Marantz 4270 - AM Alignment Frequency Range and Tracking; AM Alignment Signal Strength Meter; Marantz 4270 FM Alignment Procedure

18.2 AM Frequency Range and Tracking Alignment
Ps
2,
3.
4,
5.
6.
Set AM signal generator to 525KHz. Turn the tuning capacitor fully closed (place the
tuning pointer at the low end.) and adjust the oscillator coil L152 for maximum audio output.
Set the signal generator to 1650KHz. Place the tuning pointer in the high frequency end
and adjust the oscillator trimmer on the oscillator tuning capacitor for maximum audio
output.
Repeat the step 1 and 2 until no further adjustment is necessary.
Set the generator to GOOKHz and tune the receiver to the same frequency and adjust a slug
core of AM ferrite rod antenna and RF coil L151 for maximum output.
Set the generator to 1400KHz and tune the receiver to the same frequency and adjust both
trimming capacitors of antenna and RF tuned circuit for maximum output.
Repeat the step 4 and 5 until no further adjustment is necessary.
Note: During tracking alignment reduce the signal generator output as necessary to avoid AGC
action.
18.3 AM Signal Strength Meter Alignment
Set an AM'signal generator to 1000KHz at 74dB/m, and adjust R152 so that the signal strength
meter may read 80% of the full scale.
19. FM ALIGNMENT PROCEDURE
1.
2.
Connect a FM signal generator to the FM ANTENNA terminals and a oscilloscope and an
audio distortion analyzer to the TAPE OUTPUT jacks on the rear panel.
Set the FM SG to 87.5MHz and provide about 3 to 5uV. Place the tuning pointer at the low
frequency end by rotating the tuning knob and adjust the core of oscillator coil L104 to
obtain maximum audio output.
Set the FM SG to 108.5MHz and provide about 3 to 5uV output. Rotate the tuning knob
and place the tuning pointer at the high frequency end and adjust the trimming capacitor
C106 for maximum output.
Repeat the step 2 and 3 until no further adjustment is necessary.
Set the FM SG to 90MHz and tune the receiver to the same frequency. Decrease signal
generator output until the audio output level decreases with the decreasing generator output.
Adjust the antenna coil L101, RF coil L102 and L103 and IF transformer L105 for minimum
audio distortion.
Set the FM SG to 106MHz and tune the receiver to the same frequency. Adjust the trimming
capacitor C102, C104 and C105 for minimum distortion.
Adjust the secondary core (upper) of discriminator transformer L201 so that the center tuning
meter pointer indicates its center at no signal applied. Set the FM SG to 98MHz and increase
its output level to 1 KuV and tune the receiver to the same frequency so that the center
tuning meter pointer indicates its center. Adjust the primary core (lower) of L201 for
minimum distortion.
Set the FM SG to 98MHz at 100KuV, and adjust R374 so that the signal strength meter
may read 90% of the full scale.
19.1 Stereo Separation Alignment
1.
2
Set
the
FM
SG
to
provide
1
KuV
at
98MHz.Tune
the
receiver
to
the
same
frequency
so
that
the
center
tuning
meter
pointer
indicates
its
center.
Turn the FM SG modulation off (with the pilot signal turned off), connect a frequency
counter‘to test point J310, and adjust R311 so that the frequency counter may precisely
read 1900KHz.
Modulate the FM SG with stereo composite signal consisting of only subchannel signal (of
course a pilot signal must be included).
Adjust the trimming resistor R301 for maximum and same separation in both channels.
10