Author Topic: Trolling motor noise (Read 36309 times)

maxfli · « **on:** June 10, 2014, 05:10:17 AM »

Well I'm back Greg. 798 on bow has had trolling motor noise since I put it in service last year. Finally tired of it and needing a fix. When trolling motor is running the interference makes the side scan and down scan unreadable. The regular sonar has blue vertical lines while motor running. Called HB, and they were great, set me a sheilded power cable, (which I already had in place) and a new down scan tranducer. While installing and testing the transducers I do not have the intereference whith tranducers laying on deck of boat, only when I run the cable down the trolling motor shaft and mount the ducer do I get it. The cable running parallel to the power wires in the trolling motor tube appear to be the culprit. I've put a ferrite suppressor on the transducer cable (close to ducer) no help. Will try putting it at the head unit in morning. There has got to be a fix for this. I know the pros don't put up with this. I have read someone suggested putting tin foil sheild around cable (thats gonna look like crap), and also grounding trolling motor. Where do you find ground in a boat? Negative buss? Give me a hand Greg I know your the man!

geemul · « **Reply #1 on:** June 10, 2014, 06:29:25 AM »

I know Greg is "the man" for this.

My experience may help, I had precisely that problem on both my Bow and Helm 798's caused by my iPilot Link motor.

The local dealer here in Australia did what Humminbird/Minnkota suggested to you, he also did the following,

Ran the power for the Minnkota off the dedicated battery I supplied for the job
Powered the Humminbird's off the starting battery in the boat
Ran an external earth wire to the motor head and connected it to the negative terminal on the dedicated Minnkota battery

The dedicated Minnkota battery is not connected in any way to the boats starting battery, it is a standalone electrical system only charged when at home by an external battery charger.

The below photo shows the external ground connection back to the negative terminal of the Minnkota battery.

maxfli · « **Reply #2 on:** June 10, 2014, 10:37:06 AM »

Hummm, I may experiment with another battery at some point, but my humminbird is powered from the cranking battery sure enough, but my trolling motor has two separate batteries dedicated to trolling only. Nothing else on them. I would think that would be sufficiently isolated from one another.

maxfli · « **Reply #3 on:** June 10, 2014, 10:52:36 AM »

UPDATE; More testing this morning showed that with the xducer laid out across boat; no noise. With xducer clamped to motor, only a little interference. When cable is taped to motor shaft, complete white out. now with that said if the motor is on high the noise is much less than down in lower speeds. I've got a ferrite suppressor at the cable going into control head. No help there. I did think about soldering a wire to the motor and either taking it to neg of its own batteries, or taking back to jack plate and let water be earth ground. Lot of trouble involved in that one. Surely there is a easier cure.
Heres some specs.
TM=Minn Kota maxxum 80
Unit is a HB 798ci SI sn9020303-1612
transducer hb sent me is a XTM-9 DI-25T; The ones that came with it have no ID tag on cables, but one is a full size side scan xducer, and the other is a compact SI xducer. Never had the latter on, but have tried the new one with only loss of side scan to show for it. Got old one back on for now trying to get this interference cut down. You guys at HB might know what xducers they sent in the combo by the SN. IDK just some info to help you terouble shoot.

Humminbird_Greg · « **Reply #4 on:** June 10, 2014, 11:17:50 AM »

maxfli,
The ferrite that you installed; was that from Minn Kota or Humminbird? If not, ask them for one as just like any other electrical component there are many sizes/values available and if you do not use the correct one you may not get the best results.

Contact Humminbird about that XTM-9-DI-25-T transducer because the 798ci Si unit should be using the XTM-9-Si-180-T on the trolling motor. Using the XTM-9-DI-25-T leaves one Si sonar (the right I think) open and very susceptible to electrical interference.

