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ELEX K2 (Hohner Stringvox) (r3) K2-110 & K2-12 Switching Board: Schematic
Cello
GND
Cello
Cello
Cello
Strings
Strings
GND
Strings
(bass)
(left)
(bass)
(treble)
(treble)
(bass)
(bass)
(left)
(treble)
fader
audio
fader
audio
fader
audio
fader
1
2
3
4
5
6
7
8
R13
47K
C9
C8
C7
S11
220n
220n
220n
f
e
R14 47K
d
c
R15 47K
b
R16 47K
a
dashed lines are traces on the K2-12 board
Full Keyb.
Component codes are assigned arbitrarily in the absence of
documentation, except terminal pins which are numbered as
on the board.
PH – Piano Harpsichord, PHB – Piano Harpsichord Bass
Strings
GND
PHB
PHB
GND
Cello
strings
(treble)
(left)
(bass)
(bass)
(right)
(treble)
treble
audio
audio
audio
Decay
bar
(to treble
on/off
power
/all)
(+20)
9
10
11
12
13
14
C6
220n
S10
S9
f
f
e
e
d
d
c
c
b
b
a
a
Ensemble
Bass
There are two separate ground connections here, connected from
the K2-14 left and right end connectors. They are joined (in r3) in the
M175 board, but also through the ground trace on K2-12 when either
the Full Keyboard switch is on or the Bass switch is off.
+20
Strings
ensmb.
Cello
PHB
Strings
PHB
GND
(treble)
bar
(bass)
(bass)
(bass)
(bass)
(left)
Decay
power
Decay
audio to
Decay
audio
on/off
(+20)
on/off
K2-10
on/off
to K2-9
15 16
17
18
19
20
21
PH(B)
Output
Amplifier
R11 47K
R12 47K
S8
S7
b
b
a
a
Piano
Harpsichord
Cello
Resistors are ±5%, and
⁄
W except where stated.
1
4
Piano
GND
Harps.
+13V
PH(B)
(bass)
(left)
(bass)
from
audio
fader
fader
K2-9
output
pin 6
22
23
24
25
R8
R6
R5
1K0
220K
47K
C4
C2
Q1
R4 56K
BC550B
220p
470n
R7 100K
C3
1 35V
R9 270R
1
⁄
W
2
R10 3K9
C5
220n
S6
S5
S4
b
b
b
a
a
a
Strings
Piano
Harpsichord
designed c.1975–79 ELEX S.p.A. (Excelsior)
drawn 2024 electropict
GND
Harps.
Bass
GND
Piano
GND
(left)
(treble)
audio
(left)
(treble)
(left)
fader
normal
fader
return
2
26
27
2
28
2
C1
1 35V
R1 47K
R3 47K
R2 47K
S3
S2
S1
b
b
b
a
a
a
Cello
Strings
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