Korg Trident MK1 User Manual

8.ADJUSTMENT PROCEDURE
Note: This instrument has been precisely adjusted at the factory. Therefore, do not change the position of any variable
resistors other than those necessary for servicing.
1. Power supply (KLM-297)
(1) Use a digital multi-meter to check power supply
leads (possible on any of the circuit boards) which
should measure ±15V (±14.7 — ±15.8V) and ±5V
(±4.7V — ±5.3V).
(2) Check KLM-301 +5V (above ground) directly with a
digital multi-meter and adjust VR-1 to obtain
5.000V (±0.001V).
(3) Also ascertain that the -5V supply is -4.995 —
-5.005V.
2. Key assigner (KLM-300)
(1) Assign mode: Switch away from test position, then
reset before proceeding.
1) At assign mode 1, play one key at a time and
ascertain that the LEDs light up in the order:
Di~D 8 .
2) At assign mode 2, play two or more keys at once,
then release them and ascertain that the LEDs
light up beginning from the position of the last
key released.
(2) KBD SPLIT: Check each section (synthe, brass,
strings) as follows.
1) KBD SPLIT at < t>— all 61 keys sound.
2) KBD SPLIT at ◄ — only lower two octaves
sound.
3) KBD SPLIT at >-only upper three octaves
sound.
4) Check to see that there is a clear and accurate
split between C3 and B2 for all 8 units. If not,
adjust VR-1 as necessary.
3. Programmer (KLM-292)
(1) With EG INT (EG INTENSITY) at 0, adjust VR-1
so that EG INT CV (302-24-4 or 29243-3) is
0.00V (±60mV).
(2) With EG INT at -5, adjust VR-2 so that the EG
INT CV is +5.00V (±60mV).
(3) With EG INT at +5, ascertain that EG INT CV
is -5.00V (±60mV).
(4) Adjust V R-3 if these tolerances cannot be met.
(5) Reset EG INT to standard 0 setting after adjust¬
ment.
(6) PW/PWM CV adjustment
Set VCO 1 scale to 16', waveform to PW, and PW/
PWM to 10. Use a digital multi-meter to ascertain
that PW/PWM CV (301-25-1 or 292-43-6) is 2.9V
(±50mV). Adjust VR-4 if necessary.
4. Synthesizer (K LM-302)
(1) Offset check and adjustment
1) Set VCO waveform to r\, set cutoff frequency
to 0 (and set other controls to standard settings).
Check SY-SIG OUT (302-24-13) with oscillo¬
scope (0.1 sec/cm, 50mV/cm).
2) Play any single key and ascertain that the DC
output pulse is within ±50mV for units 0—7.
3) If tolerances are not met, set assign mode to 2,
and adjust VR-1 for the unit in question.
4) After finishing, return assign mode to 1 and cut¬
off frequency to 10.
(2) VCA check and adjustment
1) Set VCO 1 waveform to r\and check SY-SIG
OUT (302-24-13) with an oscilloscope (1 msec/
cm, 0.65V/cm).
2) Play key C3 and ascertain that sawtooth wave¬
form amplitude is 0.65Vp-p (±0.05V) for units
0-7.
3) If tolerances are not met, adjust VR-4 for the
unit in question.
4) After finishing, set waveform to PW.
(3) Resonance adjustment
1) Set PW/PWM to 10, cutoff freq to 5, and reso¬
nance to 8. Measure cutoff freq CV (302-24-1)
with a digital multi-meter and adjust cutoff freq
and cutoff freq fine to obtain OmV (±10mV).
2) Measure resonance CV (302-24-3) with the multi¬
meter and adjust resonance to obtain 8.00V
(±80mV).
3) Measure SY-SIG OUT (302-24-13) with an
oscilloscope (1 msec/cm, 0.15V/cm).
Play any single key and ascertain that the VCF
waveform amplitude (sine wave) is 0.15Vp-p
(±10mV).
4) If tolerances are not met, adjust VR-3 for the
unit in question.
(4) Cutoff frequency adjustment
1) Set resonance to 10, PW/PWM to 10, and cutoff
freq to about 6.3 (ascertaining that this gives
OmV ±10mV). Measure SY-SIG OUT (302-24-
13) with an oscilloscope (1 msec/cm, O.IV/cm)
and a frequency counter.
2) Play any single key and adjust VR-2 so that the
filter oscillation frequency (measured with
WT-12) is C=523Hz for units 0-7.
3) Adjust cutoff freq and cutoff freq fine to obtain
3.00V (±10mV) for the cutoff freq CV (302-
