depth in all areas 0.9m

[jezjez]

My depth sounder is telling me it's 0.9m deep wherever I am and wherever I go & has done so all season. This would be quite a drag on my speed if it were true.
A new transducer and wiring has not helped. Is it possible that the display unit is the cause of the problem? It seems strange but there is no other obvious reason.

 

[Peterduck]

You may be suffering from the same problem as Simon & Tanya; corrosion of terminals. In your case, you are dealing with very small currents which can be stopped dead by the slightest corrosion of contacts. I appreciate that the sender and cables are new; how about the contacts on the back of the readout unit? Are they bright and shiny? Even dull contacts can stop the signal dead in its tracks. Alternatively, there may be a'dry joint' somewhere inside the readout unit. This is where there is an invisible hairline crack within a dot of solder attaching a resistor or similar to the circuit board. If the whole unit is sealed up there is little that you can do in this respect. I was given several echo-sounders of the 'Seafarer' type which had stopped working, and were simply replaced. I wasn't able to get them going either.
Peter.

 

[Keith 66]

Several years ago i had a very similar problem, the sounder read 2ft all holiday and in the end we gave up using it and dug the lead line out of the bottom of the locker.
It was only after returning home to our mooring that i chanced to look in the bow locker where lives the transducer, it had fallen over and was pointed at the watertank 2ft away.........