How it Works
Tascam
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122
Service Manual
64 pgs36.87 Mb1

Tascam 122 Service Manual

TASCAM
TEAC
Production
Products
SERVICE
MANUAL
MASTER CASSETTE DECK
April.
1981
810041
5704008406
122
I
TABLE
OF
CONTENTS
1. Specifications . . . . . . . . . . . . . . . . . . .
..
3
6-4. Capstan assembly
thrust
.........
44
2. Features and controls
6-5. Takeup torque . .
..... . ........
44
2-1.
Front
panel features and controls . . 4
6-6. Fast forward and rewind torque
...
44
2-2.
Rear
panel connections . .
.......
5
6-7.
Pi
nch roller pressure
...... . .....
44
3. Circuit description
6-8. Tape
speed
.. . ................
45
Control section
6-9. Wow and
flutter
. . . . . . . . . . . . .
..
45
3-1. System control I C
.............
6
7. Record/reproduce amplifier checks
and
3-2. System control I C
input/output
adjustments
circuits.
. . . . . . . . . . . . . . . . . . .
..
9
7-1. Reproduce
output
level setting
....
47
3-3. Solenoid drive circuit . . . . . . . . .
..
10
7-2.
VU
meter setting
..............
47
3-4.
Reel
motor
drive
circuit
.......
" 15
7-3. Reproduce frequency response
....
47
3-5. Capstan
motor
ci
rcu
it
. . . . . . . . .
..
18
7-4.
Bias
setting adjustment
..........
48
3-6. Tape-end detection
circuit . ... . ..
18
7-5. Record level
.................
. 48
3-7. Memory
circuit
................
20
7-6. Overall frequency response
.......
48
3-8. Power supply circuits
............
20
7-7. Overall signal-to-noise ratio .
.....
49
3-9. Overall operation
of
the deck
.....
24
7-8. Overall
distortion
....... . ......
49
3-10. Muting circuits
................
26
7-9. Erasure ·
....... . ... . ..........
49
Amplifier
section
7-10. Channel separation
.........
.
..
, 50
3-11. Reproduce circuit
....... . ..... . 30
7-11. LED lighting
of
VU
meter (PEAK
3-12.
Monitor
circuit
................
32
indicator)
..........
.
.........
50
3-13. Record circuits
................
34
7 -12.
Dolby
Noise Reduction effect
....
50
3-14.
Dolby
HX
circuit . .... " .......
37
7-13.
Dolby
HX
effect
............
.
..
50
4. Parts location
.....................
41
7-14. Headphones
output
level
.. . .... . 51
5. Essential maintenance
7-15. Bias trap adjustment
............
51
equipment/material
........ . ... . ...
42
7-16. BIAS/REC calibration check
.. . ..
51
6. Electro-mechanical checks and adjustments
8. Exploded views and parts lists
.... . ...
52
6-1.
Head
base
plate positioning
......
43
9.
PC
boards and parts lists
...
..
. .
......
58
6-2. Microswitch (A) assembly
10. Semiconductors lists
..............
. . 67
clearance
....................
43
11. Assembling hardware coding lists
......
68
6-3. Microswitch (B) assembly
12. Block-diagram
....................
69
clearance
...................
.
43
NOTES: 1. I n the diagram
of
each
PC
board, its pattern surface
is
shown.
2. With certain exceptions, the reference numbers in the 100's,
3OO's
and 700's refer
to
the Lch, and those in the 200's, 400's and 800's
to
the Rch. .
3. Parts marked
with
I!:::,
are
safety critical components.
They must always
be replaced
with
components specified
by
TEAC.
4. Service data are found where
they
are
necessary.
Improvements may result in service data
changes
without
notice .
•
Dolby
Noise Reduction System manufactured under license
from
Dolby
Laboratories Licensing Corporation .
•
'Dolby'
and
the
double-D symbol are trademarks
of
Dolby
Laboratories
Licensing Corporation.
1---------
482mm
(19")
---
- -
----1
345mm (13 ·
5/S")
I
~~~S~~IFlc~~llc~I
I
~'--fL
o 0 0 E
~
E'::::
I~-~~@@@
~~
,"======,;:D~=OdJ
[ ••C)(U)C) 0 0 )
_______
......Lt
2
122
1. SPECIFICATIONS
MECHANICAL
Tape: Track
Format:
Tape
Speed:
Speed
Accuracy:
Wow
& Flutter:
Fast
Wind
Time:
Motor: Head
Configuration:
Dimensions
(WxHxD):
Weight:
ElECTRICAL
Line
Input 1,
2: I nput Impedance: Maximum
Source
Impedance:
Nominal
Input
Level:
Minimum
Input
Level:
Line
Output:
Minimum
Load
Impedance: Output Impedance: Nominal
Output
Level:
Maximum
Output
Level:
Headphone
Output:
Bias
Frequency:
Equalization:
Frequency
Response
3
)
(R
Icard/reproduce):
Total
Harmonic
Distortion
(THD)3):
Signal
to
Noise
Rati0
3
):
Adjacent
Channel
Separation: Erasure: Headroom:
Recording
Amplifier:
Reproduce
Amplifier:
Power
Requirements:
I n
these
specs
. 0
dB V is
referenced
to 1 V.
Philips
Type
Cassette
C·SO
and
C·90
4·Track,
2·Channel
Stereo
1·7/8
ips
and
3·3/4
ips
1·718
ips
±0.5 %Deviation
3·3/4
ips
:to.5 %
Deviation
1·7/8
ips
1)
±0.085 %
peak
(DIN/IEC/ANSI
weighted)
±0.18 %
peak
(DIN/IEC/ANSI
unweighted)
O.OS %(NAB
weighted)
0.
11 %(NAB
unweighted)
3·3/4
ips
2)
±0.055 %
peak
(OIN/IEC/ANSI
weighted)
±0.13 %
peak
(OIN/IEC/ANSI
unweighted)
0.04 %
(NAB
weighted)
0.07 %(NAB
unweighted)
90
secs.
for
MTT·501
(C·SO)
1
FG
Servo
Controlled
0 C
Motor
1 0 C
Reel
Motor
3
Heads:
Erase.
Plavback/Record
482 x 147 x 345
mm
(19" x 5·13I1S" x 13·9/1S")
19·13/1S
Ibs.
(9
kg)
net
50k
ohms
unbalanced
10k
ohms
or
less
-14
dBV
(190
mV)
-24
dBV
(SO
mV)
25k
ohms
or
more,
unbalanced
3.5k
ohms
or
less
-10
dBV (0.3
V)
-7.5
dBV
(0.42
V)
100
mW
Maximum
at 8 ohms
100
kHz
1·7/8
ips
3180
/lS . +
70
/lS.
31
80
~s.
+
120
/lS. switchable
3·3/4
ips
3180
/lS. +
35
/lS.