Well if the Humminbird web site was up (its down right now for some technical reason…) I would post a link to the trolling motor interference FAQ page. Maybe when the site comes back up you can search for it. Otherwise you should call the Humminbird Customer resource folks again about this. There are several things that they will have you do and it is not always the first one or two that fix this problem on all boats.

maxfli · « **Reply #5 on:** June 10, 2014, 11:30:23 AM »

Here is a shot of the interference I took a few days ago. works fine with motor not running.

maxfli · « **Reply #6 on:** June 10, 2014, 11:34:46 AM »

True Greg. I got the ferrite from work. We use them to cut out automation noise in plc signals. no greater than 24 vdc, and not near the current the motor pulls. I'll get back with them later today on xducer and proper ferrite.

maxfli · « **Reply #7 on:** June 10, 2014, 11:36:07 AM »

software is 4.780 too by the way

Humminbird_Greg · « **Reply #8 on:** June 10, 2014, 01:28:18 PM »

maxfli,
There have been some software changes to try and help with trolling motor noise issues but I don’t know if they will help enough in your case. You may want to try updating the software before you call them.

maxfli · « **Reply #9 on:** June 10, 2014, 03:13:27 PM »

that may be an issue in my case Greg. I'm afraid if I upgrade too much it will brick my Interlink. Remember I'm linked with an old 987. I may loose it if my 798 gets too smart to talk to it. LOL

rnvinc · « **Reply #10 on:** June 10, 2014, 10:59:35 PM »

Check your xducer cable very carefully for nicks, abrasions, and maybe even came loose at the point where the cable enters the xducer housing...(and this means even removing possible wire ties)..

I have troubleshooted (is this even a word?...)...this very same scenario for another user that led to a minuscule nick under a cable tie allowing RF to enter the xducer cabling...

And nothing short of a new xducer solved it...

Rickie

maxfli · « **Reply #11 on:** June 11, 2014, 01:57:42 AM »

Humminbird sent me a new transducer and it didn't help. My old one did have a bad spot in cable but it was at port in the bow where the cable comes up out of boat. The stainless sheild over the the hole cut into it. It has been taped up for a year probably. Can't say the cut made any difference, it still looks just like it always did, but then it is away from the motor and shaft.

maxfli · « **Reply #12 on:** June 11, 2014, 02:26:23 AM »

Greg; I'll call HB tomorrow. Can you give me an Idea of what I should ask for? The lady on the phone though very nice and eager to help, I feel might be ignorant to the technical side of this issue, (partly due to the fact she sent me the wrong xducer). Without knowing what the stock xducer models are that were sent with unit I probably sound a bit ignorant myself. Fact is I don't know what to request. Suggestions?

geemul · « **Reply #13 on:** June 11, 2014, 08:12:41 AM »

Quote from: maxfli on June 10, 2014, 11:30:23 AM

Here is a shot of the interference I took a few days ago. works fine with motor not running.

That's precisely what I was seeing on mine, I tried all sorts of ferrites and filters myself as well. (I'm an electrical engineer)

Right down to the interference being much improved with the motor at full speed and worse at lower speeds.

The only thing that worked was as described above.

I'll see if I can find some screen grabs of mine from when it was acting up.

Geoff

Ok, here are the only two I can find. The gaps in the interference are caused by switching off the Minnkota, I can't remember exactly the test speed but 5 sort of sits.

First one is the Bow 798 with the Helm 798 turned off. The boat was in my garage as the original thoughts from the dealer was prop wash.

Second one is the Helm 798 with the Bow 798 turned off. Again in the garage to eliminate prop wash.

maxfli · « **Reply #14 on:** June 11, 2014, 09:58:54 AM »

Ok check this out. I used the tin foil shield on only part of the cable that was in close proximity to the TM and tried to ground it on both negatives on both sets of batteries. This is the result. The homemade shield does work much better on the TM Negative than its own negative. This was taken while running TM at 50% which is what I use most of the time and holding the shield wire on the neg. firmly. Not attached solid mind you. Looks pretty good now, but it is in my shop not in water. I think i can do this shield a bit better and make some solid connections and solve this for the most part. Gonna look like crap though. HB could solve all their noise issues by using a good shielded twisted pair cable for their transducers.
Comments?

maxfli · « **Reply #15 on:** June 11, 2014, 09:59:25 AM »

maxfli · « **Reply #16 on:** June 11, 2014, 10:00:04 AM »

