Teac A-400 User manual

GENERAL INTRODUCTION
This Service Manual is compiled to assist service technicians by
providing procedures and corrective measures for adjustment, care
and maintenance, and the ordering procedures for needed parts.
lf adjustments or repairs are too complicated and are difficult for
you to accomplish, or if you have any technical questions, please
contact the nearest TEAC Factory. Service Department or write
: directly to a TEAC office, the addresses of which are written on the
back cover.
NOTE
When ordering replacement parts, please refer to the PARTS
* “Dolby” and the Double D
symbol “OQ” are trademarks of
Dolby Laboratories Inc. The
Noise reduction circuit is made
under license from Dolby Labo-
ratories Inc.
LIST which is printed separately from this manual.
CONTENTS
1. Specifications & Service Data ............2 0.000: 3 4. Electrical Checks and Adjustments .........+5--55 13
2. Partial Dis-assembly of Main Parts ................ 4 General Notice ........ 0.000 ee BB
Test Equipment Required... ..----+++ 13
2-1. Cabinet Removal .............-204 4
2-2.
Front
Panel
Removal
...........0e08
4
4-1
Monitor
Performance
.......-+++000-
14
2-3. Cassette Holder Removal ............. 5 : 4-1-1. Specified Input Level Setting .......+--- 14
2-4,
Tape
Transport
Chassis
Removal
.........
5
4-1-2.
.
Minimum
Input
Level
Checks
.....----->
14
2-5.
Head
Replacement
.............
Poeee
4-1-3.
Level
Meter
Calibration
.....0--25
eee
14
2-5A.
Record/Playback
Head...
........000-
6
4-1-4.
Peak
Level
Indicator
Setting
....--.-----
15
2-5B.
EraseHead
.......0.00
cc
cc
eaeees
6
4-1-5.
Headphone
Output
Level
Checks
.....-->
.15
2-6. Pinch Roller Replacement ............. 6 4-2. Playback Performance .....----+ 0-0 es 15
2-7. Reel Table Replacement ............. 7 4-2-1. Record/Playback Head Azimuth
2-7A, Take-up Reel Table... ..........-04- 7 SMIUSIGIG 9:02. 2-g 0 ah eh series sep ens 15
278.
Supply
Reel
Table
.................
j
4-2-2.
Specified
Output
Level
Setting
...---
es
16
2-8.
Motor
Replacement..........-...00.
7
4-2-3.
Level
Meter
Indication
Checks...
+--+
+s
16
2-9. Flywheel/Capstan Belt Replacement ....... 8 oe Playback Frequency Response Checks ..... ss
2-10. Fast Wind Idler Replacement ........... 8 SScests © SHGNGL A TEDIRE A BG CRERIS sana elete SACS S
4-3, Record Performance: .......-+-++055 17
Parts Location ......... 0.0000 eee 4 4-3-1. Bias Trap Adjustments .......--+-ee0005 17
4-3-2. Bias Adjustments for ‘1’ Position
3. Mechanical Checks and Adjustments ............... 3 (CrO. Tape)... 6... ee ee ee eee V7
4-3-3. Bias Adjustments for 2” Position
Test
Equipment
Required
.............
9
(Regular
Tape)
.........--
stg
A
aden
ake
17
4-3-4. Record Level Setting .....-- 2+ - ee eee 18
3-1. Pinch Roller Pressure ...........-44- 9 4-3-5, Distortion Checks ....... 2-020 eee 18
3-2. Take-up Torque Measurement........... 10. 4-3-6. Overall Frequency Response .-----++:-> 18
3-3. Fast Forward Torque Measurement ....... 10 4-8-7. Overall Signal-to-Noise Ratio... .--. eee 19
3-4. Rewind Torque Measurement ........... 1 4-3-8. Erase Efficiency... .....-0 002 ee eee 19
Torque
Measurement
using
the
Cassette
4-3-9.
Channel
Separation
.
Sil
aces
eae
ees
20
Torque Meter .....2.......000. a 4-3-10. ~ Crosstalk between Adjacent Tracks .-.---- 20
4-3-11. Dolby *NR System Efficiency Checks ...... 20
“3-5. Tape Speed Adjustment/Wow and Flutter 4-4, Adjustment & Test Point Location ......-.- 21
Measurement... 20... 0... cee eee eee 11 :
3-6.
Solenoid
Position
Adjustment.
..........
12
5.
Level
Diagram
.....-.0.0-c
eee
ee
eee
ees
22
3-7. Muting Switch Position Adjustment ....... 12
3-8.
Voltage
Selector
Setting
Procedure
.......
12
G:
Troubie-dhootttits.eoeeed
we
ee
ea ee
ee
23
3-9. AC Power Line Frequency Adaptation..... . 12
3-10. Lubrication 2.2.0 ...0........20005 12

1.
SPECIFICATIONS
Track System
Type of Tape
Tape Speed
Inputs
(impedance and level)
Outputs
(impedance and level)
Equalization
Head Configuration
SPECIFICATIONS & SERVICE DATA
1/4-track, 2-channel stereo
Cassette tape, C-60 and C-90 (Philips type)
4.8 cm/s (1-7/8 ips) ;
Microphones: Min. input level: -67 dB +3 dB (10 Kohms or more)
Line: Specified input level: —9 dB (50 Kohms or more)
Min. input level: -19 dB +3 dB
DIN * : Min. input level: -35 dB +3 dB
Line out: Max. output level: +8 dB +2 dB (50 Kohms)
Specified output level: +3 dB
Headphones: Specified output level: —21 dB + 2dB (8 ohms)
EQ 1: 3180 us + 70 us (for CrO, tape)
EQ 2: 3180 us + 120 us (for regular Hi-Fi tape)
1/2-track, 1-channel Erase Head
Motor
Bias Frequency
Operating Position
Power Requirements
Power Consumption
Dimensions
Weight
* Pursuant to DIN Standards
SERVICE DATA
Mechanical
Tape Speed Deviation
Wow and Flutter
Pinch Roller Pressure
Reel Torque
Fast Winding Time
End-stop Activate. Time
Electrical
Frequency Response
Signal to Noise Ratio
Erase Efficiency
Channel Separation
Crosstalk between Adjacent Tracks
Total Harmonic Distortion
4+/4-track;-2-channet Record/Play back Head
DC Servo Motor with F.G. voltage control
100 kHz
Horizontal
100/117/220/240 V AC, 50/60 Hz (General Export Models)
117 V AC 60 Hz {USA/Canada Models)
220 V AC 50 Hz (Europe -Models)
11W
440 (W) x 155 (H) x 285 (D) mm [17-3/8" (W) x 6-1/8” (H) x 11-1/4" (D)}
6.0 kg (13-1/4 ibs) net, approx.
3,000 Hz +45 Hz |
Playback: 0.1% (WRMS)
400 g + 20g (13.5 ~ 15.0 oz)
Take Up: 45 ~ 70 g-cm (0.6 ~ 1.0 oz-inch)
Fast Forward: 80 g-cm (1.1 oz-inch) or more
Rewind: 100 g-cm (1.4 0z-inch) or more
90 seconds for C-60
3 seconds + 2 sec.
Refer to frequency response limits charts on pages 16, 18 and 19.
Playback method: 47 dB minimum
Record/Playback method: BIAS/EQ 1: 45 dB minimum
BIAS/EQ 2: 44 d8 minimum
With Dolby Noise Reduction used for recording and playback, S/N ratio
is improved by 5 dB at 1 kHz and 10 dB at frequencies over 5 kHz.
65
dB
minimum
:
30 dB minimum (at 1 kHz)
40 dB minimum (at 125 Hz)
BIAS/EO 1: 3.0% (maximum)
BIAS/EQ. 2: 2.5% (maximum)
NOTE: © All the items were determined using the Regular type of Hi-Fi
tape except as noted.
e improvements may result in Specifications and Service Data
changes.
© Value of “dB” in the Data refer to 0 dB = 0.775V, except
where specified. if a Test Set or VTVM calibrated to 0 dB =
1V is to be used, appropriate compensation should be made.

