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Teac A-400 - Record Performance Calibration

Teac A-400
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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

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