Teac A-7300RX User manual

2 track
MASTER
RECORDER
~A7300RX
Stereo Tape Deck with dbx System
edits
= TEAC CORPORATION
51031760 20
Poares
oS:

1.
GENERAL
DESCRIPTION
TEAC’S
A-7300RX
is
a
high
quality
stereo
tape
deck
representing
a
new
Generation
in
the
design
and
construction
of
recording
equipment.
It
contains
all
of
the
features
which
made
the
earlier
A-7300
a
highly
rated
open
reel
tape
deck.
In
addition
the
A-7300RX
has
built-in
dbx*
noise
re-
duction
circuitry
for
superior
live
recording
capability.
This
deck
includes
dbx
type
I
Noise
re-
duction
system,
MPX
filter,
CUE
system,
PITCH
CONT,
EDIT
function
system,
etc.
We
have
produced
the
new
A-7300RX,
to
provide
complete
flexibility
in
selection
of
recording
tapes
and
to
provide
state
of
the
art
quality
in
your
deck.
The
basic
design
of
the
A-7300RX
is
highly
similar
to
that
of
the
A-7300.
Therefore
much
of
the
information
in
this
Service
manual
may
be
applied
to
the
A-7300
also.
*
dbx
noise
reduction
system
made
under
license
from
dbx,
Incorporated.
The
word
dbx
and
the
dbx
symbol
are
trademarks
of
dbx,
Incorporated.
NOTE
1.
When
placing
an
order
for
parts,
please
refer
to
the
PARTS
LIST
which
is
printed
separately
from
this
manual.
:
2.
File
the
PARTS
LIST
manual
together
with
this
SERVICE
MANUAL,
Future
TECHNICAL
INFORMATION
sheets
should
also
be
kept
with
these.
3.
Section
numbers
and
Fig.
reference
numbers
are
not
directly
related.
TABLE OF CONTENTS
1.
GENERAL
DESCRIPTION
.............-
3
2.
SPECIFICATION
AND
SERVICE
DATA
.....
4—5
3.
TOOLS
FOR
TESTING
AND
MAINTENANCE
.
5
4.
PARTIAL
DIS-ASSEMBLY
..........-.--
6-9
5.
PARTS
LOCATION
..........0---0000-
10
6.
SERVICING
AND
MAINTENANCE
........
11
7.
HEAD
REPLACEMENT
AND
ALIGNMENT...
—
12
8.
MEASUREMENT
AND
ADJUSTMENT-
MECHANICAL
........00-00
0c
eee
eee
13-16
9.
BLOCK
AND
LEVEL
DIAGRAMS
.........
17
10.
MEASUREMENT
AND
ADJUSTMENT-
ELECTRICAL
ita
ogee
cece
wt
week
2
18-27
11.
TROUBLESHOOTING
.-.......--..----
28-29
12. DB CONVERSION TABLE AND TENSION/
TORQUE FORMULA .................- 30

2.
SPECIFICATIONS
AND
SERVICE
DATA
2-1
SPECIFICATIONS
Track System
Reel Size
Tape Speed
Inputs
(Level
and
Impedance)
Outputs
(Level
and
Impedance)
Playback
Equalization
Heads
Noise
Reduction
System
Motors
Bias Frequency
Power
Requirement
Dimensions
(WHD)
Weight
1/2-Track,
Two-channel
Stereo
or
mono
10-1/2"' and 7”
15
ips
(38
cm/sec)
and
7-1/2
ips
(19
cm/sec),
0.5%
Line:
Specified
Input
Level:
—8
dB
(308
mV)
/50k
ohms
Min.
Input
Level:
—18
dB(
97
mV)
MIC:
Specified
Input
Level:
—60
dB
(0.774
mV)
30k
ohms
Min.
Input
Level:
—70
dB
(0.244
mV)
Output
(SOURCE/TAPE):
Specified:
—8
dB
(308mV)
/10k
ohms
Maximum:
—2
dB
(615
mV)
Output
(ENCODER);
Specified:
8
dB
(308mV)
/50k
ohms
Headphones:
—24
dB
(49
mV)
/8
ohms
15
ips
(38
cm/sec):
NAB
(50
u
sec,
3180
p
sec)
7-1/2
ips
(19
cm/sec):
NAB
(50
y
sec,
3180
sec)
Three:
Erase,
Record
and
Playback
dbx
System
type
1
One
direct
Drive
DC
Servo
Capstan
Motor,
Two
Eddy
Current
Induction
Reel
Motors
100
kHz
(+5
kHz,
Push-Pull
oscillator)
100/117/220/240
VAC,
50/60
Hz,
83W
Transport:
470
x
455
x
300
mm
(18-1/2"
x
17-15/16"
x
11-13/16")
Amplifier:
470
x
205
x
310
mm
(18-1/2”
x
8-11/16"
x
12-1/4”")
Transport:
28
kg
(61-3/5
Ibs)
net
Amplifer:
13
kg
(28-3/5
lbs)
net
2-2
SERVICE
DATA
—MECHANICAL—
Tape
Speed
Deviation
and
Drift
Wow
and
Flutter
Pinch
Roller
Pressure
Reel
Torques
3,000 Hz +30 Hz, within 20 Hz
Playback: 0.05% (WRMS) at 15 ips
0.06% (WRMS) at 7-1/2 ips
Overall: 0.12% (RMS) at 15 ips
0.15% (RMS) at 7-1/2 ips
1.8 kg to 2.2 kg (4.0 to 4.8 Ibs)
TAKE UP TORQUE;
REEL SW TAKE-UP
LARGE | 530 to 570 gcm (7.4 to 8.0 oz-inch)
SMALL _ | 330 to 370 gcm (5.0 to 5.1 oz-inch)
BACK TENSION;
REEL SW BACK TENSION
LARGE | 430 to 470 g cm (6.0 to 6.6 0z-inch)
SMALL
|
280
to
320
g
cm
(3.9
to
4.6
oz-inch)
Con’t on next page