2. PARTIAL DIS-ASSEMBLY OF MAIN PARTS
2-1. CABINET REMOVAL 2-2. FRONT PANEL REMOVAL
Remove the Main Chassis from the Cabinet. (See Section 2-1)
Remove the 4 Control knobs from the Front Panel.
Remove the 6 screws.
Remove the Front Panel from the Main Chassis.
1. Lay the deck on its top surface as illustrated in Fig. 1.
2. Remove the 7 screws from the bottom.
3. Remove the Main Chassis from the Cabinet.
Pe NS
af 7-P M3xl2
7-W 3.216% 1.6t
Fig. 1 Cabinet Removal
Fig. 2 Front Panel Removal
NOTE: For assembling hardware shape identification, see ASSEMBLING HARDWARE CODING LIST on the Parts List.
PARTS LOCATION
POWER TRANSFORMER POWER SUPPLY PC BD. _ REC/PB AMPL. PC. BD.
FUSE
DC- SERVO AMPL. PC BD.
MOTOR FLYWHEEL SOLENOID LEVEL METER
Fig. 3 Parts Location

2-3. CASSETTE HOLDER REMOVAL
1. Remove the Cabinet and the Front
Panel. (See Section 2-1, 2-2)
2. Loosen the 2 screws (1) on the Bracket
A (2) and the 2 screws (3) on the Brack-
et B ®. At this time, the work is made
easier by expanding the Springs (5), @)
in the direction of the arrows.
3. Remove the Cassette Holder oO) from
the Tape Transport Chassis.
2-4. TAPE TRANSPORT CHASSIS REMOVAL
1. Remove the Cabinet and the Front
Panel. (See Section 2-1, 2-2)
2. Remove the 4 screws (1)- (4) .
3. Extract the Insulator Plate A (5) from
~ the Main Chassis (6) .
4. Remove the Reinforcing Angle (7) by
taking off the 2 screws and
loosing the screw (9) .
5. Retighten temporarily the screw g) ‘
6. Remove the Transport Chassis (0) from
the Main Chassis (6) :
@
NN ne ®)
5 2
CASSETTE
HOLDER
f
U
144
Fig. 4 Cassette Holder Removal
TAPE TRANSPORT °
CHASSIS
Cate : ©)
7 SSD
mm : SA M2.6x4
wy ®
BSA M2.6x4
Fig. 5 Tape Transport Chassis Removal
NOTE:
For
assembling
hardware
shape
identification,
see
ASSEMBLING
HARDWARE
CODING
LIST
on
the
Parts
List.
5

2-5. HEAD REPLACEMENT
2-5A. Record/Playback Head
1
Remove the Cabinet and the Front Panel. (See Section 2-1,
2-2}
Open the Cassette Holder door to the 45 degree position by
pushing the EJECT Lever to the right, and to the full 85
degree position by pushing the door to the left.
o. the Head Protector Ga) by taking off the 2 screws
Unsolder the wires from the head terminal pins @).
Remove the Head @ by taking off the nut 6) and the
screw 6.
as.
PINCH ROLLER
shown in Fig. 7.
2-5B. Erase Head
1,
oP oN
2-6.
Repeat steps 1, 2 in 2-5A above. (Record/Playback Head)
Place the right Rotary Lever in the PLAY mode.
Unsalder the wires from, the head terminal pins @.
Remove the Head (8) by taking off the 2 screws @).
Re-solder each head wire to the newly replaced head as
shown in Fig. 7.
NOTE
. After replacing the head and adjusting its azimuth (See
Section 4-2-1), secure the screws and the nut with a drop of
locking paint.
. Connecting the wires to the head terminal pins should be
done quickly to prevent breaking of internal wires of the
head due to overheating.
PINCH ROLLER REPLACEMENT
Remove the Cabinet and the Front Panel. (See Section 2-1,
2-2)
Qpen the Cassette Holder door to the 45 degree pasition by
pushing the EJECT Lever to the right, and to the full 85
degree position by pushing the door to the left.
Remove the Spring from the Pinch Roller (1) with the
other end of this spring remaining attached to the Head Base
Plate (2).
Remove the E-ring @® slowly fram the pivot pin 4).
Remove the Pinch Roller Ass’y D from the pivot pin 2
At this time, the work is made easier by pushing the EJECT
Lever to the right. :
Retain the Spring (5) and remember to re-install it when
replacing the Pinch Rolfer.
NOTE
Make sure that the arm fits properly into the guide (7) in
the Pinch Roller Ass’y as shown in Fig. 6.
BSA M2x4 y Wes
Oe
ey
we NS
& oe
2-BSA M2x4
9
ERAS
2-PSA M2.6x%4
Fig. 6 Heads/Pinch Roller Replacement
ERASE HEAD
REC/PLAY HEAD
T-417
Fig. 7 Head Wiring Diagram
6
NOTE: For assembling hardware shape identification, see ASSEMBLING HARDWARE CODING LIST on the Parts List.

