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Korg SDD-2000 Service Manual page 18

Digital delay

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5) Analog Converter check and adjustment
a) Setting: (any program number OK)
ATTSW
-10
D.TIME
0
LEVEL VR
7
INTENSITY
0
DIRECT VR
0
FREQ.
0
EFFECT
22
TIME x 4
OFF
F.BACK
0
MODE
DELAY
b) Input sine toneburst wave (=Sine Pulse Wave) (level:
10dBm, Freq.: 400Hz, width: 100msec) to Input Jack
and observe EFFECT OUT with oscilloscope.
*l
*2
100 msec
*3
Fig. 3
c) When you cannot get correct waveform as above;
Adjust linearity at *3 with VR3, or adjust VR4 on
KLM-833 to minimize DC drift in part *3 of the wave
form. ("Description of the above figure is almost same
as Service Manual for SDD-1000. Please refer to it.)
(Page 16)
7) VCA check and adjustment
a) Setting: (any program number OK)
ATT SW.
-10
TIME
0
LEVELVR
7
INTENSITY
0
DIRECT VR
0
FREQ.
0
EFFECT
31
TIME x 4
OFF
F.BACK
0
MODE
SAMPLING
b) Input SG
(sine wave of
1KHz, 2.5V
P-P) to
Input
Jack and play sampling.
c) Connect MIDI Keyboard and playback sampling note,
(play any key continuously)
d) Connect oscilloscope (DC 0.2V/div, 20msec/div) to
EFFECT OUT and observe waveform as below.
Key on
NG
Key on
Key on
GOOD
NG
Fig. 4
e) Confirm if the observed waveform is GOOD. If not,
adjust VR2 on KLM-833.
6) Feed back check and adjustment
a) Setting: (any program number OK)
ATTSW
-10
D.TIME
120msec
LEVEL VR
7
INTENSITY
0
DIRECT VR
0
FREQ.
0
EFFECT
22
TIME x4
OFF
F.BACK
30
MODE
DELAY
b) Connect
oscilloscope
(AC
0.5V/div,
0.5msec/div)
to EFFECT OUT and confirm
ringing when input
sineburst wave
(Freq.: 400Hz, width:
100msec)
to
Input Jack.
c) Set parameter value of FEED BACK to 28 and confirm
no ringing when input the same sineburst wave as b).
d) Adjust VR5 not to generate ringing in case ringing
occurs in above c).
e) Confirm if ....
no ringing occurs without any input.
ringing occurs with parameter value of FEED BACK
is even -30±1 and phase changes.
-24-

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