3180
/lS. +
50
Jis
.switchable
1·7/8
ips
35
Hz -14
kHz
±3
d.B
at
-20
VU
35
Hz -S.3
kHz
±3
dB
at 0 VU
3·3/4
ips
35
Hz -20
kHz
±3
dB
at
-20
VU
35
Hz -15
kHz
±3
dB
at 0
VU
1 %
at 0 VU, 1 kHz,
lS0
nWb/m
1·7/8
ips
3 %
at 9 dB
above 0 VU, 1 kHz,
451
nWb/m
3·3/4
ips
3 %
at
10
dB
above 0 VU, 1 kHz,
50S
nWb/m
A t a reference
of
3 %distortion
level
1·7/8
ips
58
dB
weighted
55
dB
unweighted
"
92
dB
weighted
with 0 BX
3·3/4
ips
S3
dB
weighted
58
dB
unweighteri
92
dB
weighted
with
OBX
Better
than
35
dB
at 1 kHz
Better
than
S5
dB
a.t 1 kHz + 10
VU
reference
Better
than
19
dB
above 0 VU
Better
than
19
dB
above
0 V U
100/12012201240 V AC,
50/S0
Hz,
41
watts
(General
Export
Modell,
120 V AC,
SO
Hz , 41
watts
(U
.S.A./Canada
Modell,
220 V AC,
50
Hz,
41
watts (Europe
Modell,
240 V AC,
50
Hz,
41
watts (U.K.lAustralia
ModeJ)
1)
Specifications
were
determined
using
TEAC
Test
Tape
MTT·ll1.
2)
Specif
ications
were
determined
using
TEAC
Test
Tape
MXT·111.
3)
Specifications
were
determined
using
TEAC
Test
Tape
MTT·50S.
Changes
in
specifications
and
features
may
be
made
without
notice
or
obligation.
3
122
2. FEATURES AND CONTROLS
2-1.
FRONT
PANEL
FEATURES
AND
CONTROLS
GPOWE R switch
fj
MEMORY
switch
This
works
in
conjunction
with
the
TAPE
COUNTER
and
rewind
function
to
rewind
to
any
required
part
of
the
tape.
The
tape
will be
rewound
to
the
000
position
on
the
tape
counter
(actually
to
999,
just
past
the
000
position).
The
000
position can
be
reset
at
any
position
on
the
tape
by
pressing
the
reset
button.
If
the
ME-
MO
RY
switch
is
in
the
STOP
position,
when
the
,
rewind (
+II
)
button
is pressed,
the
tape
will
be
rewound
until
the
counter
has
counted
down
to
999
(just
beyond
000)
and
the
tape
will
stop
0 '
automatically.
If
the
MEMORY
switch
is
in
the
PLAY position,
when
the
counter
has
counted
down
to
999,
the
tape
will
stop
and
then
be
played
back
automatically
.
8 PHONES
control
Adjusts
the
output
volume
for
the
headphones.
o PHONES jack
Suitable
for
8-ohm
stereo
headphones.
o
Cassette
holder
The
face
plate
of
this
door
can
be removed
for
easy access
to
the
heads
for
cleaning,
etc
.
(!)
Transport
controls
~
(Play)
button
+II
(Rewind)
button
..
(Fast
Forward)
button
STOP
button
EJECT
button
RECORD
button
PAUSE
button
REC MUTE
(Record
Muting)
button
If
the
REC MUTE
button
is
pressed while a re-
cording
is
being made,
only
an erase signal
is
applied
to
the
tape.
To
release
the
record
muting
mode,
press
either
the
play ( ~ )
or
PAUS E
button.
• INPUT LINE 2
jacks
This
pair
of
RCA
jacks
is
provided
as a conven-
ience,
and
duplicates
the
function
of
the
rear
(LINE
1)
input
jacks
for
connecting
a receil
veror
other
line level
source
to
the
122.
Ci)
INPUT
(LEFT,
RIGHT)
controls
These
controls
are used
to
adjust
the
levels
of
the
left
and
right
input
signals
to
be
recorded
on
the
tape. The
'left
and
right
controls
are geared
together
to
allow
simultaneous
adj
ustment
of
both
channels.
To
adjust
one
channel
independ-
ently
of
the
other
(to
alter
the
channel
balance),
hold
one
knob
while
turning
the
other
.
o
BIAS/REC
CALIBRAf'ION
trimmers
and
button
switch
With
the
button
in
the
PRE-SET
(out)
position,
the
bias levels
suitable
for
recording
on
normal,
cobalt
(Co),
chromium
dioxide
(Cr02)
and
metal
tape
can be selected using
the
B lAS
switch,
while
the
reference recording level
is
adjusted
to
match
the
average
sensit
ivity
for
each
type
of
tape. These
factory-preset
levels are average
values
for
the
three types
of
tape.
For
precise
calibration
of
the
bias
and
recording levels
to
exactly
match
°a specific
tape,
set
the
button
to
the
ADJ UST (in)
position
and
adjust
the
trim
-
mers using a screwdriver.
4
I 122
tm)
OUTPUT
control
This knob
is
used
to
adjust the level
ofthe
signals
delivered
from
the
OUTPUT
jacks on the rear
panel.
Both
channels are adjusted together. The
readings
of
the
VU
meters
are
not
affected
by
this control.
4D
Function
switches
MONITOR
switch
This switch selects the signals fed
to
the head-
phones (PHONES) jack and the
OUTPUT
jacks,
and
is
indicated
by
the
VU
meters.
SOURCE: Selects the
input
connected
to
the
II
N E 1 (rear)
or IIN E 2
(front)
jacks. The levels
displayed
by
the
VU
meters depend on the set-
ting
of
the
INPUT
controls.
TAPE:
Selects the signal
from
the tape. The
levels displayed
by
the
VU
meters are the levels
of
the signals recorded on the tape;
they
are
not
affected
by
the setting
of
the
OUTPUT
control.
Note:
For
tape playback the MON
ITO
R switch
must be in the
TAPE
position.
NR
SYSTEM switch
DOLBY
SYSTEM/NR:
Selects the
built-in
Dolby
Noise Reduction
circuit.
This position
is
used
to
make a Dolbyized recording
or
to
reproduce a Dolby-encoded cassette. DOLBY
SYSTEM/N
R +
HX:
Selects the
Dolby
Noise Reduction
circuit
and also the
Dolby
Headroom Extension
(HX)
circuit
which
gives greater headroom in recording. Tapes recorded with
the switch in this position
can
be
played
back
with
the switch in the
same
position
or
in
the DO
LBY
SYSTE
M/N
R position.
dbx
(EXT)/OUT:
Use
this position
to
record
or
reproduce
without
noise reduction
or
when
USING
THE
OPTIONAL
RX-8
DBX
NOISE
REDUCTION
UNIT.
INPUT switch
This switch selects the signals fed
to
the record-
ing
circuit
for
recording.
II
N E 1: Selects
the
signals applied
to
the rear
panel
LINE
IN j3cks.
LI
N E 2: Selects the signals applied
to
the
front
panel
LIN
E 2 jacks.