Fast Forward Torque
Fast
Forward/Rewind
Time
Brake
Torque
Pitch Control
Counter
Accuracy
2-3
SERVICE
DATA
—ELECTRICAL—
Frequency
Response
Signal-To-Noise
Ratio
Erase Efficiency
Crosstalk
Rejection
Stereo
Channel
Separation
Total
Harmonic
Distortion
1,900
g
cm
+100
g
cm
(26
oz-inch)
150
seconds
for
1,800
foot
tape
2,200
g
cm
+100g
cm
(31
oz-inch)
3,000
Hz
+5%
or
more
+1.5% at 15 ips play mode
Refer to Frequency Response Limits chart
Overall: 60 dB or higher with dbx,
48 dB or higher without dbx
65 dB or more at 1 kHz signal
(measured with input 10 dB higher than the specified Input
Level)
35 dB or more, adjacent track at 125 Hz
45 dB or more, channel to channel at 1 kHz
Overall: 0.8% with dbx at 1 kHz normal operating level
NOTE:
Service
Data
were
determined
using
TEAC
YTT
Series
Test
Tape.
Improvements
may
result
in
feature
or
specification
and
service
data
changes
without
notice.
3.
TOOLS
FOR
TESTING
AND
MAINTENANCE
A
minimum
of
the
following
tools
and
test
instruments
are
required
for
measuring
and
adjusting
to
obtain
optimum
performance.
Regular
maintenance
tools
will
be
adequate
for
those
not
listed
here.
If
any
test
instrument
listed
here
is
not
available,
a
close
equivalent
can
be
used.
WOW
AND
FLUTTER
METER........
AC
VTVM
..
0...
ee
cee
eee
ees
DIGITAL
FREQUENCY
COUNTER
....
BAND-PASS
FILTER
.........-.---
OSCILLOSCOPE
.........----005:
AF
OSCILLATOR
.........---++--
ATTENUATOR
....---
+--+
seer
eres
DISTORTION
ANALYZER
.........-.-
TOOLS
..
1
cee
ee
ee
ees
HEAD
DEMAGNETIZER
.........--
TEAC
TEST
TAPE
........----0555
TEAC
EMPTY
REEL
.......---.----
Meguro
Denpa
Sokki
K.K.,
Model
MK-668A
or
D
&
R
Co.,
Model
FL4B
Hewlett-Packard
Co.,
Model
400E
(0.1
mV
—
300
V)
Range;
10
Hz
—
100
kHz
1
kHz
narrow
band-pass
type
General
Purpose
10
Hz
—
100
kHz
General
Purpose
Basic
Freq.
400
Hz/1
kHz
Spring
scale;
O—-4
kg
(0-8
Ibs)
O—1
kg
(O—2.2
Ibs)
Hex
head
Allen
Wrench,
Plastic
alignment
tool,
Load
resistor
non-inductive
type
8
ohm/1
W
TEAC
E-3
or
equivalent
YTT-1003
(7-1/2
ips),
YTT-1004
(15
ips)
for
Playback
Alignment
test,
YTT-8013,
YTT-8003
and
YTT-8023
for
Recording
test,
YTT-2003
(7-1/2
ips),
YTT-2004
(15
ips)
for
Tape
Speed
and
Wow/
Flutter
test
RE-702
(2.5”
dia,
hub),
RE-701
(4”
dia,
hub)

4. PARTIAL DIS-ASSEMBLY
4-1 REMOVING TAPE TRANSPORT CASE, AMPLIFIER CASE AND CASE LEGS
TAPE TRANSPORT AMPLIFIER
See
illustration
for
complete
dis-assembly
instructions.
Fig.
4-1
Removing
Tape
transport
and
Case
legs
’
Fig.
4-2
Removing
Amplifier
and
Case
lgs

4-2
HEAD
HOUSING
BASE
AND
HEAD
ASS'Y
REMOVAL
HEAD
HOUSING
BASE
REMOVAL
5:
6.
1.
Remove
power
from
the
unit.
2.
Open
the
head
housing
(A).
3.
4.
Remove
head
housing
Link
ass’y
(C)
by
removing
4
Remove
Name
Plate
(B).
screws
(remove
with
spring
(D)
and
Anti-spoiler
(E).
Remove
head
housing
Base
(F)
by
removing
2
mounting
screws.
Gently
move
head
housing
base
(F)
toward
the
top
of
the deck.
HEAD
ASS’Y
REMOVAL
7.
8.
NOTE:
Remove
4
mounting
screws
from
the
head
assembly
(G)
and
remove
the
2
pin
jacks
and
the
9
pin
connector
mounted
on
the
rear
of
the
head
housing.
Lift off head assembly.
After
the
head
is
replaced
be
sure
to
replace
the
shield
case
and
tighten
the
2
counter-sunk
screws
on
the
rear
of
the
head
assembly
plate.
Also
insure
that
the
spring
(D)
on
the
head
housing
is
properly
set
in
the
slot
on
the
head
housing.
Fig. 4-3 Head Housing Base and Head ass’y Removal
4-3 REMOVAL OF REEL MOTORS
1.
2.
3.
Loosen
2
set
screws
(hex
head)
in
Reel
Turntable
ass’y
(A)
and
2
in
the
Brake
Drum
(C).
Lift
off
these
parts.
Disconnect
the
4
motor
wires
from
terminals
and
re-
lease
wire
harness
straps.
Remove 3 screws securing the Brake ass’y (D) to the mo-
tor.
NOTE: Use care not to bend the brake band or brake shap-
ing retainer during removal.
4. Remove 4 screws securing Reel motor (B) to chassis
through the front panel.
Fig. 4-4 Reel Motor Removal

