Lowrance 7TI losing the bottom-please help

[startingover]

I've done some research but hoping one of you has more concrete info than what I am finding. My 7TI unit runs fine for a while and then suddenly shows the depth at 1-5 feet. I know it has something to do with the big motor. The motor is a 1989 300hp Johnson. I've got the transducer as far over as I can get it. When it loses track, I can shut off the 300 and wait a few minutes and sonar will start working again. I then start the motor and sonar runs accurately for anywhere from 10 minutes to 30 minutes but it will eventually lose the bottom again. I shut the 300 off, it starts to read correct after a few minutes and the cycle starts over. I thought it might be because I had the power to the 7TI on the same battery as the 300 and as the motor runs there were voltage fluctuations on the battery so I bought another battery and have it dedicated to the sonar. Still have the same issue. Where the transducer goes through the back of the boat it looked like the transducer cable might be touching the power cables to the 300 so I put some thick pipe insulation around it so they cannot touch. I'm still convinced that the transducer cable is too close to a power cable somewhere but before I started digging into that I just wanted to see if you guys think I'm on the right track. Since it's an older boat, they didn't have the foresight to make running cables easy so you can't readily even see them. I had a *&& of a time even getting them run. Also, I did not have this problem at all last year. Just convinces me cables have settled together somewhere.

Am I on the right track? Should I be doing something else? It's not a show stopper but having the shut down the motor so often and wait for the sonar to pick back up is a PAIN!

Thanks!

[johnr]

Interesting you can relate it to the motor. My lowrance does the same thing with the 1-5’ depth reading, but it seems to have no external cause. I too thought it was voltage related, but haven’t been able to isolate and eliminate the problem. I just live with it.

[hilljack198]

First thing I would try is to update the unit to the latest software. Sounds stupid but it actually does take care of alot of problems. I started having trouble getting interference out of my trolling motor once and it just came out of the blue, I updated it and that took care of it. I won't say its a definite no but as far as electrical interference with your big motor (especially that age) while its running is doubtful again not saying it is not. I would pull up the screen to watch the volts on the Lowrance, run it and see if it drops or spikes when you loose bottom that may give you an idea of weather or not its electrical or not. It also could be the transducer? Oh and make sure you have the right one selected also that can cause funny problems too

[startingover]

JohnR, That was NOT the answer I was hoping for . But at least I'm not alone and feel a little less dumb!

Hilljack. I'll check the software update, good idea. My unit is less than 2 years old but may still have an update.

Transducer setting is good, Unit now on a dedicated battery under the console right under the unit with no other wires attached (or even near). I agree, transducer makes more sense than big motor, but for the last 3 weekends as soon as it starts acting up I shut off the big motor and it comes back within minutes (sometimes seconds). I can use the trolling motor all day and have no issues until I start the big motor up again. This is my 5th boat with electronics and have never seen this before.

I moved the transducer and the wires as far as I can get from everything else. I'll see how it does this weekend.

Any other ideas or history with this is appreciated!

Thanks!

[startingover]

After everything I did...I went to the lake Saturday and still had the same issue

I read last week you can do a "soft reboot" on Lowrance units and it can solve a lot of issues- like rebooting a computer. Most of you more experienced guys probably already know about this, I didn't. Lowrance units don't act like computers, they don't automatically reboot each time you re-start them, they just turn on where they left off.

For those of you that do not know about this, do a soft reboot (won't hurt to do it once a year to tidy things up). Turn your unit off, wait a minute, press the menu (top) button and hold it while pressing the "on" (bottom) button, continue to hold the top button until you hear the unit beep, release the top button. It will then restart and ask a couple of setup questions. It does not seem to lose any of your data.

VIOLA!!!! Problem went away!  AND with all the other things I did, I get pretty good readings up to about 30mph!

Hope this helps somebody else!