TEST:
Use
this position when setting the bias
and recording level calibration
controls
using a
separate signal generator. SPEED switch
HIGH:
Selects a tape speed
of
3-3/4 ips.
STANDARD:
This selects the normal cassette
tape
speed
of
1-7/8 ips.
EQ switch
Selec;:ts
the equalization characteristics
of
the
122
to
match the
type
of
tape being
used.
NORMAL:
The equalization
is
120
/J.s.
Co
(Cr02):
The equalization
will
match cobalt
or
chromium
dioxide
tape.
M
ETA
L: The equalization
will
match metal tape.
Note:
The EQ switch should
be
set
to
match the
tape
for
both
recording and playback.
BIAS
switch
Selects the factory-preset bias levels
to
match
the
type
of
tape being
used
for
recording
(with
the
BIAS/REC
CALIBRATION
button
in the
PRE
-S
ET
position).
NO
RMAL:
The bias
will
match normal low-bias tape. Co (Cr02 ): The bias
will
match cobalt
or
chrome-
equivalent tape.
METAL:
The bias
will
match metal tape.
Note:
The bias
has
no
effect
during playback,
by
it
must
be
set
correctly
when recording
to
get
optimum
performance
from
the tape being used.
4B
VU
meters
A
PEAK
LED
is
provided
in
each
meter; this
lights
to
warn
of
overload
at
+8 dB
input
level
which
could
result
in
distorted recording.
•
TAPE
COUNTER
2-2.
REAR
PANEL
CONNECTIONS
OUTPUT
(R,
L) jacks
LINE
1 (R, L) jacks
DBX
UNIT
terminals
These eight
RCA
pin-terminals
are
used
for
the
connection
of
the
optional
RX-8
dbx
noise
re-
duction
unit.
If
the RX-8
is
not
used, the U-link
plugs provided
must
be
left
in place.
DBX
UNIT
CONTROL
SIGNAL
socket
This
is·
a special socket
which
feeds the
control
signal
to
the
optional
RX-8
dbx
noise reduction
unit. REMOTE
CONTROL
Socket .
Allows
connection
of
the
optional
TEAC
RC-
90
Remote
Control
unit.
5
122
~
3. CIRCUIT DESCRIPTION
The
following
conditions
are
assumed:
* The deck
is
initially
in the stop mode unless
otherwise specified.
* Voltages, waveforms, and operating times
given in the
text
are
typical ones
for
reference.
* I n the description
of
ampl ifiers (sections
3-11
through
3-14), generallly, the
left
channel
is
described.
* In the illustrations,
circuit
boards, terminals,
and connectors
are
omitted.
* Part numbers are assigned
as
follows:
100-199:
Muting
circuit,
bias osciUator cir·
cuit,
and L-channel record/repro-
duce
circuit
mounted on record/
reproduce &
control
PCB
200-299:
R-channel record/reproduce
cir·
cuit
on record/reproduce & con-
trol
PCB
300-399:
L-channel
monitor,
record, and
HX
circuits and common L- and
R-channel
circuits
mounted
on
lever switch
PCB
400-499:
R-channel
monitor,
record, and
HX
circuits
mounted
on lever
switch
PCB
500-599:
Power supply
PCB
circuits.
600-699:
System
control
circuits and
mechanical parts mounted on
reo
cord/reproduce &
control
PCB
and
joint
PCB
700-799:
L-channel meter
circuit
and phone
amplifier
circuit
mounted
on
meter
amplifier
PCB
800-899:
R-channel meter
circuit
and phone
amplifier
circuit
mounted
on
meter
amplifier
PCB
CONTROL SECTION
3-1. SYSTEM CONTROL
IC
3-1-1 Pin assignments
Output Control input
Ir~----------
----------~\
r-\
.8
F.
FWO
FAST
REW
PLAY
PAUSE
AR
US01
M54410P
(T
OP
VIEWI
PLAY
STOP
f . fWO
MEMO
REW
PAUSE
REt
GNO
\~
______
....JI
'--.I ,'-
____
---11
OperOling
inpulS Control input Operating inpulS
Fig. 3-1 Pin assignments
Pin
No . Pin
name
Function
1
PLAY
Reproduce
start
signal
input terminal.
Signal
level:
L
2
STOP
Stop
signal
input
term
inal
Si
gnal
level
: L
Operation
3
F.
FWD
Fast-forward
signal
input terminal.
Signal
level
: L
inputs
5
REW
Rewind
signal
input terminal.
Signallavel: L
6
PAUSE
Pause
signal
input terminal.
Signal
level
: L
7
REC
Record
signal
input terminal.
Signal
level:
L
Control
4
MEMO
Memory
input terminal (resets
rewind
mode
when
at L
level)
inputs
9
AR
Record
inhibit
signal
input
terminal
(L
level:
record
inhibited, H
level:
record
enab
led)
10
REC
H-Ievel
signal
output terminal
during
record/reproduce
or
record/pause
mode
11
PAUSE
H
-level
signal
output terminal
during
pause
mode
Outputs
12
PLAY
H-Ievel
signal
output terminal
during
reproduce
mode.
power
13
REW
H-
Ievel
signal
output terminal
during
rewind
mode
.
14
FAST
H-Ievel
signal
output terminal
during
rewind
or
fast-forward
mode.
15
F.FWD
H-Ievel
signal
output terminal
during
fast-forward
mode.
Power
8
GND
Ground
terminal.
16
+B
Power
supply
terminal (standard:
+5
V +/-10%, absolute
maximum:
+7.0
V)
I
6
l 122
3-1-2
Block
diagram
I
F.
FWD
IN
REW
IN
STOP
IN
MEMO
REC
IN
AR
PAUSE
IN
PLAY
IN
~3
5
.----
S
or-
15
~
4
[
"""
R 6
/,--
~~
D~
~
14
13
7
9
r1->
6
I
J
.----
s
0
.J.
)R
6
1'0<
I
.----
]
\.
s 0
....-4
.L
::r
)R
6
J,
'--
r-
S 0
..L
;:]'
)~
T
J
10
II
12
---<-
16
8 )
M54410P
Fig. 3-2 Block diagram
3-1-3
Input
signals and resulting modes
F.
FWD
OUT
FAST
OUT
REW
OUT
REC
OUT
PAUSE
OUT
PLAY
OUT
+8
GNO
~
I nput
signal
I
REC
PAUSE
PLAY
REW
FAST
F.
FWD
Operating
mode
PLAY
L
L H
L
L
L
PLAY
mode
STOP
L L L L L L
STOP
mode
F.FWD
L L
L
L
H
H
F.FWD
mode
REW
L
L
L
'H
H
L
REW
mode
PAUSE
L
H
L
L
L
L
PAUSE
mode
REC
and
PLAY
H
L H
L
L L
REC/PLAY
mode
REC
and
PAUSE
H
H
L L
L
L
REC/PAUSE
mode
Notes
1.
