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or circuit, and observe all other safety precautions.
8.
Minimize
bodily
unpackaged replacement ES devices. (Otherwise
harmless motion such as the brushing together of your
clothes fabric or the lifting of your foot from a carpeted
floor can generate static electricity sufficient to damage
an ES device.)
General Soldering Guidelines
1.
Use a grounded-tip, low-wattage soldering iron and
appropriate tip size and shape that will maintain tip
temperature within the range or 500 °F to 600 °F.
2.
Use an appropriate gauge of RMA resin-core
solder composed of 60 parts tin/40 parts lead.
3.
Keep the soldering iron tip clean and well tinned.
4.
Thoroughly clean the surfaces to be soldered. Use
a mall wire- bristle (0.5 inch, or 1.25 cm) brush with a
metal handle.
Do not use Freon propelled spray-on cleaners.
5.
Use the following unsoldering technique
a.
Allow the soldering iron tip to reach normal
temperature. (500 °F to 600 °F)
b.
Heat the component lead until the solder melts.
c.
Quickly draw the melted solder with an anti-static,
suction- type solder removal device or with solder braid.
CAUTION: Work quickly to avoid overheating the circuit
board printed foil.
6.
Use the following soldering technique.
a.
Allow the soldering iron tip to reach a normal
temperature (500 °F to 600 °F)
b.
First, hold the soldering iron tip and solder the
strand against the component lead until the solder
melts.
c.
Quickly move the soldering iron tip to the junction
of the component lead and the printed circuit foil, and
hold it there only until the solder flows onto and around
both the component lead and the foil.
CAUTION: Work quickly to avoid overheating the circuit
board printed foil.
d.
Closely inspect the solder area and remove any
excess or splashed solder with a small wire-bristle
brush.
IC Remove/Replacement
Some chassis circuit boards have slotted holes (oblong)
through which the IC leads are inserted and then bent
flat against the circuit foil. When holes are the slotted
type, the following technique should be used to remove
and replace the IC. When working with boards using the
familiar round hole, use the standard technique as
motions
when
handling
outlined in paragraphs 5 and 6 above.
Removal
1.Desolder and straighten each IC lead in one operation
by gently prying up on the lead with the soldering iron
tip as the solder melts.
2.Draw away the melted solder with an anti-static
suction-type solder removal device (or with solder braid)
before removing the IC.
Replacement
1.Carefully insert the replacement IC in the circuit
board.
2.Carefully bend each IC lead against the circuit foil pad
and solder it.
3.Clean the soldered areas with a small wire-bristle
brush.
(It is not necessary to reapply acrylic coating to the
areas).
"Small Signal "Discrete Transistor
Removal/Replacement
1.
Remove the defective transistor by clipping its
leads as close as possible to the component body.
2.
Bend into a "U" shape the end of each of three
leads remain- ing on the circuit board.
3.
Bend into a "U" shape the replacement transistor
leads.
4.
Connect the replacement transistor leads to the
corresponding leads extending from the circuit board
and crimp the "U" with long nose pliers to insure metal
to metal contact then solder each connection.
Power Output, Transistor Device
Removal/Replacement
1.
Heat and remove all solder from around the
transistor leads.
2.
Remove the heat sink mounting screw (if so
equipped).
3.
Carefully remove the transistor from the heat sink
of the circuit board.
4.
Insert new transistor in the circuit board.
5.
Solder each transistor lead, and clip off excess
lead.
6.
Replace heat sink.
Diode Removal/Replacement
1.
Remove defective diode by clipping its leads as
close as possible to diode body.
2.
Bend the two remaining leads perpendicular y to
5
Copyright ⓒ 2017 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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