NAD C 425, Service Manual

Page: 10 / 32

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ALIGNMENT PROCEDURES
FM/RDS SECTION
- FM mono: 1kHz, 75kHz devi., 60dB/µV
- FM stereo: 1kHz, 67.5kHz devi., 60dB/µV
Pilot signal 19kHz 7.5kHz devi.
OUTPUTS
- Connect the 47Kohm resistor unless otherwise noted.
Item Step Connection
of instrument
FM SG
output
Stereo
modulator
output
Tuning
frequency
Output
indicator
Adjustment
point
Adjust
for
Remarks
FM
IF/RF
1
Fig.1
99.0MHz
1kHz 75kHz
devi.
65dBf (60dB)
– 99.0MHz
DC voltmeter L941 0±70mV FM MUTE/MODE
switch: ON/AUTO
Repeat the steps
1 to 3 until no
further adjustment
is necessary.
2 AC voltmeter IFT on the
front end Maximum
3
Distortion
analyzer
L942 Minimum
Stereo
Distortion
Fig.2
99.0MHz Ext.
mod. 65dBf
(60dB)
Channel L
or R 1kHz 99.0MHz
Distortion
analyzer
IFT on the
front end
Minimum
FM MUTE/MODE
switch: ON/AUTO
Don’t turn more
than ±180˚
Stereo
Separation
Fig.2
99.0MHz Ext.
mod. 65dBf
(60dB)
Channel L
or R 1kHz 99.0MHz
Oscilloscope
R941
Maximum
separation
Repeat stereo
distortion and
stereo separation
alignment until
THD at minimum
and separation at
maximum.
Distortion
Meter
Minimum
Mute
Level
Fig.1 99.0MHz 18dB – 99.0MHz Oscilloscope R956
Signal
output
RDS Fig.3
99.0MHz Ext.
mod. 65dBf
(60dB)
RDS 2% MOD
– 99.0MHz – – –
Decode
the RDS-
Program station
AM SECTION
AF Modulation: 400Hz, 30%
For AH Version
Step
AM SG
output
Tuning
frequency
Output
indicator
Adjustment
point
Adjust
for
1 – 530kHz
Digital
DC
voltmeter
OSC coil
on RF
block M971
1.35±0.2V
2
600kHz
400Hz 30% mod.
60dB/m
600kHz
AC
voltmeter
RF coil
on RF
block M971
Maximum
3
600kHz
400Hz 30% mod.
60dB/m
990kHz
AC
voltmeter
L972 Maximum
For C Version
Step
AM SG
output
Tuning
frequency
Output
indicator
Adjustment
point
Adjust
for
1 –
522kHz
or
531kHz
Digital
DC
voltmeter
OSC coil
on RF
block M971
1.3±0.2V (522kHz)
1.35±0.2V
(531kHz)
2
600kHz
400Hz 30% mod.
60dB/m
603kHz
AC
voltmeter
RF coil
on RF
block M971
Maximum
3
600kHz
400Hz 30% mod.
60dB/m
999kHz
AC
voltmeter
L972 Maximum