ARP 2600 - VCO Calibration Procedures; VCO Frequency Calibration Steps

108
6.1 THE CALIBRATION
AND
ALIGNMENT PROCEDURES
out-
lined
in
the following
pages
can
be carried out without going inside
the
2600
and
without
using
any
external
test instruments other than
your
own
ears. Adjustments are
made
by
means of
the
semi-fixed
trimmers
recessed
behind
the small holes in the front panel.
Use the
small
screwdriver-supplied
with
your instrument.
If
you are uncertain of
your ability to
perform
any of these
alignments
without help, your
nearest factory authorized
servicing
dis-
tributor will assist
you
or
perform
them
for
you without
charge
within
the warranty period
of 90 days; after that you will be charged for
his
assistance and/or
service.
Note that throughout the alignment procedure the
keyboard
PORTAMENTO,
TUNING, and TONE INTERVAL switches should
always
be
in their
right-hand position.
The PANPOT
slider
may remain
centered.
6.1 1 BEGIN
with
the VCO's. Each oscillator must be set
so
that
its out-
put
frequency
corresponds
at
least
roughly
with the markings
on
the
INITIAL
FREQUENCY
slider
and
so
that it tracks
in unison with
the
other
VCO's over
a wide
range of
frequencies. In addition,
the
square-
wave
output
from
VCO-1 must be adjusted so that it is exactly sym-
metrical.
6.111 VCO FREQUENCY
CALIBRATION.
1
.
Set all
SLIDE CONTROLS
to
their
MINIMUM,
i.e.
down
or
left position.
2.
On the
KEYBOARD, all switches should
be
set to their
RIGHT-HAND
position.
3.
On VCO-1, the FINE
TUNE
slider
should
be
centered,
and
the range switch set to
AUDIO.
4.
Insert
a dummy
plug or the end of a patch cord
into
the
KBDCVjack input to VCO-1
.
5.
Now
set the INITIAL OSCILLATOR FREQUENCY slider
to
the
100Hz
panel marking.
6.
Advance
VCO-1
Input on Filter to maximum;
advance
Filter
INITIAL FILTER FREQUENCY to maximum;
advance
Fil-
ter input
to
Mixer, and Speaker Volume controls, so that
a
tone is audible.