2-7. REEL TABLE REPLACEMENT
2-7A. Take-up Reel Table
1.
2-2)
2. Open the Cassette Holder door to the 45 degree position by
pushing the EJECT Lever to ‘the right, and the full 85 degree
position by pushing the door to the left.
3. Remove the Cassette Guide Plate @) from the Tape 2-PSA
Transport Chassis by taking off the 4 screws @): eae
4, Remove the Index Counter Belt 3) from the groove of the
Take-up Reel Table(4)and the Index Counter Pulley.
5. Remove the Flywheel Ass’y (See 2-9).
6. Remove the Cassette Holder Stopper ®) and the Reel Table
Remove the Cabinet and the Front Panel. (See Section 2-1,
@ TAKE-UP
REEL TABLE
@ simultaneously by taking off the 2 screws 6).
_- 2-7B. Supply Reel Table
1.
2.
2-8.
Repeat steps 1 to 3 in 2-7A (Take-up Reel Table).
Remove the Cassette Holder Stopper ® and the Supply
Reel Table at the same time by taking off the 2 screws
MOTOR REPLACEMENT
After removing the Tape Transport Chassis from the Main
Chassis, do the following procedures (See Section 2-1, 2-2,
2-4).
Remove the Capstan Belt (1) from the Motor Pulley @.
Remove the PC Board (part of the Motor Assy) @ from the
Main Chassis. ,
Bend open the Wire Clamp ®@ to loosen the wires.
Unsolder
the
2
wires
(5)
(connected
from
the
Power
Supply
PC
Board)
to
the
PC
Board(3).
Remove the screw (6) attaching the Cassette Guide B ®,
and loosen the screw 43) and turn the Guide slightly in the
direction of the arrow. (for access to the Motor)
Remove the Motor Assy (incl. the Motor Mount. Plate @)
from the Transport Chassis by taking off the 3 nuts (0).
Remove the Motor Assy a) from the Motor Mount. Plate
@) by taking off the 3 screws qd.
NOTE
Since the entire Motor Assy includes the DC-servo Ampl. PC
Board (provided for motor speed control), always replace the
Motor together with its PC Board.
Fig. 8 Reel Table Replacement
o)
ND
I.
\
y 7 Ne y
j
<9 | {
Al |
|
B)WHT/ALK,
4
™
ee
NOTE:
For
assembling
hardware
shape
identification,
see
ASSEMBLING
HARDWARE
CODING
LIST
on
the
Parts
List.

2-9. FLYWHEEL/CAPSTAN BELT REPLACEMENT
1. After removing the Tape Transport Chassis from the Main Q ®
Chassis, perform the following process. (See Section 2-1, ©
2-2, 2-4) FLY WHEEL.
2. Remove the Flywheel Bearing Plate a) from the mounting
studs (2) by taking off the 2 screws (3).
3. Retain the Spacer @) and remember to re-install it when
replacing the Flywheel Assy.
4. Remove the Capstan Belt ® from the Flywheel Assy 6)
and the Motor Pulley 6).
5. Remove the Oil Retaining Washer @® from the shaft of the
Flywheel. : :
@) CAPSTAN BELT
PSA M2.6x8
i>
6. Carefully Tift out the Flywheel G5) from the Capstan
Housing (8).
— Viewed from Rear of Transport All driving surfaces
NOTE aces Siar moana
After reinstalling the Flywheel, always do the following.
1. Clean all driving surfaces of the Flywheel with TEAC Fig. 10 Flywheel/Capstan Belt Replacement
TZ-261A Head Cleaner or with pure alcohol as shown in “A”
in- Fig. 10.
2. Clean the Capstan Belt with TEAC TZ-261B Rubber Cleaner As OM 494-9
or
with
pure
alcohol.
\
Pe
ME
TAPE
RECORDER
3. Apply a drop of a light machine oil 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 TZ-261A Head
Cleaner.
2-10. FAST WIND IDLER ASS’Y REPLACEMENT
1. First perform the steps fisted below.
Cabinet Removal (Section 2-1)
Front Panel Removal (Section 2-2)
Tape Transport Chassis Removal (Section 2-4)
Flywheel/Capstan Belt Removal (Section 2-9)
. Take-up Reel Table Removal (Section 2-7A)
2. Remove the Spring @ from the Fast Wind Idler Assy @
and the Fast Wind Plate G3). (Note that the position of the FAST WIND
Spring a and the arm of the Fast Wind Idler Ass’y. on Pree)
which the Spring is mounted. Position the Spring and
%
pape
the arm correctly when replacing or re-installing the Fast
Wind Idler Ass’y. )
3. Remove the E-ring(@)from the pivot pin(S).
4. Lift out the Fast Wind Idler Assy Q) from the pivot pin
5. &. re-assembling the Idler Assy, turn the left Rotary
Lever to the FF position to simplify remounting. :
— Viewed from Rear of Transport Chassis —
: Fig. 12 Fast Wind idler Replacement
NOTE: For assembling hardware shape identification, see ASSEMBLING HARDWARE CODING LIST on the Parts List.

3.
MECHANICAL
CHECKS
AND
ADJUSTMENTS
TEST EQUIPMENT REQUIRED
1.
Spring
scale:
For
take-up
torque
check:
0
~
70g
(0
~
2.5
02)
For
fast
forward
and
rewind torque
checks:
0
~
200g
(0
~
7.0
oz)
2.
String:
Length:
about
50
cm
(20”)
3.
Cassette
Reel
Adapter:
Diameter:
22
mm
* The
tools
above
(1
~3)
are
constructed
as
shown
in
Fig.
13.
4.
Cassette
Torque
Meter:
For
take-up
torque
check:
0
~
100
g-cm
For fast forward and
rewind torque checks: 0 ~ 160 g-cm
*
Use
of
the
Cassette
Torque
Meter
instead
of
the
spring
scale,
if
you
have
one,
is
recommended
for
easier
measuring,
(See
Fig.
19
on
Page
11)
Fig. 13 Spring Scale and Cassette Reel Adapter
5,
Spring
scale
(for
the
Pinch
Roller
pressure
check):
O~1kg
(2.2
Ibs)
6.
TEAC
MTT-111
test
tape:
For
tape
speed
and
wow/flutter
checks
7.
Wow/Flutter
meter:
MEGURO
DENPA
SOKKIK.K.
Model
MK-668A,
D
&
R
Co.,
FL-
ae
or
equivalent:
8.
Frequency
counter:
Digital
type,
capable
of
10
Hz
to
100
kHz
indica-
tion.
NOTE
All
the
mechanical
checks
and
adjustments
should
be
done
with
the Cabinet and the Front Panel removed. (See Section-2-1, 2-2)
PINCH ROLLER PRESSURE
The Pinch Roller pressure should be: 400 g + 20 g- (13. 5 as
15.0 oz)
Open the Cassette Holder door to the left.
Switch the POWER switch to the ON position.
Place the deck in the PLAY mode with no tape loaded.
Attach the spring scale to the Pinch Roller shaft as shown in
Fig. 14.
Gently draw-the scale away (in the direction of the arrow)
until the Capstan shaft and the Pinch Roller are completely
separated.
Gradually release the tension on the scale until the Pinch
Fe Oe
Roller
just
begins
to
rotate.
The
scale
should
then
be
reading
©
—-
Bend
here
to
adjust
1-407
approximately
400
g
+
20
g
(13.5
~
15.0
o2).
:
If
the
reading
is
out
of
specified
range,
adjust
the
tension
of
Fig.
14
Pinch
Rotler
Pressure
Measurement
the Pressure Spring by bending the tab of the Pinch Roller
Assy slightly.

