NAD 7155 - Dyn Sep Adjustments; Synthesizer Frequency

6
14
Increase
FM
generator
level
upwards
from
0
and
adjust
R
167
“ST
SW”
so
that
stereo
light
turns
on
and
audio
outputs,
as
watched
on
VTVM’s
and
oscilloscope,
switches
to
one
channel
only
at
10
uV
input
level.
TOLERANCE +5 uv
NOTE:
When
turning
input
level
down
the
unit
will
switch
into
mono
at
a
lower
level,
typically
7
uV.
Stereo separation.
Set FM generator output to 1000 uV, modulate left channel only.
Adjust R 158 for minimum on right channel VTVM.
Modulate
FM
generator
right
channel
only
and
adjust
R
158
for
minimum
on
left
channel
VTVM.
If
the
minimum
in
step
8
and
9
are
different,
adjust
R
158
so
that
the
readings
are
the
same
in
both
channels.
SPECIFICATION better than 50 dB separation
MPX filter
Turn
off
audiomodulation,
leaving
pilot
tone
only.
Disable
IHF
filter,
or
external
19
kHz
filter.
Check
19/38
kHz
suppression.
SPECIFICATION
more
than
60 dB
If
unit
does
not
meet
specification
adjust
FL
102
“MPX
FILTER”
on
left
channel
and
FL
103
“MPX
FILTER”
on
right
channel
to
minimum
output.
NOTE:
DO
NOT
ADJUST
THE
MPX
FILTERS
UNLESS
NECESSARY,
the
cores
are
brittle
and
break
easily.
Release the DYN SEP DEFEAT switch (out).
DYN SEP ADJUSTMENTS.
Turn
R
256
“DYN
SEP
OFF”,
R
249
and
250
“DYN
SEP”
fully
clockwise.
DYN SEP separation effect.
Observe
output
from
left
channel
with
FM
generator
output
level
1000
nV
and
modulated
1
kHz
left
channel
only.
Reduce
audiomodulation
only
from
stereo
generator
so
that
left
channel
output
is
reduced
by
6
dB
(50%
stereo
modulation).
The 19 kHz pilot signal MUST REMAIN modulated 8 - 10%.
Set
FM
generator
output
to
50
nV
and
adjust
R
249
“DYN
SEP”
for
—30
dB
separation
left
to
right
channel.
TOLERANCE +2dB
Switch
modulation
to
right
channel
only
while
maintaining
the
same
modulation
levels:
Adjust R 250 “DYN SEP” for —30 dB separation right to left channel.
TOLERANCE +2dB
DYN SEP auto defeat level.
Set
generator
output
to
200
uV
and
adjust
R
256
“DYN
SEP
OFF”
so
that
separation
starts
increasing
when
watching
left
channel
VTVM.
Adjust
FM
generator
output
up
and
down
around
200
uV
and
make
sure
switching
occurs
around
200
HV.
TOLERANCE +100 nV — 30 nV
SYNTHESIZER FREQUENCY
Tune
to
a
known
accurate
frequency
source,
i.e.,
broadcasting
station
or
synthesized/digital
display
FM
generator
preferably
in
the
midband
95
-
100
MHz.
Connect DMM across TP 104 (negative) and TP 105 (positive).
Adjust
C
209
“FQ”
so
that
DMM
reads
the
same
as
recorded
in
E
—
7.
TOLERANCE +10mV
R167
TP108