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ELEX K2 (Hohner Stringvox) (r3) Power Supply: Schematic
T. EE13
33 4V
~
240V
~
[1]
19 8V
~
Component numbers are assigned arbitrarily in
the absence of original schematics, except K2-0
terminal numbers which are as on the board,
and the Zener diodes where codes have been
copied from the K4 schematic. (Most
components on that schematic are not
individually numbered.)
M282
F1
F2
2 × T500mA
5
Q3 BC286
+44V
[1]
[2]
1
R3
43R
2
D1–4
R1
1N4003
1K5
C4
3
1m0
25V
C3
D5–8
2m0
1N4003
4
35V
[2]
–26V
[1]
9
10
Wiring sheath colours are shown as found.
(Earlier revisions used different colours.)
It is not certain what the original specification for
capacitors was. The installed components vary.
Rev.2 information received gives C1 as 35V, C3
as 50V, C6 & 7 as 16V and C8 as 2mF.
Q5
2N3055
6
7
Q2 BC286
R4
1K5
VR1
R2
2K2
1K8
DZ1
R8
BZX
33K
79C11V
C1
DZ2
220
BZX
25V
85C15
[3]
Q1
TIP32C
R6
3K0
[1] The + and – bridge outputs should be proportionately
lower with 220V AC in; some K2s were built for 117V
and had different transformer connections; the outputs
would also be different there.
[2] Earlier revisions had fuses on the K2-0 board after the
bridges and did not have the M282 board, but in r3 the
fuses have been moved to the outside of the enclosure.
designed ELEX S.p.A. (Excelsior) c.1975–79
C8
2m2 50V
8
Q4 TIP41A
[4]
C5
R5
2K7
100
35V
C2
R7
R9
220
10K
10K
35V
11
K2-0
[3] The DZ2 Zener voltage seems to be 15 4,
which should make it a BZX 85C15, but the
end of the code is not quite legible.
[4] Q4 seems to have been replaced and may not
be the original specified part. (The K4
schematic had another BC286, which seems
drawn 2024 Electropict
C7
1m0
25V
R10
R12
330R
56R
(5W?)
(5W?)
[5]
R11
120R
1
[6]
5W
+27
+20
+13
C6
1m0
+12
25V
GND
GND
–15
–26
9
to have been used in a K2r1; it also
had BC160b for Q1.)
[5] Earlier revisions had no R12.
[6] Earlier versions had different power
connectors with a different
arrangement of terminals.
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