c. Qulckly move the soldering iron tip to the junction of theFuse and Conventional Resistor
component lead and the printed circuit foil, and hold itRemoval/Replacement
there only until the solder flows onto and around both the1. Clip each fuse or resistor lead at top of the circuit board
component lead and the foil.hollow stake.
CAUTION: Work quickly to avoid overheating the circuit2. Securely crimp the leads of replacement component around
board printed foil.notch at stake top.
d. Closely inspect the solder area and remove any excess3. Solder the connections.
or splashed solder with a small wire-bristle brush.CAUTION: Maintain original spacing between the replaced
component and adjacent components and the circuit board
IC Remove/Replacementto prevent excessive component temperatures.
Some chassis circuit boards have slotted holes (oblong) through
which the IC leads are inserted and then bent flat against theCircuit Board Foil Repair
circuit foil. When holes are the slotted type, the followingExcessive heat applied to the copper foil of any printed circuit
technique should be used to remove and replace the IC. Whenboard will weaken the adhesive that bonds the foil to the circuit
working with boards using the familiar round hole, use theboard causing the foil to separate from or "lift-off" the board.
standard technique as outlined in parapraphs 5 and 6 above.The following guidelines and procedures should be followed
whenever this condition is encountered.
Removal
1. Desolder and straighten each IC lead in one operation byAt IC Connections
gently prying up on the lead with the soldering iron tip as theTo repair a defective copper pattern at IC connections use the
solder melts.following procedure to install a jumper wire on the copper
2. Draw away the melted solder with an anti-static suction-pattern side of the circuit board. (Use this technique only on IC
type solder removal device (or with solder braid) beforeconnections).
removing the IC.
Replacement1. Carefully remove the damaged copper pattern with a sharp
1. Carefully insert the replacement IC in the circuit boare.knife. (Remove only as much copper as absolutely
2. Carefully bend each IC lead against the circuit foil pad andnecessary).
solder it.2. carefully scratch away the solder resist and acrylic coating
3. Clean the soldered areas with a small wire-bristle brush.(if used) from the end of the remaining copper pattern.
(It is not necessary to reapply acrylic coating to the areas).3. Bend a small "U" in one end of a small gauge jumper wire and
carefully crimp it around the IC pin. Solder the IC connection.
"Small-Signal" Discrete Transistor4. Route the jumper wire along the path of the out-away
Removal/Replacementcopper pattern and let it overlap the previously scraped end
1. Remove the defective transistor by clipping its leads asof the good copper pattern. Solder the overlapped area and
close as possible to the component body.clip off any excess jumper wire.
2. Bend into a "U" shape the end of each of three leads
remaining on the circuit board.At Other Connections
3. Bend into a "U" shape the replacement transistor leads.Use the following technique to repair the defective copper
4. Connect the replacement transistor leads to thepattern at connections other than IC Pins. This technique
corresponding leads extending from the circuit board andinvoloves the installation of a jumper wire on the component
crimp the "U" with long nose pliers to insure metal to metalside of the circuit board.
contact then solder each connection.
1. Remove the defective copper pattern with a sharp knife.
Power Output, Transistor DeviceRemove at least 1/4 inch of copper, to ensure that a
Removal/Replacementhazardous condition will not exist if the jumper wire opens.
1. Heat and remove all solder from around the transistor leads.2. Trace along the copper pattern from both sides of the
2. Remove the heatsink mounting screw (if so equipped).pattern break and locate the nearest component that is
3. Carefully remove the transistor from the heat sink of thedirectly connected to the affected copper pattern.
circuit board.3. Connect insulated 20-gauge jumper wire from the lead of
4. Insert new transistor in the circuit board.the nearest component on one side of the pattern break to
5. Solder each transistor lead, and clip off excess lead.the lead of the nearest component on the other side.
6. Replace heatsink.Carefully crimp and solder the connections.
CAUTION: Be sure the insulated jumper wire is dressed so
Diode Removal/Replacementthe it does not touch components or sharp edges.
1. Remove defective diode by clipping its leads as close as
possible to diode body.
2. Bend the two remaining leads perpendicula y to the circuit
board.
3. Observing diode polarity, wrap each lead of the new diode
around the corresponding lead on the circuit board.
4. Securely crimp each connection and solder it.
5. 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.
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ACEC
