Topic: 898 display

[FloorBoss]

I installed my 898 on the bow. I was getting feed back from the trolling motor, I called Humminbird they sent me a Ferrite ring, every thing was OK for 3 years now the same problem. When I turn on the trolling motor the depth will roll up to 200 ft and will be all within the top 1/2 inch of the screen, when I turn off the trolling motor after a few minutes it will read correctly. It dosn't matter what speed I have the trolling motor on. I have a 24 volt MotorGuide trolling motor. I have a 20 ft Aluminum boat. I need some adult help, I cannot figure this out. The front of my boat is screwed doen, it takes me about 2 hours to get the screws out to look under the deck. But I can take the deck up again if I need to.

[rnvinc]

The brushes in your TM are wearing over time - which creates a harmonic frequency that the HB is "listening" for  ...

The complete "fix" is to fix the TM brushes  ... But that's not always cost feasible nor easily done  ...

The 1st test should be removing the xducer (and it's cable)  from the TM and inspect it very closely for damage = nicks in the housing, nicks in the cable, cable strain relief cracking  ...

Any damage will allow interference to encroach into the xducer circuit  ...

The 2nd test is to hang the xducer in the water far away from the TM  ...

If the interference goes away = we know definitely the interfence is encroaching into the xducer circuit somewhere  ...

If the interference is still present = the xducer circuit is not even the encroachment Avenue = and the unit power circuit should next be investigated  ...

Rickie

[FloorBoss]

Thank you I will do what you said and see what happens.  Thanks again.