My first Post... Is not a good one. - Interference

Hi there guys. Ill start by introducing myself as smitty010203 from NC. I have read a little on this forum and figured it was time for me to post since I am desperate need of help. I have a pretty new G3 20cc that I just added my second Garmin unit to. The first was a Echomap Chirp 73sv at the helm (kicking myself for not getting a 9" unit). And I just recently added a Garmin Striker plus 9sv at the bow of the boat. Which is where my woes begin. For starters, it is an absolute Pain to get a transducer rigged up on the Minn Kota Powerdrive Trolling motor, but I knew it would be. I have researched and seen it all for months before I even added the transducer. Even then its still a pain. My real issue however is INTERFERENCE.......

I have talked with Minn Kota several times, I have talked with Garmin a couple times.

Setup: Garmin Striker plus 9sv with CV52HW-TM (same ducer on both units actually). 24v Minn Kota Powerdrive with Ipilot (2016ish model)
Problem: Anytime the tm is running I get interference ACCEPT at speed 10. It really shows up worst on Sidevu and Clearvu, traditional isnt as bad.
Things I have tried:

• Checked fuse in head of TM
• Unhooked fuses on minn kota 3 bank charger at the cranking battery
• Ran Garmin power to separate battery off the boat
• added ferrite beads all over the dang place (does nothing)
• opened up Powerdrive where the battery indicator is since MK is sending me a beed to put there and apparently there already is factory installed ferrite bead in place
• changed frequencies on garmin
• ran ground wire from hole drilled in skeg (bare metal) to all sorts of places (does nothing)
• checked the brush wires in the motor to make sure they weren't touching the barrel (multiple times). Already familiar with this since I had to replace that barrel almost immediately when I got my TM because the magnet inside was cracked. There has been no water intrusion in the motor since I did this repair myself almost a year ago and the motor has ran just fine.
• Tried putting electrical tape over the brush wires (have since removed)
• Connected the TM transducer to my helm Echomap unit, (got interference)

The only effects:

• I have only seen a change by doing a couple things aside from changing brightnness settings (gain) on the Garmin.
• taking the transducer off the motor makes the interference go away, the closer i get it back to the unit the more interference shows up. It also makes a difference is if point the transducer at the trolling motor in a way. Either way, once I am within 6" of the TM, interference starts showing back up.
• On one occasion, I pulled the fuse in the head of the unit off the ground wire and it actually made the interference go away a little bit. I stopped the motor and restarted it then it just came back worse, so I put the fuse back in then it was back to its normal interference.

Having a fishfinder on the Bow has been amazing, I have always wanted one and when I am fishing without the trolling motor running its the greatest thing ever, problem is I almost always have the TM running. so this issue is going to drive me insane.

I am taking the powerdrive to the local Minn Kota repair man today to fix a seperate issue since its covered under warranty (really wobbly at the knuckle, a bushing in pin is broken I believe). I am going to have him also replace the brushes if he has the parts, they seem to be a little chipped up and worn where they make contact with the copper plates on the armature. maybe ill get lucky and that will help

Aside from that working which I doubt it will, I am at a loss. I can normally fix all sorts of things because I am mechanically inclined and very good at researching things. But this issue is kicking my tail. I am at the point where I am going to try and get my hands on another trolling motor to see if it does anything, or just buy another trolling motor, OR... put the friggin transducer on a pvc pipe and stick it in the water whenever I am putting the motor down.

If any of you guys have any bright ideas left that I could try out I sure would appreciate it.

Get a new Trolling motor

Interference drives everyone nuts. A transducer designed to operate on trolling motor may help. Unfortunately not familiar with the transducer you are using. Interference can be caused by so many things. Some of which you are already taken care of.

Transducers that are designed for installing on trolling motor usually have extra shielding to combat the interference. I had a humminbird that gave me fits. It was finally solved by installing different ducer.

You know the interference is coming from the trolling motor? So it Looks like you have done everything that can be done. Your solutions are to replace that old trolling motor or mount your transducer on a stick. Adding a ground wire on my Minnkota along with making some adjustments solved 95% of my issue.

Quote:

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Originally Posted by ifishinxs

You know the interference is coming from the trolling motor? So it Looks like you have done everything that can be done. Your solutions are to replace that old trolling motor or mount your transducer on a stick. Adding a ground wire on my Minnkota along with making some adjustments solved 95% of my issue.

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Yes those options are what I am afraid of. What sucks is that TM isnt even a year old I dont think. I have 2 new brushes coming in the mail right now, that will be my last ditch effort to fix this issue. The interference is definitely coming from the lower unit of the trolling motor.

