NOV
10 1977 SH-2000
GUIDE ON ENGINEERING CHANGES
Details
of
engineering changes are described in
each
section concerned. The
gist
of
them are summarized here
for
quick
comprehension.
1.
VC0-2
IT132
is
used in place
of
µPA41C formerly used
..
These are interchangeable each other..
2.
OP-12
OP-12C
is
used
in
place
of
OP-12B.
The
difference
is
that
R575,
47KS1 on foil side
of
OP-12B
is
brought
onto
parts side
on
OP-12C.
Therefore,
the
foil
pattern
differs slightly each other..
The
two
PCB's are per-
fectly
interchangeable
..
Also, in
recent
products,
2SK30A
GR's
are used
in
stead
of
2SK30A
Y
in
hold
circuit
of
older
products.
In
conjunction
with this change,
R513
and
R514
are
changed
to
100KS1 from 33KS1. When replacing
the
F ET's, change
the
resistors,
too
..
This change has
been made with a view
to
reducing
the
leakage
voltage
..
3.
MOUNTING
SCREW
In
order
to
increase
structural
strength,
two
mounting
screws are
added
in
recent
products
..
One
is
to
secure:
control
unit
(left)
to
side
board
..
The
other
is
to
secure:
keyboard
chassis (right)
to
side
board
..
CHANGES OF
PCB's
SERIAL NO.
VCF-2-+ VCF-2A
*Interchangeable
..
Value
of
R819
on
MX-1
differs
for
each
..
See Circuit Diagram.
Tone
differs slightly
..
PS-14C-+ PS-14C-D
PS-21C-+ PS-21C-D
*Interchangeable
..
578049
578050
608899
608900
4. AR-2, VG-7, MX-1
For
increased reliability,
FET's
2SK44
C and
2SK44
D are changed
to
2SK30A
0
and
2SK30A
Y respec-
tively,
on
PCB's AR-2, VG-7 and
MX-1
of
recent
products.
The
FET's, accordingly
the
PCB's, are inter-
changeable each
other.
5.
PS-14C
- PS-14C-D
IC
830C
used on PS-14C
is
no
longer available
..
Instead µA78M15UC
is
used on PS-14C-D
of
present
products.
In
conjunction
with
this change, R601
and
R602
are changed
to
33S1
from
1
OOS1
of
PS-14C
..
The
two
PCB's are interchangeable
..
Also, interchanging
the
IC's
is
also possible by taking
into
account
that:
1)
the
pins are slightly
different,
and
2) R601 and
R602
values are different.
OP-12
VC0-2
VCF-2
I PS-14C I
B
G
PS-21C
MX-1
OP-12
VC0-2
VCF-2A
I PS-14C I
B
G
PS-21C
MX-1
OP-12
VC0-2
1
VCF-2A
IPS-14C-DI
B G
PS-21C-D
MX-1
.·
1
!@Roland
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