A detailed analysis of the ferrimagnetic ground state of Mn3Si2Te6has been performed using inelastic neutron scattering. Although the proposed valence of the nominal Mn2+ ions would have quenched orbital angular momentum, a significant exchange anisotropy exists in Mn3Si2Te6. This apparent exchange anisotropy is a manifestation of a weak spin-orbit coupling in the layered material. We employ a detailed simulation of the spin-wave spectrum coupling traditional refinement of dispersion parameters to image analysis techniques, while including Monte Carlo simulations of the instrumental resolution to accurately identify the exchange couplings to the third nearest neighbor. An independent validation of our results is made by comparing our final Hamiltonian to heat capacity measurements.