44
REMOVAL
OF
TENSION
ARM
(RIGHT)
AND
DRIVE
ROLLER
ASS’Y
.
Remove
power
from
the
unit.
.
Remove
Tape
transport
Case
(See
step
4-1
on
page
6).
.
Loosen
1
set
screw
in
Drive
Roller
Pulley
(A).
_
Lift
off
the
Drive
Roller
ass’y
(B).
Watch
for
the
spacer.
_
Remove
4
screws
in
Tension
Arm
Ring
(C).
_
Lift
off
these
parts,
Tension
Arm
Ring
(C)
and
Tension
Arm (D).
Dunk wn
Fig. 4-5 Right Tension Arm and Drive Roller ass’'y Removal
4-5 REMOVAL OF TENSION ARM (LEFT)
1. Do steps 1 and 2 of Section 44.
2. Unscrew Cap (A) from front panel.
3. Remove 4 screws in Tension Arm ass’y (B). Lift off these
parts.
NOTE: When replacing Tension Arm ass’y be sure to posi-
tion tape guide section in the original position.
Fig. 4-6 Left Tension Arm Removal

4-6
REMOVAL
OF
PINCH
ROLLER
ASS’Y
AND
PINCH
ROLLER
ARM
1.
Do
steps
1
and
2
of
Section
4-4.
2.
Loosen
3
set
screws
in
Solenoid
Arm
(A).
3.
Lift
off
Pinch
Roller
Arm
(B)
from
front
panel
Watch
for the washers.
T-559
Fig.
4-7
Pinch
Roller
ass‘y
Removal
4-7 REMOVAL OF CAPSTAN MOTOR ASS’Y
1. Do steps 1 and 2 of Section 4-4.
2. Dis-connect Multi 11P Socket (B).
3. Remove 3 mounting screws on Motor ass’y.
4. Carefully lift off the Motor ass’y. (A).
Capstan shaft tolerance adj.
Refer to step 8-3 on page 14
for more detailed explanation
T -597
Fig. 4-8 Capstan Motor ass’y Removal

10
5. PARTS LOCATION
Power
Brake
Solenoid
R156
Transformer
7 4
‘e DLL
“Mm |
me Sees i :
‘ 4 Voltage Selector
and Frequency SW
Reel Motor
(Right)
Reel
Motor
(Left)
C155
Reel Motor
pee
Stablilizer
Unit
B
Solenoid
Power
Unit
Drive Unit
Stabilizer Unit
Capstan
Motor ass’y
Impedance
Roller
Drive Roller
Fig. 5-1 — Mechanical Section —
Fig. 5-2. — Amplifier Section —
Connections Location

6.
SERVICING
AND
MAINTENANCE
6-1
CLEANING
6-3
TEAC
MAINTENANCE
FLUIDS
TEAC
TZ-261A
and
TZ-261B
may
be
used
for
following
places.
TZ-261
CORUER
Ni
TZ-261B
TZ-261A
Pinch
roller
rubber
Counter
belt
Brake
drums
Heads
Capstan shaft
Tape run guides
6-2
LUBRICATION
A
a
: :
Fig.
6-2
TZ-261
Tape
Recorder
kit
Under
normal
operation,
lubriaction
is
required
only
once
each
year.
Operate
the
deck
for
30
minutes
to
1
hour
immediately
prior
to
oiling.
After
oiling,
keep
the
deck
in
the
upright
position
for
3
to
4
hours
to
allow
thorough
penetration
of
the
oil.
Approximately
once
each
year
or
after
2,000
hours
of
use,
apply
TEAC
TZ-255
Lubricating
Oil
to
the
following
places
only;
Pinch
roller
shaft
.-....---
1
drop
(Remove
cap)
Capstan
shaft...
---------
2
drops
(Remove
the
dust
cap
for
access
to
the
oil
pit)
NOTE:
Neither
the
reel
motors,
which
utilize
oilless
metal
bearings,
nor
the
direct
drive
DC
capstan
motor
require
oiling.
Therefore,
no
oiling
access
tubes
are
provided.
Excessive
oiling
will
scatter
oil
inside
the
deck.
Check
for
slippage
and
clean
all
parts
inside
the
deck
before
operating
after
lublication.
Check
for
oil
emission
after
operation
and
before
returning
6-4
DEMAGNETIZATION
OF
HEADS
deck
to
the
customer.
Fig. 6-3 TZ-225 Oil kit
If
the
record
or
Playback
heads
becomes
magnetized,
noise
will
increase
and
tonal
fidelity
will
deteriorate
For
this
(GD)
reason
it
is
advisable
to
use
non-magnetic
tools
when
work-
ing
near
the
heads.
If
the
heads
heve
had
any
con
tact
with
current
or
magnetized
metal
parts,
demagnetize
them
with
4
a
TEAC
E-3
eraser
or
Equivalent.
Fig.
6-1
Capstan
Shaft
and
Pinch
Roller
Shaft
Oiling
Points
Fig.
6-4
TEAC
E-3