Humminbird_Greg · « **Reply #17 on:** June 11, 2014, 02:22:41 PM »

Quote from: maxfli on June 11, 2014, 02:26:23 AM

Greg; I'll call HB tomorrow. Can you give me an Idea of what I should ask for? The lady on the phone though very nice and eager to help, I feel might be ignorant to the technical side of this issue, (partly due to the fact she sent me the wrong xducer). Without knowing what the stock xducer models are that were sent with unit I probably sound a bit ignorant myself. Fact is I don't know what to request. Suggestions?

maxfli,
I would start by letting them know that you were sent the wrong transducer (XTM-9-DI-T) or that you at least received the wrong transducer and still need the correct one.

Next would be to ask a ferrite ring for the transducer cable. They should know about the trolling motor interference – if not, they have someone they can ask about it.

Limit your testing of this and other fixes to on-the-water only as you could get a false positive or negative result otherwise.

We use shielded cables on these transducers, some have multiple shielding. Let us not forget that the root cause of the problem is the trolling motor and all we are trying to do is ground or shield the Humminbird unit from the RF that the motor is causing.

maxfli · « **Reply #18 on:** June 11, 2014, 04:48:47 PM »

Ok, transducer ordered, with ferrite ring. Humminbird support is the best I will say. Will keep you posted on results. Heading to KY. lake for the weekend and will test what I have come up with on the water. The new stuff won't be here till next week, so I'll have to make do. I'm stopping in local electronics place in the morning to get 8' of heat shrink to solidify this contraption. As you can tell I like messing with stuff like this. Eager to see If I've done any good. Thanks Greg; I'll keep you posted.

maxfli · « **Reply #19 on:** June 13, 2014, 06:07:53 AM »

I read a post from like 2011 on here that described attaching a wire to the TM motor (under xducer clamp) an taking it to positive on The unit side. Not a very good idea in my opinion, but for testing sake I tried it, with nominal results, but I attached it to the tM Negative like I was doing my makeshift shield and noise went away.
so I have removed all the tinfoil and gone with this one ground wire. Heading to river for the week end and will let you know on Monday what happened. This may get me by till I get the stuff from HB.

maxfli · « **Reply #20 on:** June 25, 2014, 02:24:23 PM »

Got the xducer from HB along with the ferrite ring a few days ago. Have not installed them yet, due to inability to get to river, but the above mentioned and pictured wire to neg. did make the side scan usable when I went to river. Funny when you first drop it in water and try it it is clear as a bell, but as time passes some distortion seems to reappear. Take it out a while and drop it in again, same results. Funny seems the longer it stays in water it comes back, but not nearly to the extent it was. You can actually see stuff now.

maxfli · « **Reply #21 on:** June 30, 2014, 12:05:21 PM »

I was really hoping I would have some good news by now, but actually Things have gotten worse. Put new xducer on today with ferrite ring. No joy. looks like down scan and sonar are clear, but sidescan is like always. Very noisy. Worse than when I had ground wire on. First pic shows this.

maxfli · « **Reply #22 on:** June 30, 2014, 12:11:52 PM »

Messed around with the setup using ground again, cables loose you name it. No help. Went back to original setup, that was working pretty fair, and it has gone to crap now, as far as sidescan goes. Doesn't look any better or worse than new stuff. I got off work this morning and my patience is not where it needs to be for this, so I will horse around with it more in morning. Really disappointing though. I thought we were on to something.

This is what it looked like before messing with it today.

jimham82 · « **Reply #23 on:** June 30, 2014, 01:04:07 PM »

Guys, I have done everything in the book for years -- earth grounds, wiring going down separate sides of the boat for the TM and the electronics, shielding all cables, RF chokes, trying different transducers, etc., etc. (By the way, the universal transducer in my Fortrex 101 is worthless. Tons of interference.)

What I have found, as stated above, is that having the cable close to the TM shaft causes interference. I believe that I have the 2D interference to a minimum, which really helps in deeper water, but the DI/SI still has plenty. I use the 2D and 360 most of the time at the bow and the 360 doesn't seem to have much interference.

