Topic: wierd depth screens

[jimmythegreek]

I dont have a pic but basically when Im using my terrova ipilot to lock onto a spot (other times also do it rarely) my 998SI will do wierd bottom views.  It will usually show correct depth but it like triples the sonar view on top of eachother on the screen then goes to double then back to the right whole screen view.  it basically shrinks the image to 1/3 height of screen and triples it then doubles it then back to single correct screen size.  I use split screen alot w 2d on the left and GPS map on right to hold my waypoints using the GPS on the terrova TM.  The ducer is on the back of the boat.  It does it alot in 20-30 FOW and I went in and manually set it to 30, 40 50ft max and didnt make a difference.  any ideas?

[ITGEEK]

Electrical interference.

[Humminbird_Greg]

Yep, sounds like trolling motor interference.  You can go to the Humminbird web site and look at some possible fixes there but your best bet may be to just call the Humminbird Customer Resource folks and see what they suggest.  Just be aware that what works for one boat may not work for your boat so you may have to try several things before you get it to stop interfering or it may be eliminated with the first fix.
http://www.humminbird.com/FAQ.aspx?ContentId=1849

[jimmythegreek]

i had issues w my terrova when the 998 was first installed.  They sent me the choke that I installed and didnt help.  I found info that suggested removing the head and checking the ground fuse.  It was a mini 3amp and was blown, replaced that and its perfect since w the SI. I have the noise turned up and this is the only issue I have since, I havent really watched it to see if the depth readings go crazy right before it happens