oberheim ob-xa servicemanual
TRANSCRIPT
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Service
McUluai
D
D
RF.CEIVED
JUN
6
98
Ans d.:
olyphonic
ynthesizer
PRELIMIN RY
[c L l .,_., T (a l T .\ ~ Pr1 ~f l te U
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7/25/2019 Oberheim OB-XA ServiceManual
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OB
-Xa
T ES
T P
ROC
EDU
RE
[FI
ELD
SE
RVIC
EJ
=-~==================================================================
===
=-==
=
Thi
s p
roc
edu
re w
ill
e
nab
le
t
h e
te
ch
nic i
a n
to c
a l i
b r a
te
th
e
fo
llow
ing
fu
n c t i
on s
:
1
.Po
wer
S
upp
ly
2.
M od
ula
tion
A
sse
mbl
y
3 .
Con
tro
l /P
roce
sso
r boa
rd
4 .V
oic
e
Car
ds
5.M
oth
er bo
ard
Eq
uipm
ent
r
equ
i red
:
D ig
i ta l
V o
ltm
eter
Strobe tune r op tiona l)
Aud
io am
p li
f ie r
w
ith
spe
ake
rs or
h
ead
phon
es
Os
cill
osc
ope
P
OWE
R SU
PPL
Y TE
ST
CMO
S M
EMO
RY
CU
RRE
NT
DRA
IN
E
FOR
E
AP
PLY
IN G
AC
POW
ER
th
e cu r
ren
t d r
a in
of
th
e C
MOS
mem
ory (
651
4's>
i
s
m
eas
ured
.
r1 t
s im
po
rtan
t
no
pow
er
ha
s be
en a
pp l
ied
t o
t
h e
un i
t
f
o r
a
mi
nimu
m o
f 5
m .
te s
b
efo
re m
akin
g
t
h i s
m
eas
urem
en
t. J
Ch
eck
fo r
an
y gr
oun
d con
nec
t ion
s
to
th e
DV
M c
om m
on in
pu t
o the
r
th
an t
h e
one
gro
und
lead
us
ed
fo
r th
e m
eas
ure
men
t.
Loc
ate
th
e
10K r e
s i s
to r
to th
e r
ig h
t of
th
e
ba t t
e ry
on
th e
up
per
co
n tr
o l
b
oar
d.
Me
asur
e
t
h e
vo l
tage
ac
ro s
s
th
e
10k
r e
s i s
to r
I t sho
u ld
be
l e s
s than
5
0m
V.
Th
is
cor
resp
on
ds
to
a cu
rre
n t dr
a in
of
5
uA.
POW
ER
SUPP
LY
CAL
IB R
ATIO
N a
nd
V E R
IF IC
A T I
O N
T
wo vo
lta g
e s
a re
ad j
u s t
ab l
e th
e
-5V
a
nd +15
V s
up
p l ie
s .
L ocate
th e
tr immer
nex t
to
th e le f tm ost
723
vo ltage
regu la to r ;
t
i s
lab led
-5
'. Lo
cat
e t
h e
tri
mm
er n
ext
to
t
h e
r ig
h tm
os t
72
3
vo
ltag
e
re
gu
la to
r ;
t i s
l
a.ble
d +15
.
A
ttac
h th
e
DVM
g
rou
nd lea
d t
o
pin
4 of
c
onn
ecto
r
C (o
n th
e
low
er con
tro
l
b
oar
d) .
+1
5V
A
DJU
STME
NT
A t
tach
th
e D
VM
po s
i t iv
e le
ad
to
p
in of
con
nec
to r
K
(u
pper
con
tro
l bo
ard)
.
Mo
nito
r t h
i s
vo
ltag
e ;
ad
ju s
t th
e
15 V
t
r im
mer
fo r
+1
5.0
00V
+
/-20
mV
.
-5 V
AD
JUST
MEN
T
A
tta
ch
th e
DV
M p
o s i
t iv e
lead
t
o p
in
10o
f c
onn
ect
or
C
(u
pper
mo
t~er
boa
rd>
.
