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Co-Operator
MAINTENANCE
4-3
Performance
Evaluation
These
are instructions for
thoroughly checking
the
performance of
the
Co-Operator.
The
evaluation includes
checks of
the
power
supplies,
input
stages,
VCAs,
gate
control
circuits,
VCA
control
circuits,
meters,
high-frequency
limiters,
output
stages,
and
overall
performance.
This procedure
is
useful
in
detecting
and diagnosing problems,
as well as for
checking
routine
performance.
See assembly drawings
in
Section 6
for locations
of components, jumpers, and
test
points.
All
jumpers
and
test
points are located
on
the
main
circuit
board.
Perform
procedures
in
order without skipping
steps.
Equipment
required:
-
Oscilloscope
DC-coupled,
with
at least
5MHz
vertical
bandwidth.
-
Digital
voltmeter
Accurate
to
0.1%.
-
Audio
voltmeter
Accurate
to
2%. Sound
Technology
1
71
OB
or equivalent preferred.
-
Low-distortion
audio
oscillator
With
verified
residual
distortion
below 0.003%.
Sound
Technology
171
OB
or equivalent
preferred.
-
THD
analyzer
With
verified
residual
distortion
below 0.003%.
Sound
Technology
171
0B
or equivalent
preferred.
-
Spectrum
analyzer
with tracking
generator
Tektronix
5L4N
plug-in with
51
1 1
bistable
storage mainframe,
or
equivalent.
Alternatively,
a
sweep
generator
with
50-20,
000Hz
logarithmic
sweep
can be used
with
an
oscilloscope
in
X/Y mode.
1
)
Remove
the top cover.
Remove
the
six
screws
that
hold
the top
cover
in place,
then
lift
off the top cover.
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