Teac A-300 User manual

Stereo
Cassette
Deck
with
Dolby
System
NOTE
If
any
of
the
adjustments
or
repairs
seem
too
compli-
cated
or
are
difficult
to
accomplish,
please
contact
the
nearest
TEAC
Factory
Service
Department
or
write
directly
to
a
TEAC
office,
the
addresses
of
which
are
printed
on
the
back
cover
of
this
manual.
When
ordering
replacement
parts,
please
refer
to
the
PARTS
LIST
which
is
printed
separately
from
this
manual
and
included
as
an
insert.
TEAC
CORPORATION
51032580

TABLE OF CONTENTS
1. Test Equipment Required ............. 2 5, Mechanical Checks and Adjustments ...... 9
5-1. Take-up & Supply Torque ...........-. 9
2. Specifications & Service Data ........... 3 5-2. Fast Forward & Rewind Torque ......... 9
5-3. Pinch Roller Pressure... 2... 2. ee eee 9
TEAC Test Tape... 0... eee ee 3 5-4, Tape Speed/Wow and Flutter ........... 10
3. Parts Location .......... 0002-00000. 5 6. Electrical Chekcs and Adjustments........ 11
6-1. Playback Performance .............04. 11
4, Itlustrated disassembly procedures ........ 6 6-2. Monitor Performance .............-5- 13
4.1, External Parts 2.2.0... .0...0c..0.00000- 6 6-3. Recording Performance .............-. 14
4.2. Cassette Damper (Damper Cord Stringing)... 6 6-4, Adjustment Location ..............0- 20
4.3, Cassette Holder Ass’y .............0.. 6
4.4, Heads and pinch rollers ............... 7 7. Block Diagram ...... in deft ae at aes Ste tagey on 21
4.5, Reel Tablesi a cescc.e onc oa tho ee aeceeacre 7
4-6. Brake Plate Ass’y ............200000. 7 8. Eevel Diagram 2.440 eck os ee obese Oakes 21
4-7. MOtobs ax 42d tiled ge 884 see Fons 8
4-8, Capstan Drive Assy .............000. 8 9. Voltage and Frequency Setting .......... 23
4-9, Lubrication vc ..cg shee eiaiee sy oP RSS 8
4-10, Ilder/Tension Pulley Ass’y ............. 8
* Noise reduction circuit made under license from Dolby
Laboratories Inc. The word “Dolby” and the Double-D
symbol are trademarks of Dolby Laboratories Inc.
1. TEST EQUIPMENT REQUIRED
1. Cassette Torque Meter: For take-up check: 0 ~ 100 g-cm (0 ~ 1.4 02-inch)
For fast forward & rewind torque checks: 0 ~ 160 g-cm (0 ~ 2.2 02-inch) |
NOTE: When ordering Cassette Torque Meter, allow for longer delivery time that is required for it.
2. Spring scale: For Pinch Roller pressure check: 0 ~ 500 g (1.1 Ibs)
3. Wow/flutter meter: MEGURO DENPA SOKKI K.K., Model MK-668A :
4, Frequency counter: Digital type, capable of 10 Hz to 100 kHz indication. fore
5. AF oscillator: 10 Hz ~ 100 kHz
6. AC Voltmeter: 0.1 mV ~ 300V
7. Attenuator: General Purpose
8. Distortion analyzer: Basic frequency 400 Hz/1 kHz
9. Oscilloscope: General Purpose
10. Band-pass filter: 1 kHz narrow band-pass type
11. Test load resistor: Non inductive type 8 ohm/1 W
12. Plastic alignment tool:
13. Head demagnetizer: TEAC E-3 or equivalent 5
14. Cleaner: TEAC TZ-261 Tape Recorder Cleaner kit or pure alcohol §
15. Oil: TEAC TZ-255 Oil kit or equivalent
Fig. 1-1 Plastic Alignment Too!

2.
SPECIFICATIONS
&
SERVICE
DATA
SPECIFICATIONS
———____—CO
TTT
Track System
3 Heads
Type of Tape
Tape Speed
Inputs
(level and impedance)
Outputs
(level and load impedance)
Equalization
Head Configuration
Motor
Bias Frequency
Operating Position
Power Requirements
Power Consumption
Weight
* Pursuant to DIN Standards
TEAC TEST TAPE
REMARKS:
0
dB
=
DIN
Reference
level
(333
Hz)
For
tape
speed
&
wow/flutter
test
MTT-111:
For
Playback
method
3,000
Hz/—10
dB
NOTE:
The
TEAC
test
tapes
require
longer
delivery
time
MTT-501:
For
record/Playback
method
(blank
tape):
than
normal
parts.
MTT-150:
For
Dolby
level
calibration
Dolby
B-type
tone
(400
Hz
tone),
200
nWb/m
MTT-316:
For
frequency
response
test
for
EQ:
CrO2
3,180 us + 70 ys
315
Hz/—4
dB,
31.5
Hz
~
14
kHz/—24
dB
MTT-216:
For
frequency
response
test
for
EQ: NORMAL
3,180 ps + 120 us
315
Hz/—4
dB,
31.5
Hz
~
14
kHz/—24
dB
4-track, 2-channel stereo
Erase, Record and Playback
Cassette
tape,
C-60
and
C-90
(Philips
type)
4.8 cm/s (1-7/8 ips)
MIC:
Specified
input
level:
—57
dB
(1.09
mV)/10
kohms
Min.
input
level:
—67
dB
(346
uV)
LINE
IN:
Specified
input
level:
—9
dB
(275
mV)/50
kohms
Min.
input
level:
—19
dB
(86.9
mV)
DIN
IN*:
Min.
input
level:
—35
dB
(13.8
mV)
OUTPUT:
Max.
output
level:
—2.5
dB
(580
mV)/SO
kohms
Specified
output
level:
—5
dB
(436
mV)
Headphones:
Specified
output
level:
—21
dB
(69
mV)/8
ohms
CrO2: 3180 us + 70 us
NORMAL: 3180 us + 120 us
1/2-track, 1-channe] Erase Head
1/4-track,
2-channel
Dual-gap
Record
and
Playback
Heads
FG Servo Controlled DC Motor
100 kHz
Horizontal
100/117/220/240
V
AC,
50/60
Hz
(General
Export
Models)
117
V
AC,
60
Hz
(U.S.A./Canada
Models)
220 V AC, 50 Hz (Europe Model)
240
V
AC,
50
Hz
(U.K./Australia
Models)
12W (U.S.A. Model)
11W (All except U.S.A. Model)
7.5 kg (16.5 Ibs) net
7.8
kg
(17.2
Ibs)
net
(General
Export
Models
for
Limited
Area)
For
playback
performance
alignment
For
record
performance
alignment
(blank
tape)
MTT-506
or
equivalent:
For
BIAS
&
EQ:
CrO2
MTT-501
or
equivalent:
For
BIAS
&
EQ:
NORMAL
Fig. 2-1 - TEAC Test Tape

