transducer check

shetland536

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25 Jan 2005
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is there a check i can do to see if my transducer is knacked,how do i find what hertz it is to get a replacement.if its any help its a sowester 770, the connection is 2 wires and looks like a tv arial socket connection.(please dont tell me to plug it into the tv).
cheers
 

William_H

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It is quite likely bthat the log paddle transducer (I hope that is what we are talking about) has a reed switch in it. This is a little glass tube with two pieces of iron that move together in a magnetic field. The contact is made when the tiny magnet on the paddle passes the switch. The switch is encapsulated in the body close to the perimeter of the wheel.
To check you connect a multimeter on low ohms scale and you should see the resistance go from low to high as the wheel is slowly turned. If so this indicates OK. if not take the wheel out screws are the needle point bearings and pass the wheel near your compass. You should be able to identify the poles of the magnets. These are often a rod about 1 or 2 mm in diameter running from one perimeter across to the other. There may be two magnets. This will give you a general idea. if you come to the point of buying a new transducer then try to pull the guts out of the old one from the inboard end where the wires go in. it is possible to replace the reed switch (from Maplin) and replace the wires where you will probably find the corrosion problem. The whole lot can be resealed with a silicone (non acid type) have a go you may be able nto fix it if you try. If you ruin it no loss.
tgood luck will PS my experience is with an old Smiths log on which I rebuilt the transducer so many times but I think they are often similar.
 

shetland536

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sorry for confusion,its an echo sounder transducer,thanks for your reply though william,its good to know you can source help from all over the world.thankyou. any help is gratefully recieved-i am a little green to all this stuff but i am rapidly learning.thanks.
 

ecb

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If its the echo transd. then you can switch on the unit and hold a screwdriver blade against the transducer.... put your ear to it and you should hear it click click clicking.
 

nealeb

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How is the transducer mounted? I had an identical problem when I relaunched this year, and the problem turned out to be that I have an internal oil bath-mounted transducer (so no hole through hull) and I have lost a little bit of oil so the transducer is no longer in the oil. Although the oil bath is sealed, I was able to test by undoing the locking nut on the transducer and lowering it towards the hull - when the sounder burst into life! So, just need some more castor oil in there.
 

shetland536

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ok nealeb, as far as i can make out i have a double skin boat, from memory it has been mounted in a piece of plastic pipe which has been slid through the internal skin,it was a very tight fit in the pipe and was covered in copious amounts of sealant.i will need to look to see if the bottom of the pipe is sealed to hold any liquid.
does it have to be castor oil? only asking because although i have heard of it before i have never brought or used any and have always assumed it to be used for cooking.
would cooking oil work?
this is an interesting theory for me to try to investigate this weekend.
thankyou
 
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