OK. So the display has not disappeared, it's not a problem with the display device (presumably, as far as displaying goes anyway.) Just that the values don't seem to be getting to the device.
You said they are not working 'anymore'... so, then, you presumably had them working before this.
In which case, I think the connection, along the line from the transducer to the C80 display, should be disconnected, and the connectors on both sides cleaned, by scrubbing off with a clean dry brush for at least 20 seconds. Then both connectors on both sides, should be wiped down with a clean dry cloth until the metal shines.
Then re-connect firmly, power On the system, see if the depth and speed come from the transducer properly and are displayed OK.
- If they are, good, and a rating for my advice would be appreciated.
- If not, if the problem is unchanged, then aside from examining the wiring in detail along its entire length, for sharp bends, cuts, etc., and aside from thinking back as to whether the transducer has suffered any possible collision damage from grounding or bumping into a dock etc... then there is the question, as to what other devices are hooked up to the C80, and whether they seem to be communicating with it OK. And also, how old the C80 is, and how old the transducer that doesn't seem to be talking to it anymore, is -?
Let me know, please, once you have tried that - at your convenience, of course. Thanks.