Korg POLY-61 - Page 22

3) PW/PWM.
(1) Observe with oscilloscope as in "1" above; confirm
six voices for C3.
(2) Adjust oscilloscope TIME/DIV and confirm rectan¬
gle wave duty ratio of 50~45%. (See Fig-4.)
0.5V/div, 0.2msec/div
50 ~ 45%
< - >
-' I !
Match with
Match with Time/DIV.
knob.
Fig-4
(3) Change PARAMETER 13 (PW/PWM) VALUE one
step at a time from 1 to 7 and confirm that pulse
width becomes gradually narrower.
Confirm that variation between voices is within 2%.
(4) Confirm that at VALUE 7, PW/PWM duty ratio is
3%~10%.
Confirm deviation between voices is within 2%.
NOTE: When duty ratio changes, DC level also
gradually changes and amplitude gradually increases,
reaching about 1.2—1.5 times the original at
VALUE 7.
There is a time constant of several seconds before
amplitude settles down.
(5) Set to PROGRAM 16; raise PW/PWM from 1 to 7
and confirm gradual increase in PWM depth. At 7,
PW maximum should be 45~50% and minimum
should be 3~10%; confirm that it does not exceed
50% or disappear altogether. MG FREQUENCY
may be raised to 2~3.
3. DC02 check.
1) O CTAVE.
(1) Connect PW/PWM CV terminal TP2 (R6 100kS2
connection point to D1) +5V (CN24-2) and confirm
that DC01 waveform no longer appears.
(2) At above setting, connect oscilloscope to IC6 1-pin
(IC3 1 PIN) and observe DC02 waveform.
(3) Confirm change in OCTAVE from 16' to 8' to 4'
when PROGRAM is changed from 17 to 18 to 21.
At the same time, confirm stepped waveform with¬
out abnormalities at each setting. Number of steps
corresponds with number of feet. Amplitude is
about IVp-p.
See Fig-5. Note: Old production units have slightly
different waveforms, as shown in Fig-5 (OLD).
8' 8-steps
AAAA/
8'
nrum
4' 4-steps
mwm
4' 4-steps
rnrnm
Fig-5 (OLD) Fig-5 (NEW)
(4) A t PROGRAM 21, switch PARAMETER 22 (DCO
WAVEFORM) from 0 (OFF) to 1 ([\) and confirm
DC fluctuation is no more than 1.0V.
2) WAVEFORM.
Change PROGRAM from 22 to 23 to 24 and confirm
change from 16' to 8' to 4' waveforms with no
abnormalities (for 6 voices). Amplitude is about
IVp-p.
3) INTERVAL.
Change PROGRAM from 24 to 25 to 26 to 27 to
28 (INTERVAL 1 -> ■ 5) and confirm change to minor
3d, perfect 3d, perfect 4th, and perfect fifth, respec¬
tively (in relation to root note (for 6 voices).
4) DETUNE.
(1) Set to PROGRAM 31, play A3 and check output
with tuner.
(2) Change PARAMETER 24 (DETUNE) from 1
through 6 and confirm pitch changes listed below.
(Only necessary for 1 voice.)
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