If your BT77 or BT74R does not find a fix at all or takes longer than you expect, follow these steps to reset the device to it's original configuration.
Take the battery out of the GPS unit for 5 minutes. This will reset the device to manufacturer's original configuration.
Put the battery in and switch the unit on.
Place it in clear sky.
After a few moments (upto 5 minutes), the GREEN LED on the BT74R or the RED LED on the BT77 will start to flash intermittently. This signals that the GPS unit has locked onto Navigation Satellites.