7. HEAD REPLACEMENT AND ALIGNMENT
—MECHANICAL—
7-1
HEAD
REPLACEMENT
1.
Remove
head
housing
and
head
ass’y.
Refer
to
section
4-2
on
page
7.
2. Loosen 2 counter-sunk screws (A) from the rear plate of
the
head
assembly
and
remove
2
small
screws
(B)
from
the
top
of
the
head.
Then
slide
off
the
shield
case
(C).
3.
To
replace
a
single
head,
a
nut
driver
is
required.
Re-
move
the
2
nuts
(D)
on
the
defective
head
through
the
access
hole
provided.
This
releases
the
head
from
the
mounting
plate.
ue
Plate
Fig. 7-1 Head Replacement (Playback)
7-2 HEAD ADJ. SCREWS AND ALIGNMENT
T-362-1
@ : Azimuth adj. screws
© : Height and Tilt adj. screws
©: Tangeney adj. Nuts
Fig. 7-2 Head Adjustment Screws and Alignment
12
7-3, VISUAL HEAD ALIGNMENT
Since the propriety of head alignment affects the frequency
response on both playback and recording, the head align-
ment should be done carefully. The head can be adjusted in
TILT, TANGENCY , HEIGHT and AZIMUTH.
For head alignment, perform the following coarse adjust-
ments first. Then fine alignment should be accomplished
electrically while playing back the Test Tape.
Coarse Adjustment:
Without Tape
TPs start es By Height and tilt screws
This alignment is performed by viewing from
the side without tape threaded.
Check that the head surface is parallel to the
tape guide surface.
With Tape
TANGENCY ... By Head mounting Nuts
Loosen the head mounting nuts. Adjust the
head so that the vertical alignment of the head
gap is perpendicular to the surface of the tape,
then tighten the head mounting Nuts.
HEIGHT ....... By Height and Tilt screws
This alignment is checked visually by looking
at the position of the head.
The head core for track-1 (inner core) should
be even with the inner edge of the tape.
AZIMUTH ...... By Azimuth adj. Screw
Adjust the azimuth adj. screw so that the gap
of the head is perpendicular to the tape travel.
NOTE: After this coarse adjustment is made, the adj.
screws and the Head mounting nuts should be
realigned according to electrical head alignment
paragraph which follows in this Service Manual.
7-4 MIS-ALIGNMENT OF THE HEADS
TILT HEIGHT
(view from side of head)
(view from front of head)
Adjust by @ Screws
Adjust by @ Screws
[2] TANGENCY
(view from top of head)
AZIMUTH
view from front of head}
i
7 (3)
Adjust by @ Nuts Adjust by @ Screws
Teo
Fig. 7-3. Head Mis-Alignment —Examples—

8. MEASUREMENT AND ADJUSTMENT
—MECHANICAL—
These
adjustments
should
be
performed
by
experienced
technicians,
and
then
only
when
going
through
the
complete
test
and
check
procedures
on
the
unit
which
is
being
tested.
The
TEAC
A-7300RX
uses
highly
reliable
AC
Motors
for
both
reel
motors,
and
a
DC
direct-drive
capstan
system.
It
should
require
a
minimum
of
mechanical
maintenance
or
adjustment.
These
adjustments
are
made
at
the
factory.
Readjustments
should
only
be
required
after
long
periods
of
operation
or
component
replacement.
The
following
procedures
are
primarily
performance
checks.
Before
performing
these
checks
a
|
complete
cleaning,
demagnetization
and
lubrication
should
be
accomplished
as
outlined
in
the
preventive
maintenance
section
of
this
manual.
See
page
11.
8-1
CHANGING
THE
POWER
LINE
SETTING
Disconnect
the
deck
from
ELECTRICAL
Power.
Voltage Selection:
1.
Remove
the
outer
case
of
the
Transport
Unit.
2.
Locate
the
voltage
selector
plug
shown
in
Fig.
8-1.
3.
Pull
out
the
plug
and
reinsert
it
so
that
the
desired
volt-
age
appears
in
the
cut-out
window
of
the
plug.
4.
Only
the
voltages
indicated
on
the
selector
plug
socket
can
be
selected
with
the
selector
plug.
If
you
desire
to
use
your
deck
connected
to
a
voltage
that
is
not
indi-
cated
on
the
plug
socket,
please
contact
your
TEAC
authorized
service
center
or
TEAC
dealer.
Frequency
Conversion:
To
change
the
selected
power
line
frequency,
just
set
the
slide
switch
pictured
in
Fig.
8-1
to
the
50
or
60
Hz
position
as
desired.
Remove
the
outer
case
of
the
trasport
Unit
for
access
to
the
slide
switch.
Fig. 8-1 Power Line Setting Location
8-2 ADJUSTMENT OF D.C.
(on STABILIZER UNIT)
NOTE:
To
prevent
damage
to
the
motor
and
control
circuitry:
|.
Remove
terminal
Block
A
from
the
Control
PC
board.
See
Fig.
8-2.
2.
Disconnect
the
11
pin
connector
from
the
motor.
See
Fig.
8-4.
Adjustment procedure:
1. Place the Power switch to ON.
2.
Connect
a
Voltmeter
or
VIVM
across
the
24
V
Test
Point.
3.
Adjust
VR-21
if
needed
to
obtain
24
V
+0.5
V
DC.
4.
Adjust
VR-22
for
5
V
+0.25
V
at
output
Test
Point
(Pink
Lead
Socket).
Terminal block A
eeevnnreeavenn
is Fb aibcaprant le yee
Fig. 8-2. Terminal Block A Location
Fig. 8-3. Adjustment Location
Capstan motor
Pink Lead Socket fur 5V
11P Conne tor
Connector
Block Red Lead Socket fo. 24V
Fig. 8-4 Test Points
13

