NAD 602 - Alignment Method; Tape Speed; Azimuth; Playback Level

ALIGNMENT METHOD
IMPORTANT
The
tape
path
(heads,
tape
guides,
capstan,
pinch
roller)
should
be
cleaned
and
degaussed
before
alignment.
This
tape
recorder
is
designed
to
work
well
with
a
variety
of
tapes,
however,
maximum
performance
will
be
obtained
with
recommended tapes or similar tape formulations.
Recommended tapes For North America
Type I Maxell UDS-I
Type I Maxell XL-II
Type IV Maxell MX
For Europe-DIN
Maxell UD-I, BASF TP18, R723DG
Maxeil XL-0, Teac MTT-5561
Maxell MX, TDK AC712
Before
adjusting,
switch
DOLBY
NR
off,
and
set
PLAY
TRIM
to
center
position.
DOLBY
NR
level
200nWb/m
=
245mV
RMS
on
testpoints
P201A
(PLAYBACK
and
RECORDING
)
on
Main
PCB;
approximately
930mV at line outputs.
1. TAPE SPEED
Connect one output to Wow and Flutter Meter or Frequency
Counter, Play speed test tape TEAC MTT-111=3kHz or TEAC
MTT-211=3.15kHz and adjust the semi-variable resistor, for
correct reading on Wow and Flutter Meter or Frequency
Counter. (See Fig. A) Tolerance: +/-1%
2. AZIMUTH |
Connect VTVM’s and/or Oscilloscope to outputs. Start play-
ing Azimuth tape TEAC MTT-113 or MTT-114. Rotate azimuth
screw for maximum output and/or maximum and in-phase
on Oscilloscope. Reseal adjustment screw with nail polish or
similar (do not use glue). (See Fig. B)
3. PLAYBACK EQ
THIS ADJUSTMENT tS NOT NEEDED UNLESS THE HEAD
HAS BEEN REPLACED OR REPAIR HAS BEEN DONE IN
HEADAMP CIRCUIT.
Play level / azimuth tape TEAC MTT-256 and adjust R217 (L)
and R218(R) for identical output at 315 / 6300 Hz (MTT-255)
or 250 / 6300 Hz (MTT-256).
Tolerance: +/-0.5dB
4. PLAYBACK HIGH FREQUENCY EQ
THIS ADJUSTMENT SHOULD BE DONE ONLY WHEN HEAD
HAS BEEN REPLACED.
Before adjusting, cut the links J201 to J208. Play the
frequency response tape TEAC MTT-256 or MTT-256U and
check the playback level at 14kKHz. Adjust to the 400Hz level
by connecting the links J201 to J208, as follows:
If itis higher link J205(L) & J206(R).
Links J207(L) & J208(R) will reduce it further.
If level is lower then link J201(L) & J202(R) and/or J203(L) &
J204(R) which will increase the fevei.
Tolerance: +1.5/-0.5dB
5. PLAYBACK LEVEL
Connect VTVM’s to testpoints P201A on Main PCB.
Play Dolby NR level tape TEAC MTT-150 and adjust R233 (L)
and R234{R) for 245mV RMS.
Tolerance: +/-2.5mV RMS.
Output should be approximately 530mV RMS.
6. BIAS TRAP
Insert
a
blank
type
IV
tape
and
start
recording.
Turn
record
level
all
the
way
down.
Connect
VTVM's
and/or
oscilloscope
probes
to
testpoints
P601A
and
adjust
L603
(L)
and
L604
(R)
for
minimum.
Tolerance: Less than 300mV RMS.
7. RECORD LEVEL
Connect
VTVM’s
to
testpoints
P201A
on
Main
PCB.
Insert
a
type
I
tape.
Connect
audio
oscillator
to line
inputs,
turn
record
levels
to
maximum
(clockwise).
Adjust
audio
oscillator
frequency
to
400Hz
and
output
so
that
VIVM’s
read
30-40mvV.
(Use
a
convenient
reference
point
on
the
VTVM’s
)
Reset
tape
counter
to
0
and
release
pause
to
start
recording.
Record
for
approximately
5
seconds,
rewind
to
0
on
tape
counter
and
play
back
while
observing
the
VIVM’s.
The
VTVM's
should
indicate
the
same
level
as
when
the
tape
was
recorded.
Adjust
R601(L)
and
R602(R)
if
necessary
and
repeat
the
record
/
play
procedure
until
the
readings
are
the
same.
Tolerance:
+/-0.5dB
from
record
level.
Less
than
0.5dB
difference
between
channels.
8. BIAS ADJUST TYPE I TAPE (NORMAL)
Leave the connections of the VITVM’s as under 7.
Set audio generator to 400Hz. Set level to -20dB.
Reset
tape
counter
to
0
and
start
recording.
After
5
seconds
change
audio
generator
frequency
to
6.3kHz
(do
not
stop
the
machine
or
change
levels)
and
continue
recording
for
another
3
seconds
Stop
and
rewind
to
0
on
tape
counter.
Play
back
while
observing
VTVM’s.
There
should
be
no
level
difference
between
the
400Hz
and
the
6.3kHz
tone
when
played
back.
If
6.3kHz
is
different
in
level
to
400Hz,
adjust
R663
(L)
and
R664
(R)
and
repeat
the
record
/
play
procedure
until
both
frequencies
play
back
at
same
level.
Tolerance: +/-0.5dB
WARNING:
Greater
tolerance
will
grossly
affect
the
Dolby
NR
tracking
and
especially
the
Dolby
C
tracking.
Record
level
(
step
7)
should
be
checked
and
if
necessary
adjusted.