Motorguide Tour 109/lowrance HDS12/9 Interference

[AllyFishing]

"I know mine doesn't have the ground strap but don't know if that would help either. I would hate to tear mine apart & it still not work. Ground the unit like Keith did is essentially grounding it to the shaft since that bracket is tied to the shaft. Sure hope it works."

tracer, I tested mine this morning for continuity and I have determined that mine does not have the ground strap in the lower unit. So that confirms, in my mind, that what Trionix did to keith's by installing that ground wire is essentially the same thing as having a ground strap in the lower unit. All the ground strap does is make a connection from the ground wire in the lower unit to the actual casing. Same thing with the green wire in the head with the same ground wire. I'm doing this to mine and see what happens. no need to go pulling apart your lower unit to add a ground strap.

Troy, that would make me totally nuts if I had interference like you did on your humminbird. I DVR Timmy Hortons shows and he has lots of video shots of his electronics both bow and console and I have never seen interference on either of his Raymarines!! His screen shots are perfect and with much greater definition than what I've seen on any of my Lowrance units.

I've been die hard Lowrance my entire fishing life and for me to say that about Raymarine says a lot. If I were independently wealthy I would go Raymarine.

[tracer1]

Already did mine Ally, will test it in the next couple of days & let you know. Good luck with yours.

[TroyBoy30]

my 1198's were terrible. i was able to get rid of all of it, but it was not easy. here's a list of what i did. my 1198 on the back is terrible with the motor running. I was able to remove all of this when i moved over to garmin

installed the tmc1
ground from trolling batteries to starting battery
ferrite rings on all power cables
ferrite rings on all transducer cables
added quick disconnect on on-board charger connection to starting battery so I could disconnect and reconnect for charging
had my fortrex internally grounded

[Wayne P.]

my 1198's were terrible. i was able to get rid of all of it, but it was not easy. here's a list of what i did. my 1198 on the back is terrible with the motor running. I was able to remove all of this when i moved over to garmin

installed the tmc1
ground from trolling batteries to starting battery
ferrite rings on all power cables
ferrite rings on all transducer cables
added quick disconnect on on-board charger connection to starting battery so I could disconnect and reconnect for charging
had my fortrex internally grounded

Every installation is unique, if you put the same sonar unit/brand and the same trolling motor brand/model to two different boats, one may have RFI and the other not.

You can change motor brands or models and may or may not eliminate RFI, same with sonar units.

If it was easy to eliminate, it would have been done over 40 years ago. The imaging models use up to four different regular frequencies, 83/200/455/800. That is four frequencies that can be affected by RFI. If your motor is "broadcasting" on one of those frequencies, you get RFI.

A friend with two Lowrance units had 200 kHz RFI at the bow and solved it. He decided to move his console unit to the bow and put a larger display model at the console.
When he did that, he got RFI on the bow again and he could not eliminate it, had the MotorGuide rebuilt and that lessened it some and still had to do more measures to get rid it of.

Took me about three months of trial and error to lessen mine on Imaging, and I still get it slightly if I use 800 kHz Imaging. I have Motor Guides.
Along with several other measures, my final resolution doesn't make sense but it works. I ran a wire from the upper trolling motor shaft to the screw on the foot pedal that holds the cable clamp. If I disconnect that wire, I get RFI on 455 and 800 kHz.

I did all that Troy did and more including the Motor Guide internal ground strap--brush card to case.
When I did the negative bonding wire between the TM negative and starting battery negative, it made it worse. Works for some and not for all.

[keith47]

Got back from the lake and the interference was not present until my 2nd day of fishing (small amount). I now have a bigger problem. The 2nd day, I started receiving a continuous HI voltage alarm >18+volts. I raised the setpoint on my Lowrance units but still receive the HI alarm. I will be taking my boat back to Trionics next Tuesday. I will keep you guys posted, just be aware I would rather have the interference than the HI voltage and burning up $6K of new equipment.

[AllyFishing]

whoa that sucks!! Sitting here thinking on this doesn't sound as though grounding to the metal would cause that high voltage. It has to be something else that is a coincidence. I specifically asked the MG tech if there are any drawbacks or things to be aware of by adding that ground wire up under the head and he said not. It's no different than adding a ground strap in the lower unit just located in the head.

Keep us posted on what it ends up being. Things you can try at home yourself is checking the voltage at the battery with a multimeter and at each power cable to your HDS units by touching the 2 large holes on the power plug.