8-3
CAPSTAN
SHAFT
TOLERANCE
ADJUSTMENT
Check
that
the
capstan
motor
moves
freely
without
binding
on
the
Thrustplate.
2.
Check
that
the
clearance
between
the
motor
shaft
tip
and
the
Thrustplate
is
between
0.1
and
0.3
millimeter.
3.
To
adjust,
first
loosen
the
locking
nut;
then
set
with
a
common
screwdriver
for
approx.
0.2mm
clearance.
Check
by
observing
the
capstan
movment.
.
Tighten
the
Lock
Nut
and
secure
with
locking
paint.
—
a
Shaft
a a
Tolerance
.1~
0.3mm
Son
Nut
="
@
+ Adjustment
Screw
for Capstan
Shaft
Fig. 8-5 Shaft Tolerance Adj. Location
8-4
TAPE
SPEED
ADJUSTMENT
Place
the
PITCH
CONT
to
the
OFF
position.
The
tape
speed
should
be
measured
using
TEAC
flutter
free
tape,
Model
YTT-2004
(15
ips),
YTT-2003
(7-1/2
ips).
These
tapes
contain
a
highly
accurate
3,000
Hz
tone.
Con-
nect
a
digital
frequency
counter
to
either
line
OUTPUT
jack.
See
Fig.
8-7.
The
indicated
frequency
should
be
3,000
Hz
(+10
Hz
or
less)
for
both
speeds.
If
necessary,
adjust
Tape
Speed
adjusters
on
the
CAPSTAN
MOTOR.
See
Fig.
8-6.
+ Increase
©
LOW 7-1/2 ips ,~
~ @ (®)
Fig. 8-6 Tape Speed Adjustments
Lock Nut
14
8-6 WOW AND FLUTTER CHECK
NOTE: Before performing this measurement, clean the
head and Tape run guides, also check pinch roller
pressure, etc. .
Use new Test Tape if possible for following adjus-
ments.
Values obtained with different standards of equip- -
ment cannot be compared.
PLAYBACK
1. Connect Test equipment to the unit as shown Fig. 8-7.
(Except oscillator).
2. Load TEAC YTT-2004 (for HIGH, 15 ips) or YTT-2003
for LOW, 7-1/2 ips) and playback tape.
3. Read the indication on the Wow and Flutter meter.
4. The Wow and Flutter should be
0.05% or less for 15 ips (WRMS)
0.06% or less for 7-1/2 ips (WRMS)
OVERALL
1. Connect Test equipment to the unit as shown in Fig. 8-7.
2. Load TEAC YTT-8003 (blank tape) Test Tape on the
unit and Record a 3000 Hz input signal.
3. Rewind and playback the recorded signal.
4. The reading on the Meter should be
0.12% or less for 15 ips (RMS)
0.15% or less for 7-1/2 ips (RMS)
NOTE: These figures apply to any tape position (such as
full take-up reel, full supply reel or about mid-
point). Also examine the tape counter ass’y for
evenness of operation.
FREQUENCY COUNTER
OSCILLATOR
DECK wow 8 FLUTTER METER
under TEST
LINE IN
ft)
T-aas
Fig. 8-7 Test Connections for Wow/Flutter and
Tape Speed Test

8-7
PINCH
ROLLER
PRESSURE
NOTE:
Pinch
roller
pressure
is
supplied
by
the
pinch
roller
solenoid
arm
and
it
is
most
important
that
the
solenoid
plungers
be
fully
bottomed
before
taking
pressure
measurement.
—
.
Load
tape
or
block
the
shut-off
arm
in
the
“ON”
posi-
tion.
Remove
the
Pinch
Roller
Cap.
2.
Attach
a
suitable
spring
scale
to
a
screw
inserted
in
the
pinch
roller
shaft.
3.
Place
the
unit
in
the
PLAY
mode,
and
holding
the
spring
scale
as
illustrated,
slowly
draw
it
away
from
the
pinch
roller.
(Do
not
allow
the
string
to
rub
against
the
pinch
roller.)
4.
Note
the
reading
on
the
spring
scale
at
the
instant
the
pinch
roller
stops
rotating.
.
The
scale
should
indicate
2
kg
+0.2
kg
(4.4
Ibs
+0.4
Ibs)
_
If
adjustment
is
necessary,
loosen
the
3
mounting
screws
on
the
capstan
solenoid
and
position
the
solenoid
for
optimum
pressure.
screw
M312
ai Shaft
Fig. 8-8 Pressure Measurement
nw”
Decrease
2
Increas
Adjustment
™ 3 Screws
Fig. 8-9 Adjustment Location
8-8 BRAKE TORQUE
The brake torque is actuated mechanically. Pressure is set
by the Leaf spring force. While making these measurements
and adjustments, be careful not to bend the brake bands.
As brake torque will change with cleaning, brake drums and
brake shoes should be cleaned only when absolutely neces-
sary. If cleaning is required, use TEAC cleaner TZ-261B.
After cleaning, operate the brakes by depressing the play
and STOP buttons several times to completely dry out the
brakes before performing the following procedure.
NOTE: Brake adjustments are made with NO power con-
nected to the equipment.
1. Place an empty large hub reel on the left reel table, and
fasten one end of a 30” length of string to the reel
anchor.
2. Wind several turns of string counterclockwise around the
hub and attach a suitable spring scale to the free end of
the string.
. Pull on the spring scale until the reel begins rotating.
. Take a reading only when the reel is in steady motion
since the force required to overcome static friction will
produce a false, excessively high initial reading .
5. The calculated valve should be 2,300 to 2,100 g-cm (29
to 32 oz-inch).
. If adjustment is required, loosen the 2 screws shown and
position the brake for optimum torque.
7. The adjustment of the right brake is the same, with the
exception that rotations are clockwise.
(wind string CLOCKWISE around reel hub)
8. See note at the top of page 16 for explanation of torque
measurements.
pW
lox
ADJUSTMENT SCREWS
Fig. 8-10 Brake Torque Measurement and AdjL ocation
15