SERVICE DATA
Mechanical
Tape Speed Deviation
Tape Speed Drift
Wow and Flutter
Pinch Roller Pressure
Reel Torque (Take Up)
Reel Torque (Back Tension)
Fast Winding Time
Electrical
Frequency Response
Signal to Noise Ratio
Erase Efficiency
Channel Separation
Crosstalk between Adjacent Tracks
Total Harmonic Distortion
3,000 Hz + 45 Hz
45 Hz
Playback: 0.10% (WRMS)
Record/Playback: 0.25% (RMS)
400 g + 50 g (12.3 to 15.9 0z)
Play and Rec/Play: 40 to 60 g-cm (0.6 to 0.8 oz-inch)
Fast Forward: 80 to 150 g-cm (1.1 to 2.1 oz-inch)
Rewind: 100 to 150 g-cm (1.4 to 2.1 oz-inch)
Play and Rec/Play: 3 to 8 g-cm (0.04 to 0.11 oz-inch)
90 seconds for C-60
Refer to frequency response limits charts on page 12 and 16.
Playback method: 47 dB min.
Record/Playback method: BIAS/EQ, CrO2 45 dB min.
BIAS/EQ, NORMAL 44 dB min.
With Dolby Noise Reduction used for recording and playback, S/N
ratio is improved by up to 5 dB at 1 kHz and up to 10 dB at frequencies
over 5 kHz.
65 dB min.
30 dB min. (at 1 kHz)
40 dB min. (at 125 kHz)
BIAS/EQ, CrO:2 : 2.2% (max.)
BIAS/EQ, NORMAL: 2.5% (max.)
NOTE: e Improvements may result in Specifications and Service Data changes.
e dB values in the Specifications and Service Data are based on 0 dB = 0.775 V. In case the AC Voltmeter
being used is calibrated to some other standard such as 0 dB= 1 V etc, please use the voltage values
given in parentheses as the test values.
17-1/2“(444 mm)
16-3/16'(410mm)
11-1316'(300mm)
r
i
t
t
1
t
!
1
1
1
i
4
1
1
L
FEEEEER coe ©
~1/4"(IS8mm)
bee eee eo ee
T-1038~I
* Broken line indicates General Export Models for Limited Areas.
Fig.2-2 Dimensions

3. PARTS LOCATION
VOLTAGE SELECTOR PCB Ass’y
(for
General
Export
Models)
IN/OUTPUT
PCB
Ass’y
Power
Transformer
REC AND PLAY
MECHANISM :
PCB Ass’y AMPL. PCB Ass y
Damper
Holder
Ass’y
DC
Motor
Ass’y
Fig. 3-1 Top View
Cassette Holder Ass'y Counter Ass'y
Supply Take-up
Reel
Table
Ass'y
VU
Meters
Reel Table Ass'y
Erase Head REC-PLAY Head Pinch Roller Ass'y
Fig. 3-2 Front View

4.
ILLUSTRATED
DISASSEMBLY
PROCEDURES
GENERAL NOTES
1. Disassemble in number-order.
.
Use
the
proper
tools.
Demagnetize
the
tools
before
use.
3,
When
mounting
or
removing
a
spring,
check
the
posi-
tion
(direction)
of
the
anchor
or
hook.
The
wrong
position may change the tension.
4.
When
reassembling,
don’t
forget
to
reinstall
all
hard-
ware such as springs and washers etc.
5.
To
check
the
shape
of
assembling
hardware
(screws,
etc.)
see
ASSEMBLING
HARDWARE
CODING
LIST
in the parts list.
4-1. EXTERNAL PARTS
4-M4x6
(Round Washer Head)
BM3x6
Fig. 4-1 External Parts
4-2,
CASSETTE
DAMPER
(DAMPER
CORD
STRINGING)
Preparation
Remove in number-order.
1. Fig.4-1, 2 and 3.
T1742
Fig. 4-2 Cassette Damper
4-3. CASSETTE HOLDER ASS’Y
Preparation
Remove in number-order.
1. Fig.4-1, 1 -thru-8.
2. Fig. 4-2, 1. ee a
a Se ‘
ee a
Re a
8 pT.
W4x10.25
a CE WW 24x10.5
W4x10.5,
. oo ee tiga
Pe,
Dyk mS
oe |S _
2-PSA Bae 6
M2.644 Y
Fig. 4-3 Cassette Holder Ass'y

