Stihl BT 131, Инструкция по эксплуатации

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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.
2.4 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 outlined in paragraphs 5 and 6 above.
2.4.1 IC 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.
2.4.2 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 re apply
acrylic coating to the areas).
2.5 "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 remaining 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
.
2.6 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.