Transmitter Precautions - Codan X-2 Service Manual

X-2 Technical Service Manual
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Track repair
Broken or burned sections of printed circuit track can be repaired by bridging
the damaged section with tinned copper wire. The section where the repair
is to be made must be cleaned, observing the precautions outlined above
before soldering.
Integrated circuit replacement
It is often possible to desolder and remove components from the board
without damage to the component or the tracks on the board. However,
integrated circuits with many connections, mounted on double-sided circuit
boards with plated-through holes are almost impossible to remove intact and
the operation is likely to damage the circuit boards. To replace these
components their leads must be cut individually until the body of the
component can be removed. Individual leads must be unsoldered and
removed. Excess solder must be removed before inserting the replacement
component. Refer to the bullet section "Remove solder" before inserting
replacement components.
5.2.3

Transmitter Precautions

When taking measurements of the low level stages of the exciter it is
advisable to remove the drive to the PA and Filter PCB. The supply voltage
is applied to the PA when the transceiver is switched on. Due care should be
exercised when connecting probes.
Publication No: 15-02047
Observe orientation - Before replacing defective diodes, transistors,
electrolytic capacitors or integrated circuits, observe any marking
indicating polarity or orientation. It is essential that these types of
components are installed with the correct connections. Consult the
manufacturer's data for indications of the polarity of diodes or capacitors
and transistors.
Heat sinking - When soldering to the board, use long-nosed pliers or
another form of heat sinking on the leads of heat sensitive components.
Thermal conduction - When replacing transistors that are mounted on
heat sinks, ensure good thermal conduction between the heat sink and
the replacement. This can be done by cleaning the mounting surfaces and
recoating them with a thermal conduction compound such as Jermyn
Thermaflow A30.
Maintenance 5-3