M
oni
tor
th
i s v
o l t
age
; a
d ju
s t t
h e
-SV
trim
me
r fo
r
-5 .
000
0V
+/.-2
0mV
.
j
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Page
2
VOLTAGE VERIFICATION
'
All
v o l t ag es a re
D.C.
u n l e s s
s p e c i f i e d
o t h e r w i se .
Refe r
to t h e
c h a r t
below:
CONTROL BOARD,
upper
and l ower , co n n ec t o r s K A. r e s p e c t i v e l y :
PIN# VOLTAGE
TOLERANCE
----------------.-------------
1
'5 .5Vac
+/-2V
2
+5.0V
+/-250mV
.,..
+5.0V
+/-250mV
4
key
5
+15.0V
+/-20mV
6
+15.0V
+/-20mV
7
gnd
8
gnd
9
-15 .0V
+/-750mV
10
-15 .0V
+/-750mV
MOTHER BOARD, upper and l ower . connec to r D:
PIN# VOLTAGE
TOLERANCE
------------------------------
1
.....
Lo
3
4
5
6
7
8
q
10
-15.0V
key
+15.0V
+15.0V
gnd
gnd
gnd
gnd
-5 .0V
-5.0V
+/-750mV
+/-20mV
+/-20mV
+/-20mV
+/-20mV
UPPER CONTROL BO RD VOLTAGE
VERIFICATION
V e r i fy t h e
+5.6V
s u p p l y
a t
p in 16 of I .C . 145 (4051>. t o l e r a n c e i s
+/-200mV.
Ver i fy
t h e - lOV
s u p p l y
a t p i n
7 of I .C . 149
(4053>.
t o l e r a n c e i s +/ - lV.
LOWER
CONTROL BO RD VOLTAGE
VERIFICATION
V er i f y t h e +5.6V supp ly a t p i n
6
o f
I . C . 4 5
4051>,
t o l e r a n c e s +/-200mV.
V er i f y t h e - lOV s u p p l y a t
p i n
7 o f I .C . 4H3
4053) ,
t o l e r a n c e s + / - tV .
POT BO RD VOLTAGE
VERIFICATION
Two
v o l t a g e s
a r e deve loped on t h e po t board , +5.6V
and
- 5 . 0V .
v e r i f y
t h e
5.6V s u p p l y a t
p i n
16 o f
I . C . 1 5
on t h e pot boa rd . To le rance i s
+/ -350mV.
V er i f y t h e -5 .0V s u p p l y
a t p i n
7 o f I .C . 5 . Tole rance s
+/-500mV
--
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P
ag
e
5
M
e
a
::.
ur
e
t
h
e
v
o
l
ta
g
e
a t
p i
n
9
o
f
c
o
nn
e
c
to
r
C
. T
h
is
v
ol
ta
g
e.
,
w
h
i
ch
s
ho
u
ld
b
,
;. o
o
ov
+
/-
20
m
V
,
s
th
e
be
n
d
c i
r
c
u i
t
o f
f
s e
t
v
o
l t
a
g e
.
T
h
i
s
v
o l
ta
q
e
m
u
st
b
e
a
~y
e
d
t
o
t
h
e
v
o
l
ta
g
e
s
s t
a
te
d
f
o
r
t
h
e
f
o
ll
ow
in
g
t
h
re
e
a
dj
ustments:;;
3
-
U
p
B
en
d
A
d
j
us
tm
en
t
;
M
o
ve
t
h
e
b
en
d
l
e
v e
r
f
u
l l
y
t
o
w
ar
d
s
th
e
f r
o
n
t
o
f
th
e
u
n
i
t .
M
o
n
ito
r
t
h e
vo
l
ta
g
e
a
t
p
i
n
9
o
f
co
n
n
ec
t
or
C
(
lo
w
e
r c
o
n
tr
o
l
bo
a
r
d )
.