44. HEADS AND PINCH ROLLER
Preparation
Remove in number-order.
1. Fig. 4-1, 1-thru-8.
2-Sw 2
2-8 o® Y 5
M2xi2 ; Pr ®
Ye
We
SW 42
BM2xi2
Fig.4-4 Head/Pinch Roller
ERASE HEAD REC~PLAY HEAD
unt oT iy
NO) aT
> YEL
3G OYBLU
ie ° a WHT
WHT WHT
T1744
DD
Fig. 4-5 Head Wiring Diagram
NOTE: 1. After replacing the head, always adjust the head
alignment, especially the Record/Playback
Head’s azimuth and then secure the screws and/
or the nut with a drop of locking paint.
2. Connect the wires to the head terminal pins
quickly to prevent breaking of internal wires of
the head due to overheating.
3, After replacement, always clean the driving sur-
. faces of the Pinch Roller with the TEAC TZ-
261B Rubber Cleaner or with pure alcohol,
then proceed directly to the PINCH ROLLER
PRESSURE adjustment section.
4-5. REEL TABLES
Preparation
Remove in number-order.
1. Fig.4-1, 1 -thru- 8.
2. Fig.4-2, 1.
3. Fig. 4-3, 1 -thru- 13.
4
3 £ -
5 . aa <
(\O" 7 ee B15x84x10.25
2-€ 012 EN \ Za
6.
/ x?
ST x10.5
be) SS
Fig. 4-6 Reel Tables
4-6. BRAKE PLATE ASS’Y
Preparation
Remove in number-order.
1. Fig.4-1, 1 -thru- 8.
2. Fig.4-2, 1.
3. Fig. 4-3, 1 -thru- 13.
Eeae
W $3X10.25
3
Fig.4-7 Brake Plate Ass’y

4-7, MOTOR
Preparation
Remove in number-order.
1. Fig. 4-1, 2 and 3.
Fig. 4-8 Motor
NOTE: 1. When re-assembling, clean the pulley and the
Belt with TEAC TZ-261 Cleaner kit (“A” for
the Pulley, ““B” for the Belt) or with pure
alcohol.
2. Take off or remount the Motor Ass’y taking
care not to scratch or otherwise damage the
Motor Pulley.
3. When re-attaching the Drive Belt to the Pulley
do not twist or stretch the belt.
4-8. CAPSTAN DRIVE ASS’Y
Preparation
Remove in number-order.
1. Fig. 4-1, 1-thru- 3.
2. Fig. 4-8, 1 -thru-3.
Fig. 4-9 Capstan Drive Ass’y
4-9. LUBRICATION
Refer to Fig. 4-9.
Lubrication should be generally done at about every 1,000
hours of operating time of the tape deck. Use high quality
oil for this purpose.
For efficient oiling, it is recommended that lubrication be
done after nearly 1 hour of idling of the deck and while it
is still warm.
Normally, it is necessary to lubricate only the areas de-
scribed below.
1. Apply a drop of a light machine oil of good quality
(e.g.: TEAC TZ255) with an oil applicator to the shaft
of the Flywheel and spread oil evenly over the shaft
with a flannel cloth. After installing the Flywheel, be
sure to clean the tape moving portion of shaft with
TEAC TZ-261 A Head Cleaner or with pure alcohol.
2. Apply a drop of the proper oil in the same way as
above to the innermost area of capstan shaft (next to
the Flywheel).
3. Apply a film of light grease to the well of the Flywheel
Bearing.
4-10. IDLER/TENSION PULLEY ASS’Y
Preparation
Remove in number-order.
1. Fig. 4-1, 2 and 3.
2. Fig. 4-8, 1-thru-3.
3. Fig. 4-9, 1-thru-4.
Fig. 4-10 Idler/Tension Pulley Ass’y

