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ELEX K2 (Hohner Stringvox) (r3) K2-10 Piano & K2-9 Bass Boards: Schematics
K2-10
+27
8
R1 12K
audio to
Bass output
6
C3
470n
C2
220n
R4
7
100K
GND
7
Q1
BC550B
audio from
Bass attenuator
5
C6 220n
GND
7
R5 3K9
R10 1K0
C7
10 25V
R12 15K
audio to
Bass attenuator
4
R13 100K
R15 47K
2
R17 220K
R18 100K
2
C17 *
GND
2
R21 15K
2
R23 560R
1
⁄
W
2
C14
22 63V
PHB (bass) audio
1
R24 22K
(from K2-110 and/or
Bass Pedal)
C16
470n
Component numbers are assigned arbitrarily in the absence of original
documentation. Terminal numbers are as on the K2-14 board.
Electrolytic capacitors are ±20%. Resistors are ±5%, and
PHB = Piano, Harpsichord, Bass
On an r1 String Orchestra, K2-9 capacitors found for C2 & C30 are 25V, and C16 is 35V.
* C17 was used in earlier revisions and probably in the r3, but may have been removed from
this example. Its value is uncertain, but 470n has been successfully tried as a replacement.
C1
R2
R3
470
1K0
220K
16V
C4
2 2 50V
R8 56K
1
⁄
W
2
C5
220p
R6
100K
C8
2 2 50V
R7 560R
⁄
W
1
2
Q2
BC550B
R9 39K
C9
56n
R14 82K
R11 120K
C12
C11
120n
1 0 50V
R16 82K
C10
470n
R19 47K
C13
120n
Q3
BC550B
R22 39K
R20
220K
C15
R25 56K
4 7
16V
R26 100K
1
⁄
Watt except where stated.
4
K2-9
R8 22K
C1
470p
PHB (bass) audio
10
from K2-110
GND
8
C10
1n2
audio to
Harpsichord (bass)
9
R15 47K
R17 47K
attenuator
GND
8
R19 18K
audio to
Piano (bass)
7
attenuator
R21 220K
+13V out
6
R22 47K
R24 15K
R26 1K0
C16
470 16V
R27
R28 1K0
8K2
R30 15K
+27
5
R32 47K
R33 220K
audio to
Piano (treble)
4
attenuator
R34 18K
GND
2
audio to
Harpsichord (treble)
3
R39 47K
R37 47K
attenuator
C21
1n2
GND
2
PHB (treble or all) audio
1
C29
470p
R45 22K
designed c.1976–79 ELEX S.p.A. (Excelsior)
Q1 BC550B
R1 15K
C2
R2 1K5
22
C5
63V
470n
C4
470n
C3
4 7 16V
C11
2n2
R10 12K
R16 2M2
⁄
W
1
2
C6
R14 10K
R20 82K
2n2
C9
10n
R18 82K
R7 47K
R13 22K
C8
C12
10n
10n
C13
56n
R12 15K
C14
56n
C15
120n
C17
120n
C18
56n
R42 15K
C19
56n
C24
C20
10n
10n
R41 22K
R36 82K
R47 47K
C23
10n
C25
R35 82K
R40 10K
2n2
R38 2M2
1
⁄
W
2
R43 12K
C22
2n2
C31
4 7 16V
C28
R50 100K
470n
C30
C27
R53 1K5
470n
22
63V
R52 15K
Q6 BC550B
drawn 2024 electropict
R6 39K
R4 100K
R3 56K
R5 22K
C7
R9 150K
2n2
Q2
BC550B
R11 39K
R23 39K
Q3
BC550B
R25 150K
R29 150K
Q4
BC550B
R31 39K
R44 150K
Q5
BC550B
C26
R46 150K
2n2
R51 56K
R48
R49 39K
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