IC Remove/Replacement3. Solder the connections.
Some chassis circuit boards have slotted holes (oblong) throughCAUTION: Maintain original spacing between the replaced
which the IC leads are inserted and then bent flat against thecomponent and adjacent components and the circuit board to
circuit foil. When holes are the slotted type, the following techniqueprevent excessive component temperatures.
should be used to remove and replace the IC. When working with
boards using the familiar round hole, use the standard techniqueCircuit Board Foil Repair
as outlined in paragraphs 5 and 6 above.Excessive heat applied to the copper foil of any printed circuit
board will weaken the adhesive that bonds the foil to the circuit
Removalboard causing the foil to separate from or "lift-off" the board. The
1. Desolder and straighten each IC lead in one operation by gentlyfollowing guidelines and procedures should be followed whenever
prying up on the lead with the soldering iron tip as the solderthis condition is encountered.
melts.
2. Draw away the melted solder with an anti-static suction-typeAt IC Connections
solder removal device (or with solder braid) before removing theTo repair a defective copper pattern at IC connections use the
IC.following procedure to install a jumper wire on the copper pattern
Replacementside of the circuit board. (Use this technique only on IC
1. Carefully insert the replacement IC in the circuit board.connections).
2. Carefully bend each IC lead against the circuit foil pad and
solder it.1. Carefully remove the damaged copper pattern with a sharp
3. Clean the soldered areas with a small wire-bristle brush.knife. (Remove only as much copper as absolutely necessary).
(It is not necessary to reapply acrylic coating to the areas).2. carefully scratch away the solder resist and acrylic coating (if
used) from the end of the remaining copper pattern.
"Small-Signal" Discrete Transistor3. Bend a small "U" in one end of a small gauge jumper wire and
Removal/Replacementcarefully crimp it around the IC pin. Solder the IC connection.
1. Remove the defective transistor by clipping its leads as close as4. Route the jumper wire along the path of the out-away copper
possible to the component body.pattern and let it overlap the previously scraped end of the good
2. Bend into a "U" shape the end of each of three leads remainingcopper pattern. Solder the overlapped area and clip off any
on the circuit board.excess jumper wire.
3. Bend into a "U" shape the replacement transistor leads.
4. Connect the replacement transistor leads to the correspondingAt Other Connections
leads extending from the circuit board and crimp the "U" withUse the following technique to repair the defective copper pattern
long nose pliers to insure metal to metal contact then solderat connections other than IC Pins. This technique involves the
each connection.installation of a jumper wire on the component side of the circuit
board.
Power Output, Transistor Device
Removal/Replacement1. Remove the defective copper pattern with a sharp knife.
1. Heat and remove all solder from around the transistor leads.Remove at least 1/4 inch of copper, to ensure that a hazardous
2. Remove the heat sink mounting screw (if so equipped).condition will not exist if the jumper wire opens.
3. Carefully remove the transistor from the heat sink of the circuit2. Trace along the copper pattern from both sides of the pattern
board.break and locate the nearest component that is directly
4. Insert new transistor in the circuit board.connected to the affected copper pattern.
5. Solder each transistor lead, and clip off excess lead.3. Connect insulated 20-gauge jumper wire from the lead of the
6. Replace heat sink.nearest component on one side of the pattern break to the lead
of the nearest component on the other side.
Diode Removal/ReplacementCarefully crimp and solder the connections.
1. Remove defective diode by clipping its leads as close asCAUTION: Be sure the insulated jumper wire is dressed so the
possible to diode body.it does not touch components or sharp edges.
2. Bend the two remaining leads perpendicular 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.
Fuse and Conventional Resistor
Removal/Replacement
1. Clip each fuse or resistor lead at top of the circuit board hollow
stake.
2. Securely crimp the leads of replacement component around
notch at stake top.
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ACEC
