-16-2
Bias
and
finally
outputed
through
LINE
OUT.
+24
V
is
applied
to
the
base
of
Q201
through
RELAY
K101
is
energized.
(This
part
of
the
Record
Control
Circuit’’.
13.
In
the
SYNC
mode
of
operation,
one
channel
R358 and D356 to turn it on. The +24 V is
applied to energize the POWER MUTE
RELAY, K102. (This part of the circuit is
not shown in Fig. 1-16(A)). The relay
connects the amplifier output (pin 1) of
U101(2/2) to the LINE OUT jack. When
OUTPUT SELECT is set to REPRO or
SYNC, Q201 and K102 go on in the same
way.
QIO7
4. At the same time, +24 V is also applied to f
the cathode side of D112 from al through
D118, R204 and R159 to set the gate poten-
tial of Q110 to zero, turning it on. The input
audio signals (previously selected through the
INPUT switch) coming from the LINE IN
jack are fed from the INPUT VR through
pin 7 of U102(1/2) to R202, R156 and
then sent to the OUTPUT VR to be amplified
is set to REPRO.
7.When OUTPUT SELECT is set to REPRO,
circuit is not’ shown in Fig. 1-16(A)). When
this relay is activated, the input pin of the
primary side of the step-up transformer
(T101), is disconnected from the reproduce
O+15V
SYNC RELAY
KIO!
6
w8]
PB
EQ
AMPL.
Ee
REPRO HEAD —> §
yo
R127
TAPE SPEED r
11.
RI20
hi
| ||
LJ
When the SPEED selector has been set to
HIGH and OUTPUT SELECT is set to SYNC,
+24 V is applied to the cathode side of D104
through b1 of the SYNC switch which sets
OUTPUT AMPL.
INPUT = SYNC REPRO 2
Quo O
+] |
|
POWER MUTE
RELAY
U302 1/2
OUTPUT SELECT
may be operated in the PLAY mode while
the other channel is in the REC mode of
operation. In this situation, the recording
bias signal may flow into the adjacent channel
©) [LINE OUT?
Se eed
| PHONES
VU METER
to pin 1 of U101 for routing to LINE OUT. | | sgor ove sige? bigee | aed
5. Meanwhile, the signals selected through the PLAY MUTE i ae a ead
INPUT select switch are supplied to the %
motor circuits from pin 7 of U102(1/2) ise ee an ee
through R140 and a2 of the INPUT select ners i al a,
switch,
H
METER
AMPL.
+15V
6. Now, assume that the SPEED selector has O
been set to HIGH and that OUTPUT SELECT
t
if
+24 V is supplied through c1 of REPRO to
(INPUT SELECT
the cathode side of D102 to set the gate os oe [LINE]
potential of Q101 to zero, turning it on, [Mic] Otisv
Switching Q101 on allows the reproduced aune}. © att LINE AMPL.
frequency response to be modified to f : a~le PR sh ate
precisely
match
the
tape
speed
and
the
E>
We
i
0
SS
reproduce head which is to be used. During mic ee wail eee
the low speed (7-1/2 ips — 19 cm/sec.), this ; Rie!
Fig. 1-16 (A). Amplifier Circuit Diagram
: Q30
modifying is done by Q102 being turned a
on. N
8. Meanwhile, when OUTPUT SELECT has
been set to REPRO, 0105 is turned on to
connect the EO amplifier output signals to
74 75