Marantz 4070 - Performance Testing Details; Maximum Power Output Test; Harmonic Distortion Testing Procedure; Channel Separation Measurement Guide

2.
Set
the
distortion
analyzer
controls
for
voltage
measurements
and
apply
power
to
the
amplifier.
Set
the
VOLUME
control
fully
CCW.
Set
the
SELECTOR
switch
to
CD-
4/AUX
and
the
MODE
switch
to
DISCRETE.
If
the
distortion
analyzer
indicates
more
than
3mV,
refer
to
the
trouble
analysis
section
of
this
manual.
Set
the
VOLUME
control
fully
CW.
If
the
distortion
analyzer
indicates
more
than
3mV,
refer to
the
trouble
analysis
section
of
this
manual.
3.
4.
D. Maximum Power Output
7
2.
3.
Connect
the
audio
oscillator
to
the
CD-4/AUX
input.
Set
audio
oscillator
frequency
to
1
KHz.
Set
SELECTOR
switch
to
CD-4/AUX.
With
the
distortion
analyzer
connected
across
the
output
load
(8-ohm),
set
the
analyzer
on
the
30V
AC
scale.
Turn
the
analyzer
on
and
increase
the
audio
oscillator
output
to
190mV,
and
verify
the
analyzer
indicates
more
than
10.9V.
E. Harmonic Distortion Test
1.
2.
3.
4
a
8.
9.
10.
Set the frequency of the audio oscillator and the distortion analyzer to 20 KHz.
Set the controls of the analyzer for voltage measurement on the 30-volt scale.
Adjust
the
audio
oscillator
output
level
until
the
analyzer
meter
indicates
10.9
volts.
Switch
the
distortion
analyzer
to
Set
Level
—
Manual
mode,
and
adjust
SENSITIVITY
for
full scale reading on 0-1 scale.
Measure
the
total
harmonic
distortion
with
the
analyzer
and
verify
it
is
less
than
0.9%.
NOTE:
Any
parasitic
oscillation
in
the
amplifier
will
be
displayed
on
the
oscilloscope,
when
capacitance
is
switched
into
the
load.
Switch the distortion analyzer back to SET LEVEL MANUAL.
(Do not adjust sensitivity of analyzer.)
Change
the
frequency
of
the
audio
oscillator
and
distortion
analyzer
to
1
KHz.
Adjust
audio
oscillator
output
as
necessary
to
have
a
full
scale
reading
on
the
0-1
scale
on
the
analyzer.
Measure the distortion, verifying it is no greater than 0.9%.
Repeat steps 7 and 8, changing frequency to 40 Hz.
Distortion should be no more than 0.9%.
Check for parasitic oscillations; there should be none.
F. Channel Separation
ue
aOkWN
Set
audio
oscillator
to
20
KHz.
Connect
oscillator
to
front
left
channel
CD-4/AUX
input
only,
with
shorting
plug
(10
Kohm)
in
all
other
channels
CD-4/AUX
input.
Connect
distortion
analyzer
to
front
left
channel
speaker
output
terminals.
Adjust oscillator output until distortion analyzer indicates 0 dB (2.8V).
Measure
RF, LR,
RR
channel
output.
Distortion
analyzer
should
indicate
—30
dB
or
less.
Repeat
step
1
and
2
with
substituted
channel
driving.
If
indication
is
not
less
than
—30
dB,
adjust
input
wires
to
preamp
board
until
reading
is
—30
dB or
less.