NorthStar MX500 Operator's & Installation Manual page 250

Installation Manual
7. Ensure that Time Interval (ms) is set to 25.
8. Leave the MX 500 Series Software Update program alone for
now and go to the MX 500 unit. Press and hold down the NAV
button on the MX 500 unit and power ON the unit.
(Release the 'NAV' key after the unit is powered on.)
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Installation Notes
Version 3.0