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RS120 - NO FIX being reported on Pathfinder Series Display or Multifunction Display


NO FIX is being reported on Pathfinder Series Display or Multifunction Display. I have a Raystar 120 GPS Sensor supplying the display with GPS data. How can I diagnose and correct this problem?

Raymarine's hsb[1] & hsb2 Series Displays and Multifunction Displays have no inherent GPS capabilities. These displays rely on an external GPS data source to provide position, course over ground (COG), and speed over ground (COG) to the display. Raymarine's Raystar 120 GPS sensor (RS120) was produced during the timeframe that the hsb[1] and hsb2 Series Displays were in production to satisfy the external GPS data source requirements of these displays. The RS120 GPS sensor was produced in SeaTalk and NMEA 0183 versions and feature a medallion on their upper surface specifying whether the sensor is the SeaTalk or NMEA variant.

Before beginning diagnostics, verify the following:
1) that the problem can be reproduced at the time of this diagnostic
2) that the boat's batteries are fully charged or that you are connected to shore power
3) if you have more than 5 SeaTalk devices, it is recommended that a second power insertion point be added after the last SeaTalk device to ensure adequate sufficient power to the SeaTalk network

The following diagnostic can be used to troubleshoot a NO FIX condition for the RS120 SeaTalk (most common). Verify the following:
- verify that the GPS is installed such that it has a clear view of the horizon and is not installed below any hard surfaces
- verify that the GPS is not installed within 3' of a radar scanner (if mounted within its beam angle) or VHF antenna
- measure voltage across the RS120's red and bare wire leads. The measured voltage should be between +10.5VDC to +13.5VDC.
- measure voltage across the RS120's yellow and bare wire leads using an analog voltmeter. The voltmeter’s needle should bounce between +9VDC and +11VDC. The bouncing needle is indicative of data communications.
- cycle power to the RS120 (verify that the power as measured on the red and bare leads drops to 0 when power is removed). This will force the GPS to reset. Does the GPS acquire satellites and a fix afterwards? If so, nothing more need be done.
- via the GPS status page, restart the GPS.

If the RS120 fails to fix or the fix is intermittent, then RS120 should be serviced by Raymarine's Factory Service Department or alternatively replaced with a Raystar 125 GPS Senstor (RS125) . If replacing the RS120 with a RS125, the RS125 can be spliced into the existing RS120 cable. If creating a splice, be certain to cut the cable in a manner that sufficient cable remains to permit a splice to be performed. The RS125 would be spliced to the RS120 (SeaTalk version) as follows:
Red & Green leads..................................Red lead
Yellow....................................................Yellow lead
Brown & Black or Bare leads..................Bare lead