LC37/LC37F
Fuses and conventional Resistor Removal/Replacement
1. Clip each fuse or resistor lead at top of circuit board hollow
stake.At Other Connections
Use the following technique to repair defective copper pattern at
2. Securely crimp leads of replacement component around 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 DEFECTIVE
COPPER
temperatures.
REMOVED
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 follow-
ing guidelines and procedures should be followed whenever this
condition is encountered.Insulated Jumper Wire
In Critical Copper Pattern Areasconnections other than IC Pins. This technique involves the instal-
High component/copper pattern density and/or special voltage/cur-lation of a jumper wire on the component side of the circuit board.
rent characteristics make the spacing and integrity of copper pattern1. Remove the defective copper pattern with a sharp knife.
in some circuit board areas more critical than in others. The circuitRemove at least 1/4 inch of copper, to ensure hazardous condi-
foil in these area is designated as Critical Copper Pattern. Becausetion will not exist if the jumper wire opens.
Critical Copper Pattern requires special soldering techniques to
ensure the maintenance of reliability and safety standards, contact2. Trace along the copper pattern from both wire sides of the pat-
your Hitachi personnel.tern break and locate the nearest component directly connected
to the affected copper pattern.
At IC Connections
To repair defective copper pattern at IC connections, use the follow-3. Connect insulated 20-gauge jumper wire from the nearest com-
ing procedure to install a jumper wire on the copper pattern side ofponent on one side of the pattern break to the lead of the near-
the circuit board. (Use this technique only on IC connections.)est component on the other side. Carefully crimp and solder the
1. Carefully remove the damaged copper pattern with a sharpconnections.
knife. (Remove only as much copper as absolutely necessary.)CAUTION:Be sure the insulated jumper wire is dressed so
that it does not touch components or sharp
2. Carefully scratch away the solder resist and acrylic coating (ifedges.
used) from the end of the remaining copper pattern.
Frequency Synthesis (FS) Tuning Systems
1. Always unplug the instrument AC power cord before discon-
BARE JUMPERnecting or reconnecting FS tuning system cables and before
WIRE
removing or inserting FS tuning system modules.
2. The FS tuner must never be disconnected from the FS tuning
control module while the power is applied to the instrument.
CRIMP AND
SOLDER
3. When troubleshooting intermittent problems that might be
caused by defective cable connection(s) to the FS tuning sys-
Install Jumper Wire and Soldertem, remove the instrument AC power as soon as the defective
connector is found and finish confirming the bad connection with
3. Bend a small ?U? in one end of a small-gauge jumper wire anda continuity test. This procedure will reduce the probability of
carefully crimp it around the IC pin. Solder the IC connection.electrical overstress of the FS system semi-conductor compo-
nents.
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.
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ACEC
