Thales 421, Эксплуатация и обслуживание, Страница: 153 / 256

LLZ 421
Operation and Maintenance Maintenance
ILS 420
6−11
Ed. 01.10 SOAC
6.3 NORMAL MAINTENANCE
6.3.1 Replacing the Lithium Battery (LCP)
To back up the real time clock in case of a voltage drop, the subassembly LCP contains a Lithium
battery (LS 14250, 3.6V/0.95Ah, make SAFT; Thales Ref. Nr. 97991 28479). Lithium batteries have an
extended life time. The battery back up function is enabled via jumper, set during first setup or before
replacing the respective pc board. Always observe the label on the battery. The Lithium battery has
to be replaced by the same battery type. Other types of lithium batteries are not approved by Thales.
WARNING
Do not recharge, disassemble, heat above 100 °C or incinerate the lithium cell. Do not
short circuit, or solder directly on the cell. Disregard of the norms regarding the use of
lithium batteries may cause risk of fire, explosion or leaking out of toxid liquid and gas.
Run−down batteries are objects that can pollute the environment and must be disposed
of with proper precautions.
The backup battery can be replaced without switching off the power. The battery is disconnected with
jumper X36 on the LCP. To unsolder the battery a soldering iron with a grounded soldering tip should
be used. A battery short−circuit via the soldering iron for the duration of soldering is unlikely to harm
the relatively high−impedance battery, but should however be avoided wherever possible.
Replace the Lithium battery as follows:
− Open the cabinet front door.
− Remove jumper X36 on the LCP.
− Unsolder the minus and plus pole of the old battery from the soldering terminals on the LCP board.
− Remove the old battery
− Re−tin the soldering terminals of the new battery in order to ensure a good soldered connection.
− Insert the new battery, and solder the minus and plus pole of the battery to the soldering terminals.
− Set jumper X36 on the LCP.
− Close the cabinet front door.
6.3.2 Check of Emergency Battery Voltage
The overall battery voltage is monitored by the transmitter assembly LCP. However it is recommended
to measure the battery voltage to check the performance of the battery. The voltage measured is that
between the BAT1 or BAT2 terminals against GND (BAT0), see 2−13, 2−14. The half voltage value
should be exactly half the full value. Should unbalance occur, a fault is indicated. The deviation in the
ratio of 2:1 for the half voltage measurement increases the further the aging process of a cell is ad-
vanced. If the deviation from the ratio of 2:1 is minimal, the battery can be maintained in service, but
should be kept under observation.
If the deviation is greater (from as little as a few tenths of one volt), each cell must be measured under
load in order to determine the weak cell. This should be replaced by a new cell as soon as possible.
The battery half to be examined may be determined as follows.
Voltage ratio: locate faulty cell:
> 2:1 (e.g. 47: 23 V = 2.043:1) between center and minus
< 2:1 (e.g. 47: 24 V = 1.958:1 ) between center and plus
CAUTION
Before replacing the battery or individual cells, always check:
− Is the battery−charged power supply switched on ?
− Switch off fuse switch F20 (50 A) in battery fuse box, if the BCPS is on.