Samsung RCD-750 - Chip Replacement; Precautions, Tools, and Chip Types

3.
Chip
replacement
3-1.
Precaution
for
the
Chip
Replacement
(1)Do
not
touch
the
part
body
directly
with
the
soldering
iron.
ICS,
especially
TSOP,
are
easily
damaged
by
heat.
(2)
Use
care
regarding
soldering
iron
tip
and
avoid
rapidly
heating
parts.
Some
parts
can
be
damaged
by
sudden
heating.
Preheat
the
part
at
about
100°C
for
several
minutes
before
installing
it.
(3)
Use
soldering
tip
temperature
of
about
240°C
or
larger
parts,
use
a
slightly
higher
temperature
(about
280°C).
(4)
The
thin
(0.3mm)
solder
for
miniature
parts
does
not
contain
adequate
flux.
Supplementary
flux
is
thus
needed
in
most
cases.
The
NoteMaster
486S/25N
series
systems
are
manufactured
using
flux
which
can
be
cleaned
by
water
in
the
factory.
When
your
replace
the
part
or
troubleshooting,
use
proper
flux
and
solder
which
can
be
cleaned
by
water.
Soldering
area
will
corrode,
if
proper
flux
and
solder
are
not
used
in
replace.
And
it
may
cause
a
fatal
error
to
the
system.
(5)
Use
care
not
to
damage
the
circuit
pattern,
especially
when
removing.
(6) Because of the many pins, cleanliness of the
pattern
is
extremely
important
after
removing
the IC.
(7) Use care to avoid solder bridges. Remove any
that occurs.
(8) Position the part carefully. This will also affect the
soldering
operation.
Be
very
precise
in
positioning
the
IC.
Soldering
opposite
pins
first
holds
the
IC
in
place
and
makes
soldering
the
other pins easier.
(9) Do not reuse removed parts.
(10)
Check
for
solder
joints,
especially
miniature
parts
with
small
lead.
(11)
A
defective
trimming
resistor
cannot
be
adjusted
externally.
Replace
with
an
ordinary
variable
resistor.
(12)
It
is
important
to
inspect
the
work
with
a
magnifier.
Check
after
installing
(cold
solder
Joints,
etc).
3-2.
Tools
for
the
Chip
Replacement
The
tools
for
the
chip
replacement
are
as
follows:
(1) Thin tip type soldering iron
(2) Small flat-blade tip type soldering iron
(3) Special desoldering tip iron
(4) Airblower unit
(5) Flat Package Pick-up
(6) Flux can be cleaned by water
(7)
0.3mm
thin
solder
can
be
cleaned
by
water
(8)
Desoldering
wire
(9) Tweezers
3-3.
Chip
Resistors
and
Chip
Capacitors
3-3-1.
Kind
jof
the
Part
The
kind
of
chip
resistors
and
chip
capacitors
as
follows
(1) Thick Film Chip Resistors
(2) Carbon Film Chip Resistors
(3) Metal Film Chip Resistors
(4) Chip Ceramic Capacitors
(5) Chip Trimming Resistors
3-3-2. Removing the Part
The
kind
of
chip
resistors
and
chip
capacitors
as
follows
(1) Using two soldering irons:
© Use thin tip soldering irons.
@
Use
soldering
tip
temperature
of
about
280°C
@
Simultaneously
heat
both
ends
of
the
part.
@
While
heating,
grasp
the
part
with
the
tips
of
the
soldering
irons
and
remove
it.
©)
Use
desoldering
wire
to
completely
remove
the
old
solder
from
the
part
location
of
the
board.
©
A
clean
pattern
for
installing
the
new
part
is
very
important.
FIG, 4
3-3-3. Installing the Part
(1)
Clean
the
area
where
the
new
part
is
to
be
mounted.
(2) Apply flux.
(3) Set part correctly into position, prevent it from
shifting.
(4)
Bring
the
soldering
iron
tip
close
to
the
part
contact
without
actually
touching
it.
Melt
thin
(0.3mm)
solder
between
the
tip
and
part
so
that
it
flows
into
the
part
contact.
(5) Check work quality with a magnifier.
mtn