3-2. TAKE-UP TORQUE MEASUREMENT
The take-up torque should be: 45 ~ 70 g-cm (0.6 ~ 1.0
oz*inch)
Open the Cassette Holder door fully to the left.
Remove the Cassette Guide Plate. (See 2-7A in Section 2-7)
Switch the POWER switch to the ON position.
Set the Cassette Reel Adapter (22 mm Dia.), connected to
the spring scale (Q ~ 70 g, or 0 ~ 2.5 oz) by the string, on the
Take-up Reel Table as shown in Fig. 15.
Place the deck in the PLAY mode.
6. Allow the rotation of the Reel Table to draw the scale
Pons
n
Take-up Reel Table
pointer toward the Adapter with the spring scale moving in
the same direction at nearly the same speed as the tape would
be moved, and obtain the scale reading. Make reading only
when the pointer becomes stable.
7. The scale should indicate 41 ~ 64 g (1.4 ~ 2.2 02).
This corresponds to a torque of 45 ~ 70 g:cm (0.6 ~ 1.0
oz‘inch). For the torque calculation, refer to Fig. 16.
8. If the reading is out of specified range, clean the driving
surfaces of the Reel Table Assy, the Play Idler and the
Flywheel with the TEAC TZ-261B Rubber Cleaner or with
pure alcohol (Fig. 17) ;
9. If the above cleaning is ineffective for torque correction,
replace the Reel Table Assy. (See Section 2-7)
3-3. FAST FORWARD TORQUE MEASUREMENT
The fast forward torque should be: 80 g-cm (1.1 oz-inch) or
more
1. Repeat step 1 to 3 in 3-2 above.
2. Set the Cassette Reel Adapter (22 mm Dia.), connected to
the spring scale (0 ~ 200 g, or 0 ~ 7.0 oz) by the string, on
the Take-up Reel Table as shown in Fig. 15.
3. Place the deck in the FF mode.
4. Permit the revolution of the Reel Table to pull the scale
pointer toward the Adapter, and obtain the scale reading. Do
not read until the pointer becomes stable.
5. The scale should indicate 73 g (2.6 oz) or more.
This corresponds to a torque of 80 g-cm (1.1 oz-inch) or
more. .
6. If the indication is out of specified range, clean the driving
surfaces of the Reel Table Assy, the Fast Wind Idler Assy and
the Flywheel with the TEAC TZ-261B Rubber Cleaner or
with pure alcohol. (Fig. 17)
7. |f the above cleaning is ineffective for the torque correction,
replace the Fast Wind Idler Assy. (See Section 2-10)
10
- /Fast Wind Idier Assy
Supply Reel Table { 7-406
Fig.
15
Take-up/Fast
Forward
Torque
Measurement
Cassette Reel Adapter
T-409
T = Fxr For example:
T: torque (g-cm) if F=41g
F: force (g)
r: radius (cm) T=Fxr
=41x 1.1
= 45 (g-cm)
;
Consequently
the
torque
is
45
g-cm.
Fig.
16
Torque
Calculation
Method
Flywheel
Play Idler
Take-up Reel Table
Capstan Belt
~
xe
‘Our
Ne
a
mess
Motor
Supply
Reel
Table
7-386
Fig. 17 Tape Drive System

3-4, REWIND TORQUE MEASUREMENT
The
rewind
torque
should
be:
100
g-cm
(1.4
oz*inch)
or
more
Repeat
the
above
procedure,
but
use
the
Supply
Reel
Table
and
the
REW
mode
for
measuring
the
rewind
torque.
(See
~ Fig. 18)
The
scale
should
indicate
91
g
(3.2
oz)
or
more.
This
corresponds
to
a
torque
of
100
g-cm
(1.4
oz-inch)
or
more.
TORQUE
MEASUREMENT
USING
THE
CASSETTE
TORQUE
METER.
The
torque
measurements
can
be
easily
done
with
the
Cassette
Torque
Meter
indicated
below.
For
take-up
torque
measurement:
0~
100
g°cm
For
fast
forward
and
rewind
torque
measurements:
6
~
160
g-cm
By
this
use,
it
is
possible
to
directly
obtain
the
torque
value
without
calculation,
and
to
do
the
measurement
simply
with
no
removal
of
any
parts.
If
repairs
are
necessary,
the
Cabinet
and
the
Front
Panel
must
be
removed.
3-5.
o
Take-up Reel Table (
Supply
Reel
Table
-
9
Cassette Ree! Adapter (22mm Dia.)
‘7-405
Fig. 18 Rewind Torque Measurement
TAPE SPEED ADJUSTMENT/WOW
AND FLUTTER MEASUREMENT
The
tape
speed
deviation
indication
should
be:
3,000
Hz
+
45
Hz
The
wow
and
flutter
should
be:
within
0.10%
WRMS
NOTE
The
adjustment
explained
in
this
section
employs
the
play-
back method.
Before
performing
this
adjustment,
clean
all
the
tape
path,
.
particularly
the
Capstan,
the
Pinch
Roller
and
the
Heads
with
TEAC
12-261
Cleaner
Kit
or
with
pure
alcohol
as
appro-
priate.
As
the
measured
results
will
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.
Connect
a
digital
frequency
counter
and
a
wow
and
flutter
meter
to
either
OUTPUT
jack.
Place
the
OUTPUT
contro!
on
the
deck
in
the
specified
setting.
(See
Section
4-2-2)
Load
and
play
a
TEAC
MTT-111
test
tape
(3,000
Hz
signal
is
recorded)
on
the
deck.
Adjust
the
semi-fixed
resistor
(See
Fig.
21)
on
the
DC-servo
Ampl.
PC
Board
for
reading
of
3,000
Hz
+ 45
Hz
on
the
frequency
counter.
(Tape
speed
adjustment)
Read
the
indication
on
the
wow
and
flutter
meter.
The
wow
and
flutter
value
should
be
0.10%
WRMS,-max.
_
lf
the
wow
and
flutter
is
out
of
the
specification,
check
the
Load
the
Meter
on
the
deck
and
read
the
painter
indication
on
Fig. 19 Cassette Torque Meter
Pinch
Roller
pressure
and
the
take-up
torque,
and
see
that
the
tape
path
is
clean,
and
that
the
Capstan
Belt
is
not
stretched
or
oily.
8.
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.
Playback
Frequency
3
Ampl.
Section
Counter
oe
Po
coal
ood
—
—
o
m0
Ey S|
=
a LC)
2
©
5
ae
e
Wow
&
Flutter
Meter
Fig.
20
Tape
Speed/Wow
and
Flutter
Measurement
Setup
Fig.
21
Motor
Speed
Adjustment
Location
11

