[TG] [TG11] Axiom MFD with Twin RV200's

[Tom - Raymarine - Moderator]

Hello Eddie,

Our MFDs and black-box sounders use a 'sense' line in the transducer wiring to detect that the transducer is there. It's a simple resistance measurement (some other sounder systems using Airmar Chirp transducers also use digital 'XID' communications as well), so there is very little to go wrong.

What we have seen on some Axiom/RV systems is that if the display's power supply isn't stable, or there's some electrical noise being picked up on the transducer cable then that can cause intermittent issues with this transducer 'sense' detection. The sense resistance measurement is just voltage-in compared to voltage-out equals resistance, so if the voltage-out isn't correct, that will lead to an incorrect resistance reading and so incorrect transducer detection.

For example, one one boat I dealt with, the sounder worked perfectly at low speed but then as engine tacho climbed above say 2,500rpm, the display showed the same message you're seeing. That turned out to be unstable, noisy charging output from the engine and the problem was solved by separating the electronics onto an isolated house battery (it could also have been solved by cleaning up the engine's charging output.)

Is there any pattern in when the problem occurs, for example only when engines are running, only when courtesy lights are on (LED light drivers can be very noisy) etc.?

Regards,
Tom