Help!! Interference with my Garmin and out of ideas.

[Capt No Fish]

Hello, I am hoping someone here on BR maybe able to help or provide some idea.  In December I purchased a used 2019 Tracker Pro 170 with a 20 HP Mercury 4 stoke EFI.  I sold my previous boat and took my electronics, transducer, trolling motor and mounted them on this boat.  I never had an issue with my previous boat and the electronics on that boat which was a 96 Crestliner sportfish.

 

Taking my boat on on the lake to try everything to make sure it works and I am ready for the fishing season.  When running my Mercury motor I get interference on my screen.  This first picture was taken with everything wired on my starting battery.  I verified that the motor has a ground wire hooked up to the mounting bracket on the motor. For my unit I have a 10G tinned copy wire going directly from the unit to the battery.

 

In this next picture as I went through all my trouble shooting.  I completely pulled the 10G direct wire back through the boat so it wasn't touching any other wire and put a separate battery in the middle of the boat next to the console to completely isolate it.  It has it's very own battery and very own wire.  When going under say 2k RPM it seems ok.  If I give it any gas the interference shows up.  Below you can see when I gave it gas, then pulled the throttle back and then gave it gas again.  That is in the 2 bars.  You can see it in the side view and the 2 D.  I have the ferrel installed on the transducer. Very bottom picture shows the interference when running.  

 

I am open to any and all ideas as I am out of them. Thank you in advance!

 

 

 

[casts_by_fly]

that looks more like propwash interference and not electrical from the SI view.

 

 

edit:  Ah, I see the faint bars you're talking about.  I don't know on that one.

[Capt No Fish]

43 minutes ago, casts_by_fly said:

that looks more like propwash interference and not electrical from the SI view.

 

 

edit:  Ah, I see the faint bars you're talking about.  I don't know on that one.

One of the tests I did was to try it in Neutral so to take the prop wash out of the equation.  It occurred then as well.

[Siebert Outdoors]

Is the transducer coming up out of the water when you hit over 2k rpm? 

[Scott F]

Hook the electronics to a separate battery and try it again. 

[DogBone_384]

Sounds like you've done all the basics regarding power/ground.

 

Do you have an old cassette Walkman around?  If so, play it without a tape in it and hold it near wire harnesses.  The tape head acts like a microphone of sorts and you'll hear noise w/in harnesses.  It's an old Jedi trick from the OLD car stereo days.  Worked like a charm.

 

Try taking the transducer cable from where you ran it and drape it over the hull so it's far away from existing wiring.  If the interference is gone, you'll have to route your cable accordingly. 

 

Lastly, check the transducer cable for sharp kinks/cuts. 

 

Another thing that just popped in my head, did you check your ground's resistance or for what kind of voltage drop you have between  the battery & +12V @ the Garmin?

 

Best of luck.

[WRB]

No interference running the TM?

Ferites are frequency dependent and need to be installed on the wire causing the interference.

You might want to replace the spark plug wires and connectors, that is more then likely the interference source.

Tom

[Capt No Fish]

2 hours ago, DogBone_384 said:

Sounds like you've done all the basics regarding power/ground.

 

Do you have an old cassette Walkman around?  If so, play it without a tape in it and hold it near wire harnesses.  The tape head acts like a microphone of sorts and you'll hear noise w/in harnesses.  It's an old Jedi trick from the OLD car stereo days.  Worked like a charm.

 

Try taking the transducer cable from where you ran it and drape it over the hull so it's far away from existing wiring.  If the interference is gone, you'll have to route your cable accordingly. 

 

Lastly, check the transducer cable for sharp kinks/cuts. 

 

Another thing that just popped in my head, did you check your ground's resistance or for what kind of voltage drop you have between  the battery & +12V @ the Garmin?

 

Best of luck.

Will give these a try, thanks.

2 hours ago, Scott F said:

Hook the electronics to a separate battery and try it again. 

That is what I did in my second test with the second screen shot.  I had the battery in the center of the cockpit area with a direct wire.  Same Results.

 

2 hours ago, Siebert Outdoors said:

Is the transducer coming up out of the water when you hit over 2k rpm? 

I wasn't able to check that because I was by myself on the boat.  I did however per my dad suggestion try it in neutral.  I actually had the boat on the trailed when I tested that and there was still interference on the screen.

 

44 minutes ago, WRB said:

No interference running the TM?

Ferites are frequency dependent and need to be installed on the wire causing the interference.

You might want to replace the spark plug wires and connectors, that is more then likely the interference source.

Tom

 

I didn't have the trolling motor even hooked up when this was happening. I have a 24 V trolling motors and took one of the batteries to due the test where I had the Garmin hooked up on it's own batter and put that in the center of the boat.  

 

Do you still feel it could be the spark plug wires?

 

I guess I can also try a test where I take my unit to the front of the boat and pull the transducer wire up there and see if it is happening. How far away do you think spark plug wires could cause interference?

[WRB]

Could be the spark plug wires/connectors are arching and your Sonar is picking that up or it’s coupling onto unshielded wire power wire.

Tom