Table of Contents
Advertisement
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 components. ie. 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 bristle wire brush.
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 of 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 outlined.
Removal
Remove solder and straighten each IC lead in one operation by gently prying up on the
lead with the soldering iron tip as the solder melts.
Draw away the melted solder with an anti-static suction-type solder removal device (or
with solder braid) before removing the IC.
Replacement
Carefully insert the replacement IC in the circuit board.
Carefully bend each IC lead against the circuit foil pad and solder it.
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
Remove the defective transistor by clipping its leads as close as possible to the
component body.
Bend into a "U" shape the end of each of three leads remaining on the circuit board.
Bend into a "U" shape the replacement transistor leads.
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
Heat and remove all solder from around the transistor leads.
Remove the heat sink mounting screw (if so equipped).
Carefully remove the transistor from the heat sink of the circuit board.
Insert new transistor in the circuit board.
Solder each transistor lead, and clip off excess lead.
Replace heat sink.
Diode Removal/Replacement
Remove defective diode by clipping its leads as close as possible to diode body.
Bend the two remaining leads perpendicularly to the circuit board.
Observing diode polarity, wrap each lead of the new diode round the corresponding
lead on the circuit board.
Securely crimp each connection and solder it.
Inspect (on the circuit board copper side) the solder joints of the two "original" leads.
If they are not shiny, reheat them and if necessary, apply additional solder.
10
Advertisement
Table of Contents
