In article .com,
Peter Bennett wrote:

I suspect that the transducer is the most likely problem, if there are
no obvious problems with the wiring or connectors. Best way to check
would be to borrow a transducer from a dealer, and try jut hanging it
over the side of the boat.

Actually, the "Best" way to check a transducer is with an Impedance
Bridge designed specifically for looking at Barium Titonate Transducer
Crystals, but few Marine Electronic Shops have these. One of the other
test that can be done, is to stick the transducer up to your ear and
listen for the "tick tick tick" of the transmitting pulse, while the
depthsounder is operating. If the crystal is fractured, or the wires
open, or shorted, you will not hear the "tick tick tick" and it is time
to go buy a new transducer.

Bruce in alaska an old Marine RadioMan, from the Old School.....
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add a 2 before @