Maintenance; Introduction; General; Cmos Devices - Codan X-2 Service Manual

X-2 Technical Service Manual
5

5.1 Introduction

This chapter provides maintenance and fault finding procedures that can be
carried out on the X-2 transceiver. It covers general warnings and cautions
to be observed when working with electronic equipment. It outlines fault
finding steps when receive, transmit failures occur and provides removal and
installation procedures. A section on unlocked synthesizers has been
provided should VCO1 or VCO2 lose lock.

5.2 General

5.2.1

CMOS Devices

Complementary Metal Oxide Semiconductor (CMOS) devices in the
Transceiver 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
servicing equipment in which they are installed. The following precautions
should be observed:
Packaging
Replacement CMOS devices are supplied in special conductive packaging.
They should remain in this packaging until required for use.
Switch off
Ensure that power supplies are switched off before making connections or
disconnections between circuit boards.
Handling
Handling of circuit boards and particularly touching any conductive parts
should be kept to a minimum.
Grounding
Anything connected to or touching the circuit board tracks should be
grounded. Observe the following:
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Publication No: 15-02047
Test equipment connected to a board should be grounded through its
mains lead.
Static charges that may build up on a person can be discharged by
touching a grounded metal surface with both hands. This should be
done before, and at frequent intervals during work on circuit boards.
Wearing a suitably grounded conductive wrist strap will minimise the
static build-up on the person.

Maintenance

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