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Full Version: Raymarine C80 Chartplotted with 300 DSM issue?
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My Raymarine C80 "head unit" screen, only as part of the Fish Finder function, displays random multi-color scatter slowly moving across the screen, as if functional, while the digital depth reading is stuck on 7.2... at times flipping back and forth from 7.2 to 7.3 or 7.1ft.

The thru-hull sonar/transducer seems functional as I can hear its usual rapid ticking while powered on - it is connected to the binnacle mounted head unit, through a DSM 300 mounted inside near the Transducer.

The DSM, with the head unit on in Fish Finder mode, shows a solid "on" amber LED indication; that same LED flashes 2x amber with the head unit disconnected.

This condition suddenly appeared while otherwise functioning normal, last June 2017 - it has not reversed itself since then, even after powering up and down; disconnecting the DSM and re-connecting; conducting a factory reset at head unit; and my latest attempt to wake it back up by re-wiring all power connections to ensure full battery power (12.8V) is received at all components.

Everything else works just fine - Charts, Radar, GPS receiver...

With this, I am hoping someone can point me in the right direction to get the depth/finder unit up and running again.


CAL 2-34
Perth Amboy, NJ
Welcome to the Raymarine Forum Paulus,

The amber LED is indicative of a failure to sense the transducer as indicated within the Status LED table found on page 26 of the DSM30/300's Owner's Manual. It would be recommended that:
1. the power circuit supplying power to the DSM be switched OFF
2. the transducer's plug be unplugged and inspected for signs of corrosion on the contacts ... if corrosion is found, then the transducer and/or DSM may need to be replaced should the contacts be unable to be adequately / safely cleaned
3. the transducer's plug be inspected to ensure that its locking ring is installed ... if not a new locking ring should be ordered from Gemeco, Inc. (Airmar’s US distributor (803 693 0777)) and that it be installed.
4. the transducer's cable be inspected from the plug to the transducer to ensure that it has neither been modified nor damaged ... if damage or modification is found, then the transducer should be replaced
5. that the transducer's plug then be reconnected to the DSM, ensuring that its locking ring has been rotated into the locked position
6. the power circuit supplying power to the DSM be switched ON
7. that the system be tested again.

Should the problem persist then the problem would be rooted in either the transducer or the DSM. Fault isolation would typically be performed by testing the DSM with another compatible transducers which had been connected to the DSM in a temporary manner and then simply suspended over the side of the hull or, in the case of fiberglass hulls less than 1" thick, placed atop a water-filled ziplock bag resting on the inside of the hull. Should the problem persist with the test transducer, then the DSM would need to be sent to Raymarine’s Product Repair Center to be bench checked / serviced or that it replaced with an operational second hand DSM. Raymarine no longer produces DSMs having a hsb2 communications interface ... unlike later models of MFDs, the C-Series Classic MFDs were designed to communicate with a DSM exclusively via hsb2 communications.
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