As far as my brief research shows, Harry Beck came up with his original tube map design in 1931 (which is actually quite different to what we know it as today b

As far as my brief research shows, Harry Beck came up with his original tube map design in 1931 (which is actually quite different to what we know it as today btw), while the first printed circuit board was invented in 1936 by Paul Eisler. Thus while it's possible that Harry Beck was inspired by circuit diagrams, it's surely not possible that he was inspired by (printed) circuit boards.