Haier TV-8888-09, Руководство по обслуживанию

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9
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 depart 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 i.e. as absolutely
necessary).
2. Carefully scratch away the solder resist and acrylic coating (if used) from the end
of the remaining copper 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 with 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 copper 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 1/4 inch of copper, to insure 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 clamp and solder the connections.
Caution: Ensure the insulated jumper wire is dressed so that it does not touch
components or sharp edges.