oh-oh - Motorguide trolling motor interferes with my transom mounted structurescan

[donberry]

color me
I recently purchased a Motorguide W75, wireless trolling motor. I had a Lowrance HDS 5 already installed and had zero problems. Just recently got a LSS-1 StructureScan and a 2nd HDS 5. Was sooooooo happy. Out of the box it worked like a champ - no tweaking necessary and even I can see if it really is a fish or not.
Turns out now I am not so happy.
Trolling motor is bow mounted and run by it's own set of batteries.
The trolling motor wiring is 8 gauge and on the opposite side of the boat of the LSS-1 and HDS wiring.

The LSS-1 transducer is mounted on the transom. I googled the heck out of interference problems, but everything I come across is a transducer mounted on the trolling motor.
The 2 HDS and LSS-1 are wired up to the cranking battery.

The interference - at any speed except for the highest, the screen is unreadable. It turns white. You can sort of make out vague stuff in the background if you stare hard enough - I am talking big trees, not just bait fish
The wiring for the trolling motor and the Lowrance gear share nothing - not even a fuse box as they all have inline fuses.

I came across something that said to ground the negative of the cranking battery to a negative on the trolling motor batteries - tried that and did not help one bit.

Just as bad on 455mhz as 800mhz.

When the trolling motor is on high speed, there is some interference "waves", but you can read the screen.

I am really bummed.
Pulled my old sonar off the bow and installed a 2nd HDS. I havwe not mounted the 85/200 transducer yet as I am trying to figure out the best way to do it - is not easy with the W75 T.M. Figured no problem, tho it would be reading from the back of the boat I would still have sonar......nope.
So now if i am say drifting a shoreline, using the t.m to help against the current, guide me or whatever, I have no bow mounted sonar I can read at the moment.
Is a real pain, but worse is i was so happy the installation went so smooth....I patted myself on the back too soon.
ANY ideas appreciated.

 

[John_S]

Re: oh-oh - Motorguide trolling motor interferes with my transom mounted structuresca

Given your description, I'd say the Lowrance units are picking up noise from the PWM. On high, PWM is essentially off, and your screen noise seems to diminish at full. It also sounds like it was not a problem until you added SS. If you unplug all the SS and isolate from the HDS, does it go away? I'd start with discussion with Lowrance tech support. Is this an alum or fiberglass boat?

Yes, the Wireless makes for a challenging transducer mount. Here is what I came up with: http://joefish.homestead.com/TMTDmount.html

 

[donberry]

Re: oh-oh - Motorguide trolling motor interferes with my transom mounted structuresca

John_S - so your the guy. I came across your transducer install when i was researching how to do it myself. Where there's a will, there's a way huh. I think it is a safe bet anyone who has ever owned a wireless without sonar has come across your pictures.......
Mine - it is definitely the LSS-1. I came across this site HERE that has very good info and am going to try that stuff before i contact support. I just have a feeling when I contact support i will be getting on a merry go round.
I may skip right to his lawn tractor battery idea 1st tho, just to see if it works.
Was thinking tho - I would guess the interference is caused by the transducer, not the module. While it has it's own wiring, all on the other side of the boat from the t.m. wiring, I did mount the LSS-1 under my dash........thinking maybe i should try moving that. Doubt it works, but at this point, who knows. I never would have thought i would have this problem to begin with.
If(when) I do find a fix, i will post what it was.

 

[fucawi]

Re: oh-oh - Motorguide trolling motor interferes with my transom mounted structuresca

o.1 uf capacitor as near to the motor brushes as you can get and another across supply cables inside the controll head. You may have to resort to some 1 A RF chokes in the supply to the sounder

 

[donberry]

Re: oh-oh - Motorguide trolling motor interferes with my transom mounted structuresca

fucawi - thanks for the info. If the other info I linked to does not work, i will give this a shot. Capacitors are something i have a bunch of lying around as my other hobby was audio and I repaired/restored quite a few vintage pieces of gear.