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IC Remove/Replacement
IC Remove/Replacement
Some chassis circuit boards have slotted holes (oblong) through
Some chassis circuit boards have slotted holes (oblong) through
which the IC leads are inserted and then bent at against the cir
which the IC leads are inserted and then bent at against the cir
-
-
cuit foil. When holes are the slotted type, the following technique
cuit foil. When holes are the slotted type, the following technique
should be used to remove and replace the IC. When working with
should be used to remove and replace the IC. When working with
boards using the familiar round hole, use the standard technique
boards using the familiar round hole, use the standard technique
as outlined in paragraphs 5 and 6 above.
as outlined in paragraphs 5 and 6 above.
Removal
Removal
1. Desolder and straighten each IC lead in one operation by
1. Desolder and straighten each IC lead in one operation by
gently prying up on the lead with the soldering iron tip as the
gently prying up on the lead with the soldering iron tip as the
solder melts.
solder melts.
2. Draw away the melted solder with an anti-static suction-type
2. Draw away the melted solder with an anti-static suction-type
solder removal device (or with solder braid) before removing
solder removal device (or with solder braid) before removing
the IC.
the IC.
Replacement
Replacement
1. Carefully insert the replacement IC in the circuit board.
1. Carefully insert the replacement IC in the circuit board.
2. Carefully bend each IC lead against the circuit foil pad and
2. Carefully bend each IC lead against the circuit foil pad and
solder it.
solder it.
3. Clean the soldered areas with a small wire-bristle brush.
3. Clean the soldered areas with a small wire-bristle brush.
(It is not necessary to reapply acrylic coating to the areas).
(It is not necessary to reapply acrylic coating to the areas).
"Small-Signal" Discrete Transistor
"Small-Signal" Discrete Transistor
Removal/Replacement
Removal/Replacement
1. Remove the defective transistor by clipping its leads as close
1. Remove the defective transistor by clipping its leads as close
as possible to the component body.
as possible to the component body.
2. Bend into a "U" shape the end of each of three leads remaining
2. Bend into a "U" shape the end of each of three leads remaining
on the circuit board.
on the circuit board.
3. Bend into a "U" shape the replacement transistor leads.
3. Bend into a "U" shape the replacement transistor leads.
4. Connect the replacement transistor leads to the corresponding
4. Connect the replacement transistor leads to the corresponding
leads extending from the circuit board and crimp the "U" with
leads extending from the circuit board and crimp the "U" with
long nose pliers to insure metal to metal contact then solder
long nose pliers to insure metal to metal contact then solder
each connection.
each connection.
Power Output, Transistor Device
Power Output, Transistor Device
3. Solder the connections.
3. Solder the connections.
CAUTION: Maintain original spacing between the replaced
CAUTION: Maintain original spacing between the replaced
component and adjacent components and the circuit board to
component and adjacent components and the circuit board to
prevent excessive component temperatures.
prevent excessive component temperatures.
Circuit Board Foil Repair
Circuit Board Foil Repair
Excessive heat applied to the copper foil of any printed circuit
Excessive heat applied to the copper foil of any printed circuit
board will weaken the adhesive that bonds the foil to the circuit
board will weaken the adhesive that bonds the foil to the circuit
board causing the foil to separate from or "lift-off" the board. The
board causing the foil to separate from or "lift-off" the board. The
following guidelines and procedures should be followed whenever
following guidelines and procedures should be followed whenever
this condition is encountered.
this condition is encountered.
At IC Connections
At IC Connections
To repair a defective copper pattern at IC connections use the
To repair a defective copper pattern at IC connections use the
following procedure to install a jumper wire on the copper pattern
following procedure to install a jumper wire on the copper pattern
side of the circuit board. (Use this technique only on IC connec-
side of the circuit board. (Use this technique only on IC connec-
tions).
tions).
1. Carefully remove the damaged copper pattern with a sharp
1. Carefully remove the damaged copper pattern with a sharp
knife. (Remove only as much copper as absolutely necessary).
knife. (Remove only as much copper as absolutely necessary).
2. carefully scratch away the solder resist and acrylic coating (if
2. carefully scratch away the solder resist and acrylic coating (if
used) from the end of the remaining copper pattern.
used) from the end of the remaining copper pattern.
3. Bend a small "U" in one end of a small gauge jumper wire and
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.
carefully crimp it around the IC pin. Solder the IC connection.
4. Route the jumper wire along the path of the out-away copper
4. Route the jumper wire along the path of the out-away copper
pattern and let it overlap the previously scraped end of the
pattern and let it overlap the previously scraped end of the
good copper pattern. Solder the overlapped area and clip off
good copper pattern. Solder the overlapped area and clip off
any excess jumper wire.
any excess jumper wire.
At Other Connections
At Other Connections
Use the following technique to repair the defective copper pattern
Use the following technique to repair the defective copper pattern
at connections other than IC Pins. This technique involves the
at connections other than IC Pins. This technique involves the
installation of a jumper wire on the component side of the circuit
installation of a jumper wire on the component side of the circuit
board.
board.