GPSMAP 640 Owner’s ManualAppendixAppendixCalibrating the ScreenPower the unit on in marine mode, or switch to marine mode. Seepage 33 for calibration instructions.Resetting Your GPSMAP 640If your GPSMAP 640 stops responding, turn off the GPSMAP 640,and then turn it back on. If this does not help, reset yourGPSMAP 640 by removing and reconnecting the battery.Updating the Software1. Go to www.garmin.com/products/webupdater, and downloadWebUpdater to your computer.2. Connect the GPSMAP 640 to your computer using the mini-USB cable.3. Run WebUpdater, and follow the on-screen instructions.After confirming that you want to perform an update, WebUpdaterautomatically downloads the update and installs it on yourGPSMAP 640.Clearing User DataiMPoRtaNt: This deletes all user-entered information.1. Hold your finger on the upper-left corner of the GPSMAP 640screen while turning on the GPSMAP 640.2. Keep your finger pressed on the screen until the pop-up windowappears.3. Touch Yes to clear all user data.All original settings are restored. Any items that you have saved areerased.Battery InformationTo maximize the life of the battery, do not leave yourGPSMAP 640 in direct sunlight, and avoid prolonged exposure toexcessive heat.The battery icon in the corner of the Menu page and the Homescreen indicates the status of the GPSMAP 640 battery. To increasethe accuracy of the battery gauge, fully discharge the battery andthen fully charge it. Do not unplug the GPSMAP 640 until it istotally charged.Note: If the device will not be used for an extended period oftime (longer than one week), remove the battery pack.