A
d
ju
st
th
e
U
p
B
e
nd
t
r i
m
m
e
r
u
n
t i
l
th
e
v
o l
ta
g
e
s
-1
.
00
0
V
+
/-
2m
V
C
+
/
- o f
f
s e
t
>
.
4
-
D
o
w
n
B
e
nd
A
d
ju
s
tm
e
n
t;
M
o
v
e
th
e
b
en
d
le
v
e r
f
u
l l
y
to
w
a
r
d s
t
h
e
ba
c
k
o
f
th
e
u
n
i t
,
m
o
n
it
o
r t
h
e
v
o
l t
a
g
e
a
t
p i
n
9
of
c
on
n
e
c t
o
r
C
.
A
d
ju
s
t
t
h e
D
ow
n
Be
n
d
t r
im
m
e
r
u n
t
i l
th
e
v
o
lt
a
g
e
i s
+
1
.0
0
0V
+/
-2
m
V
(+
/
-
o
f
f s
e
t>
.
5
-
N
a
rr
ow
Be
n
d
A
d
j
us
tm
en
t
:
P
r
e s
s
th
e
N
ar
ro
w
s
w
i
tc
h
,
and
move th e
bend
lev e r
f t1 l ly
towards
t
h
e
f
ro
n
t
of
th
e
u
n
i t
.
M
on
i
to
r
th
e
vo
l
ta
g
e
a
t
p
in
9
of
c
o
n
n
ec
to
r
C
.
A
d
ju
s
t
th
e
N
a
r-
ro
w
B
en
d
tr i
m
m
e
r
u
n
t i
l
th
e
v
o
l t
ag
e
s
-
0 .
1
67
V
+
/
-2
m
V
/
-
o
f f
s
e
t )
.
6
-
U
p
T
r
an
s
p
os
e
A
d
ju
s
tm
e
n
t;
M
e
a
su
r
e
th
e
vo
l
ta
g
e
a
t
p
in
5
of
c
o
n
n
ec
to
r
C.
P
r
e s
s
th
e
U
p T
r
an
s
p
os
e
s
w
i
tc
h
,
-
7/25/2019 Oberheim OB-XA ServiceManual
7/13
P
ag
e
6
T
h
er
e
a r
e
6
t
r i
m
m
er
s
fo
r
c
a l
ib
r
a t
io
n
o
n t
h e
u
pp
p
er
a
nd
lo
w
e
r c
o
n
tr
o l
b
o
a r
d s
.
T
h
ey
a r
e
d
es
c
r i
b e
d
b
e
lo
w
:
D
C
O
ff
se
t
D
AC
S
c
a l
e
L
o
w
er
LF
O
U
pp
er
LF
O
:
L
ow
e
r
P
or
ta
m
e
n t
o
U
pp
e
r Po
r
ta
m
en
to
D
AC
O
F
FS
E
T A
D
JU
ST
M
EN
T
P
re
ss
t
h e
Un
s
io
n
sw
i
tc
h .
P
re
ss
lo
w
C
(
CO
)
.
M
e
as
u
re
t
h e
v
o
lt
ag
e
a
t p
i
n 7
of
IC
#
64
a
nd
ad
ju
s
t
tr i
m
m
er
T
6
n
ea
r
IC
#
35
>
, fo
r
O
O
OO
V
+
/-
2m
V
.
DA
C FU
L
L
S
CA
L
E
AD
JU
S
TM
E
NT
P
re
s
s h
ig
h
C
-
7/25/2019 Oberheim OB-XA ServiceManual
8/13
P
a
ge
7
P
r
e s
s
t
h e
Sp
l
i t
S
w
it
ch
.
T
he
k
ey
b
oa
rd
i
s
s p
l
i t
a t
no
t
e C
2.
P
r
og
ra
m
A
l
t
h
e
bo
tt
om
h
a
l f
o
f
th
e k
ey
b
oa
rd
an
d
p
ro
gr
am
A
i
s
on
th
e
t
op
ha
l
f o
f
th
e
k
1
bo
a
rd
.
