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GNS 400W Series Maintenance Manual
Page 5-13
190-00356-05
Rev. A
5.4.5 Main Board Memory Battery (Figure 5-8; all units)
The Main Board contains an internal battery used for the real time clock and GPS system
information that will last approximately 5-8 years. Regular planned replacement is not necessary.
A ‘low battery’ message is displayed when replacement is required. Replace the battery within 1
to 2 months after the low battery message is displayed. If the battery is not replaced and becomes
completely discharged, the unit will remain fully operational but the GPS signal acquisition time
may be increased.
Partial disassembly of the unit is required to replace the battery. Once the Main and Nav Chassis
are separated, the Main Board is exposed and the Main Board Memory Battery can be replaced.
Removal
1.
Remove all electrical grounds from the unit to prevent the battery from shorting out if a
grounded tip soldering iron is used.
2.
Unsolder the battery leads from the bottom side of the Main Board.
3.
Carefully remove the battery by pulling it out from the top side of the Main Board. The
battery leads are soldered to the battery and cannot be removed.
Replacement
1.
Install new battery and solder the leads from the bottom side of Main Board.
2.
Clip battery leads to insure the battery does not short to the chassis.
3.
Turn unit on.
4.
Verify the Memory Battery Low message does not appear.
5.
Turn unit off and carefully turn it over.
6.
Verify memory battery voltage (measure from positive side of the battery to ground) is at
least +2.9 V dc.