Problem FA50-M1835-VX2 communications

[kliph]

Communication/intermittent problem Question.
- I have a FA50, connected via Network Cable to a Navnet VX2 and to a M1835 via the 422/0183 interface.
- The M1835 has a heading thru 0183 from a Raymarine course Computer output and appears to be stable.
- I can xmit (vhf) using the AIS antenna, it appears to work OK. The VSWR is very low and the transmission is picked up through a handheld VHF so I'm assuming the antenna is working.
My problem - The AIS targets will occasionally disappear from both displays. More often from the VX2.
- I can power both displays down/up and the M1835 comes up in a minute or two, but sometimes the VX2 doesn't show targets for 5 or more minutes.
- Often the VX2 will lose targets for a long period of time while the M1835 still displays them.
- Judging by the yellow LED on the FA50, signals are being received during this time.
I haven't yet pinned down the problem. Any ideas are greatly appreciated.

My Question - if the FA50 GPS antenna has a problem would/could that be the cause?
Thanks, Cliff

 

[Johnny Electron]

If the GPS antenna of the FA50 has a problem it would only affect your transmissions not receive. Are you trying to share a whip antenna between the FA50 and the VHF?

 

[kliph]

Johnny, I'm using a separate VHF antenna. I did use the ship's masthead ant. for testing which verified the AIS VHF ant.was OK. I did eliminate a below deck VHF connector to be sure. Something I did find was a faulty RG58 connector on the AIS GPS antenna cable. This I eliminated by soldering. I also unplugged the AIS ethernet and connected the AIS 422 output to the VX2 port 2 to look at the data, this is the same connection for the 1835.
On the VX2 - Several hours of run-time tonight showed no loss of targets. Will be running all day tomorrow to verify.
On the M1835 On power up it displays the targets faster than the VX2 does. It seems stable also. However I thought the AIS would supply the "own ship position" on the 422 but it doesn't seem to. This I discovered when I turned off the nav data from the GP-32 on port 1, losing the targets. Turning the GP32 back on solved that.

Longer run time tomorrow should show if there's any problems.

Question - Am I correct in thinking the FA50 doesn't output "own ship" position on the com output, and the 1835 needs a separate position source?
Thank you, Cliff

 

[Johnny Electron]

The FA50 by default doesn't put out GPS position. You would have to set it up to do that but when it does it is very raw GPS data and we never recommend using it as a primary source of position data. Ultimately it's GPS antenna is for its own clocking/timing use.

 

[kliph]

Hi Johnny - (re: the FA50 Position) That explains what I suspected but didn't know.

After running the VX2 and 1835 all day today we watched the AIS targets disappear completely on the VX2 after 6 hours. Switching from FA50 Com 422 back to VX2 ethernet made no difference. No amount of rechecking connections, restarting, erasing all marks & lines, etc had any effect. Suspect possible VX2 fault. The Chart display and operation other than AIS appears to work OK.
We're headed for Gibraltar end of this month, there's a Furuno Dealer there, so we'll contact them.
Meanwhile the 1835 and FA50 ran faithfully all day so we're happy with that.
As we normally sail with the GP32 and Radar on, this gives us what we need for safety.

Thank you for your input and replies, very much appreciated.
Cliff

 

[Johnny Electron]

I would recommend that you check that the Vx2 software is current and that you are not using a MEGA WIDE chart card that isn't compatible. Charts larger than the unit will digest properly will bog the machine down and cause AIS to drop.

 

[kliph]

Hi again, the charts aren't Megawide and the SW is up to date.. They have been reliable since 2015, after that we didn't run the VX2 for an extended time. We also had the charts updated to see if that helped. We have checked all the other functions on the VX2, everything else works perfectly. The FA50 and M1835 are working perfectly now.
I suspect, as a retired ET, that a good possibility for the cause of the problems is non use for a period oftime. The problems were occasional at first, degenerating over time. This is reminiscent of some difficult problems I've had in the past, especially in a damp or harsh environment.
I think I've eliminated all the easy solutions, which leaves me with a possible PCB/IC problem. Your input was valuable and much appreciated.
As schematics aren't available there's nothing I can do except a board replacement.
Beat Regards and Thanks again,
Cliff