The
mode
is
set
at
the
decaying
edge
of
the input
signal
waveform.
2.
The
output
retains
the
,current
mode
until
an
input
signal
indicating
a different
mode
is
received.
3.
Output
REC
remains
at Las
long
as
input
AR
is
l.
4. 0 utput R
EW
remains
at Las
long
as
input
MEMO
is
l.
7
122
3-1-4 Mode transition The table below summarizes transition
from
one
to
another due
to
an
input
signal.
~
STOP
F.FWD
REW
PLAY
PAUSE
REC/PLAY
REC/PAUSE
Input
signal
STOP
------
STOP
STOP
STOP
STOP STOP
STOP
F.
FWD
F.FWD
------
F.FWD
F.
FWD
F.FWD
F.FWD
F.FWD
REW
REW
REW
-------
REW REW
REW
REW
PLAY
PLAY
PLAY
PLAY
-----
PLAY
-------
REC/PLAY
PAUSE
PAUSE
------
------
PAUSE
------
REC/PAUSE
---=--==--
REC
and
PLAY
REC/PLAY
REC/PLAY
REC/PLAY
REC/PLAY
REC/PLAY
~
REC/PLAY
REC
and
PAUSE
REC/PAUSE
~
------
REC/PAUSE
REC/PAUSE
REC/PAUSE
------
3-1-5 Operation
with
more than one
input
signal
When
more than one
input
signal
is
received simultaneously, the deck enters the mode indi­cated below. When
input
signals applied simul-
taneously
are
removed in sequence, the mode
indicated
by
the last signal
to
be removed
is
normally
enabled.
If
REC and
PLAY
or
REC
3-1-6
Input/output
levels
Input/cutput
levels and voltages are given below.
8
Note. A diagonal
line
indicates
that
the
current
mode
remains
unchanged.
and PAUSE
are
combined, the record/reproduce
or
record/pause mode wiH
be
enabled regardless
of
the sequence in which
the
input
signa,ls
are
removed.
If
F.FWD (REW) and REC
or
PAUSE
are
combined, the fast-forward (rewind) mode
will
be
enabled regardless
of
the sequence in
which the
input
signals
are
removed.
Input
signal
A
Input
signal
B
Resulting
mode
STOP
Any
combination
of F.FWD, REW, REC,
PAUSE,
and
PLAY
STOP
mode
REW
STOP
mode
F.FWD
REC
and/or
PAUSE
F.FWD
mode
PLAY
STOP
mode
REW
REC
and/or
PAUSE
REW
mode
PLAY
STOP
mode
PAUSE
REC/PAUSE
mode
REC
PLAY
R
EC/PLAY mode
PAUSE
and
PLA
Y
REC/PAUSE
mode
PAUSE
PLAY
REC/PLAY
mode
Item
Minimum
Standard
Maximum
Absolute
maximum
Maximum
supply
voltage
- - -
7.0
V
Maximum
input
voltage
- - -
5.5
V
I
Recommended
supply
voltage
4.5
V
5.0
V
5.5
V
-
H-I8Vel
input
voltage
2.0
V
- -
-
L·
level,
input
voltage
-
-
0.8
V
-
Open·input
voltage
3.2
V
-
- -
H·level
output
voltage
2.9
V
-
-:-
-
L-
I8Vel
output
voltage
- -
0.4V
-
16
-
.8
I
PLAY
PLAY
12
IN
OUT
0603
6
PAuSE
PAUSE
"
IN
OUT
R614
R616
3
F.F'NO
F.
FWD
I~
IN
OUT
5
REW
R[W
13
IN
OU
T
7
R[C
R[C
10
IN
OUT
2
STOP
FAST
"
IN
OUT
•
MEMO
$69!1
R622
IN
C607
AR
U601
e601
""
C60~
O.OI/!>OV
C606
tOllOV
R610
,-----I------r----t--
CAPSTAN
SOL.
DRIVE
CIRCUIT
,----Y>h---t--t-
..
FAST
SOL.
DRIVE
CIRCUIT
R627
t---t--
REC
SIGNAL
CONTROL
CIRCUIT
0601
0604
0610
R623
R630
D605
0606
122
R621
R628
0604
RECORD
LED
__
~>M---II'!--
PAUSE
LED
t5.3v
.--------------r---t-
PINCH
ROLLER
SOL.
DRivE
CIRCUIT
R629
·
_
C607
O.OI/~OV
OV
~----------------4-------------------------------------4---4--0V
Fig. 3-3 System control Ie
input/output
circuits
3~.
SYSTEM
CONTROL
IC
INPUT/OUTPUT
CIRCUITS
3-2-1 Initial
reset
circuit
See Fig.
3-3
.
The
initial reset
circuit
generates a signal
which
puts
the
deck
in
the
stop
mode
immediately
after
power
is
turned
on,
preventing
incorrect
operation
during
the
time
the
DC
supply
volt-
age
is
unstable.
1)
When
no
cassette
is
loaded
When
no
cassette
is
loaded, cassette-in switch
S695
is
set
to
N.O.,
which
is
the
state
entered
when
the
stop
button
is
depressed. I n
this
way
the
deck
enters
the
stop
mode
when
power
is
turned
on.
2) When a cassette
is
loaded
When a cassette
is
loaded,
cassette-in
switch
S695
is
set
to
N.C.
and
isolated
from
the
stop
circuit. If
the
power
is
turned
on
at
this
time,
current
from
system
control
IC
U601 charges
the
noise suppressing
capacitors
(C601 -
C607)
in
the
control
input
circuit
of
U601.
It
takes
approximately
20
msec
to
charge
C601 -
C605
due
to
their
low
capacity.
When
the
capacitors
are fully charged,
the
PLAY,
PAUSE,
F.FWD, REW,
and
REC
input
terminals
switch
to
H level. It takes
approximately
100
msec
for
the
STOP in-
put
terminal
(and MEMO
input
terminal)
to
rise
to
H level since
C606
has a large capacity.
In
this
way,
of
the
operation
input
terminals,
only
STOP
takes
longer
to
switch
to
H level.
As a result, a flip-flop
is
reset
in
U601
when
power
is
turned
on
and
the
deck
enters
the
stop
mode.
Unless
C606
is
fully
charged
and
the
STOP
input
terminal
is
at
H level, U601
does
not
switch
from
the
stop
mode
to
another
mode
even if
operation
signals are
input.
9
122
3-2-2
Output
control
circu
it
When
power
is
turned
on,
the
initial
reset
cir-
cuit
puts
U601
in
the stop mode.
This
circuit
does
not
operate
when
power
is
turned
off.
When
power
is
cut
off
and
+5.3 V is
decaying,
U601
may
generate a
wrong
signal
momentarily
due
to
deviation
from
the
logic
threshold
level.
The
circuit
comprising
Q606,
0605,
R629,
and
R630
prevents
the
mis-operation
of
the
deck
if
U601
generates
an
incorrect
signal.
