HDS 9 interference from trolling motor

[Joepapar]

I just installed an HDS 9 touch on the bow of my bass boat and every time I hit the trolling motor, it throws interference to the HDS. It looks like a semi transparent curtain hanging from the top to the bottom of the screen whenever the foot control is activated. As soon as I take my foot off the foot control, it clears up. Any suggestions on how to eliminate the interference? Thanks.

 

[kjsAZ]

completely independent wires for the supply Plus AND minus) directly to the battery may help. The trolling motor most likely generates "noise" on the supply as they switch very high currents. Keep the new wires as far away as possible from the wires used for teh trolling motor or you may get crosstalk.

 

[Joepapar]

I used shielded wire from the lowrance supplied power wire harness to a separate fuse box that all of the electronics are hooked to. The flush mount hds 5 on the bow doesn't show any interference, just the hds 9 mounted to the front deck. The flexible wire harness for both the hds 9 and trolling motor do cross at the front of the deck so I don't know if that's causing an issue.

 

[kjsAZ]

and the trolling motor is not sharing any "ground" or supply wires? There also could be a "loop" as in a cross-connection between either supply or ground which could cause that. Very difficult to diagnose without "touching the system".
You may want to use two wires to connect the HDS9 to a battery to see whether that fixes it (naturally with an inline fuse close to the battery). Or supply the HDS9 from an extra battery (temporary) to see whether that helps.
Crossing, especially at an angle close to 90deg will generate little crosstalk. Only running parallel is an issue. If you can hold the wires further apart and check whether it's gone or better. As there's more than supply in the harness something could be injected in a far more sensitive signal wire.

 

[Joepapar]

They do not share any "ground" or supply wires. I'm going to get behind the front panel and make sure they are completely separated back there. While I'm on the lake this weekend I'll be able to play around with the front deck harness configuration and see if any changes occur.

 

[kjsAZ]

sound good! These types of problems are always a bit difficult to track down once the major issues are taken care off (like joint wiring). Most likely you have to play around quite a bit to find the source of the issue.

 

[Barnacle_Bill]

Make sure you are getting power for the unit from your starting battery and not the trolling motor's battery. Here is another popular fix (see The #1 fix) http://www.biggeorgiaspots.com/boat...her-stuff/180-aaargh-sonar-noise.html?start=6

 

[Joepapar]

I'm getting power from the cranking battery, not the trolling batteries. I also noticed today that I'm getting interference on both the hds 5 and 9 up front but only with the structure scan. The sonar doesn't appear to be showing interference.

 

[kjsAZ]

Strange.... That means it's something which interferes only with the signal from the structure scan sounder. Could it be that the switching frequency of your trolling motor controller is a sub-harmonic of the structure scan sounder? Really far fetched, I know.

I know that you shouldn't do this so only do it for a very (VERY) short time: pull your trolling motor out of the water and check whether the interference gets less.

 

[Joepapar]

I tried that. The interference appears to be the same when I run the trolling motor out of the water.

 

[Joepapar]

I wonder if it would help for me to run the shielded wire right up to within a couple of inches of the power plug. Right now I have about a foot and a half of the supplied power cord leading into the shielded cord. Could the interference be getting picked up there or is it getting picked up directly through the unit itself? Both units are networked through Ethernet and NMEA2k as well.

 

[dingbat]

Where is the transducer mounted? Unhook the transducer from the unit and see if the screen clears up. If it does, it EMI off the motors pulse width modulator. A ferrite on the HDS power cord should get rid of the problem Another check.... Check continuity between TM ground wire and the negative terminal of the battery. Should have continuity. Any resistance is a faulty ground.

 

[Joepapar]

The structure scan transducer is mounted on the transom and is plugged into the structure scan box that is mounted in the starboard front rod box.

 

[Joepapar]

Sorry guys, brain fart. When all three units showed interference with the structure scan from the TM the light clicked on the old memory and I remembered that I took the system off the crankin battery and moved it to the trolling batteries because I was running the crank down if I had two units and the structure scan on for a period of time. Sorry about that. It just slipped my mind that I moved it. Which, I guess leads to another question. Is there any way to install a filter that would allow me to keep the electronics on the deep cycle batteries?

 

[Barnacle_Bill]

There should never be any electronics on the trolling motor battery. Every time you step on the TM's go button there is a surge on that line. Electronics do not like surges as it tends to let all the smoke out of them and they won't work any more. Did you read the #1 fix in the link I gave earlier?

 

[Joepapar]

Yeah, interference goes away when hooked back to the crank battery. Just tryin to figure out a way to run electronics without the risk of draining the crank. I really don't want to add a four battery for electronics.

 

[Joepapar]

Yeah, interference goes away when system is hooked back to the crank battery. Just trying to figure out a way to avoid running the crank down when I've got electronics running for long stretches of time and I really wanted to avoid adding a fourth battery.

 

[Joepapar]

Problem solved. I went ahead and installed another deep cycle battery exclusively for the electronics. Hopefully, I'm good to go. Thanks for all of the suggestions and help.

 

[Joepapar]

OK, here we go again. The interference problem has resurfaced. Running a 2008 ranger 188. I have a lowrance gen 2 hds 5 and 8 and a 9 touch. All connected to structure scan box in the starboard rod locker. All power goes through a fuse box in the same rod locker and power from the fuse box is running through shielded wire and off of a separate battery. I had this problem before I ran the system off of a stand alone battery but once I ran a stand alone, the problem disappeared for a season. Last year the problem seemed to resurface. I'm running the 5 and 9 on the bow and when I hit the foot pedal on the trolling motor, interference shows vertically on the screens until I take my foot off the pedal. Can't figure out why the problem resurfaced but I'd like to figure it out before the first tournament of the year. All are connected through NMEA as well. Thanks.

 

[sam am I]

So a year and little over half ago..............hmmm. What has change in your setup in that time? Nothing? Just the noise came back with no system changes/additions what so ever?

If that's the case then the "age" of things has then to do with it I'd guess.......i'd then guess loosening and/or corroded electrical connections/grounds.

Perhaps brushes in the motor just wearing and getting "sparkier"....that's a real word? http://www.collinsdictionary.com/dic...glish/sparkier

With perhaps sparkier brushes emitting more RF, maybe your loosing a filter/bypass cap/s in the TM as well.

Probably check for loose/corroded ground/s tho first...go from there.

If you've been adding things....time to back-up/disconnect a piece at a time in the order you've added until the noise stops....

Did you save "Restore" points?...................J/K. If only life had restore points, the late 70's, early 80's weren't too bad cept I'd have the munchies already