H
ol
d
n
o t
e
t
an
d
w
h
ile
l
i s
t e
n
in
g
to
t
h e
o
s
c i
l l
a t
o
~
be
in
g
m
od
u
la
te
d .
a
d
ju
s t
t r
im
m
e
r
T
5 C
l
ow
e
r
b
oa
rd
>
fo
r
a
LF
O
r
a
t e
o
2
-4
Hz
.
is
H
o
ld
no
t
e
C
2
a
n
d w
h
il
e
l i
s t
e n
i
n g
t
o
th
e
o
s
c i
l l
a
t o
r
b
e
in
g
m
o
du
la
te
d
,
ad
j
u s
t
th
e
t
r i
m
m
er
on
th
e
to
p
bo
a
rd
,
(
n
ea
r
IC
#1
4
B>
,
f
o
r a
LF
O
r a
t
e
o
f 2
-
4
Hz
.
D
I
P
S
W
ITC
H
F
U
NC
T
IO
N
O
n
th
e
p
o
t
b
oa
rd
in
s
id
e
th
e
O
B
Xa
i s
a
8
p
o
s i
t io
n
D
IP
s
w
it
ch
. T
h
is
s
w
it
ch
i s
us
e
d
fo
r
vo
ic
e
se
le
c
t i
o n
~
i
t
i s
la
b
le
d
V
O
IC
ES
.
I f
th
e
sw
it
c
h
i
s
do
w
n ( t
h
e
op
en
p
o
s i
t i
o n
)
t
h a
t
v
o i
c
e
i s
o
f f
.
P
o
s i
t io
n
1
i
s
fo
r v
o
ic
e
o
n
e .
po
s
i t
io
n
s
f
o
r v
o
ic
e
tw
o
,
a
nd
s
o
o
n.
PO
RT
A
ME
N
TO
CA
L
IB
RA
T
IO
N
P
u
t u
n
i t
in
to
m
a
nu
a
l.
S
e
t t
h e
f
ro
n
t p
an
el
c
o n
t
ro
ls
a
s
f
o
l lo
w
s
:
P
o
ts
a l
l
f u
l
l
CC
W
e
x
ce
p
t
th
e
f
o l
lo
w
in
g
;
F
i l
t e
r
fr
eq
u
en
c
y
-
F
u
l l
CW
V
C
A
an
d
V
C
F s
u
s t
a i
n
-F
u
l l
C
W
A
l
l
sw
i
tc
h
es
o
f f
ex
c
ep
t
th
e
f
o
l lo
w
i
ng
;
O
SC
1
-
On
W
it
h
th
e
vo
i
ce
s
e l
e c
t
io
n
D
I
P
sw
i
tc
h
tu
r
n
v
o
ic
e s
5 t
h r
o
ug
h
8
o
f
f .
P
re
s
s n
o
te
C
O
4
t i
m
es
th
en
tu
rn
t
h
e
P
o
rt
am
e
n
to
po
t
f
u
l l
CW
P ress
no te
Cl
4
t im es
(3
t im
e
s
f
o r
a
6
v
o
ic
e>
w
h
il
e
l
i s
t e
n
in
g
fo
r
t
h e
am
o
un
t
o
f
p
or
ta
m
en
to
o
n
e
ac
h
vo
i
ce
;
i
e
t
h
e
a
m
ou
n
t o
f
t i
m
e
i
t
t a
k
e
s
th
e
o
s
c i
l l
a
to
r s
t
o ch
an
g
e
fr
o
m o
n
e
p
i t
c h
t
o
th
e
n
e>
:t
. Re
p
ea
t
t
h i
s
p r
oc
e
du
re
of
l
i s
t e
n
in
g
to
t
h e
am
o
un
t
o f
p
or
ta
m
en
to
a
t e
ac
h
oc
ta
v
e (
C2
,
C
3.
