Troubleshooting Depthsounder Transducer

[Neil McDonald]

I have a Navman depth sounder that is acting up. It appears that the display may not be getting a signal from the transducer.

Can I run an (offline) electrical continuity test on the transducer wiring system to see if I have a wiring fault?

 

[Chief RA]

Make sure the transducer is clean if in water, bonded properly if in bilges. Continuity check if you have specs to compare with readings. Visual check of cable run as mice,rats love to chew it up! Chief

 

[Neil McDonald]

Continuity check if you have specs to compare with readings. Chief

Thanks Chief but some clarification would be appreciated. When you refer to "specs" I assume you mean measuring the circuit resistance. I do not have such manufacturer's specs. However when I talk about doing a continuity check, I mean "Can I succesfully run a nominal voltage through this circuit"?

Your thoughts?

 

[Chief RA]

As far as the multimeter,you can apply its internal battery power to the circuit, such as while on resistance scale. With no schematic and resistive info (specs) I would get a friend to read his transducer for you and then at least you would have a basic ohms reference for the entire loop through transducer and back. You usually can't remove the cable down at the transducer so just cable continuity checks are difficult. Any ohms reading down and back would at least tell you your coax is not severed. Difficult to assist with so little info. Chief

 

[Don12364]

I just went out into my garage and measured the resistance of a working Raymarine sounder transducer with my digital meter. I expected it to read open circuit - and it did.
I expect yours will read likewise so a resistance measurement is not a satisfactory check - unless yours reads lower than OC. In which case water may have got into the cable or transducer.
If possible try to borrow another transducer, plug it into your instrument and just hang it over the side. Also put another instrument on to your transducer to check that out too.
Don't worry about the make as most are made by the same firm and most work on the same frequency.