3-6. SOLENOID POSITION ADJUSTMENT
1. Place the deck in the PLAY mode with no power applied.
2. Depress the plunger by hand until the plunger is fully
bottomed, and the Latch Arm latches the solenoid pin.
3. Adjust the Solenoid position by loosening the 2 screws so that
the clearance between the Latch Arm and the solenoid-pin is
approximately 0.5 mm (1/64) as shown in A of Fig. 22.
4, After adjusting, retighten the 2 screws and secure them with
a drop of locking paint.
P oP Solenoid Pin
Plunger
3-8.
VOLTAGE
SELECTOR
SETTING
PROCEDURE
(General
Export
Models)
1. Disconnect the power
cord of the deck fram the
source.
2. Turn thedeck around and
locate the voltage selector
on the rear of the deck.
(See Fig. 24)
3. Loosen the screw on the
right end of the metal bar
covering the voltage selec-
tor and then rotate the
Latch Arm
Solenoid
approx. O.Smm(v64")
Screws
T-411
Upper right hand corner of Transport Chassis
(viewed from front )
Fig. 22 Solenoid Position Adjustment
3-7. MUTING SWITCH POSITION ADJUSTMENT
1. Before adjusting this, be sure that no power is applied to the
deck.
2. ‘Loosen the 2 screws as shown in Fig. 23.
3. Turn the right Rotary Lever to the PLAY position.
4. Lightly force the Muting Switch PC Board to the right
{toward the arrow) as far as possible by hand, and retighten
the 2 screws.
5. After adjusting, secure the 2 screws with a drop of locking
paint.
Right Rotary Lever
PLAY mode
Screws
1-410
Muting Switch PC Board
Fig. 23 Muting Switch Position Adjustment
12
bar so the slotted center
post of the voltage selec-
tor can be adjusted.
4. To increase the selected
220
voltage, turn the slotted
center post clockwise. : \(
5. To decrease the selected
voltage, turn the slotted
center post counter- :
240
clockwise.
6. The numerals that appear \K
in the cut-out window of
the voltage selector indi-
Fig.
24
Voltage
Selector
Setting
cate
the
selected
voltage.
3-9. AC POWER LINE FREQUENCY ADAPTATION
Since the A-400 employs a DC-servo controlled motor, 50 Hz
or 60 Hz operation is permitted without power line fre-
quency adaptation.
3-10. LUBRICATION
Apply
1
or
2
drops
(approx.
0.2
cc)
of
a
light
machine
oil
with
an
oil
applicator
to
the
shaft
bearing
portion
of
the
‘Capstan
Assy.
See
Fig.
25.
(See
Section
2-9
for
lubrication
of
the
newly
replaced
Flywheel!
Assy.)
No other lubrication is normally necessary .
NOTE
Lubrication
of
the
Capstan
Assy
should
be
generally
done
at
about
every1,000hour
operating
time
of
the
tape.
deck.
Use
high
quality oil for this purpose.
Apply lor2 drops”
y A (approx: O.2¢c) of Oil here
8 Capstan Assy
T-408
Fig. 25 Lubrication of Capstan Assy

4.
ELECTRICAL
CHECKS
AND
ADJUSTMENTS
GENERAL NOTICE
Before
performing
adjustments
on
the
amplifier
section
of
this
deck,
thoroughly
clean
and
demagnetize
the
entire
tape
path,
particularly
erase
head,
record/playback
head,
capstan
shaft
and
pinch
roller.
2.
In
general,
checks
and
adjustments
for
other
than
specified
items,
are
dene—in—the—sequence—of
teft-channel_then-right
channel.Double
designated
REF.
NO.
indicates
left
channel/right
channel
(example:
VR101/VR201).
3.
Value
of
“dB”
in
the
text
refers
to
0
dB
=
0.775
V,
except
where
specified.
Ifa
VTVM
calibrated
to0dB=1V
is
to
be
used,
appropriate
compensation
should
be
made.
4.
The
load
impedance
for
OUTPUT
terminal
is
50
k-ohms.
5.
The
load
impedance
for
Dolby
Test
Point
is
1
M-ohms
or
more.
6.
While
performing
all
electrical
alignments,
the
INPUT
switch
should
be
placed
in
the
LINE
position,
unless
otherwise
indicated.
7.
All
checks
and
adjustments
should
be
made
with
the
Cabinet
and
the
Front
Panel
removed.
(See
Section
2-1, 2-2)
TEST
EQUIPMENT
REQUIRED
1.
TEAC
test
tape:
For
playback
performance
alignment:
MTT-150:
For
Dolby
level
calibration
MTT-116L:
For
playback
frequency
response
check
For
record
performance
alignment:
MTT-505:
For
record
test
with
BIAS/EO
an
MTT-501:
For
record
test
with
BIAS/EQ
“gn
2.
AF
oscillator:
10
Hz
~
100
kHz
3.
VTVM:
0.1
mV
~300
V
4.
Attenuator
General
Purpose
5.
Distortion
analyzer:
Basic
frequency
400
Hz/1
kHz
6.
Oscilloscope:
General
purpose
7.
Band-pass
filter:
-
1
kHz
narrow
band-pass
type
8.
Test
load
resistor:
|
~
Non
inductive
type
8
ohm/1W
9. Non-inductive driver
10. Head demagnetizer TEAC E-1 or equivalent

4-1. MONITOR PERFORMANCE
NOTE
Place DOLBY NR switch to OUT position for this monitor
circuit alignment procedure.
4-1-1. Specified Input Level Setting
1. Connect an AF oscillator to the LINE IN jacks, through an
attenuator.
2. Connect a VTVM_ between the T.P. (test points) for
VR102/VR202 and ground on the REC/PB amplifier PC
board.
Load a TEAC MTT-505 test tape (blank) on the deck.
Adjust for -25dB on VTVM
(Specified RECORD control setting}
VTVM
—25dB(43.5mv)
OSCILLATOR
Place the deck in the PAUSE mode.
Apply a 400 Hz signal/—9 dB (274 mV) to the LINE IN jacks.
Turn the RECORD controls to obtain the reading of —25 dB
(43.5 mV) on the VTVM. Note the position of the RECORD
control as this is the specified RECORD control setting
referred to in subsequent procedures.
7. Connect the VTVM between the Dolby T.P. (test points) and
the ground on the REC/PB amplifier PC board.
8. Adjust VR102/VR202 to obtain 580 mV (2.5 dB).
oO or oo
4-1-2. Minimum Input Level Checks
9. Turn the RECORD controls fully clockwise.
10. Apply a 400 Hz test tone at minimum input level as listed
below to each input jack.
11. Check for (the specified value of) 580 mV (-2.5 dB) at the
Dolby test points using the VTVM.
INPUT Switch
Position
Input Jacks Minimum Input Level
19 dB +3 dB (61.5 mV ~ 122 mV)
-67 dB +3 dB (0.244niV~0.488mV)
-35 dB +3 dB (9.75 mV ~ 19.4 mV)
LINE IN LINE
Mic MIC/DIN
DIN MIC/DIN
4-1-3. Level Meter Calibration
“12. Set the INPUT Switch to the LINE position.
13. Set the AF oscillator for 400 Hz at —9 dB (274 mV) and set
RECORD controls to specified level. (same as set in 4-1-1)
14. Adjust VR103/VR203 for +3 VU (marked'with “O0”) on
the level meter on the deck.
VTVM
—2.5dB (580mv)
OSCILLATOR
OodoLey TP |
400Hz
ATTENUATOR
RECORD}: Max. Position
Minimum Input Level
DECK under TEST
(PAUSE mode) .
Fig. 27 Test Condition for Minimum Input Level Checks
T~398
14 NOTE:
TP.
(for
VRioz/VR202)
POOLBY
TRI
400Hz
ATTENUATOR
VRio2/VR202,
DECK under TEST
(PAUSE made)
i)
Adjust for -2.5dB on VTVM
VTVM
-2.5dB (S80mv)
OSCILLATOR
vRioz/VReoz
DECK under TEST
(PAUSE mode) T397
Fig.
26
Test
Condition
for
Specified
Input
Level
Setting
OSCILLATOR
Adjust
for
+3VU
on
Level
Meter
VRi03/VR203 + 3vu
LEVEL METER |
RECORD control : Specified Setting
DECK under TEST
{PAUSE mode) TOROS
Fig.
28
Test
Condition
for
Level
Meter
Calibration
400Hr
ATTENUATOR
For actual adjustment/test point locations, see page 21.

