I bought a NDC-4 AIS from you in about 2009 and it has worked well until I refitted the C80 multi display unit.

AIS source – Digital AIT1000 – AIS talker - This is working and signals received by other vessels, but no display on C80 or VHF or Navtex.

NDC-4 rapid green flashing indicates data received.

Continuity on the 4 NMEA wires from NDC-4 to C80 plug, but no data on display.

The C80 chart was upgraded but I also borrowed another C80 display which also received no data.

I should be grateful for any advice.