Teac A-300 - Recording Performance Adjustments; Bias Trap, Record Bias, and Record Level

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