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Post by hambone on Mar 16, 2019 8:06:58 GMT -5
So I’m scratching my head on this one, hope some of you guys have a solution. For some reason I am now getting bad interference on fish finder. I have a Garmin 93 sv mounted on console and transducer mounted on stern of boat. Trolling motor on bow of boat, trolling motor is a Minn Kota riptide, there is no other fish finder on the boat. So with trolling motor in water, when you turn it on the fish finder goes blue with interference. But if you the faster you speed up trolling motor the clearer the screen gets, with motor wide open interference completely goes away. I have pulled motor out of water and turned on and there is no interference, but if you lower down soon as it comes in contact with water we have immediate interference. I am at a loss with what is going on, any ideas?
I did put a new propeller on motor back in winter, because last time out in fall hit a dock and broke propeller. Thought this could be problem but it is exact replacement.
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Post by greywalls on Mar 16, 2019 13:43:31 GMT -5
RFI is never fun to track down! A few questions and thoughts...
First, you'd mentioned, "I have pulled motor out of water and turned on and there is no interference, but if you lower down soon as it comes in contact with water we have immediate interference." So, running full speed out of water produces no interference, but running any speed (until the highest) in the water generates interference, right? That is, it's not simply an ON/OFF power issue or an IN CONTACT WITH WATER / OUT OF CONTACT WITH WATER issue...
If this is the case, then I think one of the following two potential issues most likely are in play -- both related to when you hit a dock and broke your prop: A. Easy issue is that last Fall's impact blew the internal grounding fuse inside your TM. I don't completely understand how it works, but this is a noise reduction circuit -- and I'd be willing to bet that this is your issue. Fuse is in your TM head unit -- check it out. B. More problematic issue is that your hit bent something internal JUST enough to throw the hub out of balance, which now makes an excessive/abnormal amount of RFI (TMs throw out a crazy amount of electrical noise). It's also possible that your new prop was not manufactured correctly and is running out of balance enough to cause RFI under load. That's tough to fix, although you might try adding some ferrite rings around our transducer cable (iffy results) or, more reliably, as noted below, check/re-configure your wiring to make certain that your TM circuit is 100% separated from your electronics circuit...
If all of the above checks out, then some way or another you have a connection between the TM batteries and the circuit that runs the electronics (obviously, you might be running everything off of one battery -- or you could have some shared connection between TM and electronics). Since I don't know your setup, the main thing I can say is that your trolling batteries and TM need to be on a 100% isolated circuit from everything else --and if your TM and electronics are sharing the same, then you've just been lucky not to have issues previously. Hopefully some of this advice will prove helpful, and I hope that you will find that a simple fuse replacement solves your issues.
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Post by hambone on Mar 16, 2019 14:55:36 GMT -5
Thanks Greywall for response and all that info!!
To clarify, yes when trolling motor is out of water I can run at any speed and there is no interference....
If I lower into water while running, as soon as it comes in contact with water there is immediate interference, and actually I even tilted motor into water without letting the propeller touch water (just motor housing touching water) and this also results in immediate interference.....
With motor in water,the slower the speed the worse the interference is, as you speed up its gets a little clearer, then full speed it’s clear as a bell
I will have to look for that fuse you’re speaking of, didn’t no there was such a thing, and yes that’s a good idea about something bent, didn’t think of that, I did hit dock pretty hard
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Post by greywalls on Mar 16, 2019 15:25:31 GMT -5
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Post by FishON on Mar 17, 2019 18:52:45 GMT -5
It your trolling motor and your fish finder hooked to the same battery? I had my Lowrance wired up to one of my trolling motor batteries and had the same issue. Then I ran the lowrance power wires to my cranking battery and it solved the problem.