5.
MECHANICAL
CHECKS
AND
ADJUSTMENTS
5-1. TAKE-UP AND SUPPLY TORQUE
Specifications:
—
5-3. PINCH ROLLER PRESSURE
Take-up: 40 to 60 g-cm (0.6 to 0.8 oz-inch)
Supply: 3 to 8 g-cm (0.04 to 0.11 oz-inch)
Depress POWER Switch ON to apply AC power.
Load the cassette torque meter (for take-up and supply
torques).
Place the deck in the play mode and read the pointer
indication on the right-hand dial scale to check the
take-up torque.
While continuously playing, read the pointer indication
on the left-hand dial scale to check the supply torque.
If the reading(s) are out of the specified range, clean
the driving surfaces of the reel table ass’y and all other
driving parts relative to the take-up and supply torque
function with the TEAC TZ-261B rubber cleaner or
which pure alcohol.
If the above cleaning is ineffective for torque correc-
tion, replace the Reel Table Ass’y.
5-2.
FAST
FORWARD
&
REWIND
TORQUE
Specifications:
Fast Forward torque: 80 to 150 g-cm
(1.1 to 2.1 oz-inch)
Rewind
torque:
100
to
150
g-cm
(1.4
to
2.1
oz-inch)
Depress
POWER
Switch
ON
to
apply
AC
power.
Load
the
Cassette
Torque
Meter
(for
fast
forward
and
rewind
torque).
Place
the
deck
in
the
FF
or
REW
mode
and
read
the
pointer
indication
on
the
dial
scale.
The
Meter
should
indicate
a
torque
of
80
to
150
g-cm
(1.1
to
2.1
oz-inch)
as
Fast
Forward
Torque
and 100
to
150
g-cm
(1.4
to
2.1
oz-inch)
as
Rewind
Torque.
If
the
indication
is
out
of
specified
range,
clean
the
driving
surfaces
of
the
Reel
Table
Ass’y
and
all
other
driving
parts
relative
to
the
Fast
Forward
&
Rewind
torque
function
with
the
TEAC
TZ-261B
Rubber
Cleaner
or
with
pure
alcohol.
—
“If
the
above
cleaning
is
ineffective
for
the
torque
correction,
replace
the
driving
parts
relative
to
these
torques.
Fig. 5-1 Cassette Torque Meter
Specification: 400g + 50 g (12.3 to 15.9 02)
RWNe
Remove Front Panel, then Cassette Holder Ass’y.
Depress POWER Switch ON to apply AC power.
Place the deck in the PLAY mode with no tape loaded.
Attach the spring scale to the Pinch Roller shaft as
shown.
Gently draw the Pinch Roller away from the Capstan
shaft in a directly downward direction until the Cap-
stan
shaft
and
the
Pinch
Roller
are
completely
sepa-
rated,
Gradually
return
the
scale
back
until
the
Pinch
Roller
just
begins
to
rotate.
The
scale
should
then
be
reading
approximately
400
g
+
50
g
(12.3
to
15.9
oz).
If the reading is out of specified range, replace the
Pinch Roller Ass’y or the Pressure Spring or adjust the
Spring Arm as shown.
Bend here
to adjust
Fig.
5-2
Pinch
Roller
Pressure
Measurement

5-4. TAPE SPEED/WOW AND FLUTTER
Specifications:
Tape Speed Deviation: 3,000 Hz+ 45 Hz
Tape Speed Drift: 45 Hz
Wow and Flutter: Playback: 0.10% (WRMS)
Record/Playback:
0.25% (RMS)
NOTE: 1. Before performing this adjustment, clean all
parts in the tape path, particularly the Capstan,
the Pinch Roller and the Heads with the appro-
priate liquid from the TEAC TZ-261 Cleaner
Kit or with pure alcohol.
2. Wow and flutter should be checked in two
ways; Playback only and Record/Playback
methods. First correct tape speed and wow and
flutter using the playback only method. Then
measure wow and flutter using record and play-
back method.
3. As the measured results may vary with respect
to location on tape at which it was taken, three
points — at beginning, middle and near the end
of the tape — should be measured.
54-1. TAPE SPEED
1. Connect test equipment to the deck, except the AF
oscillator, as shown in Fig. 5-3.
2. Set the EQ switch to NORMAL position, and then load
and play a TEAC MTT-111 test tape (3,000 Hz signal
is recorded),
3. Adjust the control located at the center of the Motor
for reading of 3,000 Hz + 10 Hz on the frequency
counter,
(NOTE: This tape speed setting should be done after
approx, 30 seconds of operating time of the deck).
4. Then, verify the reading on the frequency counter as
within the specified range of 3,000 Hz + 45 Hz, and
the tape speed drift is within 45 Hz at any portion of
the tape run.
5. If the tape speed is extremely out of the specification,
check the Pinch Roller pressure and the tape driving
function for correction, and make sure the tape path
is clean.
5-4-2, WOW AND FLUTTER
After making the tape speed measurement, perform the
wow and flutter test using the Playback Method and the
Record /Playback Method successively.
PLAYBACK METHOD
1. Play the MTT-111 test tape.
2. Read the indication on the wow and flutter meter.
3. The wow and flutter value should be 0.10% WRMS,
max.
10
FREQUENCY COUNTER
wow & FLUTTER METER
DECK
under TEST ¢
+463
Fig. 5-3 Tape Speed/Wow & Flutter Measurement Setup
,
TAPE SPEED ADJ. ¥
f 3,000Hz + 10Hz
OA aude wr
T-1679
Fig. 5-4 Tape Speed Adjustment Location
4. If the wow and flutter is out of specification, check the
Pinch Roller pressure and the take-up torque, see that
the tape path is clean, and that the Capstan Belt is not
stretched or oily.
5. If the above checks are ineffective for excessive wow
and flutter correction, repair or replace the Pinch
Roller, the Capstan Belt and/or any other defective
parts.
RECORD/PLAYBACK METHOD
NOTE: When using this method, adopt the maximum wow
and flutter value obtained by repeated play and
stop modes of operation. This operation is neces-
sary to make sure wow and flutter content be-
tween record and playback will not be in phase to
create a false reading.
1. Connect test equipment to the deck as shown in Fig.
5-3.
2. Set LINE or RECORD controls on the deck to obtain
convenient input levels.
3.
Load
a
TEAC
MTT-SO1
test
tape
(blank)
and
set
the
BIAS/EQ switches in the NORMAL positions.
Apply and record a 3,000 Hz signal.
Rewind and play this recorded section.
Read the indication on the wow and flutter meter.
The wow and flutter value should be 0.25% RMS max.
If the measured value is. out of specification, repair
using the same methods as stated in steps 4 — 5 in the
Playback Method procedure.
On Nn