Seo
TORQUE MEASUREMENT PROCEDURE
“oe
a
a
RAINS
STENT
ET
I
IIE
CE
ETRE
s
NOTE:
The
following
torque
measurements
should
be
made
with
a
spring
scale
that
is
calibrated
to
read
Torque
in
gram-cm.
for
a
7”
reel
with
a
small
reel
hub.
If
the
spring
scale
you
are
using
is
calibrated
.
to
read
Force
or
Weight
in
grams
the
Torque
must
be
calculated
using
the
Foumula:
Torque (in gm-*cm or oz*in) =
Weight or Force (in gr. or 02.) x
radius of hub (in cm or inches)
"If
you
are
using
a
reel
with
other
than
the
standard
2.5”
or
-
6.0
cm
(approx.)
diameter
hub,
the
Torque
must
be
calcu-
lated
using
the
same
formula
and
substituting
the
actual
radius
and
Weight
or
Force
reading.
All
Torque
and
Tension
measurements
must
be
made
with
-
the
automatic
shut-off
switch
(right
tension
arm)
held
in
the
ON
position.
Brake
Torque
Measurement
should
be
made
using
large
hub
-
reel
with
a
hub
diameter
of
4”
or
10.2
cm.
REO
so
\
> takeve ToROUEFWO)
628
sy
rane
ES
WENT
AE
GS
OER
RN
I
AS
SO
Ea
Fig.
8-11
Torque/Tension
Measurement
and
Formula
8-9
TAKE-UP
TORQUE
1.
Place
the
empty
reel
and
attach
spring
scale
on
the
right
reel table.
2.
Place
the
unit
in
the
Play
mode.
3.
Allow
the
rotation
of
the
reel
to
slowly
draw
the
scale
toward the hub.
4,
Hold
the
spring
scale
with
enough
force
to
allow
a
steady
reading.
5.
The
torque
reading
should
be
approx.:
REEL
SW
TAKE-UP
LARGE.
|
530
to
570
g
cm
(7.4
to
8.0
oz-inch)
SMALL
|
330
to
370
g
cm
(5.0
to
5.1
oz-inch)
16
8-10 BACK TENSION
1. Place an empty 7” reel with small hub on the left reel
table, and fasten one end of a 30” length of string to the
reel anchor.
2. Wind several turns string counter-clockwise around the
hub. Attach spring scale to string.
. Place the unit in the Play mode.
4. Pull the scale away from the reel against the motor tor-
que with a steady, smooth motion.
5. Note the scale reading while it is in steady motion.
(The string must not rub the reel flanges)
6. The calculated valve should be approx.:
REEL SW BACK TENSION
LARGE | 430 to 470 g cm (6.0 to 6.6 0z-inch)
SMALL j 280 to 320 g cm (3.9 to 4.6 oz-inch)
Ww
Adjustment Location
If necessary, adjust slider of the resistors until you have the
correct scale reading for optimum torque. Refer to adj.
location below.
‘ Loosen
, _ this
screw
{ to Adjust
Decree = = A
Adjust
R154... TAKE-UP TORQUE LARGE or SMALL
R155... BACK TENSION LARGE or SMALL
Fig. 8-12 Wire Wound Resistors Adj. Location
8-11 FAST FORWARD AND
REWIND TORQUE CHECK
Specification;
F.F/ REW (LARGE) _ 1.9 kg cm (27 oz-inch)
F.F/ REW (SMALL) _ 1.6 kg cm (22 02-inch)
No adjustment provided.FIXED Resistor (R156)

9.
BLOCK
AND
LEVEL
DIAGRAMS
9-1
BLOCK
DIAGRAM
rc. 74 7
puaraack!
PLAY
EQ
AMPL
:
{>
Oo
oo
ie
"T]
cE
DER U
Td
vec
1
BIAS OSC UNITT
1.
REF. NOs.
shown
in
the
diagram
relate
t
a t
he Left channel. to +8 (42v)
only
to
t
>—1
STABILIZER
UNIT
1
1
H
>
+282
(24v)
a !
1
1
=
bP Vee (+15V)
'
>—ASTABILIZER
UNIT
(B)
|
vee
-isvy
L---——---—--=-
Fig. 9-1 Block Diagram
— 808 (10k 1.)
-10
-20
[PHONE]
a —24dB/81.
30!
-40
,
at
ape
. OUTPUT control is positioned at specified
-50
output
Level.
2. Each level given in the diagram shows values
-60
55
HEAD
during
playback
with
YTT-1004(400
Hz/O
dB)
= Test Tape.
3. 0 dB =0.775V
Fig. 9-2 Level Diagram — Playback
+10
——
COUTEU
(LINE_IN}
ENCODE
ao
8
REC HEA
. Record control is positioned at specified
Input level.
0 dB = 0.775 V meth
. Each level given in the diagram shows values
when 400 Hz Specified Input level is applied.
wr
Fig. 9-3 Level Diagram —Record—
17

