problem with depth finder

[IA4PATS]

I have a brand new 859 ci hooked up to a brand new Terrova. But the depth is jumping all over the place. Any thoughts?

[gunner55]

1st thing I would check is where the transducer plugs into the back of the unit.

[IA4PATS]

I keep trying that, but doesn't help

[tunrevir]

If it only happens when the trolling motor is turned on then it is electrical interference and there are cables that can be purchsed to reduce the interference.

 

Tunrevir~

[Chris Haley]

Here are a few suggestions from Minn Kota:

Step 1. Confirm the number of sonar units mounted on the boat – If more than one sonar unit (Humminbird or any other brand), are both units running sonar at the same time? If the answer is yes, turn the sonar off of the unit that is not on their trolling motor. Does this solve the problem? If yes, this is sonar to sonar interference. There is nothing that can be done about this other than to only run one sonar unit at a time. Some models/software versions have the ability to tap the power button and a screen will pop up showing Sonar, Light and Background Menus. From the Sonar menu, you can turn Sonar off by using your left cursor button. When you are ready to turn the sonar back on you just tap the power button and right cursor to turn it back on. If the answer to either of the above questions is no, then please continue to Step 2.
Step 2. Update Software, Adjust Filter Settings - Always make sure that you have the most up to date software installed in your Humminbird depth finder. Go to www.humminbird.com to login and download the software for your depth finder. You can also try adjusting your depth finders Noise Filter to attempt to decrease the interference, adjusting the Sensitivity may also help. If you have more than one transducer make sure only one is in use. Using two transducers at the same time could cause interference.
Step 3. Check US2 Fuse and Connections - Check the connections on the Universal Sonar 2 Adapter Cable (MKR-US2-8) connecting the trolling motor transducer cable to the depth finder. There is also a transducer cable connection located in the control box under the top cover. Even though the two ends are connected, they MUST be screwed tightly together to eliminate interference. Ensure that the knurled ends are tight. US2 models also have a brown ground wire with a mini 3 amp fuse, if this fuse is blown then this could be the cause of the interference. The fuse should be tested with a digital V.O.M. Replace the fuse, if needed and retest.

installed fused ground wire.   Note: If this fuse is blown, a circuit loop is being completed through the ground wire. This indicates that an improper power connection is being made to either the motor or depth finder. This improper connection must be located and corrected to prevent a circuit loop and further interference issues.

Step 4. Check wiring - Make sure the deep cycle/trolling motor batteries are not linked to the Cranking Battery. Disconnect chargers, Perko switches, and anything else that may link the two sets of batteries. Try to keep the depth finder power cable away from the trolling motor power cable when rigging. It is also recommended that the excess length of power and transducer cables not be coiled. If you find that interference is still present then you might try using a separate small 12 volt battery to power the depth finder and retest.
Step 5. *Add Chokes - If the interference is still present then you may need to add the Humminbird PC-11 Power Cable (if it did not come with your unit) and the US2 Ferrite Ring (470085-1). If your trolling motor is a PowerDrive V2 or Terrova model you can also add the Ferrite Bead (2887313) to the positive and negative motor output leads on the coil cord closest to the control board. *All 2013 Terrova and PowerDrive V2 models will include a factory installed Ferrite Bead.  All Humminbird Side Imaging units have come with the PC 11 for several years and most Down Imaging units are being packed with the cable as of March 1, 2013. 

[Rick]

I have a brand new 859 ci hooked up to a brand new Terrova. But the depth is jumping all over the place. Any thoughts?

​I noticed that you didn't 'Like this' on any of the answers? Why not?