I found the same thing while fishing this summer. I had a wide angle LCD graph type unit on my TM that stopped working. I put on a cheap Humminbird with a 20 degree transducer and started seeing fish and my tiny jigs or minnows on the screen. I now have 20 degree units on the back and the trolling motor so I can zero in on those brush tops and fish. I'm using Humminbird Fishfinder 525 units now and really like 'em. High power, easy to use and low cost. $125 at BPS. After all these years I'm finally catching fish with a fishfinder and not just seeing the bottom. Seeya, Don