Service manual
8·2. Removing and installing
the
LSI
and chip
components
on
the
FPC
PWB
(When
a defective component
is
known without separating
the
FPC
PWB
from the key
PWB)
(1) Remov
ing
the
LSI
a. Connect the
LSI
soldering tip to the soldering pencil
(see
figure), set the surface temperature of the tool
to
260
o
±S"
C,
and secure it on the
vise
installed on the
workbench.
....
~_·
Tip
of
the
soldering
pencil
So
ldering
pencil
If
it
is
heated above the given temperatlJre, it might
separate the circuit pattern
or
the
FPC
PWB
itself.
The soldering pencil
is
held up to prevent solder, flux,
and
gas
from invading the back
of
the
key
PWB,
where
the key contact pattern. the
LCD
rubber connector,
is
mounted.
b.
Evenly apply a proper amount
of
flux over the leads
of
the LSI, and
fill
up the back side of the chip with solder.
-
17
-
-
PC
- I600
c.
Lift
the
PWB
with your hand and carefully mount it
over
the
leads
of
the
LSI. When
the
solder on the leads
melts after five to six seconds, remove
the
LSI
from the
PYlB
using a tweezers (or a small flat tip screwdriver).
d. Clean away solder fragments remaining on the pattern
side
of
the
LSI
using a solder wick. Then, evenly apply a
thin layer
of
solder over
the
surface.
e. Apply a small amount
of
solder to
the
leads of the new
LSI
, and
so
lder
the
leads with care. Press
the
mold of
the
L
SI
with your finger
tip
while soldering
the
leads .
(2) How to remove and install
the
chip component
a.
Melt both
si
des
of
the chip component using two
soldering pencils
at
the same time. Remove the com-
ponent quickly.
2:"'~~-
Sold";,,,
pencils
Chip
component
b. After the removal
of
the chip component, clean the
pattern with a so
ld
er
wick.
c,
Solder one side of
the
new
chip component.
Le
t it
cool for ten seconds; then solder the other side.