The condition of almost everywhere convergence for a functional series with a weak analogue of the orthonormality property

The almost everywhere convergence condition similar to the Menchoff–Rademacher condition is obtained for functional series with some weak analogue of the orthogonality property. As a corollary, the results of almost everywhere convergence of series with respect to Riesz systems, Hilbert and Bessel systems, and frames are obtained.