When
+5.3 V supply
voltage falls
to
approxi-
mately
5 V
after
power
is
turned
off,
zener
diode
0605
turns
off
and,
therefore,
Q606
turns
off
together
because
its
base
current
is
cut
off.
As
Q606
is
off,
the
emitters
of
transistors Q601
-
Q605
are disconnected
from
the
0 V
(GND)
line.
As
a result, Q601 -
Q605
will
not
turn
on
even
if
U601 generates
an
incorrect
signal
while
+5.3 V supply
voltage is
falling.
This
protects
the
deck
from
erroneous
operation.
Further,
if
power
is
turned
off
when
the
deck
is
operating in
any
mode,
the
deck
enters
the
stop
mode
as
soon
as
Q606
turns
off,
preventing
the
tape
from
becomming
slack.
On
the
other
hand, when
power
is
turned
on,
0605
and
0606
do
not
go
on
until
the
+5.3
V
line rises
to
approximately 5 V.
Q601 -
Q605
do
not
operate
before
Q606is
turned
on.
This
means the deck does
not
start
to
operate
before
the
DC
supply
voltage is
sufficiently
high.
3-3.
SOLENOID
DRIVE
CIRCUIT
3-3-1
Functions
of
solenoids
There are three solenoids in
the
deck;
fast sole-
noid
(L691),
head
base
solenoid
(L692),
and
pinch
roller
solenoid
(L693).
These solenoids
have specific
functions
and operate in
certain
modes
as
described below.
1) Fast solenoid
(L691)
This
operates in the
fast-forward
and
rewind
modes
to
perform
the
following
mechanical
functions.
(' Releasing brakes applied
to
the
left
and
right
reel disks.
• Disengaging
the
reel
disk
drive gear
from
the
right-hand
(takeup)
reel
disk
and
locking
the
intermediate
pulley
assembly in
the
fast-
forward
position.
2) Head
base
solenoid
(L692)
This
operates
in
the reproduce, pause,
record/
reproduce, and record/pause modes
to
per-
form
the
following
mechanical
functions
.
• Raising
the
head
base
to
bring
the
erase and
record/reproduce
heads
into
close
contact
with
the
tape.
10
•
Lifting
the
pinch
roller
to
the
pause posi-
tion.
(The
pinch
roller
does
not
press against
the capstan
shaft
in
this
position.)
• Releasing brakes
applied
to
the
left
and
right
reel disks.
3) Pinch
roller
solenoid
(L693)
This
operates in
the
reproduce and
record/
reproduce modes
to
bring
the
pinch
roller
(raised
to
the
pause
position
by
the
head
base
solenoid)
into
contact
with
the
capstan
to
cause the tape
to
run
at
constant
speed.
3-3-2 Fast solenoid
drive
circuit
See
Fig. 3-4.
When
the
deck
is
in
the
stop
mode,
the
circuit
shown in Fig. 3-4
is
as
fol
'lows:
* Pin
14
of
U601:
L level
*
Q605, Q515,
Q516,
Q518:
off
*
Emitter
of
Q515:
+13 V is
applied via
0506.
During
fast
(fast-forward
or
rewind)
mode, a
fast
mode
signal (H level)
is
output
from
pin
14
af
U601.
This
signal causes fast solenoid L691
to
operate
in
the
following
sequence.
a.
As
pin
14
of
U601 is
at
H level,
base
current
flows
through
transistor
Q605
and
turns
it
on .
b. As
Q605
is
on,
base
current
flows
through
transistor
Q515
and
turns
it
on.
c.
As
Q515
is
on,
current
flows
via paths
CD
and
®.
(The
supply
voltage
that
causes
current
to
flow
via paths
CD
and ®
is
low
and there-
fore
the
cu
rrent
on
path
CD
can
not
energize
the
fast solenoid.)
d.
The
current
on
path ® (which
charges capa-
citor
C516)
causes
transistor
Q516
to
tu
rn on.
e.
As
Q516
is
on,
base
current
flows
through
transistor
Q518
and
turns
it
on.
f. As
Q518
is on,
current
flows
via paths @ and
@.
At
this
time,
the
supply
voltage
that
causes
current
to
flow
is
+39
V and there-
fore
a large
amount
of
current
flows
through
the fast solenoid (via
path
@)
to
energize
it.
g.
The
current
on
path
@ charges
C516
and
it
stops
flowing
when
C516
is
fully
charged.
Since
the
base
current
of
Q516
is
cut
off,
it
turns
off.
The
time
interval
between
the
turn-
ing
on
of
Q515
and
the
turning
off
of
Q516
(i.e.,
the
time
taken
to
charge
C516)
is
ap-
proxrmately
100
msec
which
is
determined
by
the
time
constant
of
capacitor
C516
and
resistor R536.
h. As
Q516
is
off,
Q518
turns
off
because
its
base
current
is
cut
off.
,In
this
way
the
current
on
path @ is
cut
off
.
I
122
,----,
I
DRIVER
I
;mSHIN;;CIRCUI~
- - - - -
--;
INO
LOAD
I
I
I
I
I
+ 13 V
I
I I
I I
+ 39V
U601
FA S T
0:
1 _4
-+I--.---H'
OUT
0610
C516 0511 R5 36
,------,
, I I
l@
I •
0510
t I
(D®
I
L
___________
...J
Fig. 3-4
Fast
solenoid drive circuit
i.
Current
is
sti"
flowi
ng
through
the
fast sole-
noid
via path
CD
even
though path @
is
cut
off.
Once the fast solenoid
is
energized
by
the
strong
current
on path @ , this weak
current
flowing
via path
CD
can
hold
it
on.
Thus a high voltage (strong drive current)
is
supplied
to
the solenoid when energizing
it
while
a
low
supply voltage (weak current)
hold
it
on.
This ensures solenoid operation
by
generating a strong mechanical force and prevents the solenoid
from
heating
up
by
reducing the hold­ing current. The
circuit
which
switches
the
supply
voltage
of
the solenoid
is
called the flashing
circuit.
When a fast mode
is
released (the STOP
button
is
depressed
during
fast-forward
or
rewind
mode), the
following
sequence
of
operations
takes place.
j.
As
soon
as
a fast mode
is
released, pin
14
of
U601 tu rns
to
L level.
k.0605
turns
off,
because its
base
current
is
cut
off.
I.
As
0605
is
off,
0515
turns
off,
as
its
base
current
is
cut
off
.
m.As
0515
is
off,
the solenoid
is
reset, because
its
holding
current
which
was
flowing
via path
CD
is
cut
off.
At
the
same
time, C516 dis-
charges
via
path ®
to
prepare
for
the
sub-
sequent
start
of
a fast mode.
3-3-3 Head
base
solenoid
drive
circuit
See
Fig. 3-5.
The head
base
solenoid operates
during
the
re-
produce (record/reproduce) and
pause
(record/
pause) modes. In the reproduce mode, a repro-
duce mode signal (H level)
is
output
from
pin
12
of
U601.
