Fostex A-2 - Page 14

Then,
thread
the
15
ips
alignment
tape
on
the
recorder
‚ and play the tape.
12
.
Both
meters
should
indicate
O
VU
levels
during
playback
of
the
1
KHz
reference
tone.
If
not,
adjust
the
reproduce
amplifier
level
for
а
0
VU
reading
by
the
REP
LEVEL
pot
(R205,
50KQ,
B).
These
pots
are
accessible
by
removing
the
bottom
plate
of
the
recorder.
.
Similarly,
during
playback
of
the100
Hz
and
10
KHz
tones,
both
meters
should
indicate
levels
specified
for
the
align-
ment
tape.
If
not,
adjust
the
playback
equalization
by
the
REP
EQ
HI
pot
(R204,
10KQ,
B).
(Figure
7).
.
Set
the
INPUT/SYNC/REPRO
selector
to
SYNC
but
all
other
controls
as
set
in
above
Item
2,
and
play
the
align-
ment
tape
again.
.
As
before,
all
meters
should
indicate
O
VU
levels
during
playback
of
the
1
KHz
reference
tone.
If
not,
adjust
the
reproduce
amplifier
level
for
a
0
VU,
in
the
same
way
as
for
above
REPRO
mode
checking
and
adjusting,
by
the
SYNC
LEVEL
pot
(R206,
20К0,
B).
Then,
adjust
the
reproduce
frequency
response
by
the
SYNC
EQ
HI
pot
(R203,
10KQ,
B).
.
Switch
tape
speed
to
LOW
(7-1/2
ips),
reproduce
the
7-1/2
іре
NAB
alignment
tape
and
check
in
same
way
as
for
high
speed
(15
ips).
If
meter
reading
is
off
spec,
set
MONITOR
selector
to
REPRO
and
adjust
reproduce
frequency
response
by
the
REP
EQ
LO
pot
(R202,
20KQ,
B).
Then,
set
the
MONITOR
selector
to
SYNC
and
adjust
the
reproduce
frequency
response
again
by
the
SYNC
EQ
LO
pot
(R201,
20KQ,
B).
.
Set
the
CAL/LINE
OUT
selector
to
LINE
OUT
and
reproduce
the
15
ips
reproduce
alignment
tape.
Adjust
the
OUTPUT
level
control,
on
the
amplifier
trim
panel,
for
a
0
VU
reading
on
the
meter.
NOTE
!:
After
adjusting
the
EQ
pots,
reproduce
the
reference
level
to
check
for
а
0
VU
reading,
апа
if
not,
readjust
the
pois.
2:
Whenever
the
HI
EQ
pots
are
adjusted,
always
check
the
LO
speed
frequency
response
and
readjust
if
necessary.
CHECKING RECORD ALIGNMENT
1. After performing the reproduce check, thread a blank
recording tape on the transport (Ampex 357 or Scotch
227 is recommended) and set speed selector to HIGH (15
ips).
2. Depress all RECORD MODE selectors (ready mode), and
depress both INPUT buttons (INPUT mode).
3. Apply a 1 KHz signal to the recorder inputs at nominal
— 10 dBV level. Both meters should indicate 0 VU. If not,
adjust to 0 VU by the INPUT control knob on the trim
panel. (see Figure 8.)
4. Depress both REPRO buttons of the INPUT/SYNC/REPRO
selectors, put transport in the record mode and adjust the
REC LEVEL pot (R209, 2KQ, B) for a 0 VU meter reading.
OVERALL FREQUENCY RESPONSE CHECK
1. Taking channel L as an example, apply the input signal to
INPUT L jack and connect an AC voltmeter to OUTPUT L.
Then,
put
channel
L
in
the
record
mode,
and
set
the
ІМ-
PUT/SYNC/REPRO selector to REPRO.
Switch
tape
SPEED
selector
to
HIGH,
apply
a
—
20
dBV
(0.1V)
signal
of
40
Hz
through
20
KHz
to
the
INPUT
jack,
put
transport
in
record
mode,
and
check
the
overall
fre-
quency
response.
It
is
in
normal
condition
if,
with
reference
to
400
Hz,
the
response
is
within
+
3
dB
throughout
the
range
of
40
Hz
through
20
KHz.
If
necessary,
adjust
the
REC
EQ
HI
pot
(R211,
2KQ,
B).
Do
the
same
on
channel
R.
2.
Switch
tape
SPEED
to
LOW,
apply
а
—
20
dBV
(0.1V)
signal
of
40
Hz
through
22
KHz
to
the
INPUT
jack,
put
transport
in
record
mode,
and
check
the
overall
frequen-
cy
response.
It is in normal condition if, with reference to 400 Hz, the
response is within +3 dB throughout the range of 40 Hz
through 18 KHz.
If
necessary,
adjust
the
REC
EQ
LO
pot
(R210,
1KQ,
B).
Do
the
same
on
channel
R.
BIAS LEVEL AND RECORD LEVEL
ADJUSTMENTS
Switch
tape
SPEED
to
LOW
and
thread
a
blank
tape
on
the
transport.
Applya
6.3
KHz
signal
of
approximately
—
20
dBV
(0.1V)
to
the
INPUT
jack
and
connect
an
AC
voltmeter
to
the
OUTPUT
jack
corresponding
to
the
above
INPUT
jack.
Switch
the
INPUT/SYNC/REPRO
selector
to
REPRO
and
depress
the
REC
MODE
button
for
the
channel
whose
bías
current
is
to
be
adjusted.
Put
transport
in
record
mode,
and
after
temporarily
rotating
the
BIAS
LEVEL
pot
(R208,
100
КО,
B)
fully
CCW,
slowly
rotate
it
CW
while
watching
the
AC
voltmeter.
Fix
the
pot
when
the
reading
passes
the
peak
and
reaches
4
dB below
peak
level.
After
completing
bias
level
adjustments,
check
the
overall
frequency
response
for
15
ips
and
7-1/2
ips
speeds.