C
4
, C
5
)
wh
i
le
a
d
j~
s
t in
g
tr
im
m
e
r
TB
u
n
t i
l th
e
a
m
ou
nt
o
f p
o
rt
am
e
n
to
i s
ap
p
ro
x i
m
a t
e l
y
3 t
o
5
s
ec
on
d
s
p
e
r
o
c
ta
v e
.
U
s
in
g
T
he
D
I
P
s
w
it
ch
tu
rn
vo
ic
e
s
1
th
ro
u
gh
4
o f
f
a
nd
v
o
ic
es
5
t
h r
ou
g
h
8
on
.
Ne
x
t r
e p
e
a
t
th
e
a
b
ov
e
p
ro
ce
d
u r
e
fo
r t
h
e
u
pp
e
r
t r
a
y .
u
s
in
g
tr
im
m
er
T
7
to
ad
ju
s
t
t
h e
am
o
u
nt
o
f
p
o r
ta
m
e
n t
o .
-
7/25/2019 Oberheim OB-XA ServiceManual
9/13
P
ag
e
8
V
O IC
E
CA
RD
CA
LIB
RA
TIO
N
-
-
--
---
--
---
--
--
---
--
---
--
---
--
---
--
--
---
--
---
--
---
--
--
---
--
---
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---
--
---
--
h ,e
fo
l l
o w
in g
eq
u i
pm
en
t
is
re
q u
ire
d
fo
r
c a
l ib
r a t
in
g t
h e
v
o i
ce
c a r
d s
i
n t
h e
DBX
a:
A
ud
io
a m
p l
i f ie
r
w
ith
sp
ea
k e r
s
o
r he
adp
ho
nes
M
ini
t o
M
in
i j
um
per
c
l ip
O
sc
i l lo
s c
o p
e (
o p
t io
n a
l )
T
he
re
a r
e
15
tr i
m m
er
s
or
. t
h e
OB
Xa
v o
ic
e
c a
rd
f
o r
c a
l ib
r a t
io
n ,
th e
y
a r
e :
P
u l
se
w
id
th
:
I n
i t i
a l
f
req
u e
n c
y
C
VCO
l &
V
C0
2)
V
PO
(VC
01
&
V
C0
2>
H
i-
t ra
c k
(
VC
Ol
&
VC
02)
: R
es
ona
nc
e
(2
p o l
e
f i
l t e
r >
:
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i t i
a l
f re
q u
en c
y
(
b o
th
f i l
t e
r s )
VPO
I n
i t i
a l
fr
eq
ue
ncy
- c
e n
te r
(LE
D
ou
t>
All
sw itch p a ram e te rs
o f f ,
u n le s s
s p e c i f i e d
o th e rw ise .
T
he s
w i
tch
s
e t t
i n
g s
f
o l l
o w
:
V
C0
1
Wa
vef
orm
''
T r
ack
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ns
pos
e~
T
e s
t l
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sio
n
-on
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p u
lse
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n
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ow
n
o
c t
av e
-do
wn
-
7/25/2019 Oberheim OB-XA ServiceManual
10/13
P
a
ge
9
V
OL
T
PE
R
O
C
TA
V
E
/IN
I
TI
AL
FR
E
QU
E
N
Y
AD
JU
S
TM
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NT
vc
ri
1
l
H
o
ld
in
g
n
o t
e
C
l
l i
s
t e
n
t o
th
e
o
s
c
i l
l a
t o
r
s
b
e
a t
.
T
u
rn
t
h
e
I n
i t
i a
l
F
.. -
eq
ue
n
cy
tr immer
u n t i l
no
be a ts are
hea rd .
H
o
ld
in
g
no
te
C
2
tu
rn
th
e
V
P
O
t r
im
m
e
r
u n
t
i l
n
o
b
ea
ts
a
r
e
h
ea
rd
.
H
o
ld
in
g
n
o
te
C
l
r
e a
d
ju
s
t
t
h e
I n
i
t i
a l
F
re
q
ue
nc
y
t
r i
m
m
er
.
