Question for Humminbird Greg or anyone else that might have encountered this

[maachuu]

I have a 798c HB (down image & side image) that everything seems to work but the down image part, the bottom readout is very very light and sometime you can even see anything but a black screen, dont show any structure of fish or anything at times. The side image works as it suppose to, I mean I can see it and see structure and fish. The regular sonar part that is color works fine just the down image part seems to have a problem. I have this mounted on a Terrova w/iPilot if that matters Im not sure, also forgot to mention that when I go to the simulator the Down Image looks fine ??

thanks

maachuu

[vic n]

Was it this way out of the box, or did it work ever? When I have these types of problems, I "restore default settings" and start all over. If you can't get any image with factory settings, my guess would be the transducer, but as Greg suggested in another thread, take your head and plug into another boat with SI and see if it gets an image.

[Humminbird_Greg]

maachuu,
If the Si sonar is fine thna the Down Imaging sonar should be fine. This is bacause the unit takes the Si sonar and displays it as the Di sonar - there is no separate transducer beam for the Di sonar in your 798 unit. So I would do as vic n suggested and reset the menus and start again. It would not hurt to make sure that the software is up to date as well.

[maachuu]

maachuu,
If the Si sonar is fine thna the Down Imaging sonar should be fine. This is bacause the unit takes the Si sonar and displays it as the Di sonar - there is no separate transducer beam for the Di sonar in your 798 unit. So I would do as vic n suggested and reset the menus and start again. It would not hurt to make sure that the software is up to date as well.

Greg, used the unit today, did notice that the DI was working better but still would be come very light on the bottom, like it wasnt getting a good bounce back of the signal, at the same time I would see the sonar part change the lines showing on the bottom, you have the first line and the it will change colors under the sonar line to indicate what type of bottom you are coming over if I remember correctly. well I would see the sonar drop all the bottom reading except at the very start of the bottom, no other colors would be below it to indicate what type of bottom it was, at that same time the DI would become very faint on the bottom also, I tried blue and both ambers and for awhile it would work fine and then it would start fading away. I also checked the SI and it to would kinda wash out, fade to the point of the screen being black. I have put the old s/w back on the unit and that is what I have on it now, dont know that the new would make a difference since I noticed this before when I had the latest s/w loaded on the unit.

thanks

Larry

[Humminbird_Greg]

Larry,
It is starting to sound more like you are either moving over a very soft bottom type (as the sonar is reflecting back less sonar) or that the unit is losing its overall sensitivity. This could be due to a low input voltage or possibly something starting to fail in the unit or transducer. Check the input voltage that can be displayed on your unit as well as all electrical connections between it and the battery it is powered from. No loose or dirty (corroded) connections – even in the fuse holder. I would also try testing another Humminbird Si unit on your boat to see if the same thing happens or not and/or testing your unit on someone else’s boat that runs a Humminbird SI unit. Does not have to be another 798 unit owner as any of the Si units will work for this test. Just plug in only the power and transducer for the testing.

[maachuu]

Larry,
It is starting to sound more like you are either moving over a very soft bottom type (as the sonar is reflecting back less sonar) or that the unit is losing its overall sensitivity. This could be due to a low input voltage or possibly something starting to fail in the unit or transducer. Check the input voltage that can be displayed on your unit as well as all electrical connections between it and the battery it is powered from. No loose or dirty (corroded) connections – even in the fuse holder. I would also try testing another Humminbird Si unit on your boat to see if the same thing happens or not and/or testing your unit on someone else’s boat that runs a Humminbird SI unit. Does not have to be another 798 unit owner as any of the Si units will work for this test. Just plug in only the power and transducer for the testing.

Thanks Greg, will start by checking the connections to the battery and work from there

thanks

Larry