4-1-4, Peak Level Indicator Setting
15. Adjust VR106/V.R206 so that the peak level indicator lights
at full intensity when 400 Hz signal at —6 dB (388 mV) (+3 dB
above specified input level) is applied to the deck; and goes ©
off completely when the 400 Hz signal is reduced to —8 dB
(308 mV) (+1 dB above specified input level).
4-1-5. Headphone Output Level Checks
The value should be: -21 dB +2 dB (54.8 mV ~ 86 mV)
NOTE
These
checks
should
be
done
after
setting
the
specified
output
Adjust for PEAK LEVEL indicotor condition as shown on the right
OSCILLATOR * t
ve
TY. lights ot
8 yn KOY> cult intensity
AX
PEAK LEVEL
indicator
7
-e 4---- © goes off completely
ATTENUATOR ;
Si 8
|
|
PEAK LEVEL 7
Indicator Tae
VR206
RECORD control: Specified Setting
DECK under TEST
(PAUSE mode)
INPUT LEVEL (d8)
Fig. 29 Test Condition for Peak Level Indicator Setting
OSCILLATOR VTVM
level. (See 4-2-2.)
1. Connect test equipment to the deck as shown in Fig. 30. An
8 ohm non-inductive resistor should be used as the test load
resistor.
2. Load a TEAC MTT-505 test tape (blank).
3. Place the deck in the PAUSE mode.
4. Apply the 400 Hz signal at —9 dB and set the RECORD con-
trols to the specified setting position. (See steps in 4-1-1.)
5. Measure the level across the test load resistor.
The value should be —21 dB +2 dB (54.8 mV ~ 86 mV).
400Ht
ATTENUATOR
RECORD contro! : Specified Seting
DECK under TEST
(PAUSE mode)
Fig. 30 Test Condition for Headphone Output Level Checks
IMPORTANT
After
completing
alignment
of
the
monitor
circuit,
do
not
disturb
the
specified
input
level
position
of
the
RECORD
controls
unti!
the
remaining
checks
and
adjustments
are
com-
pleted.
“4-2. PLAYBACK PERFORMANCE
NOTE
Set the BIAS and EQ switches to position “2”, and the DOLBY
NR switch to the OUT position for this playback performance
alignment procedure.
4-2-1. Record/Playback Head Azimuth Adjustments
=
Connect an oscilloscope to the OUTPUT jacks as illustrated
in Fig. 31.
Connect a VTVM to either OUTPUT jack.
Load a TEAC MTT-150 test tape on the deck.
Play Dolby tone in the tape.
Make sure that the phase relationship between the 2 signals
(left channel and right) is within 45° on the oscilloscope.
Install a TEAC MT-T-116L test tape.
Play the 10 kHz/—10 GB signal section of the tape.
8. Slowly adjust the azimuth adjusting nut for the maximum
indication on the VTVM.
9. Secure the nut with a drop of tocking paint.
a Pew
PbAg2
Go "oe AS 90°
t
i
'
|
a
i
1
1 ae
1
t
IN PHASE OUT OF PHASE
Fig. 32 Confirming Phase Relationship
NOTE:
180°
OSCILLOSCOPE
DECK
under TEST
T> 389
Head Phase Check Setup
Fig. 31
Adjusting Nut
R/P Head
Fig.
33
Head
Azimuth
Adjustments
Location
For actual adjustment/test point locations, see page 21. 15

4-2-2. Specified Output Level Setting
1. Connect a VTVM between the Dolby T.P. (test points) an
Ground on the REC/PB amplifier PC Board. :
Load a TEAC MTT-150 test tape on the deck.
Play Dolby tone in the tape.
Adjust VR101/VR201 for 580 mV (-2.5 dB) on the VTVM.
Connect the VTVM to the OUTPUT jacks. ~
Turn the OUTPUT controls fully clockwise.
Confirm that the output level is +9 dB + 2 dB (1.73 V ~ 2.74
V).
8. Set the OUTPUT controls for a reading of +3 dB (1.09 V) on
NOP wen
-2.5dB(580mv)
VRioI/VR201
DECK under TEST (PLAY mode)
v
the VTVM. This is the specitied output level.
IMPORTANT
After setting the specified output level, do not disturb the
OUTPUT controls until the remaining adjustments and checks
have been completed.
4-2-3. Level Meter indication Checks
9. After setting the specified output level, make certain that the
indications on the level meters of the deck are +3 VU + 1.5
VU.
4-2-4. Playback Frequency Response Checks
10. Load a TEAC MTT-116L test tape.
11. Play the test tones from 40 Hz up to 10 kHz.
12. Check that the reading obtained on the VTVM is within the
response limits in reference to the 333 Hz/—10 dB signal
section of the tape.
NOTE
If the response does not meet specified response limits, the head
should be checked for accumulated oxide or dirt. Then, if no
dirt is found, the head azimuth should be readjusted.
4-2-5. Signal-to-Noise Ratio Checks
The S/N ratio should be: 47 dB (minimum)
IMPORTANT
Prior to these checks, confirm that the OUTPUT controls are at
specified output level position.
1. Connect a VTVM to the OUTPUT jacks.
2. Place the deck in the PLAY mode with no tape loaded.
3. Read the indication on the VTVM connected to the
OUTPUT jacks. ;
NOTE
Since the polarity of the AC plug has some effect on the S/N
ratio, the plug can be reversed in the wall socket when checking
the S/N ratio. The worse case value should be within the
indicated value above.
Next
set
for
+3dB.
(Specified
OUTPUT
Control
Setting)
OSCILLOSCOPE
DOLBY NR’
VRioi/VR201
DECK
under
TEST
(PLAY
mode
)
aoe
Fig.
34
Test
Condition
for
Specified
Qutput
Level
Setting
OSCILLOSCOPE
T>
389
DECK
under TEST
RESPONSE IN dB
“4 1 i HN al
i
|
250 333 500 1K 2K
FREQUENCY IN Hz
40
50
100°
ak
5K
63K
10K
Fig. 36 Playback Frequency Response Limits
4.
The
VTVM
should
indicate
-44
dB
min.
(4.88
mV
maximum).
5.
This
corresponds
to
a
signal-to-noise
ratio
of
47
dB
(mini-
mum):
difference
between
residual
noise
44
dB
(4.88
mV)
and
the
specified
output
level
+3
dB
(1.09
V).
16 ? NOTE: For actual adjustment/test point locations, see page 21.