Are you testing all these fixes with boat off the trailer and in the water? Are you using an onboard charger, if so have you tried disconnecting it from the cranking battery where your graphs are connected

http://palomar-engineers.com/ferrite...-MHz-p74396520

Maybe this can help understand the technology behind the interference. And have a better understanding of how to possibly fix it.

Trolling Motors with PWM (pulse width modulation) to control speed are notorious for this. Which many trolling motors use today, especially auto drive TM's.

You probably notice the noise goes completely or almost completely away when you have trolling motor at near max speed. This has to do with the duty cycle of the pulses to the motor.

PWM is nice for controlling speed because it is nice and smooth controlling speed and continuously variable from 0 to 100%. The down side is they put out Noise. PWM has been around forever and is used in many things. The designers of the circuit's know about the noise down fall of PWM and try to mitigate at the output by using various component's and designs. If any of these filtering component's have failed, it can cause very bad noise issues. And next to impossible to get rid of.

In the case of a trolling motor the PWM is being done at the speed controller board.
If it was me, I would start at the source of the noise, the controller. It is possible a filtering device has failed on the board. Faulty or worn brushes can cause the noise to be worse.

In my opinion, manufactures should start focusing on better filtering and or different design or this problem of sonar interference will just keep happening for many people.

Hope this helps!

I havent tried allll of the fixes in the water but I have tried a few of them. I understand being in the water makes a difference. In my case however, the results in the water and in my garage are the exact same on my fishfinder. If I am able to do something that will mitigate the interference even 50% I will then check that on the water.

I have pulled the fuses to the 3 bank charger at my cranking battery where my FF's are hooked up. Likewise I have ran power straight to a completely seperate battery on my lawn more. Makes no difference at all.

Did you try going in to your sonar advanced settings and turn the INTERFERENCE setting on HIGH and see if it helped any?

Quote:

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Originally Posted by Pipercub

Did you try going in to your sonar advanced settings and turn the INTERFERENCE setting on HIGH and see if it helped any?

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Yep, did that too. Only thing in the setting that made a difference was turning the brightness down to Auto Low...

I have the same problem that you're having. The interference setting helps some but not a lot. I have a 93sv Plus at the console and one at the bow. They're linked via ethernet so I just use the transducer mounted on the transom for my sonar at the bow. It's not what I want to do but it works great.

Before installing the Plus units I had a 93sv Chirp on the bow and had no problems whatsoever. When I put the Plus unit on the bow I started getting really bad interference although I'm using the same trolling motor (Ultrex) and the same transducer (GT-52HW). I tried some of the same fixes as you but nothing has helped.

I have read where the ethernet can cause interference (maybe anyway). Did you ever try cutting the sonar off at the consoles unit/transom, and then checking the TM ducer? Apparently they can cause interference between each other as well. Today I will be getting my new brushes in the mail. I am really hoping that helps out my issue.

Update: Put in the new brushes yesterday afternoon. The old ones were definitely pretty worn. Unfortunately, the new brushes made no difference at all.

I do have a new suspicion however. I did a resistance test on the armature while I had it out. While doing the 180 test on the copper plates (commutator bar I believe its called) everything was reading fine until I got to one of the plates and boom the resistance was out in left field. To put it in perspective. All of my readings were around 4 ohms until I got to the suspect plate which was reading something like 150 ohms. So now I am going to try and get my hands on another armature and see if that will do anything...

There have been a zillion of these interference posts on many boards. Never expected to see anything new but this one is a bit different. Went from no interference to interference by changing units. That new to me. Not sure if it's a fluke or says something about the internals of the units. If it's indicative, the echomaps have better interference rejection than the Strikers but this is a single case and we have to be careful about generalizing.

A second possible revelation is what smitty010203 just posted about these readings. If he finds a different armature with consistent readings and the interference goes away that would be interesting too.

Thanks for posting your experience with this.

I didn't get interference on my unit at the helm because the transducer was/is mounted on my transom. Only getting interference at the trolling motor with the new bow unit. I tried hooking the TM ducer all the way at the helm unit and ended up getting interference on that unit as well. Its not the unit. Its the trolling motor that's causing the interference, specifically the motor portion. Now I just have to get my hands on a new armature. I will 100% let you guys know what happens with it. May be a couple days or it may be a week. Either way. I feel like if this is the fix (which would make sooo much sense now) I believe I may have cracked the lid off a case that will help tons of other people who run into the same dead end as me. I have yet to see anywhere someone talk about testing the resistance on the armature as it relates to transducer interference. Basically I now know there is a short or some sort of damage in the armature. That's gotta be it.

Curious also:thumb up2:, that would be considered an open or high resistance.

Is this something that just started occuring one day? Or have you always had the interference? Not sure if you mentioned that.

