Lost sonar at 600 or so feet??

[Banyan Wren]

Hey guys. First post.

Hoping someone has a clue on this one. Have a 165T/265LH-PM488 pocket transducer on a twin tzt3 system with scx20 and dff3d. Headed out to chase swords the other day and sonar stopped working (screen just displayed vertical bands of repeated gibberish noise) about 600 feet deep. Tried low and high frequency. Tried both units. Tried turning off and restarting. No dice until I came back in to 600 or so feet. Then it went back to working as normal.

Ideas?

 

[Banyan Wren]

Here's a pic of what I was looking at. (Sorry it's a little blurry--was running at night) Depth readout was jumping all over the place from a couple feet up to 4000 feet and everywhere in between.

 

[Johnny Electron]

Yeah, more than a bit blurry. Is that a Cat or Dog? (can't tell)
What unit are you attempting to look at here? Are you using the internal sounder or the DFF3D?
The normal part of that transducer connecting directly to the MFD or a DFF1-UHD?
It almosts looks as if someone has the sounder source setup for an MFD that doesn't have a transducer connected at all. At the top of the fish finder settings is a SOURCE that should be setup for the correct MFD that has the transducer or the DFF1-UHD external sounder. To really have an idea what is happening a few more (good) photos would be needed with a few more details of the setup. If this was looking normal and then starts jumping depth it is most likely setup for AUTO range and turbulence has set the fish finder off on a wild goose chase.