4-3. RECORD PERFORMANCE
IMPORTANT
Before making any adjustments of the amplifier, be sure that all
tests in the playback performance section have been accom-
plished and that all adjustments are correct. The playback
performance should be properly adjusted.
NOTE
Place DOLBY NR switch to the OUT position for this record
performance test unless otherwise noted.
4-3-1. Bias Trap Adjustments
The bias trap tank circuit keeps the bias signal from reaching the
record amplifier.
Adjust for minimum reading on VTVM
VTVM
Load a TEAC MTT-505 test tape on the deck.
Place the deck in the PAUSE mode with no signal applied.
Connect a VTVM between the Test Point (at junction of
L103 and C142) and ground. ©
Adjust L103 for a minimum reading on the VTVM.
Connect the VTVM between the Test Point (at junction of
L203 and C242) and ground.
Adjust L203 for a minimum reading on the VTVM.
4-3-2. Bias Adjustments for “1” Position (CrO2 Tape)
R/P HEAD
—-
' N\ Mh
TP, kio3/L203
= { a|
Cia2 /C242
Q107/Q207
T~403
—~ PAUSE mode —
Fig. 37 Bias Trap Adjustment (and T.P.)
OSCILLOSCOPE
1. Load a TEAC MTT-505 test tape on the deck.
2. Connect a VTVM to the OUTPUT jacks. bacilkaren
3. Connect an AF oscillator to the LINE IN jacks, through an
attenuator.
4. Place the BIAS/EQ switches to the ‘'1” positions. i aa.
5. Place the deck in the record mode. DECK
6. Apply 2 tone signals, in turn; a 1 kHz tone at 42 dB (6.15 attenuator MAY under TEST ine ——s SE
mV) and a 10 KHz tone at ~42 dB (6.15 mV). oe Oe, i 2°
7. Rewind and play this recorded section of the tape. 1390
8. Compare the differences between the output level of the 1 Fig. 38 Bias Adjustment Setup
kHz signal and that of the 10 kHz signal on the VTVM.
9. The output level of the 10 kHz signal must be 1 dB below the “f
1 kHz signal level. +4 ae
10. Adjust VC304/V C302, if necessary, to achieve this. us ae
11. Continue the process of the recording-rewinding-playing- roe
adjusting until this difference of 1 dB is obtained. (-30) 0 ~ Sine
{ <3 \kKHr Sed 7
o t aa
z4 es
4-3-3. Bias Adjustments for “2” Position (Regular Tape) B 6 Ss.
te) ‘
12. This adjustment is the same as using the method described in ze ~s S.
4-3-2 with the exceptions of following items. & SS
5 OPTIMUM VALUE
Test tape: MTT-501 o
BIAS/EQ switches: "2" position ie See » aa rll
Adjustments: VC303/V C301 \ BIAS CURRENT ——>
Fig. 39 Bias Current vs. Output Response Chart.
NOTE: For actual adjustment/test point locations, see page 21. 17

4-3-4. Record Level Setting
For CrO2 Tape: : For Regular Tape:
13. Installa TEAC MTT-505 test tape on the deck. 20. Repeat the above procedure, with the following exceptions,
14. Place the BIAS/EQ switches to the ‘1’ positions. for regular tape. ,
15. Apply a 400 Hz test signal at —12 dB (194 mV) to the LINE
IN jacks. Test tape: MTT-501
16. Place the deck in the record mode. BIAS/EQ switches: "2" position
17. Rewind and play this recorded section on the tape. Adjustments: VR104/VR204
18. Adjust VR105/VR205 to obtain 0 dB (0.775 V) on the
19.
VTVM. (Measured at OUTPUT jacks)
Continue __the process of the __ recording-rewinding-
playing-adjusting until this 0 dB (0.775 V) is obtained.
4-3-5. Distortion Checks DISTORTION ANALYZER
For CrO2 Tape:
i
- OSCILLATOR
The distortion factor should be: 3.0% or less.
DECK
under TEST
ATTENUATOR ‘NG
Connect a distortion analyzer to the OUTPUT jacks.
2. Connect an AF oscillator to the LINE IN jacks, through an . : : Tra94
aitannatar: Fig. 40 Distortion Check Setup
3. Load a TEAC MTT-505 test tape on the deck. .
4. Place the BIAS/EQ switches to the ‘'1” positions. For Regular Tape: ;
5. Apply a 400 Hz test tone at —12 dB (194 mV). 10. Repeat the above procedure, with the following exceptions,
6. Place the deck in the record mode. for regular tape.
7. Rewind and play this recorded section of the tape.
- 8. Read the indicated value on the distortion analyzer. Test tape: To
9. The distortion factor should be 3.0% or less. : BIAS/EQ switches: 2" positions
Distortion factor: 2.5% or less
x OSCILLOSCOPE
4-3-6. Overall Frequency Response
For CrO2 Tape:
1.
SVP
~ @
OSCILLATOR
Connect an AF oscillator to the LINE IN jacks, through an
attenuator, and a VTVM to the OUTPUT jacks.
Load a TEAC MTT-505 test tape on the deck.
Place the BIAS/EQ switches to the “1” positions.
Place the deck in the record mode. ;
Apply a test signal from 40 Hz to 12.5 kHz at 42 dB (6.15
mV).
;
.
17390
Rewind
and
play
this
recorded
section of
the tape.
Fig.
41
Overall Frequency
Response
Check
Setup
DECK
under TEST
ATTENUATOR
°"@ @ @°
SO Oe:
Make certain that the reading obtained on the VTVM are I | TEST TAPE:MTT-5O5(BIAS/EQ 1)
ae ma ae m2 {~ —— DOLBY NR OUT
within the response limits. ; il fe ee ery
In case of any deviation in the high frequency range of the \ HI ee aes
. . 2 had t +
response limits, clean the heads and if this cleaning is ant mone
g 4 tH +
ineffective adjust L105/L205. 2 aa
w -2 1
a
u
a
es
#
1
-6 or ute a
P N-,
: il .
a [htt
SO 63 100 125 250 400 500 1K ak SK 63x 10K 125K
FREQUENCY IN Hz
Fig. 42 Overall Frequency Response Limits (for BIAS/EQ 1)
en OP a A SS SR A EP A POF AO TI,
18
' NOTE: For actual adjustment/test point locations, see page 21.