[tracer1]

Took my boat out today, dropped my trolling down, turned on my Elite 7 HDI and guess what.........no interference. It's gone totally. Many thanks to Keith & all the guys on here for their great assistance.

[AllyFishing]

WOOHOO!!! Happy to hear!!! I have to wait another month or 2 before I can test mine. Honestly, if mine works out as well eliminating interference then I'll call MG again and talk to that tech and tell him our experience. Why not install a ground strap from the factory if it had worked in the past for some users but maybe not all. Better than nothing.

[tracer1]

+1

Hope Keith gets his worked out with high voltage warning.

[keith47]

Wasn't able to take the boat to Trionics, I went to Lake Conroe fishing instead. I ran the units all day and not once did I receive an Hi voltage alarm. I even lowered the setpoint back to 18Volts. The units performed like they should, no interference. Hopefully it was just a glitch and not being familiar with the new Lowrance units settings. Glad to read that some of you guys have got your interference resolved. Keep me posted if anyone starts having the Hi voltage as I did.

[Lou r Pitcher]

WOOHOO!!! Happy to hear!!! I have to wait another month or 2 before I can test mine. Honestly, if mine works out as well eliminating interference then I'll call MG again and talk to that tech and tell him our experience. Why not install a ground strap from the factory if it had worked in the past for some users but maybe not all. Better than nothing.

Unsure if the phone support tech you spoke with is an engineer as he seems unaware the addition of the internal grounded strap where the trolling motor lower assembly in the water previously "floated", increases the occurance of damaging galvanic corrosion/electrolysis for some trolling motor designs.

[AllyFishing]

Unsure if the phone support tech you spoke with is an engineer as he seems unaware the addition of the internal grounded strap where the trolling motor lower assembly in the water previously "floated", increases the occurance of damaging galvanic corrosion/electrolysis for some trolling motor designs.

I'm not sure what you are talking about exactly? The term "floated" has me confused referring to the ground strap. We did talk about the externally consumer installed ground wire from the skeg to a negative terminal post to the boat but he did not commit to it.

Please explain more, thanks

Glad you got your problem solved keith! Did you ever test your HDS power cables and the battery voltage?

[Lou r Pitcher]

I'm not sure what you are talking about exactly? The term "floated" has me confused referring to the ground strap. We did talk about the externally consumer installed ground wire from the skeg to a negative terminal post to the boat but he did not commit to it.

Please explain more, thanks

A non US2 connected, composite shafted MK trolling motor , with no boat owner added ground path in the bilge over to the cranking battery, will electrically "float" relative to the cranking battery grounded skeg of the boat engine. So when the 'floating' TM metals in the lower assembly touch water, their voltages have no relevance, and there can not be stray electrolysis currents through the water. The TM "floats" electrically. This is the best setup.... until TM generated interference appears.

If US2 is used or whenever the cranking battery negative is strapped over to the TM negative in the bilge, the powered TM lower unit is now grounded if the factory or owner has also installed an internal ground wire across the MK TMs composite shaft. Compared to a cranking battery negative terminal, the water touching metals in the TM will now have a small positive voltage during TM use. This positive voltage on a ground is normal due to the natural voltage drops across the trolling motors's wiring carrying 40 or 50 so amps. It results in stray currents in the water (between the TM and boat engine's lower unit) whenever the TM is powered. They can be damaging, such as to skegs and water touching metals more so in brackish or salt waters.

Seems most boat owners/shops don't really get how important faraday shielding of a motor is needed, or how the rfi of a TMs chop circuits is beng path routed into their boat's sonars.

[AllyFishing]

Wasn't able to take the boat to Trionics, I went to Lake Conroe fishing instead. I ran the units all day and not once did I receive an Hi voltage alarm. I even lowered the setpoint back to 18Volts. The units performed like they should, no interference. Hopefully it was just a glitch and not being familiar with the new Lowrance units settings. Glad to read that some of you guys have got your interference resolved. Keep me posted if anyone starts having the Hi voltage as I did.

Hey Keith.....just got out on the water today finally and tested my "ground wire to the inside of the head" for reducing interference and BINGO....that did the trick!!! Thanks for posting that fix by that company. Worked for me. No interference at all and none on the High CHIRP 2d either. That's awesome!!

[AllyFishing]

happy happy happy!!!!! No interference

[tdt91]

Great thread guys

[javelin90]

I just found this thread and will give it a try.