6.
ELECTRICAL
CHECKS
AND
ADJUSTMENTS
GENERAL NOTES
1.
Before
performing
adjustments
on
the
amplifier
section
of
this
deck,
thoroughly
clean
and
demagnetize
the
entire
tape
path,
particularly
erase
head,
record/play-
back
head,
capstan
shaft
and
pinch
roller.
2.
Make
sure
the
deck
is
set
for
the
proper
voltage
and
frequency
for
your
locality.
3.
In
general,
checks
and
adjustments
for
other
than
specified
items,
are
done
in
the
sequence
of
left
chan-
nel
then
right
channel.
Double
designated
REF.
NO.
indicates
left
channel/right
channel
(example:
VR101/
201).
4.
dB
values
in
this
test
procedure
are
based
on
0
dB
=
0.775
V.
In
case
the
AC
Voltmeter
being
used
is
calib-
rated
to
some
other
standard
such
as
0
dB
=
1
V
etc,
please
use
the
voltage
values
given
in
parentheses
as
the
test
values.
6-1.
PLAYBACK
PERFORMANCE
NOTE:
All
alignments
in
the
PLAYBACK
PERFOR-
MANCE
only
have
to
be
done
with
EQ
switch
set
to
CrOz
position
unless
there
is
a
special
rea-
son
which
requires
that
other
positions
also
be
checked.
6-1-1,
RECORD-PLAYBACK
HEAD
AZIMUTH
ADJUSTMENTS
ray
Load and play a TEAC MTT-150 test tape.
2.
Make
sure
the
phase
relationship
between
the
2
signals
(left
channel
and
right
channel)
is
within
45°
on
the
oscilloscope.
Load a TEAC MTT-316 test tape.
Play the 10 kHz signal section of the tape.
Adjust the azimuth adjusting nut for the greatest out-
put level.
6. After adjustment is made, apply a drop of locking
paint to the adjustment nut.
aA b&w
Adjusting Nut
ica
R-P Head
Fig.
6-2
Head
Azimuth
Adjustment
Location
5.
The
AC
Voltmeter
used
in
the
procedures,
including
the
measurement
at
Dolby
test
points,
must
have
load
impedance
of
1M
ohm
or
more.
6.
To
correctly
complete
these
performance
checks,
keep
the
order
as
explained
in
this
chapter.
NOTES
CONCERNING
PREPARATIONS
To
fully
understand
the
contents
of
the
Preparations
in
the
boxed-in
area,
note
these
points.
a.
For
each
procedure,
make
the
initial
equipment
test
set
up,
connections
and
switch/control
settings
as
shown
in
the
associated
illustrations,
then
follow
the
steps
in
the
procedure.
b.
Each
of
the
switch
settings
marked
with
hyphen
(—)
in
the
Switch
Setting
chart
have
no
effect
on
the
proce-
dures.
Preparations:
DECK
under TEST
Fig. 6-1
DOLBY
NR
MONITOR
Control
Setting:
OUTPUT:
Set
for
convenient
output
level.
MIC,
LINE:
Minimum
Connection
Switch Setting:
i
0°
(IN
PHASE)
45°
30°
180
T-1493
Fig.
6-3
Confirming
Phase
Relationship

6-1-2. SPECIFIED OUTPUT LEVEL SETTING
Specifications:
Specified output level: —5 dB (436 mV)
Maximum output level: —2.5 dB +2 dB (461 mV to
731 mV)
1. Lodand play a TEAC MTT-150 test tape.
Adjust R10/R20 for 580 mV (—2.5 dB) on AC Volt-
meter connected to the Dolby test points. (Fig. 6-4)
3. Change the AC Voltmeter connection to the OUTPUT
jacks as shown in Fig. 6-5.
4. Set the OUTPUT controls to maximum and confirm
that —2.5 dB +t 2 dB (461 mV to 731 mV) is obtained
at OUTPUT jacks.
5, Set OUTPUT controls again for —5 dB (436 mV) speci-
fied level.
The position of the OUTPUT controls will now be set
to the specified output level setting. Do not change the
setting of these controls for the remainder of this pro-
cedure unless otherwise indicated.
6-1-3. VU METER CALIBRATION
Specification: +3 VU
6. With the specified setting in paragraph 6-1-2, play the
MTT-150 test tape and adjust R70/R80 for +3 VU
indication on the VU Meters.
6-1-4. FREQUENCY RESPONSE —-PLAYBACK—
7. Load and play the MTT-316 test tape.
8. Play the 315 Hz section of the test tape to get a refer-
ence level on the AC Voltmeter. Then play the re-
quired test signals for comparison with the playback
Frequency Response Limits chart. (Fig. 6-6)
9. Adjust R11/R21 so that the readings obtained on the
AC Voltmeter will be within the response limits.
NOTE: If the response does not meet the specified re-
sponse limits, the head should be checked for
accumulated oxide or dirt. Then, if no dirt is
found, the head azimuth should be readjusted.
12
Preparations:
DECK under TEST
Fig.6-4 Connection
Switch Setting:
Pp [eon [our [Tare
Control Setting:
OUTPUT:
Set for convenient output level.
MIC, LINE: Minimum
ee
OSCILLOSCOPE
under TEST
Fig. 6-5 Connection
t +4
H TEST TAPE: MTT-316 (CrO, )
Lh 44 4
+
3
+
n
2
+
RESPONSE IN 45
%
=f
| -5
in ie |
405063 100125 315 500 1K 2K 4K SK6.3K 10K BOK
FREQUENCY iN Hz
Fig. 6-6 Playback Frequency Response Limits