One fix -- change your transducer option to use the transom mounted transducer. That will stop the interference, but the depth will be coming from the back of the boat.

This has been very frustrating to me having spent a lot of money on top end Humminbird products and Minnkota trolling motors. I just wish that the vendors let us know that this is something that will likely happen. It isn't just limited to Humminbird, I know Lowrance have had the same interference problems.

Watch the pro's boats on TV shows and you will see the interference whenever they step on the trolling motor button.

Final thought. I think that the reason this isn't a bigger issue for the manufacturers is that most of the people that use the units fish shallow, less than 10'. It is not a big deal then. Also, at shallow depts, they never pickup the sonar signals from their rear unit that you see in deeper water (> 20').

Humminbird_Greg · « **Reply #24 on:** June 30, 2014, 03:02:24 PM »

Quote from: maxfli on June 30, 2014, 12:05:21 PM

I was really hoping I would have some good news by now, but actually Things have gotten worse. Put new xducer on today with ferrite ring. No joy. looks like down scan and sonar are clear, but sidescan is like always. Very noisy. Worse than when I had ground wire on. First pic shows this.

You tested this with the transducer in the water maxfli?
Have you tried disconnecting the InterLink to see if the noise goes away?

maxfli · « **Reply #25 on:** June 30, 2014, 03:46:57 PM »

No its not in the water right now Greg. I may go out to the local lake and do some testing tomorrow, but i really don't see water helping or hindering the issue. One thing; where would be the best placement for the ferrite, close to xducer or closer to head unit?

Humminbird_Greg · « **Reply #26 on:** June 30, 2014, 04:07:11 PM »

Yes testing in the water can make a difference.
Install the ferrite ring as close to the unit head as you can get it.

maxfli · « **Reply #27 on:** June 30, 2014, 08:24:26 PM »

Out of water test;
pic 1 new xducer mounted with grn installed wires not taped to shaft.
pic 2 new xducer with wire now taped to shaft.
pic 3 new xducer with grnd from TM batt off.
pic 4 new xducer with grnd from crank batt on -
pic 5 new xducer with grnd from crank batt on +
pic 6 new xducer with grnd from TM on +
pic 7 old xducer with grnd on neg of TM
Will do exact same tests on water tomorrow.

rnvinc · « **Reply #28 on:** July 01, 2014, 09:02:57 AM »

Is there a common on-board battery charger for the TM batteries and the electronics battery in your setup...??

Rickie

krginga · « **Reply #29 on:** July 01, 2014, 09:21:26 AM »

I assume you have a variable speed TM, my 899 does this if they are both connected to the same battery, even with a big capacitor added to the power of the 899 it still does it, figured the off and on of the maximizer technology was causing voltage drops resulting in the lines, didn't fix it. I wished I had an oscilloscope to see the actual interference on the the power leads, then a filter could be made.

maxfli · « **Reply #30 on:** July 01, 2014, 12:44:13 PM »

I removed the minn kota onboard charger several years ago to allow better access to the bilge area and to save weight, so no it is not a factor. The new xducer and ferrite ring from humminbird solved the issue. here is some shots I took on the water today.
1st pic is new xducer with grnd to TM batt neg. attached.
2nd is no grnd.
3rd is same pass on ditch with brush in it (coasting no motor on).
There is just a hint of disturbance with motor on as opposed to off, but it is hardly noticeable.

maxfli · « **Reply #31 on:** July 01, 2014, 12:49:48 PM »

Just a little loss of clarity in side scan. Down is not too bad. I think I can live with this. Many many thanks to all who had input on this. I do wish I had took a pic without the ferrite in place to see which made the most difference the new xducer or the ferrite. Oh well maybe another time. I'm going fishing. Feel free to message me for some more info if you like, But honestly Greg is the man! I was skeptical that the water or having something to actually see would make that big a diff. I am humbly wrong it did.

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Author Topic: Trolling motor noise (Read 36309 times)

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