Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

Just istalled a brand new Minn-Kota terrova and connected my 2008 Humminbird 747c with M-K adapter cable. Easy installation and what a fantastic TM. But the bow sonar is picking up motor noise. Sonar is on engine battery and TM is on separate TM power system, 24 vdc, but the wires do come out of the same boat cable pipe. M-K tech support said I probably need to reroute the cables on separate sides of boat. Probably right but not exteremly practical and may not work anyway. When asked if they had a filter they said Humminbird had a filter and they do (called a choke) but it costs over $90.

Its on a Lowe 175FM 2008 model. Thought it would be good idea to get a wiring diagram and see if the low amperage sonar cable could be replaced with shielded wire instead of the high current TM wire. Anyone know where I can get one? By the way my Motor Guide W55 did not make noise on the sonar but the transducer was on the transom. The console sonar, a Lorance HDS5 did not pick up any noise but may have better rejection capability.

Anyone think shielded wire might help or have an idea on a low cost radio shack type filter ie a capacitor and/or diode acroos the line?

Thanks for any ideas.

Re: Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

1st off chasing noise issues can be allot of "fun".

It's not clear to me what you want to try with the cables.

I'd try to prove the noise was coming in on the us2 or not. Leave everything as it is. Unplug us2 at the back of the unit. Any noise still? If yes, noise is probably coming in on power cable. Try a PC11 power cable.

If no noise, temp connect your original 747 transducer. Hang it off transom. If noise, could still be coming in power lead, Try running trans cable away from any wiring from your trolling motor. If the level of the noise changes or goes away, it is being picked up on transducer cable.

If no noise when hanging off transom, try close to the trolling motor. If no noise, I'd push MK more for a solution. ie, it is likely that its coming in on the us2 and its all internal to the TM. If you do get noise when close to trolling motor, it will start to get more interesting.

The HB noise kit consists of a PC11 power cable and a wirewound choke that is to be in the power side of the trolling motor. The PC11 can be purchased seperatly for $20.

Re: Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

I have talked to the local warranty shop for Minn-Kota and all they offered was the expensive choke. The MK tech-rep on the phone immediately said the power wires in the boat were too close together and it was coming from there. That's where I am on this tonight.

Humminbird tech support sent me an email with instructions on how to go several menus deep and change the built in noise filter. Didn't make any difference to the noise levels.

I did buy an interesting kit from Cabela's this afternoon that has a battery holder and a computer interface cable to download updated software to the sonar unit. I realized when I opened the package that I may be able to run the HB sonar off that battery pack which would mayby give me a check on whether the noise was from MK US2 or the boat wiring. The battery pack holds 8 AA batteries (~12 vdc) and its purpose is to be able to take the sonar unit to the computer to connect the pc cable for the SW download.

In the morning I will do the following:
1. disconnect the US2 and run motor to see if noise is present
2. connect the original transducer located on transom to see if noise is present
3. disconnect power from engine battery and hook up the battery pack to see if noise is present on both original and US2 transducers
4. try to trace where the wires from the bow go. Seems to be a rats nest up front where about all I can do is reach into a blind compartment and try to trace where they all go into the wire harness conduit going back. I found 4 wires that had crimped connectors, 2 the wires coming out of the crimped splice had been cut and at least 1 just had a crimped spice on the end of the wire with no wire coming out. The latter may have been added by boat mfg. that were not used when the dealer configured the boat with the sonar. I know there should be power wires to the sonar, to the trolling motor and to the navigation lights. I guess the boat factory had put some wires in and maybe the previous owner had changed sonars or?? There was a lot of slack wire but I didn't have the time or lighting to get back under the panel at the bow to sort them out.

Thanks John for you ideas. I'll keep you posted on the outcome of my trouble shooting. I also have sent HB service an email and asked for more ideas.

Re: Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

Go to radio shack and get the ferrite snap chokes. They come in different sizes to match the wire diameter.
http://www.radioshack.com/product/index.jsp?productId=3012599

Re: Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

Tried the RadioShack ferrite filters with no change. With the holidays and fishing as ofter as I can I haven't had much time to continue troubleshooting.

