Korg POLY-61 - VCA and MG Checks; Total Performance Checks

5) RELEASE.
(1) Set to PROGRAM 63 with RELEASE TIME at
15~30sec. Confirm deviation of within 7sec
between 6 voices.
*NOTE: Here RELEASE TIME is the time from
when you play a single key to when you can no
longer hear the sound from the amp. At the same
time, confirm that sustain level does not remain.
(2) Set to PROGRAM 64 and connect foot switch
( ^.GND) to RELEASE jack.
Confirm that RELEASE TIME is about 100msec
when foot switch is OFF and about 5~10sec when
foot switch is ON. This may be judged by ear.
6. VCA check and adjustment.
1) GAIN.
(1) Set to PROGRAM 64 and play C3.
(2) Confirm sawtooth waveform output amplitude of
I.OVp-p (±0.05Vp-p) for all 6 voices.
(3) Adjust VR101~601 (VR103~603) if necessary.
2) MIXING LEVEL.
(1) Eliminate DC01 waveform by connecting PW/PWM
terminal (R6 100k£2 connection point to D1) to
+5V (CN24-2).
(2) Set to PROGRAM 66 and play C3. Confirm
DC02 stepped waveform amplitude of I.OVp-p
(±0.15Vp-p) for 6 voices.
(3) After completion, return PW/PWM to normal
condition.
6. MG check.
1) DCO MODULATION.
(1) Set to PROGRAM 67, play A3 and turn on HOLD.
(2) Check output with tuner; adjust TUNE knob to
obtain ±0 cent reading.
(3) Change PROGRAM from 68 to 71, 72, 73, and
confirm gradual increase in vibrato depth.
(4) At PROGRAM 73 (VIBRATO at maximum), con¬
firm swing from +35~+55 cent to —35~—55 cents.
2) VCF MODULATION.
(1) Set to PROGRAM 74, play A3 and turn on HOLD.
Observe output on oscilloscope.
(2) Change PROGRAM from 74 to 75, 76, 77, and
confirm gradual increase in Fom depth (depth of
riging cycle movement).
(3) At PROGRAM 78, move joy stick to —Y and
confirm same kind of modulation as above.
Maximum depth should be about the same as
PROGRAM 76 (MG VCF = 5). Joy stick SPEED
should be at about 2.
3) SPEED.
(1) Set to PROGRAM 81, play A3 and turn on HOLD.
(2) Confirm MG cycle of 60'~T00msec (Fig-13).
60 ~ 100msec
H-
—41^
0.5V/div, 20msec/div
Fig-13
(3) C hange PROGRAM from 82 to 83, 84, 85, and
confirm gradual slowing of MG speed. At 85
(SPEED = MIN), cycle should be 2.a~3.5sec. Also
confirm no "a" in Fig-14 appearing when HOLD is
released and A3 played. Check for 6 voices.
"a"
60 ~ 100msec
mI
b
0.5V/div, 20msec/div
Fig-14
4) D ELAY.
(1) Set to PROGRAM 86, play C3, and confirm that
DELAY TIME does not affect FcM.
(2) Set to PROGRAM 87 and confirm DELAY TIME
within 0.2~0.4sec.
(3) Set to PROGRAM 88 and confirm DELAY TIME
within 1.2~2.5sec.
7. TOTAL check.
1) OUTPUT LEVEL.
Confirm that output amplitude can be switched 10:1
(± 1 0 %).
NOTE: This will vary with amp input impedance so
test without load.
2) PHONE.
Confirm that headphone volume can be adjusted
from 0 to 10. Also check PHONE OUT with oscillo¬
scope and confirm no oscillation.
3) Backup battery.
Turn off power. Use DVM to check terminals of
KLM-509 (KLM-475) battery and confirm 3.60V~
4.3V.
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