Ashtech Promark 2 Issue

Hello All,

A few days ago I noticed an issue with my two receivers Ashtech Promark 2 : indeed the hour of its clock is initialized automatically on the date August 28, 2003, I reset the receiver and I set the date manually in configuration but as soon as the satellites are received the date resets to August 28, 2003 which makes the receiver almost unusable. I would like to know if anyone with this model has the same problem, if as if the manufacturer has limited its use to exactly twenty years If someone has  any idea how to solve this problem will be helpful and I would be very grateful.

Thanks in advance.