Quote:

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Originally Posted by smitty010203

I didn't get interference on my unit at the helm because the transducer was/is mounted on my transom.

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Sorry, I misread the post. I though you just switch units and picked up the interference.

Quote:

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Originally Posted by moetorola

Curious also:thumb up2:, that would be considered an open or high resistance.

Is this something that just started occuring one day? Or have you always had the interference? Not sure if you mentioned that.

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Couldn't tell ya. The trolling motor has always seemed to run just fine to me. I've never noticed an increase in noise or vibration or anything like that. I just happened to think about doing a test on it with the multi meter when I had it out to replace those brushes. Headed up to Smith mtn lake this afternoon for the next few days so I am calling around up there to see if anyone has one/can replace it for me.

EDIT: Just re read this. The Bow Garmin Stiker unit is brand new. I got interference the second I started the trolling motor. Havent even had it but a week or so.

Alright boys and girls. New Armature arrived yesterday, I installed it, and it did nothing... I did check the resistance on it before installing. So that wasnt the problem. :(.

I do however have anotherrrrr new solution. After speaking on the phone with Pro fishing legend G-man, thanks to my wife who knows him, we came to the conclusion, that my problem mightttt be my transducer. You see, my biggest interference issue is in the Clearvu, and Side vu. Its not all that bad with the 2D sonar. Some of you may know about the whole issue with the CV52HW transducers, but if you dont I will explain briefly. Apparently these transducers dont actually have a downscanning element. Instead. They produce a synthetic clearvu image using the left and right beams. G-man stated that back before they had real downscanning they had a similar setup with a synthetically created image using a left and right beam. Between that software and the higher sensitivity required, interference was always a nightmare with and it was something they basically just had to deal with until they started getting real down imaging.

THUS... I am going to be contacting Garmin in the hopes that I can get a GT52HW or some other transducer. If Garmin wont send me a new transducer to replace this one I will probably just return the entire unit and get something different.

Quote:

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Originally Posted by moetorola

Maybe this can help understand the technology behind the interference. And have a better understanding of how to possibly fix it.

Trolling Motors with PWM (pulse width modulation) to control speed are notorious for this. Which many trolling motors use today, especially auto drive TM's.

You probably notice the noise goes completely or almost completely away when you have trolling motor at near max speed. This has to do with the duty cycle of the pulses to the motor.

PWM is nice for controlling speed because it is nice and smooth controlling speed and continuously variable from 0 to 100%. The down side is they put out Noise. PWM has been around forever and is used in many things. The designers of the circuit's know about the noise down fall of PWM and try to mitigate at the output by using various component's and designs. If any of these filtering component's have failed, it can cause very bad noise issues. And next to impossible to get rid of.

In the case of a trolling motor the PWM is being done at the speed controller board.
If it was me, I would start at the source of the noise, the controller. It is possible a filtering device has failed on the board. Faulty or worn brushes can cause the noise to be worse.

In my opinion, manufactures should start focusing on better filtering and or different design or this problem of sonar interference will just keep happening for many people.

Hope this helps!

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This explanation is spot on....and is the only real solution for TM interference. While yes it is possible to have defective transducer shielding, it is almost ALWAYS an issue with the failed filtering components as described here. Running all the wires to this and that do absolutely nothing and in many cases make the situation worse.

Replacing components on the TM or even replacing the TM has been the only real solution.

Excellent post Brian!

Roy

Had kind of a break through last night. I took the boat out to do some fishing and as I got started I noticed something. MY INTERFERENCE WAS GONE!!! 100% clean...I couldn't believe it. Changing that armature really did make a difference.

BUT here is the thing. Whenever i would point my motor to the left, the interference would come back. And then at other times it would randomly come back. If I cut the motor then cut it back on it would sometimes clear the interference again. It was bizarre. I tried moving what cords around at the TM/Unit that I could to see if I could actually see a change in the interference but I could never get anything to happen.

So as some of you guys have said, I think being out on the water actually did make a difference. I am going to check it again in my garage today and see if it is still 100% interference like i did before (which would realllly confirm the need to be in the water for testing.). I will probably go ahead and try to run all my wires as cleanly as possible away from the TM wires before heading out as well.

I did notice my helm unit was picking up way more interference yesterday than it ever has as well for some reason which I thought was extremely odd. Regardless. I think I am still going to try and get away from Garmin.

How is getting away from Garmin going to help anything? They all have interference issues.
What about the gt-52 transducer? With dedicated DI.
One thing I've noticed, most every thread on interference, involves a digital trolling motor. Regardless of brand.
Have you tried mounting the transducer on a stick, away from the Trolling Motor?