Bill, I am a “Ham” radio operator and we Hams do this kind of tinkering with all a our equipment. The manufacturers are reluctant to provide the “service data” as it cuts into tbeir repair profits. Such information is usually found by experienced user/technicians and passed on to others through forums such as this. I will attempt to contact Lowrance for this info but doubt that they will provide it.

You folks misunderdtood my request. I should have informed you that I have been using depth finders since the late 60’s and understand how to adjust them according to the manual. What I was requesting was the “service menu” used by technicians in the shop to “tune” the unit for best performance. Most menu driven electronics today has such a menu. It is not normally provided in an owners manual but in a shop/technicians manual. Usually the the menu is accessed by holding in one or two of the units buttons while turning on the unit.

Any help would be appreciated.

Thanks