Thales 421, Эксплуатация и обслуживание, Страница: 170 / 256

LLZ 421
Repair Operation and Maintenance
ILS 420
6−28
Ed. 01.10 SOAC
6.6.1.1.3 Handling electrostatically sensitive Subassemblies
The ILS and CVOR/DVOR installations contain subassemblies (plug−in cards) equipped with com-
ponents which are sensitive to electrostatic discharge. When replacing subassemblies and plug−in
cards containing electrostatically sensitive components, special precautionary measures should be
taken during removal, transport and installation in order to prevent damage to the components. We
refer to the customer documentation of the manufacturer.
Subassemblies which contain electrostatically sensitive components are
marked with this symbol.
If any of the maintenance personnel need to touch one of these subassemblies, they should place
both hands flat on a grounded conductive surface for a few seconds to eliminate static charges. The
subassembly can be touched − preferably at an insulator (board edge, lever mechanism, etc.) − as
soon as the potential has been equalized in this manner. It is advisable to avoid touching the contacts
of the plug−in connectors, the conductor paths and the components themselves. Some of the subas-
semblies must be left in their antistatic packaging or plastic bags as long as possible. The special
procedures described below should be followed when subassemblies and plug−in boards are
replaced within the framework of repair and maintenance activities, due to the risk of damage to elec-
trostatically sensitive components.
To remove a subassembly:
− Switch off the system before beginning the replacement procedure.
− Eliminate any static body charges by touching the frame of the grounded system (rack) with both
hands.
− Remove the subassembly and lay it down on a bench with a grounded conductive worktop.
− Pack the subassembly in an antistatic plastic bag and send it off to the manufacturer for repair.
To install a subassembly:
− Eliminate any static body charges by touching the frame of the grounded system (rack) with both
hands.
− Remove the subassembly from the antistatic plastic bag.
− Install the subassembly.
− Switch on the system again.
6.6.1.1.4 Components containing Beryllium Oxide Ceramics
Some of the subassemblies are equipped with transistors containing beryllium oxide. These transis-
tors are in line with the latest state of the art and are in use all over the world. They are absolutely harm-
less in a sealed, compact condition. Beryllium oxide dust, which is detrimental to health, may however
be produced if the transistors are opened. They should not be dismantled or shattered. This applies
likewise if they are scrapped or disposed of. The following subassemblies contain power transistors
with beryllium oxide:
− MODPA : Transistor types MRFC166C
6.6.1.1.5 Handling Lead Batteries
See Chapter 6, Section 6.4ff and Part 1, Section 1.4.