For Regular Tape:
9.- Repeat the above procedure, with the following exceptions,
for regular tape.
MTT-501
"2" positions
40 Hz ~ 10 kHz
L104/L204
Test tape:
BIAS/EQ switches:
Applied frequencies:
Adjustments:
RESPONSE IN 6B
Tot tt re T fey)
TEST TAPE:MTT—501HF(BIAS/EQ 2)
— DOLBY NR OUT
--~ DOLBY NR IN
ean
i
H
Fig.
43
Overall
Frequency
Response
Limits
(for
BIAS/EQ
2)
250
©
400500
1K
4x
5K
6.3K
10K
FREQUENCY IN Hz
4050 63 100 125
4-3-7. Overall Signal-to-Noise Ratio
For CrO2 Tape:
SO Or on
The overall S/N ratio should be: 45 dB (minimum)
Load a TEAC MTT-505 test tape on the deck.
Connect a VTVM to the OUTPUT jacks.
Place the BIAS/EQ switches to ‘’1” positions.
Place
the
deck
in.the
record
mode
with
no
signal
applied.
Rewind
and
play
this
recorded
section
of
the
tape.
Read the indication on the VTVM.
The
VTVM
should
indicate
42
dB
minimum
(6.15
mV
maximum).
This
42
dB
corresponds
to
the
signal-to-noise
ratio
of
45
dB
(minimum):
the
difference
between
residual
noise
of
—42
dB
(6.15
mV)
and
the
specified
output
level
+3
dB
(1.09
V).
For Regular Tape:
9.
4-3-8. Erase Efficiency
The overall S/N ratio should be: 44 dB (minimum)
Repeat the above procedure, with the following exceptions,
for regular tape.
The differences should be: 65 dB (minimum)
NOTE
To
measure
erase
efficiency,
a
1
kHz
narrow
bandpass
filter
should
be
used.
The
test
signal
delivered
from
the
AF
oscillator
should
be
tuned
to
the
filter
used.
,
1.
SEO SY ee ey
Connect
an
AF
oscillator
to
the
LINE
IN
jacks,
through
an
attenuator.
Connect
a
VTVM
to
the
OUTPUT
jacks,
through
a
1
kHz
narrow
bandpass
filter.
Load a TEAC MTT-505 test tape on the deck.
Place the BIAS/EQ switches to the “1” positions,
Place the deck in the record mode.
Apply a1 kHz signal at +7 dB (0.869 V).
Rewind
the
tape
to
the
mid-point
of
the
recording
and
remove
the
signal
from
the
LINE
IN
jacks.
NOTE:
10.
OSCILLOSCOPE
DECK
under TEST
T 369
Fig. 44 Overall S/N Ratio Check Setup
MTT-501
"2" positions
Test tape:
BIAS/EO switches:
The
above
specified
value
44
dB
corresponds
to
the
reading
of
-41
dB
(6.90
mV)
obtained
on
the
VTVM.
That
is,
the
specified
signal-to-noise
ratio
means
the
difference
between
the
residual
noise
and
the
specified
output
level,
+3
dB
(1.09
Vv).
OSCILLATOR
ATTENUATOR
@O@O@:
°
°
10.
11.
12.
DECK
under TEST
Hz FILTER
Es
Fig. 45 Erase Efficiency Check Setup
Place
the
deck
in
the
record
mode
and
record
through
this
previously
recorded
portion
with
no
input
signal
applied.
Rewind
the
tape
to
the
starting
point
of
the
1
kHz
signal
recorded
portion.
:
Play
the
tape
and
read
the
indication
on
the
VTVM
to
obtain
the
output
level
of
both
the
unerased
portion
and
the
erased
portion
of
the
recorded
section.
Compare
the
indication
differences
between
the
2
portions.
The
differences
should
be
65
dB
(minimum).
For
actual
adjustment/test
point
locations,
see
page
21.
19

4-3-9. Channel Separation
The ratio should be: 30 dB (minimum)
NOTE
To
check
cross
talk,
a
1
kHz
narrow
bandpass
filter
should
be
used.
The
test
signal
delivered
from
an
AF
oscillator
should
be
tuned to the filter used.
1.
Connect
an
AF
oscillator
to
the
left
channel
LINE
IN
jack,
through
an
attenuator.
2.
Connect
a
VTVM
to
the
right
channel
QUTPUT
jack,
through
a
1
kHz
bandpass
filter.
ATTENUTOR |
°@4.@@°
Oe @®,
OSCILLATOR
DECK
under TEST
OUTPUT
{R)
IkHz FILTER
Fig.
46
Channel
Separation
Check
Setup
re
Record 30 seconds of a 1 kHz signal.
Rewind
the
tape
to
the
starting
point
of
recording.
Play
the
tape
and
read
the
indication
on
the
VTVM
connected
to
the
right
channel
OUTPUT
jack.
3. Load a TEAC MTT-505 test tape on the deck.
Place the BIAS/EQ switches to 1” positions.
5.
Apply
a
1
kHz
test
tone
at
-9
dB
(274
mV)
into
the
left
channel.
>
4-3-10. Crosstalk between Adjacent Tracks
"The ratio should be: 40 dB (minimum)
=
Connect
an
AF
oscillator
to
the
right
channel
LINE
IN
jack,
through an attenuator.
Connect a VTVM to the right channel OUTPUT jack.
Load a TEAC MTT-505 test tape on the deck.
Place the BIAS/EQ switches to the ‘'1” positions.
Apply
a
125
Hz
test
signal
at
—9
dB
(274
mV)
into
the
right
channel.
Make a recording of 30 seconds of a 125 Hz signal.
7.
Remove
the
MTT-505
test
tape,
turn
it
over
and
replace
it
in
the
deck.
Play
the
tape
back.
8.
While
playing
the
tape,
read
the
indication
on
the
VTVM.
9.
The
VTVM
should
indicate
—37
dB
minimum
(10.9
mV
maximum).
,
ONE
2
4-3-11. Dolhy NR System Efficiency Checks
The variation at 1 kHz should be: 5.5 dB +2.5 dB
The variation at 10 kHz should be: 10 dB +2 dB
1.
Connect
an
AF
oscillator
to
the
LINE
IN
jacks,
through
an
' attenuator.
2. Connect a VTVM to the OUTPUT jacks.
Load a TEAC MTT-505 test tape on the deck.
Place
the
BIAS/EO
switches
to
the
‘1’
positions,
and
the
DOLBY NR switch to the OUT position.
Apply a 1 kHz signal at -29 dB (27.4 mV).
Record this signal.
Rewind the tape to the starting point of the recorded. section.
Play this recorded section of the tape.
While playing the 1 kHz signal, read the indication of the
output level on the VTVM with the DOLBY NR switch at IN
_ and OUT positions.
10.
The
output
level
should
vary
5.5
dB
2.5
dB
between
the
IN
and
OUT
positions.
(The
output
level
in
the
IN
position
should
be
lower
than
the
QUT
position.)
Pe
oom mo
i
20
10.
ATTENUATOR
The
VTVM
should
indicate
-27
dB
minimum
(34.5
mV
maximum).
This
corresponds
to
the
channel
separation
of
30
dB
minimum
(with
reference
to
the
specified
output
fevel
+3
dB,
1.09V).
OSCILLATOR
DECK _
under TEST
T+ 393
Fig. 47 Crosstalk Check Setup
This
corresponds
to
the
adjacent
track
cross
talk
of
40
dB
minimum
{with
reference
to
the
specified
output
level
of
+3
dB,
1.09
V).
NOTE
The
tape
must
be
completly
erased
or
demagnetized
prior
to
this
procedure.
11.
12.
OSCILLATOR
OSCILLOSCOPE
DECK
under TEST
Fig.
48
Dolby
NR
System
Efficiency
C
heck
Setup
Repeat
the
above
procedure
changing
the
applied
test
signal
to
10
kHz
at
39
dB
(8.69
mV).
The
variation
should
be
10
dB
+
2
dB.
(The
output
level
in
the
IN
position
should
be
lower
than
in
the
OUT
position):