[CA] GPS coordinates lost on Ray50

I have a ray50 vhf, an ES127 chart plotter, and an RS150 GPS installed. Recently, my radio alarms that it has lost the GPS coordinates. After a few minutes, the coordinates are restored. When this happens the coordinates are ok on the chart plotter and there are no other errors. I checked the connections to the radio and they are tight.

What else could I check?

Thanks.