6-1-5.
SIGNAL
TO
NOISE
RATIO
-PLAYBACK—
Specification:
47
dB
(min.)
1.
Place
the
deck
in
the
PLAY
PAUSE
mode
with
no
tape
loaded,
2.
Read
the
indication
on
the
AC
Voltmeter.
3.
Compare
this
reading
to
the
specified
output
level
of
—5
dB
(436
mV).
The
difference
shall
be
47
dB
or
more.
;
6-1-6.
HEADPHONE
OUTPUT
LEVEL
CHECKS
Specification:
—21
dB
+
3
dB
(48.9
mV
to
97.5
mV)
NOTE:
An
8
ohm
non-inductive
resistor
should
be
used
as
the
test
load
resistor.
1.
Load
and
play
a
TEAC
MTT-150
test
tape.
2.
Measure
the
level
across
the
test
load
resistor.
3.
Level
shall
be
-21
dB
+
3
dB
(48.9
mV
to
97.5
mV).
6-2. MONITOR PERFORMANCE
6-2-1.
MINIMUM
INPUT
LEVEL
CHECKS
Specifications:
LINE:
—19dB+3
dB
(61.5
mV
to
123
mV)
MIC:
—67dB+3
dB
(245
uV
to
489
uV)
DIN:
—35dB+3
dB
(9.75
mV
to
19.5
mV)
NOTE:
To
prevent
mis-measurements
for
the
following
procedures,
any
connection
cords other
than
these
for
the
respective
input
check
must
be
removed.
For
example:
Do
not
connect
the
Microphone
and
the
DIN
cords
to
respective
input
jacks
when
checking
for
the
LINE
inputs.
1. Load any recordable tape.
2. Place the deck in the REC PAUSE model.
3. Set the LINE controls to maximum.
Preparations:
Connection: See Fig. 6-5.
Switch Setting:
[=
[orman|
our
[rare
_|
Control Setting:
OUTPUT:
Specified
Setting
(See
6-1-2)
MIC, LINE: Minimum
Preparations:
DECK
under
TEST
PHONES
TEST LOAD RESISTORS:
Fig. 6-7 Connection
Switch Setting:
BIAS
DOLBY
NR
|
MONITOR
——PNorwa
[our
[Tare
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
MIC, LINE: Minimum
Preparations: AC Voltmeter
OSCILLATOR
DECK under TEST
Fig. 6-8 Connection
Switch
Setting:
DOLBY NR | MONITOR
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
MIC, LINE: Minimum
13

4, Apply a 400 Hz signal at —19 dB (86.9 mV) to the
LINE IN jacks and check for -2.5 dB + 3 dB (411 mV
to 818 mV).
5. Then if the level difference between channels is more
than 2 dB, adjust R22 so that the level difference
become less than 2 dB between channels. (Minimum
Input Level checks for the LINE inputs).
6. Set the LINE controls to minimum and the MIC
controls to maximum.
7. Apply a 400 Hz signal at —67 dB (346 yV) to the MIC
jacks and check for 2.5 dB + 3 dB. (Minimum Input
Level checks for the MIC jack).
8. Remove the MIC input and apply a 400 Hz signal at
~—35 dB (13.8 mV) to the input terminals of the DIN
connector and check for —2.5 dB + 3 dB.
(Minimum Input Level checks for the DIN inputs).
9, For the following test, set the MIC controls to mini-
mum, remove the DIN connector and then connect
input signal to the LINE IN jacks.
6-3. RECORDING PERFORMANCE
NOTE: 1. Before marking any adjustments of the record-
ing circuit, be sure that the tests in the preceding
performance sections have been accomplished.
The preceding performance should be properly
adjusted, otherwise record calibration will be
inaccurate.
2. The adjustments and checks for NORMAL tape
usually may be omitted unless the technician
wishes to confirm that they also are within
specifications except for the sections where
these tape are designated.
6-3-1. BIAS TRAP ADJUSTMENTS
NOTE: The AC Voltmeter used in this procedure must
have load impedance of 1M ohm or more.
1. Connect the AC Voltmeter to the BIAS TRAP test
point.
Load any recordable tape.
3. Place the deck in the REC PAUSE mode with no signal
applied.
4. Adjust L103/L203 for a minimum reading.
nN
14
6-2-2. SPECIFIED LINE CONTROL SETTING
Specification: Specified input level: —9 dB (275 mV)
10. Apply a 400 Hz signal at —9 dB (275 mV) to the LINE
IN jacks.
11. Set the LINE controls to obtain the reading of 580 mV
(—2.5 dB) on the AC Voltmeter. Then check that
OUTPUT level on the deck is —5 dB + 1 dB 388mV
to 489 mV). At this time, the physical position of the
LINE controls indicates the Specified LINE Control
Setting referred to in subsequent procedures.
NOTE: After this setting is done, do not disturb the Speci-
fied Control Setting of the LINE controls until
the remaining checks and adjustments are com-
pleted.
6-2-3. VU METER CALIBRATION CHECKS
Specification: +3 VUt 1 VU
12. Make certain that indication on the VU Meter on the
deck is +3 VU+1 VU.
Preparations:
AC Voltmeter
Tpd LI03/L203
Q106/0206
Fig. 6-9 Connection
Switch Setting:
Pee ee eed
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
MIC, LINE: Minimum

