Marantz 2240 - Test Equipment Required for Servicing; AM Alignment Procedure

10. TEST EQUIPMENT REQUIRED FOR SERVICING
Table
1
lists
the
test
equipment
required
for
servicing
the
Model
2240
Receiver.
AM Signal Generator
Manufacturer and Model No.
Signal source for AM alignment.
Test Loop
Used with AM signal generator.
FM Signal Generator
Less than 0.3% distorsion
Signal source for FM alignment.
Stereo Modulator
Frequency Counter
Audio Oscillator
Oscilloscope
Less than 0.3% distorsion
Stereo separation alignment and trouble
shooting.
MPX Oscillator adjustment (VCO).
Weston Model CVO-100P, less
than 0.02% residual distortion
is required.
Sinewave and squarewave signal source.
High sensitivity with DC
horizontal and vertical
amplifiers.
Waveform analysis and trouble shooting and
ASO alignment.
VTVM
With AC, DC, RF range
Voltage measurements.
Circuit Tester
4
Trouble shooting.
AC Wattmeter
Simpson, Model 390
Monitors primary power to Amplifier.
AC Ammeter
Commercial Grade (1-10A)
Monitors amplifier output under short circuit
condition.
Line Voltmeter
Variable Autotransformer
(0-140V AC, 10 amps)
Shorting Plug
Commercial
Grade
(0-150V
AC)|
Monitors
potential
of
primary
power
to
Powerstat, Model 116B
amplifier.
Adjusts level of primary power to amplifier.
Use
phono
plug
with
600
ohm
|
Shorts
amplifier
input
to
eliminate
noise
across center pin and shell.
Output Load (8 ohms,
+1% 100W)
Commercial Grade
Output Load (4 ohms,
£1% 100W)
Commercial Grade
Provides 8-ohm load for amplifier output
termination.
Provides 4-ohm load for amplifier output
termination.
Table
1.
Test
Equipment
Required
for
Servicing
11. AM ALIGNMENT PROCEDURE
11.1 AM IF Alignment
1.
Connect
a
sweep
generator
to
the
J153
and
an
alignment
scope
to
the
test
point
B.
2.
Rotate
each
core
of
IF
transformer
L153
for
maximum
height
and
flat
top
symmetrical
response.
11.2 AM Freqeuncy Range and Tracking Alignment
1.
Set
AM
signal
generator
to
515
KHz.
Turn
the
tuning
capacitor
fully
closed
(place
the.
tuning
pointer
at
the
low
end.)
and
adjust
the
oscillator
coil
L152
for
maximum
audio
output.
2.
Set
the
signal
generator
to
1650
KHz.
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
600
KHz
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.
5.
Set
the
generator
to
1400
KHz
and
tune
the
receiver
to
the
same
frequency
and
adjust
both
trimming
capacitors
of
antenna
and
RF
tuned
circuit
for
maximum
output.
nad
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