Service manual
SERVICING
CM153 - 923-03443R1 6 ZLD20A1 - SERVICING
3. Solder the connections.
CAUTION: Maintain original spacing between the
replaced component and adjacent components
and the circuit board to prevent excessive
component temperatures.
CIRCUIT BOARD FOIL REPAIR
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.
AT IC CONNECTIONS
To repair a defective copper pattern at IC connections
use the following procedure to install a jumper wire on
the copper pattern side of the circuit board. (Use this
technique only on IC connections).
1. Carefully remove the damaged copper pattern with a
sharp knife. (Remove only as much copper as abso-
lutely necessary).
2. carefully scratch away the solder resist and acrylic
coating (if used) from the end of the remaining cop-
per pattern.
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 out-
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.
AT OTHER CONNECTIONS
Use the following technique to repair the defective cop-
per pattern at connections other than IC Pins. This
technique involves the installation of a jumper wire
on the component side of the circuit board.
1. Remove the defective copper pattern with a sharp
knife. Remove at least ¼ inch of copper, to ensure
that a hazardous condition will not exist if the jumper
wire opens.
2. Trace along the copper pattern from both sides of
the pattern break and locate the nearest component
that is directly connected to the affected copper
pattern.
3. Connect insulated 20-gauge jumper wire from the lead
of the nearest component on one side of the pattern
break to the lead of the nearest component on the
other side. Carefully crimp and solder the connec-
tions. CAUTION: Be sure the insulated jumper wire is
dressed so the it does not touch components or sharp
edges.