Troubleshooting external GPS with RL70RC Plus

[hlev40]

I have an RL70RC Plus. Last year the Raystar 120 died. I opted to go for an external GPS, feeding the data to the RL70RC Plus display for NMEA 0183. It fired up the first time and worked great all last season, But when I tried the system after the winter - NO FIX. The boat was outside in New England, but with a full cover.

I am working with the vendor of the GPS (Digital Yacht, GPS150) but want to see if I am missing something on the RL70.

1. When I started the units yesterday for this first time this spring, the chartplotter displayed the dreaded "NO FIX". After several restarts as well as letting it sit for 5-10 minutes with all systems on, still "NO FIX".
2. An analog multimeter shows pulsating voltages across the NMEA+/- leads coming from the GPS (seems to suggest that data is arriving at the leads to the RL70)
3. The D-GPS configuration on the RL70RC is greyed out. I'm not sure if that means it knows it is receiving data over the NMEA or if it means that it isn't seeing position data from SeaTalk.
4. The satellite status display show no satellites (seems to suggestion RL70 is not seeing any messages, though I have to admit, I don't remember if this page was relevant with the external GPS150)
5. I will next connect an RS-422 / USB to see if I can see the data on the NMEA +/- leads.

Am I missing something on the RL70RC Plus that I should be doing?

Thanks,
Harry