Testing Transducers

cb32863

cb32863

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Jun 29, 2010
1,287
Beneteau First 235 Lake Minnetonka, MN
I have both a depth transducer and a knotmeter installed in the hull of my 235. The speed gauge was removed and replace with a compass by one of the previous owners and the depth gauge has quit working before I owned the boat. I can get a used set of ST60+ instruments, so I am wondering how to test the two current in-hull transducers.

I have seen something about having a Long wave radio next tot he depth and you can "hear" clicks with power running through it. Would putting a volt meter on the knotmeter and having someone spin it show a change in voltage? My 235 is a 1992 and I have no idea what brand or models the transducers are.

Any ideas out there?
 
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Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Your depth sonar should only have 1 transducer. The knotmeter is a wheel and they usually jam up anyway with hull grass/slime. I wouldn't worry about the knotmeter and concentrate on the transducer. Maybe someone else knows how to test an in hull transducer with no power or instrument readings. I would opt to buy the used unit and hope the transducer works with it. I did it with a new panel unit and the original transducer works fine. Chief
 
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Benny17441

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May 24, 2004
7,202
CC 30 South Florida
Get a new transducer compatible with the ST60 after measuring that it will fit in the opening. Wiring splices are not very reliable.
 
John T1594

John T1594

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Jun 4, 2004
834
Hunter 340 Forked River, NJ
Three years ago my Raymarine paddlewheel speedo would not function. I cleaned and replaced the wires on the back of the display unit but that did not help. I was able to scroll through all of the functions on the display head but still got no speed data. I pulled the transducer (almost no water comes in) and spun the paddle wheel but could get no reading. I ordered a # RAYE26031 ST30 ST60 transducer from Boatersland (http://www.boatersland.com/raym78713.html)and spliced it into the current wires from the thru hull. The new transducer fits the thru hull. Raymarine also suggested that I contact GEM ElectronicsCo., the maker of Airmar transducers at 803-693-0777 to get their recommendation on replacing the transducer.
Raymarine suggested the following for Testing the Speed Sensor:
· Verify that the transducer’s paddle wheel is free of marine growth and rotates freely on its shaft
· Power down the instrument
· Disconnect the GREEN and SHIELD transducer leads from the instrument display or instrument pod.
· Connect a multimeter to the GREEN and SHIELD transducer leads and configure the multimeter to measure continuity or resistance.
· Slowly rotate the transducer paddle wheel by hand. Note that as the paddlewheel is rotated, the multimeter should alternate between an open circuit and a closed circuit with each quarter turn. As such one complete revolution of the paddle wheel should open and close the circuit four times.
Should the multimeter respond as indicated above, then the speed sensor element of the transducer would be deemed functional. If not, then the transducer has failed and should be replaced.
The paddle wheel should have magnetic arms and can be checked.
Also, water may enter the transducer and damage the electronics. Raymarine says to let it dry out for 24+ hrs and recheck for function as above. “O” rings must be intact.
 
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Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Call it a transducer if you want but................................................... need I explain to you what a sonar transducer is? Chief
 
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