I did run continuity checks on the batteries, i.e. are they connected to eachother. The trolling motor batteries, 2 configured for 24 volts, and the cranking battery are not connected. The cranking battery is connected to the boat ground and I think that is probably via the motor wiring because the battery does not go directly to ground (Al boat is grounded via motor). I have made up 2 long wires to run directly from the cranking battery to the sonar on the bow to see if the interference is coming from the power wiring for the TM and sonar being adjacent. They do go down the same cable way at the bow. Trying to figure the boat wiring out. Have started at the fuse panel and chasing the wires to where they all go, accessories, horn, lights etc. . Still have 4 out of 10 fuses to go to finish that process up. So far none go to the sonar but still have 4 to go. Had to stop and go fishing yesterday which was our best day in North Texas since Thanksgiving. Son and family have the boat out today.

I went ahead and bought a Humminbird TMC-1 choke unit but will try to isolate the problem before installing. Don't really like the installation because it has to go 4" from the TM which puts it on the bow deck and has to be screwed down so the quick release mounting plate for the TM is somewhat defeated. I got it from Amazon.com for half the price, $48 incld shipping and no tax, the shop wanted.

Talked again to HB and just got a stock answer to check a fuse in the head of the TM. Before they said the wiring was to close. Not sure why a new unit would have a blown fuse internal to the head but she says it could be. I then talked to MK to make sure that I wouldn't violate the warranty if I opened the head and got some real interest in helping resolve the issue. Not likely the fuse but said I could check it with no problem. Nice guy and actually talked like it could even be caused by a wire in the TM itself but to finish doing my trouble shooting before taking it to the warranty shop to drop the motor unit to check.

Wx in North Texas going to get colder this weekend so will use the time off the lake to continue this saga.

By the way the MK Terrova with iPilot is a great TM. The iPilot spot anchor is really fantastic. I used to get blown off my fishing spot everytime I had to divert my attention to taking the fish off the hook and putting them in the live well. Now with just a push of one button it holds the position until I can get back to navigating the boat. I actually have been less tired after a day of fishing. Hope it is reliable for the long run but am considering buying the mfg's 2 year extended warranty for $139. The MK warranty station recommende it.

Re: Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

I contacted Lowe mfg. and asked them where I could get a wiring diagramn for my Lowe Fishing Machine (FM) 175 boat. Here is their answer:
"We do not have any wiring diag. we buy all our harnesses and the supplier do not have any that are relative to what is neeeded
"
I thought that was somewhat weird answer. How in the heck do they tell the harness mfg. what to build. I wonder how the boat dealers figue it out. I do have a call into Cabelas to see if they can pull up one on the computer. They were busy and couldn't get thorough so may just go by there when I am out in that direction. They are only 4 miles from me. Oh well! To windy in North Texas to go to lake today so will go back to tracing the noise sources.

Re: Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

I have experienced similar problems. I took my Minn Kota into get serviced because I thought that the trolling motor was the problem. I honestly don't even think they looked at it. Instead they told me to go and get the Ferrite chokes which didn't work. They then told me to re-wire my boat and that didn't work. I went back and forth between Minn Kota and Humminbird until they sent me a Humminbird trolling motor choke for free. My system now works. The newer sonar units have the built in chokes.

Re: Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

Ferrite chokes are not going to work for motor noise, they are designed for higher frequency noise than you will get from a motor. Everyone here is right, you will need a wire wound choke. You may be able to find one that will work at Radio Shack that?s made to stop alternator noise in an AM/FM radio. It will handle the current draw of a sonar unit.

Re: Noise On Humminbird Sonar From New Terrova w/Universal Sonr 2

azboater2 said:

Ferrite chokes are not going to work for motor noise, they are designed for higher frequency noise than you will get from a motor. Everyone here is right, you will need a wire wound choke. You may be able to find one that will work at Radio Shack that’s made to stop alternator noise in an AM/FM radio. It will handle the current draw of a sonar unit.

Click to expand...

Strictly speaking, the noise is not traditional "motor" noise (brush noise). It is PWM (Pulse Width Modulation) for "digital" motor speed control. AZboater, as a ham, you may be aware that PWM will have harmonics out the wazoo. That is why the noise from the motor can impact a relatively high frequency sonar system. My 579DI has sonar frequencies ranging from 200KHz to 800KHz (sonar pulse frequency, not ping rate.) These are frequencies that are above the self resonant frequecy of many of those big wire wound chokes. That is why the ferrite chockes may clean up the noise. If this does not make sense to you, don't let it worry you. If you are technically savy, it may be helpful.

TerryMSU