Furuno NX-700B Service Manual

7.6 Replacement of Battery
7-20
7.6 Replacement of Battery
Replace the battery of the CPU board when is displayed in the Status display field.
When the battery is replaced, all the backed-up received messages are cleared. But the
user-programmed menu settings are not cleared.
Reference:
1. Execute “[MENU] -> Service -> Test”.
In the Memory Test, battery voltage can be checked.
Item Value for reference
Interval for battery replacement 5 to 10 years
When newly installed +3.3 VDC
display voltage 2.5 VDC or less
Minimum voltage for backup 1.8 VDC or more
Time for voltage drop from +2.5 VDC to
+1.8 VDC
1,000 hours at the shortest
2. Received messages and each setting are stored in the SRAM of the CPU board and
backed up by the battery. The EEPROM compares settings of the SRAM every hour and
update changes, if any, to back up data of the SRAM.
For instance, if the battery is replaced immediately after a setting is changed, the changed
setting has not been stored in the EEPROM yet and previous setting data is sent to the
SRAM. As a result, it follows that “setting has not been changed”.
Fig. 7.5.1 Replacement of Battery on CPU board
Battery: CR2450 F2ST2L
(Code No.000144941)
J7
1. Disconnect the plug J7 and replace
the battery. The battery is secured
with silicone rubber. Remove the
battery exercising caution so as not to
damage other parts.
2. When a new battery is installed,
secure the battery with silicone rubbe
r
as the old battery was.
3. Connect the plug J7.

Furuno NX-700B Specifications

General

Type	NAVTEX Receiver
Power Supply	12-24 VDC
Operating Temperature Range	-15°C to +55°C
Frequency	490 kHz, 518 kHz, 4209.5 kHz
Display	LCD