Samsung AM18A1(B1)E09, Service Manual

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5-7
Samsung Electronics
5-3 PCB Inspection
5-3-1 Cautions for Part Replacement
5-3-2 Procedure
The parts should be replaced in the following pro c e d u re .
1 . The human body carries much static elec-
t r i c i t y. Before touching a part for re p a i r,
replacement or the similar purpose, be sure
to touch a grounded metallic portion by
hand to let the static electricity go thro u g h
the matallic portion to the earth.
Espectially when handling any micro com-
puter or IC, carefully remove such static
electricity before touching them.
2 . When repairing any part on a work bench,
be sure to place an insulative sheet on the
bench and always keep the sheet surface
neat without any metal fragments. If any
such fragment touches a part, a secondary
t rouble will possibly be caused in the part.
3. B e f o re replacing any parts, be sure to turn
o ff the power supply. If such replacement is
done with the power supply kept on, an
electric shock, short circuit or destruction of
a part may re s u l t .
4. During replacement or repair of a part, care-
fully handle it : The printed circuit board
has fine lead wires (jumper wires) and
glass-made parts (diode) on its substrate.
So if a circuit board is roughly handled,
such lead wires and parts will be easily bro-
ken or damaged by bending or shock.
5 . When soldering the lead wires of any new
part, be sure to polish them using an emery
paper or the like before solding them.
Since the lead wires of any new part are
c o v e red with an oxide film, solder cannot
a d h e re to the lead wires if not polished.
6 . When soldering any part, care should be
e x e rcised not to apply any high-wattage sol-
dering iron to the part for a long time. Some
parts are of so low a heat resistance that
they may be broken or have the pro p e r t i e s
changed if a soldering iron is so applied
(Otherwise, the pattern may possibly be
separated and raised).
7. The heat of the soldering iron should be
t r a n s f e red to the entire object to be sol-
d e red. If the solder pieces are not well fused
due to insufficient transfer of the heat fro m
the soldering iron, no satisfactory electrical
continuity can be assured even if the sol-
d e red objects appear well connected to each
o t h e r.
8 . The solder used should be limited to a mini-
mum. If excessive solder is used, it will
cause inter-pattern contact, which may
cause malfunction of the circ u i t .
The repair is completed.
Check the operation of the new part.
Replace it with a new part.
Detach the faulty part.
Check for any faulty part.