Seatalk Failure Alarm on Autopilot when connecting Raystar 120 GPS

[simonmoore]

I’ve had an ongoing issue whereby my Raymarine Raystar 120 GPS died and I was getting a NO FIX message on my Raymarine RL70C unit.  I did all the normal checks and changed the battery in the GPS to confirm it had died. 

I have recently managed to source a good second hand Raystar 120 GPS unit which when powered up has a flashing red, then amber and finally a green light to say it has acquired satellites. However, when I check my chartplotter the NO FIX message remains and the chartplotter cannot see any satellites on the GPS set up page. 

Another complication is that when I connect the GPS to the Seatalk system the autopilot (ST5000) them gives a Seatalk Failure Alarm and the wind instrument (ST60) stops reading the wind speed.  When I disconnect the yellow seatalk cable of the GPS from the Seatalk system then the autopilot is fine again.

I suspect the faulty is either a faulty GPS antenna of an issue with the Seatalk wiring.  Any ideas on resolving would be very helpful.

[diverphil]

have you tried this .  a video on replacing the head battery https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjAq_-_94DwAhU2hP0HHeaVBlcQtwIwAXoECAYQAw&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DZfwy_BiFTa8&usg=AOvVaw39FDST_RhOhoDgxMIIb2WW

[simonmoore]

Hello, yes sure have and the battery is fine.  Thank you for the reply.

[Yngmar]

Sounds like a wiring fault. The Raystar 120 can be wired in two different modes, NMEA and Seatalk1. In your setup it would be wired as Seatalk1 unit, with Red, Yellow and Screen wires connected to the matching Seatalk colours and the green and brown wires not connected.

Could also be the cable is pinched/shorted/melted somewhere, so test it, or if the new unit came with a spare cable, just hook that up to the new unit and directly to the plotter with nothing else on the bus (you still need to power it).