Sonar intermitently reads way off

[sgrames]

Friends,
I bought a used 191 F&S with an LMS480 on it. When i bought it the 480 worked sometimes, but other times didn't. I assumed it was the angle of the transducer, but it seems to be angled correctly. Since then i sold the 480 unit(switched it onto another boat for the 520C that I had on it and sold that boat), but didn't swap out the tranducer. Now the unit seems to be weak in deep water 80 ft or more, and occasionally locks in on a 2 or 3 ft reading when we are in 60 plus feet of water? Any suggestions? Do I need to get a new transducer?
Thanks for your help,
Stephen

 

[MolarBoater]

I had a similar problem with a 2002 unit and 2002 transducer Garmin/ AirMar. Turned out when I upgraded to a new digital sounder and new transducer, it will sound in 2 foot of water at 30knots. It could be software related, check with the manufacturer's website (my 02 is no longer supported), check all electrical connections to power sources and check the settings on the sounder. Make sure you have a dual frequency transducer and the unit is set to auto.

You may have to trace the transducer cable to make sure it is not damaged or wrapped with other electrical wiring. They do not recommend splicing the transducer line at any point but I have w/o issue. You can increase "scroll speed" which I think increases the frequency of the sounder impulse emitted.

I am sure some others will chime in with similar units as yours.

 

[sgrames]

Sonar issue resolved!

Just to follow-up on this if anyone is reading past history with a similar case. I found the LMS480 uses a dual freq transducer and the C520 does not. Contacted the purchaser of my former boat and he agreed to allow me to switch out the transducers, he gets a better dual freq transducer and I get one that works on my color unit. A little more labor than I originally figured I would have to do, but I now have the units matched with their original transducers and everyone is happy. So if you are swaping units, make sure the transducers are compatible or switch them out also.