Fisher CA-272 - Page 5

RECOMMENDED
TEST
EQUIPMENTS
The
following
test
equipments
are
recommended
to
completely
test
and
align
the
Amplifier:
e
Line
Voltage
Isolation
Transformer
e¢ AC DC Multimeter
e
Accurately
Calibrated
AC
Voltmeter
e
Oscilloscope
(Flat
to
100
kHz
Minimum)
e
Low-Distortion
Audio
Sine-Wave
Generator
e
Harmonic
Distortion
Analyzer
e
Two
(2)
Load
Resistors
8-ohms,
250
Watts
(Minimum Rating)
HARMONIC
DISTORTION
TEST
CAUTION:
Limit
the
following
tests
to
no
more
than
ten
minutes
each.
Use
8-ohm
resistors,
with
a
minimum
power
rating
of
250
watts
when
connecting
a
load
across
the SPEAKERS terminal.
CONTROL SETTINGS:
Unplug
the
AC
power
cord
and
set
the
front
panel
controls
as
follows:
e
GRAPHIC
EQUALIZER
to
center
position.
®
BALANCE
control
to
center
position.
@
POWER
switch
to
OFF
© SPEAKERS switch to SYSTEM-B
FUNCTION switch to AUX
LOUDNESS switch to OFF
SUBSONIC FILTER to OFF
e
VOLUME
control
to
MINIMUM
position
e LEFT CHANNEL DRIVEN
ONE CHANNEL DRIVEN:
1)
Connect
a
low
distortion
audio
generator
to
LEFT
AUX
IN
jack.
Set
generator
frequency
to
1
kHz
ard
output
to
minimum.
2)Connect an 8-ohm load resistor
SPEAKERS
SYSTEM-A
LEFT
and
COM
terminals.
Connect
a
Harmonic
Distortion
Analyzer
and
an
AC
VTVM in parallel across the 8-ohm load.
3)
Connect
the
AC
power
cord
and
set
SPEAKERS
switch
to
SYSTEM-A.
Turn
VOLUME
control
to
MAX.
4)
Increase
generator
output
for
100
Watts
RMS
(28.2
volts
across
the
8-ohm
load).
Harmonic
Distortion
Analyzer
should
measure
0.05
%
distortion
or
less.
5)
Repeat
steps
1
through
4
for
RIGHT
CHANNEL.
BOTH CHANNELS DRIVEN
Connect
8-ohm
load
resistors
across
LEFT
and
RIGHT
SPEAKERS
SYSTEM-A
terminals,
Adjust
generator
output
and
“VOLUME”
control
for
100
watts
at
Left
and
Right
Channels
(28.2
volts
across
the
8-ohm
loads).
Harmonic
Distortion
Analyzer
should
measure
0.05
%
distortion
or
jlessat
each
channel.
CAUTION:
This
precision
high-fidelity
instrument
should
be
serviced
only
by
qualified
personnel,
trained
in
the
repair
of
transistor
equipment
and
printed
ciruiitry.
between