cpt-120 temperature

[Strbass28]

I have a CPT-120 interfaced to a A128. The temperature has always varied widely and ranged from 5-20 degrees F over the actual temperature. It fluctuates over 10 degrees in a matter of minutes. Today it hit over 100 degrees F so I decided to write this post.

Downvision and chirp work great and give nice images.

What's wrong here?

Thanks

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Strbass28,

The problem described is generally indicative of a problem with the transducer's thermistor. Please click here to view a FAQ addressing this subject. Far less often, the problem is rooted in a failure of the MFD's fishfinder circuitry which is responsible for converting thermistor resistance to temperature value. To rule out the latter, the MFD may be tested with another transducer. Should it be determined that the boat's thermistor has failed, then it would be necessary to either replace the transducer or add another source of speed/temperature data as had been identified within the FAQ. If still within warranty, the failed transducer may be sent Raymarine's Product Repair Center for replacement.