In the
pause
mode, a
pause
mode
signal (H level)
is
output
from
pin
11
of
U601.
In
both
cases,
the
H-Ievel signal
causes
base
current
of
transistor
0601
to
flow
so
it
is
turn-
ed
on. The
part
of
the
head
base
solenoid drive
circuit
after
0601
is
exactly
the
same
as
the fast
solenoid drive
circuit
described in the previous
section. Since these circuits operate in the
same
way,
the
description
is
not
repeated. Note
that
the
time
during
which
the solenoid
is
energizied
by
the high voltage
from
the flashing
circuit
(capacitor C516 and resistor R536 deter-
mine this)
is
approximately
400
msec, longer
than the 100 msec
of
the fast solenoid. The
reason
is
to
ensure operation
of
the head
base
solenoid
as
its mechanical load
is
much greater.
11
122
U601
PLAY
12
OUT
o.::....R"'
6 12
PAg~~
(j-
r-----,
r------------l
I
DRIVER
I I
FLASHING
CIRCUIT
I
NO
LOAD)
..-14--
-----
+ 13V
I I
I
R!l39
I
R618
I
11r--1
I Q514 I
L
___
-I
--J
R538
"
'..J..M~-..--H
R6 13
Q601
I
C!lI!I
0508
R534
R610
+---
-llf--_
.......
--"/.(r-...._--H
HEAD
BASE
T
SOLENOID
I
O!l09
L692
069
4
1
I
I
L
____________
.-J
Fig.
3·5
'Head base solenoid drive circuit
3·3-4 Pinch
roller
solenoid
drive
cia:uit
See
Fig. 3·6.
The pinch roller drive
circuit
(drive & flashing
circuit)
operates basically in the
same
way
as
the fast solenoid and head
base
solenoid drive
circuits and, therefore, the description
is
not
repeated. Since
the
mechanical load
of
the
pinch
roller
solenoid
is
low, the flashing interval
is
100
msec
which
is
provided
by
capacitor
C508 and resistor R 521. Here, operation
of
the power delay
circuit
and
reproduce delay
circuit
are described
as
they
are
not
incorporated
in
solenoid drive circuits.
1) Power delay
circuit
The positive side
of
capacitor C526
is
con·
nected
to
the
output
of
the
+23
V voltage
regulator. This regulated
+23 V is
used
as
the
power source
for
the amplifiers and also
as
a
reference voltage
for
the
power
supplies
which
supply
the
control
circuits, reel
motor,
12
and capstan
motor,
etc.,
with
DC
power.
(These
power
supplies are described in 3·8·2.)
When
power
is
turned
on,
the
tape
might
become slack
or
run unevenly
if
the repro·
duce mode is entered before
the
+23 V is
stable. The
power
delay
circuit
delays
the
operation
of
the
pinch
roller
until
the
DC
supply voltage ~ ises
to
a steady level
after
power
is
switched on. This
circuit
operates
as
follows.
a.
When
power
has
been turned
on,
the
+23
V
regulated
power
supply
starts
to
work
and
its
output
voltage
rises.
b. As the
output
voltage
rises,
base
current
flows
through transistor
0521
via capacitor
C526 and resistor R547,
turning
it
on.
c. As
0521
is
on,
base
current
flows
through
transistor
0508
and
turns
it
on.
d. As
0508
is
on, the
base
and
emitter
of
pinch
roller solenoid
driver
transistor
0509
122
are
shorted. Therefore,
not
flow
to
0509
and
even
if
transistor
0602 reproduce mode signal from
U601.
base
current
does
it
will
remain
off
turns on
with
a
(H
level) supplied
e.
When C526
is
fully
charged (in approxi-
mately
1.5 seconds) after
power
is
switched
on, the
base
current
of
0521
stops and
it
turns
off.
(C526 and R547 provide
the
delay
time
of
about
1.5 seconds.)
f .
As
0521
is
off,
0508
turns
off,
having its
base
current
cut
off.
Now
0509
is
ready
for
operation.
This
process keeps the pinch
roller
solenoid inactive
for
approximately
1.5 seconds
after
power
is
switched on.
REPRODUCE
DELAY
CIRCUIT
I I
I
U601
R619
I
I
p~~
0;'=-2
_..,...~R6"'''--''-1f{
L_
FRO
M
+23V
REGULATED
POWER
SUPPLY
10517)
0606
POWER
DELAY
CIRCUIT
RSl2
R618
,-------------,
I I I
R559
I
I
I C
526
R547
~1--
.........
w.-~-1i-{
:
0513
I
I
I
L
____________
-..l
I
2) Reproduce delay
circuit
The
circu~try
is
designed
so
that,
in the repro-
duce mode, the pinch
roller
solenoid operates
after
the head
base
solenoid
has
completed
operation. The reproduce delay
circuit
delays pinch
roller
operation
until
the com-
pletion
of
the head
base
solenoid operation.
Fig. 3-7 and 3-8
are a flowchart
and
timing
diagram, respectively,
of
the process which
begins
with
the
output
of
a reproduce mode
signal (H level)
from
pin 12
of
the system
control
IC and ends
with
the energizing
of
the
pinch roller solenoid. In Fig. 3-7, operations
of
the reproduce delay
circuit
are
enclosed in
bold boxes.
r---
--
PINCH
ROLLER
SOLENOID
DRIVE CIRCUIT
- -
--,
DRIVER
DRIVER
,--------,
I . 1
I
I
I I
0514
.:
L
________
.1
0694
J
L692
HEAD
BASE
SOLENOID
1-------,
:
I
I
I I
I
0:509
0695
Fig. 3-6 Pinch
roller
solenoid drive
circuit
FLASHING
CIRCUIT
~---------------I
I I I I
: I
I I
C
508
R521
I I
I
0505
I
I
I
L
___________
_
___
_ J
FLASHING
CIRCUIT
r----------------,
I I
I I
I
I
I
I
0509
I I I
L
_________
_ _ _
___
.l
I
NO
LOAD
I
+13\1
+39\1
R537
0507
13
122
Depress
PLA
Y ( ~) bunon.
Head
basa
solenoid
is
held.
(+
13V)
Pinch
roller
solenoid
is
held.
(+
13V)
Reproduce
mode
signal
is
held
.
Reproduce
mode
Fig. 3-7 Flowchart
of
solenoid operation lin reproduce
mode)
14
122
U601
Pin
12
HIGH
l OW
OSOI
OFF
ON
0514
OFF
ON
HIGH
[BASE
lOW
OSIS
COLLECTOR
HIGH lOW
0518
OFF
ON
HEAD 8ASE SOLENOID
OFF
OS02
ON
OFF
0508
ON
OFF
0509
ON
HIGit
[BASE
lOW
0511
HIGH
COLLECTOR
lOW
OFF
0510
O'
PINCH
ROLLER
SOLENOID
II
I \
lJ
I (
h
;(
\
I \
'"
\
[\ (
+39V
+24V
+9V
OV
\
\
/
/
I~
(
~
1
(
(
'-
il
(X
I)
+24V
+9V
ov
Approl.
