Humminbird 757 problems

My Humminbird 757 starts the day out working just great it seems like, then it suddenly starts working erratically by going from say the 15 foot of water we are in to showing that we are in 87 then 42 the 26 foot of water and the screen changes with it for a bottom. It is hooked to my transducer in my Terrova and it clicks. I tried to factory default setting to see if that would help but it didn't. Is it time just to get a new 959 DI so that I can network it with my 898 and then get it hooked into my I pilot link.

These units do some funny things with low power supply...

I would start by load testing the battery and checking all wire connections for corrosion...including the fuse and fuse holder...

Also some older software versions had some depth problems...what version of software is in the unit...??

Rickie

Its a brand new battery, newest software version, and I think connection are all good, thats the reason Im stumped.

It probably has something to do with that Carp being in your boat

it aint a carp its a buffalo

Do you still have the original xducer you can test with ...to eliminate the possibility that the US2 is malfunctioning ...??

Rickie

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Originally Posted by rnvinc

Do you still have the original xducer you can test with ...to eliminate the possibility that the US2 is malfunctioning ...??

Rickie

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Yes I do, I thought about doing that but kind of a pain with the terrova, I guess I could let someone take it out that had the same mount to see if it would work

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Originally Posted by clfarms1

Yes I do, I thought about doing that but kind of a pain with the terrova, I guess I could let someone take it out that had the same mount to see if it would work

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You don't even have to mount the stock xducer for testing...

Just plug it in to the unit and drop it over the side...with the face of the xducer pointing down of course...

If the depth readout never fluctuates like your OP issue...this will help determine if the US2 in the Terrova might be the problem...

Rickie

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Originally Posted by clfarms1

My Humminbird 757 starts the day out working just great it seems like, then it suddenly starts working erratically by going from say the 15 foot of water we are in to showing that we are in 87 then 42 the 26 foot of water and the screen changes with it for a bottom. It is hooked to my transducer in my Terrova and it clicks. I tried to factory default setting to see if that would help but it didn't. Is it time just to get a new 959 DI so that I can network it with my 898 and then get it hooked into my I pilot link.

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If it happened later in the trip how was your voltage to the locator? Low voltage will do wierd stuff. You say you are using the US2 in the terrova? Do you have a different 2d you can use to test with. Hook up a different transducer and simply hang it over board in the water. Does this clear up the problem? Listen closely to both transducers. Are both or one of them pinging erratically. Fast slow fast slow?? If so the 757 is struggling to find bottom. If both transducers are doing this check the connections. If the connections are clean and proper then I would reset defaults and see if it calms down. If it does, reset the the individual settings and hope it keeps chugging. If one individual setting adjustment make the locator go crazy note that setting. If all this fails call humminbird. If they are convinced it needs sent in. There is a flat rate for repair. It should be less then a new 959 locator but then you are still not networked. That will be your decision to make. I would hope to the get the 757 up and running and sell it to help pay for the 959 you are wanting.
Good luck. nice fish in Granada!!!

This didn’t only happen when the 898 unit or the trolling motor was on did it? If so you could be seeing sonar cross-talk from the 898 unit or RF interference from the trolling motor.

Try testing your 757 unit on your 898’s transducer. It will use the 2D sonar part of the transducer which is what you need for the test.

I never know when it is going to happen, It is mostly likely to happen after it has been on 3 or 4 hours. Its kind of tough to change all that wiring out on the boat, but It can be done I know.

Don’t change the wiring out; just take the connectors out of the connector collector of the 898 unit and plug them into the back of the 787 unit by hand and test it that way.