We report on the magnetic effects induced by the substitution of Mn2+ ions in the quasi-one-dimensional Heisenberg-like antiferromagnetcompound (CH3)2NH3MnCl3.2H2O bynon-magnetic Cd2+ and magnetic Cu2+ ions. In theundiluted compound three-dimensional ordering of the linear chains occurs atTN = 6.36 K. In the diluted samples we observe the appearance of aferromagnetic magnetization below TN when the samples are cooled in smallaxial magnetic fields applied along the axis of antiferromagnetic alignment.At the lowest temperatures this magnetization is five times larger in the Cddiluted sample than in the Cu diluted one. Above TN the susceptibility ofboth diluted samples shows an excess of magnetization with respect to that ofthe pure system. It is suggested that the uncompensated magnetic moments atthe end of the `magnetically broken' chains are responsible for thisbehaviour. It is also suggested that some of these `free' paramagnetic endscan couple ferromagnetically at TN, giving rise to the observedferromagnetic component. The temperature dependence of the ferromagneticmagnetization of both samples is identical, indicating a common mechanism. Theshape of this T-dependence suggests that the ferromagnetic correlations alsohave a low dimensional character.