  For orthogonal polynomials defined by compact Jacobi matrix with exponential
decay of the coefficients, precise properties of orthogonality measure is
determined. This allows showing uniform boundedness of partial sums of
orthogonal expansions with respect to $L^\infty$ norm, which generalize
analogous results obtained for little $q$-Legendre, little $q$-Jacobi and
little $q$-Laguerre polynomials, by the authors.
