BUILD INSTRUCTIONS, CTD.
Now that you’ve stuffed all 3 PCBs
except for the pots and installing ICs,
put all 3 boards through your flux
cleaning procedure. Most people prefer
to use water soluble flux for this.
After cleaning the boards and
thoroughly blowing them off with
compressed air, solder the pots with
“no-clean” solder. Note that 1 pot is a
different value (the 1M). The others are
all 100K linear.
Next, install all the ICs into their sockets
in the correct locations listed on the
build tables for each respective board.
After installing the ICs, assemble the
boards together in the stack as shown in
the explode diagram on page 3. Leave
the front panel off for now.
Power the unit up and if everything went
well, you will have some waveforms and
can move on to calibration.
CALIBRATION
1) Set the controls as follows: VCO1
and VCO2 coarse and fine tune set
to center. PW1 and PW2 set to
center. PWM1, PWM2, FM1, & FM2
set to full CCW. LFO rate to full CW.
2) Monitor VCO1 (left) triangle output
with your DMM or O-Scope and
adjust TRI1 OFFSET trim pot until the
wave is centered about zero
(minimize DC offset value).
3) Monitor VCO1 saw output with your
O-scope and adjust SAW1 SHAPE
trim pot to connect the halves of the
saw.
4) Monitor LFO triangle output with
your DMM or O-scope and adjust
the LFO TRI OFFSET trim pot to
center the wave about zero.
5) Monitor LFO square output with your
DMM or O-scope and adjust LFO
SQ OFFSET trim pot to center the
wave about zero.
6) Clip your O-scope or DMM probe
onto the pad on the upper right
corner of PCB-C and adjust TRI2
OFFSET trim pot to center the wave
about zero.
7) Monitor VCO2 saw output with your
O-scope and adjust the SAW2
SHAPE trim pot to connect the halves
of the saw.
8) Plug in your 1 V/OCT CV source to
the left 1 V/OCT jack and plug the
VCO’s sawtooth wave into your
tuning app or O-scope. Hit C1 and
tune the VCO to C1 (32.7Hz). Hit
C3 and adjust VCO1 V/OCT trim to
tune to C3 (130.81Hz). Repeat this
until no further improvements can be
made. Hit C7 and adjust VCO1 HF
TRIM pot to correct any HF flatness.
9) Repeat (8) for VCO2.
Now install the LEDs, front panel. A note
about LEDs: It is recommended that you
use high-brightness type LEDs that will
look good with a resistor value of
4.7KOhm or higher. If the oscillating
currents for lighting the LFO LED are