6-3-2. RECORD BIAS SETTING
CrO2 Tape
1.
Connect
the
deck
and
the
test
equipments
as
shown
in
Fig.
6-10.
2.
Load
a
TEAC
MTT-506
test
tape.
3.
Set
the
attenuator
so
that
the
input
to
the
deck
is
-42
dB
(6.15
mV).
4.
Initially
turn
the
C164/C264
in
a
counter
clockwise
direction
until
the
capacitor
leaf
springs
open
com-
pletely.
5. Record a 6.3 kHz test tone.
6.
During
simultaneous
tape
monitoring
(playing),
turn
the
C164/C264
slowly
clockwise
so
that
the
output
reading
on
the
AC
voltmeter
rises
slowly,
reaches
a
peak,
and
then
begin
to
decrease
again.
Set
both
Trim-
mer
capacitors
for
2.5
dB
+
1
dB
beyond
and
below
the
peak
level.
2.5dBtidB
Obtain 2.5dB +1dB
over-bias position.
OUTPUT RESPONSE ——>
BIAS CURRENT ——»
Fig. 6-11 Bias Adjustment
6-3-3. RECORD LEVEL SETTING
Cr02
Ts
Load
a
TEAC
MTT-506
test
tape,
set
the
BIAS/EQ
switches
to
the
CrO2
position
and
DOLBY
NR
switch
OUT.
Apply
and
record
a
400
Hz
test
signal
at
-12
dB
(195
mV).
During
simultaneous
tape
monitoring
(playing),
adjust
the
R16/R26
to
obtain
—8
dB
(300
mV)
OUTPUT
Level.
Preparations:
OSCILLOSCOPE
Fig. 6-10 Connection
Switch Setting:
MONITOR
Specified Setting (See 6-1-2)
Specified Setting (See 6-2-2)
Minimum
CrO2 OUT
Control Setting:
OUTPUT:
LINE:
MIC:
NORMAL
10,
Repeat
the
above
“CrO2”
procedure
1
and
2,
with
the
following
exceptions.
BIAS/EQ
switches:
NORMAL
Test
tape:
MTT-501
11.
During
simultaneous
tape
monitoring
(playing),
check
that
the
OUTPUT
Level
is
within
—8
dB
+
1
dB
(275
mV
to
346
mV).
15

6-3-4. DISTORTION CHECKS
Specifications:
CrO2: 2.2% or less
NORMAL: 2.5% or less
CrO2
1. Load a TEAC MTT-506 test tape.
2. Apply and record a 400 Hz test tone at —12 dB (195
mV).
3. Rewind and play this recorded section.
4. Read the indicated value on the distortion analyzer.
NORMAL
5. Repeat the “CrO2” procedure, with the following ex-
ceptions.
BIAS/EQ switches: NORMAL
Test tape: MTT-501
6-3-5. FREQUENCY RESPONSE -OVERALL—
CrO2 Tape
1. Connect the deck and the test equipments as shown in
Fig. 6-10.
2. Load aTEAC MTT-506 test tape.
Apply and record a test signal at -42 dB (6.15 mV).
4, With the simultaneous record/playback function, make
sure the readings on the AC voltmeter are within the
response limits.
5. In case of any deviation in the high frequency range of
the response limits, clean the heads and do the L104/
L204.
Ww
NORMAL Tape
6. Repeat the “CrO2” procedure, with the following ex-
ceptions.
BIAS/EQ switches: “NORMAL” position
Test tape: MTT-501
TEST TAPE: MTT-506
DOLBY NR: OUT
+4
| |
2
I
©
RESPONSE IN dB.
-3 |
=a
SK 63KY TOK 12.5K SOK
8K
Fig. 6-13 Overall Frequency Response Limits (for BIAS/EQ:CrO2)
i
FS
40 50 63-100 125 400500 1K
FREQUENCY IN Hz
16
OSCILLOSCOPE
Preparations:
DISTORTION ANALYZER
OSCILLATOR
under TEST
Fig. 6-12 Connection
Switch Setting:
BIAS
DOLBYNR
|
MONITOR
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
LINE: Specified Setting (See 6-2-2)
MIC: Minimum
Preparations:
Connection: See Fig. 6-10.
Switch Setting:
BIAS DOLBYNR | MONITOR
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
LINE: Specified Setting (See 6-2-2)
MIC: Minimum
i
+4
+3
Bitz
z
gy O
2
g-2 |
ra
r aa
| I if
4050 63 100 125 400 S00 BK 6.3K ¥ 10K . SOK
BK
FREQUENCY IN Hz
Fig.
6-14
Overall
Frequency
Response
Limits
(for
BIAS/EQ:NORMAL)

6-3-6. SIGNAL TO NOISE RATIO —- OVERALL —
Specifications:
CrO,: 45 dB (min.)
NORMAL: 44 dB (min.)
CrO,
1. Load a TEAC MTT-506 test tape.
2. Place the deck in the record mode for a few seconds
with no signal applied.
3. Rewind and play this recorded (erased) section.
4. Read the indication on the AC Voltmeter.
5. Compare the output reading to the specified output
level (—5 dB-or 436 mV).
6. <A difference of 45 dB or more is required.
NORMAL
7, Repeat the “CrO,” procedure, except use the TEAC
MTT-501 test tape and set BIAS/EQ switches to NOR-
MAL position.
8. A difference of 44 dB or more is required.
6-3-7, ERASE EFFICIENCY
Specification: 65 dB (min.)
NOTE: To measure erase efficiency, a 1 kHz narrow band-
pass filter should be used. The test signal delivered
from the AF oscillator should be tuned to the fil-
ter used.
Numbers in parentheses correspond to steps in Fig. 6-16.
1. Load a TEAC MTT-506 test tape.
2. Apply and record a 1 kHz signal at +1 dB (0.869 V)
for several seconds... 0.0.0.0... eee eee (1)
3, Rewind the tape to the mid-point of the recording and
remove the signal from the LINE IN jacks. ..... (2)
4, Place the deck in the record mode and record through
this previously recorded portion with no input signal
APPHCds cen suet ee at Bt ee ae! Be (3)
5. Rewind the tape to the starting point of the 1 kHz
signal recorded portion ...............04. (4)
6. Play the tape and read the indication on the AC Volt-
meter to obtain the output level of both the unerased
portion and the erased portion of the recorded section
ene Pe ule atts fa Sen vitialies to Souca to's Te og RA rnateh Shah Ms Teh (6)
7. Measure the output level differences between the 2
portions.
8. A 65 dB difference or more is required.
Preparations:
Connection: See Fig. 6-5,
Switch Setting:
BIAS DOLBY NR | MONITOR
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
LINE: Specified Setting (See 6-2-2)
MIC: Minimum
Preparations:
OSCILLOSCOPE
°
AMP SPKR
@
®
AC Voltmeter
DECK,
under TEST
\kHz FILTER
Fig. 6-15 Connection
Switch Setting:
Control Setting:
OUTPUT:
Specified Setting (See 6-1-2)
LINE: Specified Setting (See 6-2-2)
MIC: Minimum
17