24-1).
4) Play any single key and adjust VR-7 for units 0—
7 to obtain C=4186Hz for the filter oscillation
frequency.
5) With cutoff freq CV (302-24-1) at OmV (±10mV),
adjust cutoff freq fine to obtain C=523Hz for
the oscillation frequency of unit 0.
6) Repeat steps 2 through 5 as many times as neces¬
sary to reduce deviation to within ±5 cents.
(5) KBD TRACK adjustment
1) Set KBD TRACK to FULL, PW/PWM to 10,
cutoff freq to about 6.3, and resonance to 10.
2) Play G3 and adjust cutoff freq fine to obtain
C=523Hz (measured with WT-12) for the oscilla¬
tion frequency of unit 0.
3) Adjust VR-2 for units 1—7 so that each unit's
oscillation frequency is C=523Hz, under the
same conditions as above.
4) Play G4 and adjust VR-5 for units 0—7 so that
each unit's oscillation frequency is C=1109Hz.
5) Repeat steps 3 and 4 as many times as necessary
to reduce deviation to within ±5 cents.
6) Check from Cl through C6 by ear to make sure
it sounds approximately like a scale. (No need to
use WT-12.)
7) Set KBD TRACK to HALF and check to see
that it changes to a 1/4 scale.
8) After finishing, switch KBD TRACK to OFF.
(6) EG INTENSITY check and adjustment
1) Set cutoff frequency to 0, EG intensity to +5,
PW/PWM to 10, and resonance to 10. Check
SY-SIG OUT with an oscilloscope (20psec/cm,
O.IV/cm) and a frequency counter.
2) Play any single key and ascertain that the oscilla¬
tion frequency for units 0—7 is 5.5kHz—6.0kHz.
If not within these tolerances, adjust VR-6.
3) After finishing, set EG INT to 0, cutoff freq to
10, PW/PWM to 5, and resonance to 0.
(7) EG check and adjustment
1) Set attack to 10 and sustain to 0. Play any eight
keys simultaneously and ascertain that the attack
time is 20—25 seconds. If not within these
tolerances, use a digital multi-meter to measure
the potential difference between the +5V power
supply and the attack common line (the chart
pattern closest to the keyboard side). Adjust
VR-8 in accordance with the chart in figure 1.
2) Set attack to 0, decay to 10, and sustain to 0.
Play any single key and ascertain that the decay
time is 20—30 seconds. If not within these toler¬
ances, use a digital multi-meter to check the
potential difference between the +5V power
supply and the decay common line (the chart
pattern after attack). Adjust VR-9 in accordance
with the chart in figure 1.
3) With attack at 0 and decay at 0, turn sustain
from 0 to 10 and check to see that there is a
smooth change in sustain level for units 0—7.
4) Set attack to 0, decay to 0, and sustain to 0.
With release time at about 5 seconds, there
should be no greater than about 1 second error
between units.
5) After finishing, return release to 0 to return to
the standard setting.
(8) Presets
1) Play keyboard, using piano 1,2, and clav.
2) Based on the data on the following page, check
and adjust test points on the page after next.
Adjust circled points only; others should only be
checked. Adjustment voltages are valid up to
two places.
Figure 1. Attack and decay voltage values vs. temperature.
Temperature
Tolerance: Within ±1mV of value on graph.
( V J
Test
point
PIANO 1
PIANO 2
CLAV
1 VC02.SCALE
+ 1.25 4’
+5 OFF
+5 OFF
2
VCOI.
WAVE FORM
-1.25 PW
-1.25 PW
-1.25 PW
3
^VCOI.SCALE
0 8'
-5 16'
-5 16'
©
PRESET VOL
+2 4
+2 4
-2 2
JD
PW/PWM
-5
-3.95
(+2.6V)
6
KBD TRACK
‘+5 HALF
-5 FULL
0 OFF
7
LFO SPEED
-10 (LOW SPEED)
(D
DETUNE
0
0
0
@
SUSTAIN
-5
-5
-4.3
© RESONANCE
+5
+3.07
+5
©
CUTOFF FREQ
+2.74
+ 1.94
+3.86
©
RELEASE
+0.64
+0.18
-5
DECAY
* 1
-5
-5
©
EG INT
+0.65
-0.66
-0.8
ATTACK
+3.2
+5
+5
16
EG MODE
+5 -A“\-
O: Need adjustment.
Others require check only.
19
KLM-292

Korg Trident MK1 Specifications

General

Brand	Korg
Model	Trident MK1
Category	Electronic Keyboard
Language	English