Sony ST-88 - Disassembly and Replacement: Internal Components; Main Circuit Board Removal; Power Supply Board Removal; Dial Cord Restringing Procedure

«oy
Fig.
2-5.
Front
subchassis
removal
(2)
2-4.
FM
(A-M)
FRONT-END/I-F
AMP/MPX
AND
PREAMPLIFIER
BOARD
REMOVAL
1.
Remove
the
wooden
case
as
described
in
Procedure
2-1.
2.
Unsolder
the
ribbon
antenna
at
the
fm
(a-m)
front-
end/i-f
amp/MPX
and
preamplifier
board
as
shown
in
Fig.
2-6.
3.
Remove
the
rear
panel
in
the
arrow
direction
by
loosening
the
three
screws
(
©
)
as
shown
in
Fig.
2-6.
4.
Loosen
the
two
screws
(
®))
as
shown
in
Fig,
2-4,
antenna,
NX
=
\
fm
(a-m)
front-end/
| i-f amp/MPX and
_” preamplifier board
Fig.
2-6.
Fm
(a-m)
front-end/j-f
amp/MPX
and
preamplifier
board
removal
5.
6.
Remove
the
two
screws
(B))
as
shown
in
Fig.
2-5.
Carefully
remove
the
board
from
the
chassis
taking
care
not
to
break
the
lead
wires.
2-5.
POWER
SUPPLY
BOARD
REMOVAL
1.
Remove
the
wooden
case
as
described
in
Procedure
2-1.
.
Unsolder
the
three
lead
wires
(red,
white
and
black)
connecting
the
power
supply
board
and
the
fm
(a-m)
front-end/i-f
amp/MPX
and
preamplifier
board.
.
Unsolder
the
ribbon
antenna
as
shown
in
Fig.
2-6.
-
Loosen
the
three
screws
(
©)
as
shown
in
Fig.
2-6.
.
Carefully
open
the
rear
panel
in
the
arrow
direction
shown
in
Fig.
2-6
taking
care
not
to
break
the
lead
wires,
.
Remove
the
two
screws
(B
3
x
5)
securing
the
power supply board.
2-6.
DIAL
CORD
RESTRINGING
1,
10.
11.
Remove
the
wooden
case,
front
panel
and
front
subchassis
as
described
in
Procedures
2-1,
2-2
and
2-3.
.
Make
a
loop
of
the
dial
cord
as
shown
in
Fig.
2-7.
.
Make
a
knot
and
hook
a
spring
to.
the
dial
cord
and
then
fasten
the
knot
as
shown
in
Fig.
2-8.
.
Loosen
the
two
screws
securing
the
dial
scale
ass’y
to
the
tuning
drum
shaft
and
remove
the
dial
scale
ass’y.
-
Hook
the
spring
to
the tab
on
the
dial
scale
ass’y
and
string
the
dial
cord
around
the
dial
scale
ass’y
and
the
tuning
shaft
in
numerical
order
as
shown
in
Fig.
2-9
and
2-10.
.
Install
the
dial
scale
ass’y
to
the
tuning
drum
shaft
and
fix
a
dial
scale
set
screw
temporarily.
.
Set
the
AFC
switch
to
OFF.
.
Tune
the
set
to
the
local
fm
station
by
turning
the
tuning shaft.
Loosen
the
dial
scale
set
screw
and
turn
the
dial
scale
ass’y
to
the
position
where
the
fm
pointer
on
the
dial
front
glass
indicates
the
local
fm
station’s
carrier
frequency.
Fix
the
two
dial
scale
set
screws.
Make
sure
that
the
correct
dial
calibration
is
also
done
at
a-m
mode.