Garmin 840xs screen blacks out

[Kodiak2359]

A friend has a Garmin 840xs which arbitrarily goes dark. We've updated the software to newest version (per garmin). But he thinks its still doing it. I have it on my bench now with no transducer to see if it will go dark when not in the boat. Has anyone ever had a transducer cause a screen fault or shutdown ? In one software update note Garmin mentioned "Fixed an intermittent shutdown when connected to certain transducers."
Garmin support says they can't repair these units. 4 years old $1500 unit dead ended.
Im thinking of trying a new transducer if it stays lit up on the bench.

 

[dingbat]

Never heard nor do I understand how a transducer would make the screen dark other than a bad transducer.

Unit set to the correct transducer type?

The first thing I’d do is to eliminate power issues. Pay particular attention to the fuse holder on the unit.,,...notorious for causing intermittent it issues.

 

[dwco5051]

The first thing I’d do is to eliminate power issues. Pay particular attention to the fuse holder on the unit.,,...notorious for causing intermittent it issues.

Had a similar problem on my fishing boat Was a few years ago and don't remember which one it was but think it was a Garman. After a couple of shutdowns and turning it on again was watching it while running and it flashed a message "high voltage" then shut down. Got home that night and figured I would check the voltages, opened the cover over the batteries and decided I would lower the motor to see better. As soon as I hit the tilt button on the motor I saw arching on the negative terminal. Cleaned up the terminals, tightened up every thing and problem solved.

 

[Kodiak2359]

Thanks guys, Before the start of this post I had removed the unit from the boat for the purpose of separating a problem with the unit from a problem with the boat wiring. If the Garmin stays powered up fine on the bench I'll start back tracking the wiring. But not until some ice melts! Both your comments point to checking the boat wiring and as a retired electrician I certainly agree. There is a small fuse panel under the console. I checked everything from the unit to the panel months ago and it all was pristeen and tight. If we can get it in a warm area we might make some progress before April. My friend related to me that when the boat was new there was some kind of dealer or factory error that resulted in a very corroded ground connection. Not sure on those details yet but it is a aluminum boat. Either the dealer or factory repaired it under warranty. That is the first place I'll check. Thanks for your inputs. If all the wiring tests good I think putting a new $130 transducer on it is a reasonable risk.

 

[dingbat]

There is a small fuse panel under the console.

The know issue is the in-line fuse holder on the power cable.

Make sure the unit is grounded to the battery. Grounding to the “hull” will not cut it.
Might want to try buzzing the transducer out. The Airmar website has schematics for most popular transducers