record aod, rewind fom
(4)
rewind um
(5)
erased md,
(= Erased
T-465
Fig. 6-16 Erase Efficiency Check Procedure
6-3-8.
CHANNEL
SEPARATION
Preparations:
OSCILLOSCOPE
Specification: 30 dB (min.)
NOTE: To check channel separation (cross talk between
channels), a 1 kHz narrow bandpass filter should
be used. The test signal delivered from an AF oscil-
lator should be tuned to the filter used. eae jurevr ke FRLTER
AC Voltmeter
° °
Numbers in parentheses correspond to steps in Fig. 6-18.
1. Load a TEAC MTT-506 test tape. Fig. 6-17 Connection
2. Apply a 1 kHz test tone at —9 dB (275 mV) into the
left channel. Switch Setting:
oe
4. Rewind the tape to the starting point of recording. (2) OUT TAPE
5. Play the tape and measure the output level differences
between the left and right channels .......... (3) Control Setting:
6. A 30 dB difference or more is required. OUTPUT: Specified Setting (See 6-1-2)
LINE: Specified Setting (See 6-2-2)
MIC: Minimum
record ead,
(1)
(2)
play and compare mamma
(3)
Signal (7 Blank
T-467
Fig. 6-18 Channel Separation Check Procedure
18

6-3-8. ADJACENT TRACK CROSSTALK
MEASUREMENT
Specification: 40 dB (min.)
NOTE:
The
tape
must
be
completely
erased
or
demagne-
tized
prior
to
this
procedure.
Numbers
in
parentheses
correspond
to
steps
in
Fig.
6-20.
1, Load a TEAC MTT-506 test tape.
2.
Apply
a
125
Hz
test
signal
at
—-9
dB
(275
mV).
3.
Place
the
deck
in
the
record
mode
for
about
30
se-
CONGS.”
Bole.
Qcsncerg
mowanan.
tgs
ed
ate
es
(1)
4.
Rewind
the
tape
to
the
starting
point
of
recording.
(2)
5.
Play
the
tape
and
measure
the
output
level
of
the
re-
corded
portion,
Note
this
reading
for
temporary
ref-
erence
level
for
the
following
measurements.
....
(3)
6.
Remove
the
test
tape,
turn
it
over
and
replace
it
in
the
De
OR
ees
as
sO
Fie
rte
Masa
beat
we
cd
vacm
ta
ace
bgen
totes
(4)
7,
Play
the
tape
back
and
read
the
output
level.
...
.
(5)
8.
Get
the
difference
between
this
reading
and
the
reading
previously
measured
for
the
125
Hz
signal.
9.
A
40
dB
difference
or
more
is
required.
record wath Side 2
(1)
(2)
(3)
Fig. 6-20 Adjacent Track Crosstalk Measurement Procedure
6-3-10. DOLBY NR EFFECT MEASUREMENT
Specifications:
Variation from reference at 1 kHz: 3dBto8dB
Variation from reference at 10 kHz: 8 dBto 12 dB
Load a TEAC MTT-506 test tape.
Apply and record a 1 kHz signal at —32 dB (19.5 mV).
Rewing and play this recorded section.
During playback, read the indication on the AC Volt-
meter and note it for temporary reference level for the
following measurement.
5. Set the DOLBY NR switch to IN.
6. Ensure the reading reduces 3 dB to 8 dB from the ref-
erence level.
7.
Apply
and
record
a
10
kHz
signal
at
—42
dB
(6.15
mV)
with
DOLBY
NR
to
OUT.
8. In the same manner as step 3 to 6, ensure the reading
reduces 8 dB to 12 dB when the DOLBY NR Switch
is set to IN.
PS
OSCILLOSCOPE
Preparations:
OSCILLATOR
DECK
under TEST
Fig. 6-19 Connection
Switch Setting:
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
LINE: Specified Setting (See 6-2-2)
MIC: Minimum
Side |
EE
meas °
(4) oO
[it
Side 2
(5)
T-466
Preparations:
Connection: See Fig. 6-10,
Switch Setting:
- BIAS DOLBY NR | MONITOR
*
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
LINE: Specified Setting (See 6-2-2)
MIC: Minimum
19

6-4. ADJUSTMENT LOCATION
20
R10/R20
R11/R21
R70/R80
R16/R26
C164/C264
L103/L203
L104/L204
TAPE SPEED.ADJ.
3,000Hz+I0Hz
Fig. 6-21 Adjustment Location
Playback Level
Playback Frequency Response
Meter Calibration
Record Level
Bias Adjustment
Bias Trap
Record Frequency Response
a a
Fig. 6-22 Test Point Location
saan erie