Topic: Need HELP

[Sigler]

How do you test for a common ground on a 24 volt system? I have 2 batteries in the back of my boat both have a positive and negative wire going to the front that connect to the female end for the trolling motor. I would say that is were it crosses over to 24 volt at the female connector. (There is NO jumper wire from one battery to the other) Humminbird sent me a power cable with a filter and I'm still having problems. It has to be something to do with the transducer  mounted to the trolling motor because when I take it of the TM it doesn't do it and I am not running down the steering cable either. Someone can even call me 618-923-0362. I'm about to pull me hair out! PLEASE HELP!!!!

[stillbear]

Sigler I called you on the phone.After you finish the proper wiring we talked about here is some more information for you.I may have come up with a fix for my 898! My motor is a Motorguide tour 782v 2001 model witch isn't a digital model.It has the speed contol in the head of the unit, I tried rubber between the transducer with little results if any. I then grounded the neg wire at the motor head, this resulted in a 50% reduction of interference. I then grounded the green (ground) wire going to the motor, this also resulted in a 50% reduction in interference. I then grounded the green wire and the neg. wire to the head of the motor and wala!!!!!! no interference!!!!!! I installed a jumper wire between the green and black wires and i then took fuse holder (3 ampe) and put one end of the wire to neg. wire and grounded the other end to an unused screw hole inside the units head just for safeties sake. Haven't tried it out on the water yet but it works great in the garage!!!!! 

[Sigler]

Stillbear I dont no how to thank you I did what you said on that TM and it is now 24v and no problem with the 788 graph. THANK YOU THANK YOU THANK YOU

[sonar2000]

Good job with your help Gary...
Ground is often over looked but it is still a path for current. We are just so used to measuring the positive side we sometimes over look the ground part of the circuit.
If the ground connection has any resistance then it becomes part of the positive current path.
Any wire that is not connected at both ends is a collector of energy that is inducted into it. (like your green wire)
Something I do on difficult problems is to move the positive meter lead to the positive source and measure backwards with the ground lead. Amazing what you will find.
We deal in such low current amounts in electronics these days that any little influence  (as in a spike or ripple) is misunderstood by the device and it goes funny..
Great work on getting to the root of the problem and especially the help to Sigler.

Chuck

[stillbear]

Thanks Sonar I was glad I could help Sigler out. Gary