Apprat
.
400mSIC
IOOmSec;
STO
P
DELAY
PLAY
Fig. 3-8 Timing diagram
of
solenoid
operation
(in repro-
duce
model
\
3-4. REEL
MOTOR
DRIVE
CIRCUIT
3-4-1
Direction
of
motor
rotation
The
reel
motor
drives the
left
or
right
reel disk
to
take
up
the tape.
Torque
is
transmitted
from
the reel
motor
to
one
of
the reel disks
during the reproduce, fast-forward, and rewind modes by
the
processes shown in Fig. 3-9 -
3-11
(as
seen
from
the
front
of
the deck). As
seen
from
Fig. 3-9 and 3-11, the reel
motor
rotates in the
same
direction
during
the reproduce and rewind
modes and
the
fast-forward
pulley
mechanically
selects
either
the
left
or
right
reel disk and drives
it
in
accordance
with
the
direction
of
reel
motor
rotation.
In the
pause
mode, the reel
motor
does
not
rotate.
MOTOR
PULLEY
---i'----i"4
RIGHT-HAND REEL
DISK
Fig. 3-9 Reel disk drive (reproduce mode)
INTERMEDIATE
PULLEY
RIGHT-HAND REEL
DISK
REEL
MOTOR
Fig.
3-10
Reel disk drive (fast-forward
model
REEL
MOTOR
INTERMEDIATE PULLEY
Fig. 3-11 Reel disk drive (rewind
model
15
122
3-4-2 Reproduce
mode
See
Fig. 3-12.
When
the
deck is
in
the
stop mode,
base
current
is
supplied
to
transistor
OSOS
via RS10,
turning
it
on. In
the
reproduce mode, the reel
motor
rotates
in
the
following
sequence.
a.
When a reproduce mode signal (H 'level,)
is
output
from
pin
12
of
U601 ,
0601
and
0602
turn
on.
b.
0601
activates the head
base
solenoid
drive
circuit.
When
the
head
base
solenoid com-
pletes
operation,
OS08
turns
off,
permitting
base
current
to
flow
through
OS09 and
turn-
ing
it
on.
c.
As OS09
is
on,
base
current
flows
through
OS01 and
turns
it
on.
At
the
same
time,
cur-
rent
flowing
via
path
CD
charges capacitor
CS04.
d. As OS01 is
on,
base
current
flows
through
transistor OS04 via path ®. and
turns
it
on.
e.
As OS04
is
on,
cu
rrent
is
su
pplied
to
the
reel
motor
via path @ and causes
the
motor
to
run.
At
this
time,
the
supply
voltage
of
+13
V is
directly
applied
to
the reel
motor
so
that
the
motor
drives the reel
disk
with
a large
starting
torque
so
that
the
tape
is
tight.
f.
As
current
on
path
CD
charges CS04 and its
charge rises,
the
voltage at
the
base
of
OS06
rises and its
base
current
increases; OS06
is
turned
on
completely
in
about
80 msec.
Now
the
base
current
of
OSOS
decreases since its
base
level falls
from
+13
V,
divided
by
RS10
REW
0:
OUT
R622
U601
F
~~~
1)",,-5
-'V.
iv-
R6
ZO
and RS09.
This
results in a decrease in
OSOS's
collector
current
(the
current
supplied
to
the
motor)
and
in
the
voltage applied
to
the
motor.
Thus
the
torque
of
the
motor
is
reduced and the reproduce mode is stabilized.
3-4-3
Rewind
mode
See
Fig. 3-12.
When
the
rewind
mode
has
been enabled, a
rewind
mode
signal (H level)
is
output
from
pin
13
of
U601 and
base
current
flows
through
OS01 via resistor
R622,
turning
on OS01.
OS04
turns
on
immediately
since
its
base
cur-
rent
f.lows along
path
® . When
OS04
is on, a
large
current
is
supplied
to
the
reel
motor
via
path
@ ,
driving
the
motor
at
a high speed. Our-
i1ng
the
rewind
mode, OS06 remains
off.
3-4-4
Fast-forward
mode
See
Fig. 3-13.
When the
fast-forward
mode
has
been enabled,
a fast
forward
mode signal (H level)
is
output
from
pin
lS
of
U601 and
base
current
of
tran-
sistor
OS02
flows
via resistor
R620,
turning
OS02 on. As OS02
is
on,
base
current
of
tran-
sistor OS03
flows
via
path
CD
,
turning
OS03 on.
Now
+13 V is
applied
to
the reel
motor,
the
large
current
flowing
via
path ® causes
the
motor
to
run
at
a high speed.
The
direction
of
the
current
is
reversed in the
fast-forward
mode
to
that
in
the
reproduce and
rewind
modes
so
the
direction
of
motor
rotation
is reversed.
+13v
'
.::...3
~~-+r
t-+---------
~~
-----------I
I
I
---H'
Fig.3-13
Reel
motor
drive circuit {fast-forward mode}
16
r---~~:;----------------------
--------
~-------------
I
+13V
0503
'A
+39'.1
®@
R519
R520
CD
0518
, , e
691..-
REEL
"
I-
g"
"
MOTOR
,.
/ ,
, ,
L
~
0509
..
R50 8 0521
'"
-",
, ,
ROLLER
T
~..1
I I I
R694
PI"';Ol".""
""
I ("""\ I
~
,,~
","
""
I •
'6'
I I I
".'"
I I
.L
.L
HIJ.L
"'''
'6'
0'041 •
,
:::
r::::
(f
I
0,0,
OUT
P!S~i
~
."'
0602
I
i
do.
U601
Fig.
3·12
Reel motor drive circuit (reproduce/rewind modes)
...
.....
~
122
·1
3-5. CAPSTAN
MOTOR
CIRCUIT
'See
Fig. 3-14.
The capstan
motor
rotates in the reproduce
(record/reproduce) and
pause
(record/pause)
modes. Its
torque
is
transmitted
to
the
flywheel
by a belt
to
drive the flywheel and capstan shaft.
In
both
the reproduce and
pause
modes,
0514
is
on
to
energize the
head
base
solenoid. When
0514
is
on,
base
cu rrent flows through transis-
tor
0692,
turning
it
on.
Now
the 0 V line
of
the
capstan
motor
servo
amplifier
is
shorted
to
the
ground line
of
the power supply circuit. The
servo
amplifier
is
activated and the
motor
starts
to
rotate. The speed
of
the capstan
motor
may
be
switched between 'standard' (tape speed:
4.76 em/sec)
an.d
'high'
(9.5 em/sec)
by
SPEED
switch S4-2.
PLAY
12
R612
OUT
PAUSE
II
R613
OUT
U601
HEAD
BASE
T
0694
SOLENOID
L692
3-6
TAPE-END
DETECTION
CIRCUIT
See
Fig. 3-15.