H
ol
di
ng
no
t
e
C
3
t
u
rn
t
hE
-
V
PO
tr
im
m
e
r u
n
t i
l
n
o
be
a
ts
a r
e
h
ea
r
d .
H
o
ld
in
g
n
o t
e
C
l
r e
ad
j
u s
t th
e
I
n i
t i
a
l
Fr
e
qe
nc
y
t r
im
m
e
r.
H
o
ld
in
g
n
o
te
C4
t
u
rn
t
h e
V
P
O
tr
im
m
e
r
u
n
t i
l
n
o
b
ea
ts
a r
e
he
ar
-d
.
H
ol
di
ng
n
o t
e
Cl
r e
a
d j
u
s t
th
e
I
n
i t
i a
l Fr
-e
qu
e
nc
y
t
r-i
m
m
er
.
Ho
ld
in
g
no
t
eC
5
tu
r
n
th
e
VP
O
t
r im
m
e
r
u
n
t i l
n
o
b
e
a
ts
a
r
e
h
e
a r
d .
Holding
no te
C l
r e ad ju s t t
h e
I n
i
t i
a l
F
r
eq
ue
n
cy
t
ri
mm
e
r-
.
I
t w
i
l l
be
n
ec
e
ss
a
ry
t
o
r
ep
e
a t
t
h e
a
b
ov
e
p
ro
c
ed
u
re
a
fe
w
t
im
e
s
u
n
t i
l
p
ro
pe
r-
t r
a c
k
in
g
o
f
t
h e
o
s
c
i l
l a
t o
r
to
th
e
ke
yb
o
ar
d
i
s o
b
ta
in
e
d .
H
I-
TR
A
C
K
A
D
JU
ST
ME
N
T
O
i:
ta
ve
s
w
it
ch
(o
n
b
en
d
a s
s
y .
)
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p
o
c t
a
v e
V
e
ri
fy
th
e
T
ra
ns
p
os
e
c i
r c
u
i t
s
w
it
h i
n
s p
e
c
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ic
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io
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( s
ee
s
e
c t
io
n
o
n
M
od
u
la
tio
n
A
ss
em
b
ly
C
a
l
ib
ra
t i
o
n )
.
Al
l
o
t
he
r
s
w
i tc
h
es
a
nd
p
o
ts
r
em
a
in
th
e
s
am
e
.
Holding
no te
C5
tu rn th e
Hi-Track
tr immer
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no be.:tts
a
re
he
a
rd
.
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SI
NG
A
S
TR
OB
E
TU
N
ER
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R
OS
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ILL
A
TO
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C
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LI
BR
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TI
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N
T
o u
se
t
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ro
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r
m
e
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g
t
h
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ch
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f
th
e
o
s
c i
l l
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o
r
f
o l
lo
w
th
e
a
bo
ve
p r
oc
e
du
r
e ,
tu
..
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in
g o
n l
y
th
e
v
o
ic
e
c
a
rd
b
e
in
g
c
a
l i
b r
a
te
d
on
.
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ug
th
e
s t
ro
b
e
tu
ne
r
i
n
to
th
e
a
ud
io
o
u
tp
u
t (u
se
th
e
m
on
o
o
u
tp
u
t)
.
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o
n
t
h e
k
e
yb
o
ar
d
w
i
ll
m
a
ke
th
e
f
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s
t
oc
ta
v
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c
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e
ap
pe
a
r-
s ta
ti
o
na
..
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o
n
t
h
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ro
b
e
t
un
e
..-
.
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2
t
h e
s
ec
o
nd
o
c
ta
v e
s
c a
l
e s
to
p
s ,
a
nd
so
o
n.
P
UL
S
E
WI
DT
H
CA
L
IB
RA
T
IO
N
W
i
th
t
h
e
D
IP
s
w
it
ch
tu
rn
o
n
ly
th
e
v
o
ic
e
t
o
b
e
c a
l
ib
r a
t
e d
on
.
P
r
e s
s
n
o
te
C3
and
ad ju s t th e
Pulse
Width ''
tr immer
fo .. -
th e
most
hollow sound.
