I once saw a Fisher F4 metal detector at a friend's. And he says that the keys on the panel are pressed badly. We took it apart and looked at it. As it turns out, hiking in the rain does the trick. Water got into the membrane and the keys slowly stop working.

It was possible to restore everything according to the collective farm, but we decided to make it more difficult. Especially considering what to buy new or not very used. almost impossible.

Schematic diagram of the Fisher F4 metal detector control buttons.

The board was originally planned in the form of a front cover. But during the development process, it became clear that measurements and transfer to DipTrace would take a very long time, thanks to the rounded corners. We decided to simplify everything as much as possible.

Fisher F4 buttons circuit board.

All project source files can be found on the project page https://tehnopage.ru/plata-knopok-fisher-f4.