10. MEASUREMENT AND ADJUSTMENT
—ELECTRICAL—
10-1 ADJUSTMENT LOCATIONS AND ADJUSTMENT POINTS
RECORD
TRIMMER
RESISTORS
S
STABI-
RECORD
MICL
MICR
LINE
ul
:
LEFT CHANNEL
L
Co
mM
=||®)
>
N
318)
a
>
a
ENCODER R M1 VR8I4 DECODER R
Adj. Component Adj. Component BIAS/EQ SW
VR-251/252 Playback Level Bias Le
VR-301/302 VU Meter (P. B) VR-709/710 Record Level
VR-203/204 Playback EQ (HIGH) Rec EQ (HIGH)
VR-201/202 Playback EQ (LOW) VR-501 (both ch) | Rec EQ (LOW #1
VR-401/402 Monitor Level
VR-707/708 VU Meter (monitor)
L-503/504 Bias Trap
L-251/252 Bias Leakage
L-552 Dummy Coil] Rec Mono (L or R)
VR-814/814 Encoder Level
VR-624/624 Decoder Level
Fig. 10-1 Ampli PC Board Location and Adjustment Points
10-2 ADJUSTMENT SEQUENCE CHART
PLAYBACK HEAD
PREPARATION || AZIMUTELADI.
-—— PLAYBACK PERFORMANCE —
SPECIFIED OUTPUT VU METER FREQUENCY |_| PHONES OUTPUT
LEVEL SETTING LEVEL SET | | RESPONSE CHECK
-—— MONITOR PERFORMANCE —
MIC INPUT VU METER SPECIFIED LINE MONITOR LEVEL
LEVEL CHECK LEVEL CHECK CONTROLS SETTING SETTING
RECORD HEAD MONOPHONC
AZIMUTH ADJ. RECORDING
— RECORD PERFORMANCE —
BIAS TRAP BIAS LEAKAGE BIAS RECORD FREQUENCY
ADJUSTMENT CHECK ADJUSTMENT LEVEL SET RESPONSE
dbx
DISTORTION
SIGNAL-TO-NOISE
CHANNEL
OPTIMUM
ERASURE
PERFORMANCE CHECK RATIO SEPARATION MEASUREMENT
Fig. 10-2 Adjustment Sequence Chart
SIGNAL-TOWOISE
RATIO CHCK

—_————.__ PLAYBACK PERFORMANCE
10-3
PREPARATION
All
the
following
(except
dbx
performance
adj.)
checks
and
adjustments
must
be
performed
with
the
switches
of
the
A-7300RX
set
as
outlined
below
unless
otherwise
specified
in
procedure.
MPX
SW
.....-
ee
eee
ee
eee
OUT
ENCODE
SW...
.
+--+
eee
ee
eee
OUT
DECODE-COPY
SW
..........
OUT
SOURCE
MONITOR
SW
...
NORMAL
METERSW....--------
NORMAL
Input
Selector
SW
Double
designated
symbol
numbers
refer
to
left
channel/
right
channel.
Fig.
10-4
Switches
Location-2
OSCILLOSCOPE
Fig. 10-3 Switches Location-1
10-4
PLAYBACK
HEAD
AZIMUTH
ADJ.
unger
TEST
NOTE:
Before
proceeding
with
the
following
head
align-
aay
eae
ments
be
sure
that
heads
have
been
properly
mounted
as
to
height,
tilt
and
tangency
(review
Fig.
10-5
Head
Alignment
Fine
Adjustment
Setup
and
page
12).
test
connections
(PLAYBACK)
-—FINE
ADJUSTMENT—
Tape
SPEED
SW
.
.
.
.
LOW
(7-1/2
ips)
MONITOR
SW..........-.-
TAPE
1.
Connect
a
VIVM
to
either
OUTPUT
SOURCE/TAPE
jack.
.
Open
the
head
housing.
.
Thread
the
TEAC
YTT-1003
Test
Tape
on
the
unit.
.
Play
the
16
kHz/—10dB
Test
Tone
in
section
2
of
the
Test
Tape.
5.
Slowly
rotate
the
azimuth
screw
(on
Playback
head)
until
maximum
indication
is
achieved
on
VITVM.
6.
Connect
an
oscilloscope
to
the
OUTPUT
SOURCE/
:
TAPE
jacks
as
shown
in
Fig.
10-5.
:
7.
Play
the
YTT-1003
tape
and
adjust
the
azimuth
screw
(If
necessary)
until
the
oscilloscope
shown
that
the
sig-
nals
are
less
than
45°
out
of
phase.
Check
at
40
Hz
to
18
kHz
signal.
8.
Secure
this
screw
with
a
drop
of
Locking
Paint.
AWN
19
simatic a

