DW1U
Fuses and Conventional Resistor Removal/ReplacementAt Other Connections
1. Clip each fuse or resistor lead at top of circuit board Use the following technique to repair defective copper
hollow stake.pattern at connections other than IC Pins. This technique
involves the installation of a jumper wire on the component
2. Securely crimp leads of replacement component aroundside of the circuit board.
stake 1/8 inch from top.
3. Solder the connections.
CAUTION: Maintain original spacing between the
replaced component and adjacent
components and the circuit board, to
prevent excessive component
temperatures.DEFECTIVE
COPPER
Circuit Board Foil RepairREMOVED
Excessive heat applied to the copper foil of any printed
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 following guidelines and procedures
should be followed whenever this condition is encountered.
In Critical Copper Pattern AreasInsulated Jumper Wire
High component/copper pattern density and/or special
voltage/current characteristics make the spacing and1. Remove the defective copper pattern with a sharp knife.
integrity of copper pattern in some circuit board areas moreRemove at least 1/4 inch of copper, to ensure hazardous
critical than in others. The circuit foil in these areas iscondition will not exist if the jumper wire opens.
designated as Critical Copper Pattern. Because Critical
Copper Pattern requires special soldering techniques to2. Trace along the copper pattern from both wire sides of
ensure the maintenance of reliability and safety standards,the pattern break and locate the nearest component
contact your Hitachi personnel.directly connected to the affected copper pattern.
At IC Connections3. Connect insulated 20-gauge jumper wire from the
To repair defective copper pattern at IC connections, use thenearest component on one side of the pattern break to
following procedure to install a jumper wire on the copper
the lead of the nearest component on the other side.
pattern side of the circuit board. (Use this technique only onCarefully crimp and solder the connections.
IC connections.)CAUTION: Be sure the insulated jumper wire is
1. Carefully remove the damaged copper pattern with adressed so that it does not touch
sharp knife. (Remove only as much copper as absolutely
components or sharp edges.
necessary.)
2. Carefully scratch away the solder resist and acrylic
coating (if used) from the end of the remaining copper
pattern.
BARE JUMPER
WIRE
CRIMP AND
SOLDER
Install Jumper Wire and Solder
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.
4. Route the jumper wire along the path of the cut-away
copper pattern and let it overlap the previously scraped
end of the good copper pattern. Solder the overlapped
area, and clip off any excess jumper wire.
6
6 GI - - |
ACEC
