External TM ground - where to connect? (TM interference issues)

[zero_cool]

Dealing with TM interference. Did all the basics; moved tdxr cable away from TM power cable, checked battery grounding is connected properly, added ferite chokes, aluminum tape to shield tdxr from TM head. Nothing has helped.

I have a 2013 Minn Kota Fortrex and it does not have a ground (24v did not come with one or I have a 2012 hold over on a 2013 boat). I am going to try an external ground from the TM.

Watched every YouTube video on the subject and found 2 conflicting methods for connecting the ground. One went to the negative post on the electrical buss up front, the other was connected to the negative connection in the TM pedal.

Which is correct/better?


Other details:
2013 Ranger z118
Garmin 73sv w/GT52 tdxc
TM is run on own batteries, wires down the starboard side
Graph powered off buss up front
TM batteries are grounded through cranking battery
All batteries share same charger

[ZeroSix]

Cool - not sure if this will assist - I went through the exact same thing with this year model and found relief after many frustrating hours. You have already tried a few of these and more - like the aluminium tape idea - never thought of that one. The text below is a cut and paste from my phone that was about a 4-month amalgamation of trial and error. I have shared this with friends over the years - please over look any grammar or spelling issues.

What I found most helpful was the ground wires from the trolling motor head down to the foot and plug to graph.

Give these a shot and feel free to PM me if you have specifics or just need to have an "F-Bomber Attack" venting session about the frustration.

Electronics Feedback from Trolling Motor

1. Check fuse on head - should be 3 or 5
2. Ensure no power cables are next to transducer wires
3. No excess power cable coiled up in bow. Pull all to back - wrap in a circle and tie in the middle
4. Install Choke (ferrite)

After you look after these:
- Run a wire from the ground on the trolling motor Plug to the ground on the graph. Should reduce the vast majority
- Next, run a 16ga wire from the skeg of the trolling motor (using a screw to attach it) to the negative post of the stater.
-I ran the ground wire up the TM shaft into to the head of the TM and spliced it into the ground wire for the light on the directional arrow. looks clean and works well.
-Take the hose clamp off that holds the transducer on and where the clamp rides on top of the TM cone file it down to bare metal (small spot, don't get too carried away).Run a ground wire from the power source that the front graph plugs into with the correct fitting.
Run that wire alongside the transducer wire and with a ring fitting on the other end sandwich it in between the hose clamp and the bare metal spot on the TM cone you created.

[zero_cool]

Thank you. I will try the last section next as it seems easiest. My graph power is connected to the power buss in the bow so running the external ground to this buss from the TM cone (under the clamp and along the tdxr cable) gets me there.

MK makes an internal ground conversion kit that connects from the bushings in the motor to the directional arrow light as you mentioned so that may have to be next.

[ZeroSix]

My pleasure. Good luck with it.

[Slim95]

Have you tried running dedicated power wire from the battery to the Garmin instead of the power bus? the internal gound conversion from minnkota should be the same as attaching an external ground to your skeg. Before you buy that I would try the external solution. Also the aluminum tape that you are using as a shield is pointless unless you have the aluminum tape attached to a ground wire. I did the same thing with the tape with no results. Also try twisting your power and ground wires from start to finish.

[zero_cool]

I ran the external ground last night so hopefully that helps. I will go back in tonight and twist the TM power wires as best I can.

Running a new set of wires direct to the battery is on the list as well if I have to. What size and type of wire is used for this? Is there a specific marine grade to buy?

Thank you for the suggestions and help.

[PlayDoh]

It pays to search. I just went through this and the thread is pretty informative. Run a ground from your sonars battery (dedicated a must IMO), from anything in contact with your Aluminum hull, if you have one. I ran a 16 ga wire from my TM skeg (drilled a small hole, bolt+nut+wire terminal) And ran that directly to the Sonars negative post.
While camping I wrapped the entire power wire with tinfoil, and put 3 ferrites on the cable at the sonar. At home, I just wrapped my power wires with copper tape that I had left over from another task. Fairly cheap on Amazon. I did my LS power cable also.

I did everything under the sun, but either the 3 ferrites, from 1 that didn’t help, or the tinfoil, or the 16 ga wire to my hull did the trick. Can’t tell you which one yet. Oh and the TM skeg wire. I’ll eliminate one at a time to see what helped and didn’t. I did run a common ground from one of my 12V TM (24v), to the sonar ground. Also one from the starting battery. Grounds galore, lol. Yet I removed those 2 and no change, still interference free.

check out my thread, there’s some links that are very informative.

http://www.bbcboards.net/showthread.php?t=1073287

[zero_cool]

PlayDoh - your thread is where I got most of the ideas for what I have tried so far. Latest addition is more ferrite rings and the external ground. My boat is fiberglass so the standard/common ground has always been through the big motor only.

I will water test this weekend and am hopeful that what I have done helps. Fingers crossed.

Thank you for this reply and the additional insight into what helped you.

[Slim95]

I ran 12ga from the battery to the unit on the bow which is roughly 25ft. for the wire you need stranded TIN coated copper wire. Anchor marine on amazon sells it the link is below. If you want the good stuff prowireusa sells MILSPEC wire and connectors

amazon wire- https://www.amazon.com/Ancor-108802-...80&sr=8-5&th=1

[zero_cool]

Update: on the water today - was better but not gone. Had to drop the gain down to 55 to clear it up. When I hit the power on the TM there is a spike in the interference and then just a regular snow like interference. Clear vu was the same way.

I will have to think about rewiring direct or learn to deal with it until I get a new trolling motor.