I f
a
n
o
s
c i
l l
o
s c
o
p e
s
b
ei
ng
us
ed
,
m
on
it
or
-
th
e
ou
tp
u
t o
f
th
e
v
o
ic
e
c
a r
d
a t
p
in
o
f
c
on
n
ec
to
r
G
.
A
dj
us
t
th
e
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u l
se
W
id
th
t
r i
m
m
er
fo
r
a
50
X d
u
ty
c
y
c l
e
.
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p
ea
t
t
h e
a
b
ov
e
V
O
c
a l
ib
r
a t
io
n
fo
r
VC
0
2,
t
u r
n
V
C0
1
-o
f
f~
an
d
tu
rn
V
C
02
-
o
n .
-
7/25/2019 Oberheim OB-XA ServiceManual
11/13
P
a
g
e
1
0
E
N
V
E
L
O
P
E
M
O
D
UL
A
T
I
O
N
C
A
L
I
B
R
A
T
IO
N
T
h
e
f
r
o
n
t
p
a
n
e
l
s
e
t t
i
n
g
s
r
e
m
a
i
n
w ith
exception o f
th e
fo llow ing :
th
e
s
a
m
e
a
s
t
h
e
V
C
O
c
a
l
i
b
r
a
t i
o
n
s
e
t
t i
n
g
s
.
F
i
l t
e
r
M
o
d
u
l
a
ti
o
n
p
o
t
F
-E
N
V
s
w
it
c
h
D
S
C
1 a
n
d
D
S
C
2
-
F
u
l
l
W
-O
N
-O
N
U
si
n
g
t
h
e
D
IP
s
w
it
c
h
t
u
rn
o
n
l
y
th
e
v
o
i
c.
e
to
b
e
c
a
l i
b
r
a
t
e
d
o
n
.
L
i
:
:;
te
n
i
n
g
to
b
o
th
o
s
c
i
l
l a
t
o
r
s
,
a
d
j
u
s
t
t
h
e
F
-
E
N
V
t
r
im
m
e
r
u
n
t
i
l
V
CO
2
s
1
o
c
ta
v
e
h
i
g
h
e
r
t
h
a
n
V
C
O
1
.
FI
L
T
E
R
C
A
L
IB
R
A
T
I
O
N
U
s
in
g
t
h
e
v
o
ic
e
se le c t io n DIP
sw itch
tu rn
th e
vo ice
to
be
ca l ib ra ted
and
a
v
o
i
c
e
to
b
e
u
s
e
d
a
s
a
re
f
e
r
e
n
c
e
,
O
N
.
P
O
L
E
C
A
L
B
R
A
T
I
O
N
S
e
t
t
h
e
f
ro
n
t
p
a
n
e
l
c
o
n
t
r
o
l
s
a
s
f
o
ll
o
w
s:
M
o
d
e
;
M
a
nu
a
l
S
w
i
tc
h
e
s
A
l
l
,
o
f
f
,
e
x
c
e
p
t
t
h
e
f
o
l
lo
w
in
g
:
T
r
a
c
k
-
O
N
N
o
i
s
e
-
O
N
P
o
t
s
;
A
ll
d
o
w
n
e
x
c
e
p
t
th
e
fo llow ing:
R
e
so
n
a
c
e
-
f
u
l
l
W
V
C
A
&
VC
F
S
u
s
t
a
in
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f
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l
l
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as
t
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r
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n
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n
s
p
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a
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)
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te
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t
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g
n
o
t
e
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3
a
l
t
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n
a
t
e
b
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t
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n
t
h
e
r
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fe
r
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n
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e
v
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n
d
t
h
e
v
o
ic
e
t
o
b
e
c
a
l
i
b
r
a
t
e
d
.
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d
j
u
st
th
e
F
i
l t
e
r
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n
i
t
i a
l
F
re
q
u
e
n
c
y
tr
i
m
m
er
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n
t
i
l
t
h
e
ne
w
v
o
i
c
e
s
th
e
s
a
m
e
p
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c
h
a
s
t
h
e
r
e
fe
r
e
n
c
e
.
