Q: Depth sounder
yacht hull) works fine...for about 1 hour, then metres/feet display starts flashing, stabilizes for a few minutes, flashes again, and after an hour or so longer, loses all numbers (dashes). It is NOT weed on the transducer
as the manual suggests for this symptom. At this stage (after 1.5 hrs), turning off then on gives no numbers even, only dashes.
ST40. I have swapped out the display with a borrowed new model - same display...but I get the exact same problem.
I CUT the sensor cable near the thru-hull sensor to replace cable. The old cable passed under engine
and was very stiff and thus I thought damaged/resistance high/or??. But a new cable I spliced to 30 cm of remaining old cable at the sensor gives same problem. I tested volts at display. Volts seem fine (>12.3 rest/>13.4 engine
My splice is a test splice - twisted wires/taped plus tin foil to complete the shield over the gap. I have not tried a full solder but the connection at rest should be sufficient to test?? The new (and old which worked for years) cable is about 12 ft/4 m long.
Q. What gives such a symptom of working then becoming faulty after running for +1 hour? Does resistance/heat build up? Piezoelectric issues? Do you think it must simply be the thru-hull sensor that has failed? The time-frame before failure is interesting.
I have done the self-tests as described in the service
manual. It passed all incl. the transducer
I have not hauled out to grind out the old thru-hull transducer to fit a new one - I am trying to avoid/delay that as long as possible as it will be a major.