Eagle Fishmark 480 Question

[crothmeier]

I have the above mentioned unit on the bow of my Alumacraft, with the transducer attached to the bottom of my MinnKota AuotPilot trolling motor. While neither of these two pieces of equipment are new, they both have worked will together for 3-4 years now. I use these two primarily lindy rigging and jigging.

A couple of fishing trips ago the locator was working fine until I ran the trolling motor. The screen (to the best of my description) "inverted" to where the display area was black, and the bottom showed as white. it still reads the depth fine, but I cannot see anything where the fish/weeds would show up. If I turn the trolling motor off, the screen returns to normal, showing everything as it should.

My best guess was that there was a break in the transducer wire causing interference when the trolling motor ran. This is only a guess, as I did not stay at a holiday inn express last night.

Does anyone have suggestions? This unit is obsolete now. I've checked the wire for signs of breakage or kinks and cannot find any evidence to support that theory.

[TrollnDrift]

If they are hooked to the same battery I have heard of trolling motors causing interferance. Try isolating the power sources maybe. Would be weird that it just started out of nowhere. Maybe battery connections got dirty?

[delcecchi]

If you remove the transducer from the TM and hang it over the side, does the same thing happen?

[BoxMN]

Are you running it through a universal sonar of the troll motor? It sounds like not. If so, it might be that it is a Universal Sonar 1, which had some problems. We have one, and now have it working with an Elite 5 just fine, but with an older unit we had to use a separate x-ducer.

The other thing it could be, and that we have seen, is when we have the unit either:

1. connected to a troll motor battery instead of the main starting battery. Not good.

2. Connected to the main starting battery, but to an accessory connection rather than direct back to the battery.

Now with all our units we have them connected via its own wiring back to a bus/fuse block right at the battery. So it is direct with no/little potential for electronic interference. We also run the wire as separate from other wiring as we can. We used to get the same thing you are seeing with different units, including the 480.

We have two 480's still working, but one on pontoon with no troll motor, and one on the duckboat with a non-AP troll motor. Good units!

[crothmeier]

It does work separate from the trolling motor, and we are using the specific transducer that was supplied when we bought the unit. Like mentioned it had been working fine for 3-4 years and even earlier this year, which leads me to believe something happened to cause this. I have not tried switching power sources, currently i believe it is hooked to the same batteries as the trolling motor, which is how it was wired when we bought the boat.

[BoxMN]

it is hooked to the same batteries as the trolling motor,

I really do think this is the issue. Even if it was working properly, that might have been luck. Maybe some shielding from the wires wore, or wires moved, or something... Ours would work sometimes and not sometimes until we totally isolated it from the troll motor. Here is what you could try - bring a totally different battery (even garden tractor batt) and hook it up in front of boat and see what happens when you have unit on and turn troll motor on. I bet it will work. That would let you check easily without running lots of wires yet.

What we do now to remove any potential is run that totally separate line (pos and neg) back and it works. You can search forum archives all over, and that is what the suggestions from the electronics guys will tell you. Also to save $$, we just get bulk stranded copper wire from Menards and it works just fine, no need to spend a fortune on Marine stuff. We solder and shrink wrap the connections.

[Pat K]

With age there may be more resistance in the internal wiring of the trolling motor, there may be corroded connections at the battery or in the head of the trolling motot, or it could be an early warning that seals or bearings in the motor are failing and that is causing interference that you didn't have before.

Using a different power source than the trolling batteries is always a good idea.

[crothmeier]

Great information. i'm going to start following wires and make sure where its connected now, and change if needed to see if that works.

I'll report back with my findings.