VOLT
PER
OCTAVE
CALIBRATI
O
N
VPO>
P
l
a
y
in
g
n
o
t
e
C
2,
a
g
a
i
n
a
l
t
e
r
n
a
t
e
b
e
t
w
e
e
n
th
e
r
e
f
e
r
e
n
c
e
c
a
r
d
a
n
d
t
h
e
c
a
r
d
t
o
b
e
c
a
l
ib
r
a
t
e
d
.
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d
ju
s
t
t
h
e
F
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t
e
r
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r
im
m
e
r
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n
t
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c
a
r
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s
a
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p
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c
h
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k
t
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l
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q
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s
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e
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t
.
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l
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in
g
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4
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g
a
in
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a
l
t
e
r
n
a
t
e
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e
t
w
e
e
n
t
h
e
r
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f
e
r
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c
e
c
a
r
d
a
n
d
th
e
c
a
r
d
t
o
b
e
c
a
l i
b
r
a
t
e
d
.
A
d
j
u
st
t
h
e
F
i
l
t
e
r
V
P
O
t
r
im
m
e
r
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n
t
i
l
t
h
e
c
a
r
d
s
t
h
e
s
am
e
p
i
tc
h
a
s
t
h
e
re
f
e
r
e
n
c
e
.
R
e
c
h
ec
k
t
h
e
I n
i t
i
a
l
F
r
e
q
u
en
c
y
a
d
j
u
s
tm
e
n
t
.
-
7/25/2019 Oberheim OB-XA ServiceManual
12/13
P
a
g
e
1
1
2
P
O
L
E
R
ES
O
N
A
N
C
E
C
A
L
IB
R
A
T
IO
N
S
e
t
t
h
e
f r
o
n
t
p
a
n
e
l.
c
o
n
t r
o
l
s
a
s
fo
l
l
o
w
s
:
M
o
d
e
;
M
a
n
u
a
l
S
w
i
t
c
h
e
s ;
A
ll
,
O
F
F
,
e
x
c
e
p
t
t
h
e
f
o
l
lo
w
in
g
:
T
ra
c
k
-
O
N
T
r
an
s
p
o
s
e
s
w
i
t
c
h
-C
e
n
te
r
o
c
t
a
v
e
P
o
t
s
;
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ll
d
o
w
n
(
f
u
l l
C
C
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>,
e
x
c
e
p
t
th
e
f
o
l
l
w
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n
g
:
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e
s
o
n
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c
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f
u
l
l
C
W
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C
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a
nd
V
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u
s
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f
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-
7/25/2019 Oberheim OB-XA ServiceManual
13/13
Page
12
MOTHER BO RD
CALIBRATION
---------------------------------------------------------------------------
Cal i b ra t i n g
c o n s i s t s
of ad j u s t i n g
two d i s t o r t i o n
t r immers .
Turn
t h e f ro n t
panel
volume
co n t ro l
to
3
o c l o c k .
Do not p res s any
keys .
Plug
t h e
amp l i f i e r i n t o
t h e
r i g h t ou t pu t j ack only .
Loca te
t h e two 1 k
t r immers on
t h e r i g h t
end of t h e mother board.
Hold
t h e
Auto-Tune swi tch
down and ad j u s t
t h e
t r immer l ab l ed R'' fo r minimum loudness of t h e thump.
Plug
t h e amp l i f i e r
i n t o
t h e
l e f t ou t pu t
j ack
only . Hold down
t h e
Auto-Tune swi tch and a d j u s t t h e t r immer l a b l e L fo r
a
minimum loudness of
t h e thump.
Repeat t h e above procedure fo r t h e o th e r
mother
board .
CAUTION: BE CAREFUL TO PREVENT EXCESSIVE D.C. FROM REACHING THE SPEAKERS
WHEN
PERFORMING THE
BOVE
PROCEDURE
\