Can I test a depth transducer?

[foojin]

The former owner is a sweet old guy, but for health and age reasons is unable to help me.

There are three thru-hull depth transducers in our boat. Not sure why there are so many or whether they all work.

One is connected to a depth gauge. It, or the transducer, appears to have gone wonky, showing only dashes where the depth should be.

Two are connected to nothing; the wires from them neatly coiled, identified and zip-tied under the electronics cabinet. If they were faulty, you would think they would be marked "faulty".

Is there any way I can test transducers short of buying a new depth gauge?

I have read in forums this morning that working transducers should pulse in your hand if held. Does it require only a 12-volt circuit to activate this?

[s57ra]

Originally Posted by foojin

..There are three thru-hull depth transducers in our boat. Not sure why there are so many or whether they all work.

One is connected to a depth gauge. It, or the transducer, appears to have gone wonky, showing only dashes where the depth should be.

Two are connected to nothing; the wires from them neatly coiled, identified and zip-tied under the electronics cabinet. If they were faulty, you would think they would be marked "faulty".

Is there any way I can test transducers short of buying a new depth gauge?

I have read in forums this morning that working transducers should pulse in your hand if held. Does it require only a 12-volt circuit to activate this?

Hi ,
Depth transducers are similar to the "loudspeakers" operating in ultrasonic frequencies - usually at 50KHz (check airmar for more details). Transducer sends a short ping and instrument measures the time between transmission and reception of the echo to convert it to distance. The same element is usually used for TX and RX (loudspeaker also works as microphone).

Are you sure all of them are depth transducers and not temperature or speed sensors? If the instrument does not show depth, failure could be at transducer, instrument, wires or both.

Connect the multimeter (analog is better than digital for this) to the wires going from instrument to transducer and watch if voltage appears in short pings every second or so. If you cannot read anything, then most probably the instrument is faulty.

If you know those other transducers are also for depth - just connect them and see what happens.

[sailjumanji]

Start by checking the connections on the back of the display. If that doesn't work, easiest thing to do would be to hook up one of the other transducers to the display. If that doesn't work, try the other. Next step would be to borrow a working display.

I had an ST60 Tridata that connects to depth and speed transducers. It appeared that the transducer was going out as after running for a while, it would stop working and just flash on the last depth. If you turned it off and then back on, it would give four dashes - saying there was no depth presented. I contacted Raymarine, and they said it could be the transducer, or the processor in the display that converts the signal to depth measure. Mine turned out to be a faulty processor, which was fixed by just installing an i50 Tridata display. Its backwards compatible with the ST60.

[wingsofraven]

Take a piece of 2 or 3 inch pvc pipe about 2 feet long with a cap on one end. Have someone hold it over the transducer tightly to the hull and turn on the sounder. You will have a reading about 4 to 5 times more than the length of the pipe. Frank

[s57ra]

Is your boat in the water or on the hard?

Another idea came to my mind, piezoelectric elements also produce electricity if the mechanic force is applied to them. Just connect the multimeter to the wires of the transducer and "knock" on it with a screwdriver handle, it should show some reading.

[GordMay]

A quick way to check if the transmitter stage & transducer are working is to feel the face of the transducer with the sounder running, you should be able to feel the pulses, or hear the transducer ticking.

[OS2Dude]

Most (if not all) depth transducers need something to drive them, a sonar hub or a chart-plotter with sonar built in. If you can borrow a chart-reader that fits your unit's power and transducer cables, that may help diagnose the issue. Or perhaps take your depth reader to someone else's boat that has the appropriate power and data cables on their transducer.

You also ill need to run down the wires, checking to make sure there is not a cut or abrasion thru the insulator and/or internal wires. Check the connectors, make sure the wire was not snatched and internal wires parted there. Make sure pins are clean and not bent. If you can, use a multimeter to check connectivity. Disconnect both ends, short a pair and then use the meter on those wires on the other end.

When I got my Airmar P75 transducer, it said to NOT test it in the air. You can place it on a gallon baggie of water or antifreeze. You may be able to hear the 'ping' (usually more a 'click') but not necessarily.

[Lancerbye]

There are 2 most popular types of transducers used for depth soundings. The 50 kHz and the 200khz. The latter provides a narrow beam , uses coax cable and is most often found on low end or digital numerical type monitors. You have to identify the type first and use the proper monitor to verify. The monitor or transceiver sends pulses out in bursts at one of the above mentioned frequencies. If it is out of water you can feel the pulse or hear the ticking sound. I have worked on a lot of ultrasonic equipment over a great many years and have found that the most common fault was connections at the transceivers.

[norwegian vikin]

Originally Posted by GordMay

A quick way to check if the transmitter stage & transducer are working is to feel the face of the transducer with the sounder running, you should be able to feel the pulses, or hear the transducer ticking.

does the same metod apply to forwardlooking sonar?

[GordMay]

Originally Posted by norwegian vikin

does the same metod apply to forwardlooking sonar?

I would imagine so.

A cheap AM radio might also pick up the pulses, as "static" interference.

[grjfield]

on a related depth sounder issue...
My Standard Horizon DS41 depth sounder started acting weird... bleeding display and numbers unreadable. At about 28 years old, its had a good life.

Replacement DS41's are hard to find but I managed to find a DS45 on ebay. It seems to have the same electrical specs (200KHz) and connectors so I'm hoping it will work with the same thru hull transducer.

Anyone had a similar experience or can volunteer a comment on the probability of success?
Thanks
Gerard