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Post by hambone on Mar 17, 2019 19:07:44 GMT -5
Yes they are separate, my electronics is with cranking batteries separate from trolling batteries
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Post by SquidHound on Mar 18, 2019 15:58:47 GMT -5
Had a somewhat similar issue in the past. Mine was due to both chargers connected to a 3 way plug that I used to plug into 110. If the charger connected to the sonar batteries wasn't disconnected it created graph issues with the trolling motor/sonar
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Post by hambone on Mar 18, 2019 16:03:22 GMT -5
Well that may be an issue too, I do know that they all share same charger, I have an on board charger that is connected to all 4 batteries, I have yet to get to try anything everybody has suggested, hope to get to it sometime this week, will post what I come up with.... thanks for all the help
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Post by 31Airborne on Mar 19, 2019 6:22:30 GMT -5
H-bone - run your fingers down the coax cable to your 'ducer. You're looking for pinch points, crimps, or breaks in the insulation. Also, check the housing on the 'ducer for any cracks or gaps in the seams. That fact you're experiencing this only when the TM is in the water leads me to believe it may be a compromise in the cable or 'ducer housing.
B
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Post by hambone on Mar 19, 2019 6:59:51 GMT -5
Will do thanks
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Post by hambone on Mar 21, 2019 19:53:43 GMT -5
Well I’m still scratching my head on this tm interference deal.... I have checked everything you guys have suggested and more, with no results, still doing same thing.... there is no fuse in head of tm, tm and electronics are on separate batteries, unhooked onboard charger to make sure there wasn’t any interference coming from that, checked transducer for cracks and cable, looks fine, even traced cable all way back to console, no Knick or bends in cable, I took off new propeller and made sure everything was tight and looked at shaft, doesn’t look bent or anything........ boy this is aggravating....... only thing else I can figure is maybe the propeller is the problem, without buying another one and trying it I’m not sure what to do
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Post by mwardncsu on Mar 22, 2019 7:19:38 GMT -5
There is a ton of black magic involved. You have to try changing one thing at a time and do testing and see if it helps or hurts - hard to do when you want to go fishing.
On my older TM MinnKota RipTide ST, when it was in the middle speeds I would get a ton of noise on the fish-finder. Didn't realize it for a long time as the Lowrance HDS was set to auto, but when in manual it would basically black out the screen. I grounded the motor - ran a wire (with fuse) through the head, down the shaft and connected it to a screw mounting point on the board that has the motor brushes - this wire was then connected to the Negative at the TM trolling motor plug - and all my grounds - trolling motor batts, house batts, cranking, etc are all connected together. This did help some - didn't get rid of it all, but it did help a lot.
I don't seem to have this issue now with my Ulterra Riptide, and I've not gone in to ground it (or see if it is grounded), but I do get a lot of noise when the big motor is running - which I believe is coming from the big motor and the Aux charging cable which connects to my house battery where the sonar is powered - I've not ever bothered to try and isolate that to confirm, but given its only happening when the big motor is on I'm sure it is..... Perhaps a ferrite coil would help in that case....
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Post by codyl74 on Oct 28, 2021 12:18:24 GMT -5
I am having the same EXACT issue. Garmin GT-56UHD and GT-52 both are getting interference ONLY when the motor is in the water. When the motor is on and out of the water interference goes away. Interference appears to be only for Side Vu and not noticeable on 2d or Clear vu (down scan). Odd thing is it goes away completely when the Trolling Motor is at max speed. I read that it's actually the PWM (modulator) causing the interference. Did you find a fix? or anyone else have a solution?
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johnr
New Member
Posts: 1,297 
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Post by johnr on Oct 28, 2021 12:27:02 GMT -5
I have the same issue still. My ducer is mounted on the Xi5 TM, though not on the head anymore. I’ve done all I can to isolate and keep it away from the head with no luck.
I can filter out some of the interference, but not all. The amount of interference varies depending on sonar screen and settings.
Funny thing is, my Livescope transducer is 2’ away and has no problems.
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Post by herringbone on Oct 28, 2021 19:55:40 GMT -5
Question: Codyl74, are you in an aluminum boat? This may help with both you and johnr.
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