The ring magnet, shown in Fig. 3-15,
is
mount-
ed
on the
counter
pulley
shaft and rotates while
the tape
is
running. Variations in the magnetic
field caused
by
the
rotation
of
the ring magnet
turn
reed switch S693 on and
off
. This means
that, when
the
tape
is
moving, the reed switch
turns on and
off
repeatedly.
When the reed switch
turns
on while the tape
is
running, the charge
from
capacitor C609 flows
through the
base
of
transistor
0607
via path @ ,
turning
it
on. When the reed switch turns
off,
0607
turns
off,
as
its
base
current
is
cut
off. At this time, C609 discharges via path @ . Thus, while the reed switch
is
turning
on and
off
re-
peatedly,
0607
also
turns
on and
off
repeated-
r-------------+39V
,--;:::;;;;;;;:::;:-T----
+
13
V
I
SPEED
+
54-2
-"""'>--.!..jY
SERVO AMPLIFIER
H
FLASHING
CIRCUIT
CAPSTAN MOTOR
M692
Fig. 3-14 Capstan
motor
circuit
18
PINCH
ROLLER
T
R65 7
r--'
I ,
,
I
I
I
,
I
I
C
611'
I
, I
"659
t
122
Fig. 3-15 Tape-end
detect
circuit
19
Iy. When
0607
is
off,
capacitor
C61 0 is
charged
by
current
flowing
via path ® . When
0607
is
on, C610 discharges via path ® . Since the
time
constant
of
C610 and R631
is
much smaller
than
that
of
C610 and R656
(or
R657), the
charging
of
C610 proceeds
slowly
while
it
dis-
charges rapid Iy.
As a resu
It, the voltage at
'liJ
remains
below
+1.5
V while
0607
is
repeatedly
turned on and
off
. When the tape reaches its end and stops running, the counter
pulley
and the ring magnet stop
rotating.
At
this
time,
the
reed
switch stops
operating in
either
its on
or
off
position depend-
ing on where the ring magnet
has
stopped.
If
the reed switch
is
on, the
base
current
of
0607
stops
flowing
turning
it
off
, and
current
flowing
along path ® starts
to
charge C610
as
soon
as
U601
P LAY 12 R6 11
OUT
FAST 14 0 6
10
I STOP I
OUT
"6
06 2 STO
P
F
'N
IN L
693
C60 6 L _4_ME_MO
____
w...
_____
SO_L_EN_O_'D-,
"6
62
Q613
cu
rrent
from
path ® completes charging C609.
If
the reed switch
is
off,
0607
is
already
off
be-
cause
the
reed
switch
has
turned
off
and, there-
fore,
current
from
path ® continues
to
charge
C610.
When the voltage across C610 (voltage at ® )
exceeds
approximately 3 V,
base
current flows
through
transistor
0513
via path
(J),
thereby
turning
on
0613.
0613
turns
on
approximately
2.3 seconds
aher
0607
turns
off.
Since
0613
turning
on
is
equivalent
to
depressing the
stop
button,
the deck enters the stop mode.
When the deck enters the stop mode,
current
on
path
CD
or
(?)
stops
flowing
and
C610
dis-
charges via R656 and the fast solenoid and via
R657 and the pinch roller solenoid (current
flows
in the
direction
opposite
to
®
).
r-------------r-----
+3
9"
r-----
------
I
f--
-,--~-
+ 13"
CD
@
r-
--.-----j
_____
)
FLASHING
CIRCUIT
FLASHING
CIRCUIT
CD@
"
656
FAST SOLENOID
C6
9 3
0
693
0695
T
L 6
91
A
REED SWITCH
S
693
---"'II
0607
+
R634
®
C609
:
@®
122
3-7.
MEMORY
CIRCUIT
See
Fig. 3-16.
Counter switch S696
is
linke d
to
the
counter
and
is
closed when the
counter
reads
between
"900"
and
"999".
a.
When the deck
is
in the rewind mode, a
re-
wind
mode signal
(H
level) is
output
from
pin
13
of
system
control
IC
U601.
b. Therefore, current flows
from
pin
13
of
U601
to
charge C507 via R502 and R518. Charging
takes place
slowly
because
of
the large charg-
ing time constant.
c.
The counter counts
down
as
the tape
is
re-
wound
and, when
it
reaches
"999",
S696
turns on.
d. When 5696 turns on, C507's charge
flows
to
the
base
of
0691
via S696 and R691,
turning
0691
on.
e.
If
the
MEMORY
switch
is
set
to
STOP when
0691
has
turned on, a stop signal
(L
level)
is
output
from
pin 2 (and
pin
4)
of
U601 and
the deck enters the stop mode.
f. Pin 4 (MEMO IN)
of
U601
has
the
function
that,
if
it
becomes L level when U601 is in
the rewind mode , the rewind mode
will
be released and the stop mode enabled. In the deck, this terminal
is
connected
to
the STOP
IN terminal.
g.
If
the
MEMORY
switch
is
set
to
OFF,
the col-
lector
of
0691
is
open and S696
is
on. The
tape
will
be
rewound
to
the end and, when
the tape-end detect
circuit
detects the tape
end, the deck
wi
II
enter the stop mode auto-
matically.
•
~
R601
r
C60l
I
I- STOP
R606
r
~
2
4
C606;;;
PLAY
IN
REW
13
OUT
U601
R502
0504
STOP
IN
MEMO
IN
r
C507
h.
If
the
MEMORY
switch
is
set
to
PLAY
when
0691
has
turned on, a reproduce mode signal
(L
level)
is
output
from
pin 1
of
U601 and
the deck enters the reproduce mode.
i. The stop mode
is
entered
automatically
when
the tape
has
been rewound
to
the end before
the
counter
reaches
"999",
whether
the
MEMORY
switch
is
set
to
STOP
or
to
PLAY
.
3-8. POWER SUPPLY
CIRCUITS 3-8-1 Main regulator See
Fig. 3-17.
Transistors
0517, 0519,
0520,
and zener diode
D512
are
the main components
of
the main
regulator. The
output
of
the
main regulator
is
supplied
to
the amplifiers and also used
as
a
reference voltage in the regulated
power
supplies
of
the
motor
and
control
circuits.
1)
Equilibrium
condition
a.
The secondary voltage
of
the power trans-
former
is
full-wave-rectified
by
rectifiers
D541 -
D544,
then smoothed by capacitor
C520.
b. When power is
not
supplied
to
the regulat-
ed
power
supplies,
0517,
0519,
and
0520
are
off. (0519
is
the
currentampllifierthat
controls
0517
by
amplifying
variations
of
weak
control
current
flowing
through
0520
described later. Here, the operation
of
0519
is
not
described.)
c.
When the
po~er
supply
to
the regulated
power supplies starts, the
base
current
of
0517
flows via path
CD
. Since
0520
is
still
off
at
this
time,
current
flowing
I
MEMORY
I
STOP
S691
OOFF
PLAY
069
1
Fig. 3-16
Memory
circuit
20
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