Thales 421, Эксплуатация и обслуживание, Страница: 169 / 256

LLZ 421
Operation and Maintenance Repair
ILS 420
6−27
Ed. 01.10 SOAC
6.6 REPAIRS
6.6.1 General
The repair activities are designed to restore the ready condition of a faulty system in the shortest
possible time. The system is repaired by replacing the defective subassembly. The defective subas-
semblies can then be sent to the manufacturer for repair.
NOTE: Subassemblies and components which are sent to the manufacturer for repair or returns
must be packed in a way that no damage of the parts could arise. It is recommended to
use the original packing, e.g. of the spare part, or a comparable packing in corresponding
performance to ensure a safe shipping of defective subassemblies or components. Han-
dling of subassemblies with electrostatically sensitive components see section 6.6.1.1.3 .
6.6.1.1 Safety Precautions
6.6.1.1.1 General Regulations
The safety regulations laid down by the local authorities (e.g. concerning accident prevention, work
safety or operation of electronic equipment and navigation systems) must be observed at all times.
The purpose of safety precautions is to protect persons and property, and they must always be heed-
ed. See also Part 1, Section 1.4.
Work should not be carried out outside the shelter or on the antenna system during a storm, due to
the danger of injury by lightning.
Station shutdown due to repair and maintenance: The responsible authorities must be notified of any
work which may require operation of the system to be interrupted, in accordance with national regula-
tions.
Change of parameters is allowed only by maintenance people with specific access level (i.e. > level
2) to the PC user program (ADRACS or MCS). Changes to the established monitor alarm limits should
only be done during flight check procedure.
The mark (!) used in Fig. 6−7 (Adjustments after change) means an important action after repair. Nor-
mally it is recommended to repeat ground or flight check as defined in the Chapter 4, 5 or 7, 8 (Align-
ment Procedure). However the necessity to do so is a decision of the customer. Indicated adjustments
after change are normally performed using the PC User Program (e.g. measurement values) and re-
peating the correspondent sections of the Alignment Procedure, if necesssary.
6.6.1.1.2 Work on the Equipment
In order to avoid risks to persons and consequential damage to subassemblies, the relevant trans-
mitter must be switched off with switch TX1 or TX2 prior to removing or inserting a subassembly or
prior to removing a plug−in connector during the course of repair and maintenance activities (see
Section 6.6.3.1 for exceptions). Switches TX1 and TX2 deactivate the DC converters for the trans-
mitter 1 and transmitter 2 subassemblies respectively. The subassemblies which are common to both
transmitters are exceptions: they can be switched on with TX1 or TX2 and off with TX1 and TX2.
Switch off DC−supply before working on the PIN−Diode transfer switch subassembly with removed
covers of the driver and bias supply and the PIN−Diode switches. Regard that the internal generated
PIN−Diode reverse bias supply is up to −140 V/30 mA, to be measured at TP1.
The battery−charged power supply (BCPS) must always be disconnected from the mains before any
work, other than measuring the voltage is carried out on it.
Burned fuses must be changed only once. Use same type. If burned again check for short circuits!
RF cables must not be bent to a radius of less than 50 mm.