Cmos Devices; Circuit Boards - Codan NGT 2010 RF Technical & Service Manual

Maintenance

CMOS devices

A number of CMOS devices are used in the transceiver and most of them have built-in
protection. However, their extremely high open-circuit impedance makes them
susceptible to damage from static charges. Care must therefore be used when shipping
and handling the devices and when servicing the equipment in which they are installed.
Packaging
Replacement CMOS devices are supplied in special conductive packaging. They should
remain in this packaging until required for use.
Switching off
Ensure that power supplies are switched off before making connections or
disconnections between circuit boards.
Handling
Handle circuit boards and conductive parts as little as possible.
Grounding
Anything connected to or touching the circuit board tracks should be grounded as
follows:
•
•
•

Circuit boards

Excessive heat
Excessive heat may lift the track from the circuit boards. This will cause serious damage.
Avoid the use of high-powered soldering irons. A soldering iron rated at a maximum of
60 W, preferably temperature-controlled at approximately 370°C (700°F), is sufficient
for most tasks. A soldering iron rated at a slightly higher temperature of 425°C (800°F)
may be required for heavier components such as PA transistors. Only apply the soldering
iron long enough to unsolder an existing joint or to solder a new one.
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Ground test equipment connected to a board through its mains lead.
Discharge static charges, which may build up on a person, by touching a grounded
metal surface with both hands. This should be done before working on, and at
frequent intervals while working on circuit boards.
Wear a suitably grounded conductive wrist strap. This will minimise the build up of
static on you.
NGT Transceiver System Technical Service Manual