Faria depth gauge and Airmar transducer

[mlines]

We have an in-dash Faria depth gauge and thru hull Airmar transducer.

The gauge has started the flashing 0.0 and random extreme depth displays (98metres just off Swanwick Marina is unlikely!)

With a new gauge or transducer coming in at around £200 each, I want to get it right when fault finding. As the transducer is piezo-electric (I think) I believe a resistance test is useless.

Any ideas on any diagnosis I can do. As it is thru hull obviously any in-water testing is limited

 

[Yngmar]

I've just played this game with our depth sounder failing intermittently and eventually stopping work entirely. I've learnt a few useful things.

Firstly, the signal, despite being 200 kHz is audible underwater with your ear near the transducer - you can clearly hear the clicks. No clicks, broken transducer.

Secondly, a portable worldband receiver tuned to 200 kHz picks up the radio signal (emitted from the wire, despite shielding) from anywhere in the boat - stronger near the instrument head, the cable and the transducer.

With that information you can do quite a lot, like check if the signal is being generated, if it arrives at the transducer and if there is an echo being received. Ours was initially only doing blip-blip-blip, indicating the signal was generated and arrived at the transducer, but no echo. I dived under the boat, heard nothing, gave the transducer a good slam with my fist and oh wonder, click-click sounds appeared, and back inside the boat, the depth gauge worked again and the worldband receiver now made pairs of blips (a signal and its echo are close together in shallow water).

In our case, it's probably a lose connection inside the transducer unit, which is potted into epoxy and unserviceable. But it has worked for two days now ever since I gave it the slap. We'll hunt for a cheap spare as backup, but at least for now it's working, giving us time to look for a bargain.

 

[mlines]

Thanks - I will pop some batteries in my old radio and give it a go