10-5
SPECIFIED
OUTPUT
LEVEL
AND
MAX.
OUTPUT
LEVEL
SETTINGS
SPECIFIED
OUTPUT
LEVEL:
9.
10.
ll.
Play
the
400
Hz/0
dB
tone
in
section
1
of
test
tape.
Set
the
reference
marks
of
the
OUTPUT
controls
to
the
8
(0
VU)
position.
Adjust
VR-251/252
(on
PLAY
LINE
AMPL.
UNIT)
for
—8
dB
(308
mV)
at
OUTPUT
SOURCE/TAPE
jacks.
MAX.
OUTPUT
LEVEL:
12.
Turn
the
OUTPUT
controls
fully
clockwise
(max.)
and
check
for
—2
dB
(612
mV)
at
OUTPUT
jacks.
13.
Reduce
OUTPUT
controls
until
—8 dB
(308
mV)
is
obtained
on
the
output
VTVM.
NOTE:
This
is
the
Specified
Output
level
setting
.
Do
not
disturb
this
setting
until
the
remaining
adjustments
have
been
completed.
OUTPUT
Fig. 10-6 Specified output controls setting
10-6
VU
METER
LEVEL
SET
14,
Adjust
VR-301/302
(on
METER
PHONE
AMPL.
UNIT)
for
0
VU
reading
on
VU
Meters.
15.
With
METER
SW
in
HIGH,
check
for
-3
VU
+0.5
VU
20
reading
at
upper
scale
on
the
Lower
Scale.
(OVU
£0.5VU
reading
at
upper
scale).
10-7
FREQUENCY
RESPONSE
—PLAYBACK—
—
Tape
SPEED
SW.....
HIGH
(15
ips)
.
Thread
TEAC
Test
Tape
YTT-1004
on
the
unit.
2.
Play
Tape
and
compare
readings
on
VTVM
with
the
re-
oe
sponse limits given in Fig. 10-7.
.
If
adjustment
is
required,
adjust
VR-203/204
(on
PLAY
EQ
AMPL.
UNIT)
for
HIGH
speed.
.
Change
Tape
SPEED
SW
to
LOW
(7-1/2
ips)
position.
.
Thread
a
Test
Tape
YTT-1003
on
the
unit.
. Repeat Step 2.
.
If
adjustment
is
required,
adjust
VR-201/202
(on
PLAY
EQ AMPL. UNIT) for LOW speed.
NOTE:
If
the
frequency
response
does
not
meet
specified
response limits, especially at the high-end of the
spectrum, head should be checked for accumulated
dirt or oxides. If clean, head azimuth must be re-
adjusted.
RESPONSE IN d8
RESPONSE IN 48
1
FREQUENCY IN Hz
= oa TT r
| +- j_} 4-44-44 a
| ‘Low (7-1/2ips)
tity
a
tH
Litt |
a |
=
-
oF
50 00 BK WK 20K ‘SOK
300 1K
FREQUENCY IN Hz
Fig. 10-7 Frequency Response —PLAYBACK —
10-8 PHONES OUTPUT CHECK
1. Connect an 8 ohm non-inductive resistor across the head-
phone (PHONES) jack.
2. Connect VTVM across the resistor, VTYM should indi-
cate —17 dB +1 dB (122 mV—97 mV).
10-9 SIGNAL-TO-NOISE RATIO
—PLAYBACK—
. OUTPUT controls should be at the Sjecified Output,
Level settings.
. Thread a blank YTT-8003 on the unit kaving the tape
outside the capstan and pinch roller.
. Hold the play supply reel stationary and te press the play
(=) button.
. The VIVM connected to the OUTPUT acks should in-
dicate readings listed below.
LOW (7-1/2 ips)
HIGH (15 ips)

_——
_
MONITOR
PERFORMANCE
—-?-HH——
10-10
MONITOR
LEVEL
SETTING
MONITOR
SW
.........
SOURCE
Input
selector
SW
.........
LINE
1.
Apply
a
400
Hz
—18
dB
(97
mV)
signal
from
AF
oscil-
lator
to
LINE
IN
(L-A/R-A)
jacks.
2.
Turn
REC
MASTER
controls
and
LEFT
A,
RIGHT
A
controls
fully
clockwise.
3.
Adjust
V&-401
(L-A
and
R-A
both)
and
VR-402
(L-B
and
R-B
both
)
for
—8
dB
(308
mV)
at
the
OUTPUT
SOURCE/TAPE
jacks.
NOTE:
Adjuster
VR-401/402
is
located
on
MIC
MIXING
AMPL.
UNIT.
OSCILLOSCOPE
RI °
SOURCE/ TAPE
1-390-1
Fig. 10-8 Test Connections for Monitor Check
10-11 SPECIFIED LINE CONTROLS SETTING
4.
Apply
a
400
Hz
signal
at
—8
dB
(308
mV)
to
the
LINE
IN jacks.
5. Adjust LINE controls (LEFT A/RIGHT A) for —8 dB
(308 mV) at OUTPUT SOURCE/TAPE jacks.
NOTE:
At
this
point
both
the
Line
controls
(LEFT
A/
RIGHT
A)
and
the
OUTPUT
controls
are
at
the
“Specified
setting”.
Do
not
move
these
controls
unless
instructed
in this
procedure
to
do
so.
The
accuracy
of
many
of
the
following
adjustments
and
readings
depends
on
these
controls
being
at
the
“Specified
setting”.
6.
Repeat
the
procedure
for
the
LEFT
B/RIGHT
B
side.
10-12
VU
METER
LEVEL
SET
7.
Check
VU
meters
for
0
VU
indication.
_
8.
Adjust
VR-707/708
(on
TRIMMER
RESISTORS
UNIT)
for
O
VU,
if
necessary.
10-13 MIC INPUT LEVEL CHECK
This is a check only. No adjustments are to be made.
—
WwW
Input SelectorSW.......... MIC
MIC
ATT
SW
..
0
dB
(on
Back
panel)
. Apply a 400 Hz signal at —48 dB (3.08 mV) to the MIC
IN Jacks (L-A/R-A).
. Check for —8 dB +1 dB (345 mV—274 mV) level at
OUTPUT SOURCE/TAPE jacks.
. Place MIC ATT (dB) SW to 20 GB position.
. Apply a 400 Hz signal at —8 dB (30.8 mV) level to the
MIC IN jack.
. Check for —8 dB +2 dB (388 mV —244 mV) level at
OUTPUT SOURCE/TAPE jacks.
. Repeat the procedure for L-B/R-B side.
Fig. 10-9 Mic Att switches location — REAR VIEW —
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