Airmar Speed Tranducer ( P120/ST800 E26031) for Raymarine ST60 / + - Can it be repair

[sailor22]

Has anyone tried to repair a one of these speed transducers where the speed output doesn't?

Is there a reliable way of getting it apart and if so how, so that it will go back together again?

 

[blxm]

Its a sealed unit if my experience with a DST800 is the same. Cut it open and it was potted and not repairable.

 

[jwilson]

Are you confident it's the speed element of the unit at fault? These ST60s stop showing depth information if the TEMPERATURE sensor also built in to some Airmar transducers die, even if the speed bit is still working. I know it's stupid....

The bodge (and a good one if you don't need to know water temperature) is to put a 10K ohm or so resistor across two of the terminals of the ST60 head. This fools it into thinking there is a temperature reading. Mine has had that for about 8 years: the water temperature reading is now fixed at 26 degrees, but as I'm not trying to find whether I'm in or out of the Gulf Stream for navigational purposes (almost the only real use of the temp display) it really doesn't matter.

Of course you could have a different fault, but this is a common one.....

 

[blxm]

Are you confident it's the speed element of the unit at fault? These ST60s stop showing depth information if the TEMPERATURE sensor also built in to some Airmar transducers die, even if the speed bit is still working. I know it's stupid....

The bodge (and a good one if you don't need to know water temperature) is to put a 10K ohm or so resistor across two of the terminals of the ST60 head. This fools it into thinking there is a temperature reading. Mine has had that for about 8 years: the water temperature reading is now fixed at 26 degrees, but as I'm not trying to find whether I'm in or out of the Gulf Stream for navigational purposes (almost the only real use of the temp display) it really doesn't matter.

Of course you could have a different fault, but this is a common one.....

Wish I had known that before I threw the old unit away! As it happens a new one came with the boat but it would have been good to check as my depth had failed.
I dont think the OPs version has depth as its the ST version.

 

[sailor22]

Thank you for your contributions.
It looks as if i shall have to stump up for a new speed transducer. But it was worth sounding out the Forum.
Cheers

 

[kennyh]

Are you confident it's the speed element of the unit at fault? These ST60s stop showing depth information if the TEMPERATURE sensor also built in to some Airmar transducers die, even if the speed bit is still working. I know it's stupid....

The bodge (and a good one if you don't need to know water temperature) is to put a 10K ohm or so resistor across two of the terminals of the ST60 head. This fools it into thinking there is a temperature reading. Mine has had that for about 8 years: the water temperature reading is now fixed at 26 degrees, but as I'm not trying to find whether I'm in or out of the Gulf Stream for navigational purposes (almost the only real use of the temp display) it really doesn't matter.

Of course you could have a different fault, but this is a common one.....

Interesting post. I've just had my Temp / Speed fail - so I'll give it a try and see if I can save a few ££!

 

[earlybird]

What happens when the thermistor fails is that the instrument thinks it's not connected to a transducer and reverts to slave mode where it's looking for data on the Seatalk bus from another instrument. As said, the fix is a resistor across the input, brown and white wires.

 

[RichardS]

What happens when the thermistor fails is that the instrument thinks it's not connected to a transducer and reverts to slave mode where it's looking for data on the Seatalk bus from another instrument. As said, the fix is a resistor across the input, brown and white wires.

As an additional wrinkle, you can choose a resistance value according to what temperature you might wish to see on the display. There's a table somewhere on the web.

I chose 10K which is the normal default and my temperature reads 20 degrees (from memory). However if you want it to read a different temperature you can fit a different resistance .... or fit a pot so you can change it as the mood takes you. Of course, you can also recalibrate the reading at the display as well.

Richard